AGILITY SKILL EXECUTION
IN
RUGBY UNION
© Copyright
AGILITY SKILL EXECUTION
IN
RUGBY UNION
KEANE WHEELER
BAPPSC(HONS)
FACULTY
U
OF
SCIENCE, HEALTH
N I V E R S I T Y
O F
J
T H E
U N E
S
AND
EDUCATION
U N S H I N E
C
O A S T
2 0 0 9
Thesis submitted in fulfillment of the degree
Doctor of Philosophy at the University of the Sunshine Coast.
KEYWORDS
Biomechanics
Performance analysis
Kinematic analysis
Running technique
Change of direction
Cutting
Side-step
v
ABSTRACT
Agility is the complex skill of rapid multidirectional movement incorporating variations
to velocity and the manipulation of momentum. Agility skill execution is a
feature of open skilled sports such as rugby union, and represents a fundamental
component of successful performance. This project investigated agility skill execution
during attacking ball carries in rugby union. The ability to outmanoeuvre
defensive opponents through the expression of superior evasive strategies (agility)
contributes
an
important
determinant
to
the
success
of
attacking
ball
carries and overall team success in rugby union. Despite this, the technical
proficiency
of
agility
skill
execution
and
the
mechanisms
associated
with performance enhancement are understood poorly within the scientific
community and functional coaching environments. This is highlighted where the
published research examining agility has been confounded typically by poor
methodological approaches and operational definitions of performance.
The current project examined the determinants of agility skill execution specific
to rugby union. This project incorporated a series of distinct phases through notational
and kinematic analyses. Notational analysis demonstrated that evasive agility skill
execution lead to tackle-breaks, which subsequently promoted try scoring opportunities
and overall team success. It was demonstrated that the ability of the attacking ball
carrier to receive the ball at high running speed, combined with a side-step 1 to 2 body
lengths from the defence at an angle between 20° and 60°, then followed by a
straightening of the running line at 20° to 60° was associated with tackle-breaks. In
addition, isolating a defender meant that poor defensive positions were more likely, and
as a result the attacking ball carrier had an increased probability of achieving a tacklebreak.
Kinematic analysis demonstrated that enhanced agility performance speeds often
presented contraindications to effective running ability in rugby union. Greater lateral
movement during the initial side-step was associated with faster agility performance
speeds, but this was associated also with greater residual lateral movement acting to
diminish movement control following direction change. Enhanced agility performance
speeds were achieved also with greater periods of flight during the transition from initial
vi
side-step direction change to straightening the running line. It was found that the
inclusion of a decision-making element in agility testing restricted the development of
lateral movement during the initial side-step. In addition, the presence of contact in
agility testing elicited decreases in body height following direction change.
The resistive fend execution was then shown to represent a mechanism to enhance
lateral movement during the initial side-step. It was concluded that agility skill
execution is sports specific and that an intricate relationship exists between the speed
and effectiveness of performance.
The take home message for rugby union coaches from the current project was that
agility training programs must have a clear and direct transfer to the multidirectional
and open skilled nature of performance during match-play. In rugby union, these
training programs should focus on improving running technique so that athletes are
effective in contact and fast over the ground. To improve running ability, coaches
should combine timed efforts with technique assessment during sports specific
situations. To add to this, coaches should analyse match-play performance prior to
developing testing and training programs for any skill (not limited to agility). This must
be done with a specific goal in mind and have clear training implications, such as
examining the movement patterns that players exhibit when breaking the defensive line
during a back-line play. This information can then be used to design drills and games
that replicated sport specific performance within the training environment and will no
doubt result in a greater transfer of training to game activities.
vii
CERTIFICATE OF AUTHORSHIP
I, Keane Wheeler certify that I am the sole author of the thesis submitted
entitled Agility Skill Execution in Rugby Union (ex cept as specificall y
indicated in footnotes, quotations and the reference list) in accordance
with the requirements for a thesis issued b y the Universit y of the
Sunshine Coast Research Degrees Committee.
viii
ACKNOWLEDGEMENTS
I am pleased to take this opportunity to recognise the collective support of those
involved in this project. Firstly, I would like to acknowledge the many things that I have
learnt from my supervisor Mark Sayers. Thanks are also due to my co-supervisor
Chris Askew for his assistance during this project. I also thank the talented group of
athletes who generously volunteered their time and energy for this project.
Thank you to my friends in the post-graduate room and on the rugby field that provided
valuable advice and much entertainment. To my family, I am eternally grateful for the
support that you have always given me, extending well beyond this project.
In particular, the commitment from my parents has provided the strong foundation by
which I could successfully complete this project. I am also deeply grateful for the
encouragement, patience and much love that Neeks offered to me during my studies.
ix
TABLE OF CONTENTS
KEYWORDS ................................................................................................................... V
ABSTRACT....................................................................................................................VI
CERTIFICATE OF AUTHORSHIP............................................................................ VIII
ACKNOWLEDGEMENTS ............................................................................................IX
TABLE OF CONTENTS................................................................................................. X
LIST OF FIGURES ...................................................................................................... XII
LIST OF TABLES ......................................................................................................XVII
GLOSSARY.............................................................................................................. XVIII
ABBREVIATIONS .....................................................................................................XIX
PUBLICATIONS.......................................................................................................... XX
CHAPTER I INTRODUCTION.................................................................................... 1
BACKGROUND .................................................................................................. 1
AIM AND OBJECTIVES..................................................................................... 3
RESEARCH OVERVIEW ................................................................................... 3
CHAPTER II LITERATURE REVIEW...................................................................... 4
OVERVIEW ......................................................................................................... 4
CLASSIFICATION OF AGILITY PERFORMANCE ........................................ 5
PHYSIOLOGICAL REQUIREMENTS OF RUGBY UNION.......................... 15
NOTATIONAL ANALYSIS OF AGILITY PERFORMANCE ........................ 19
AGILITY SKILL EXECUTION AND DYNAMIC STABILITY..................... 28
AGILITY SKILL EXECUTION AND COGNITIVE FUNCTION................... 33
AGILITY PERFORMANCE AND FUNCTIONAL CAPACITIES.................. 38
BIOMECHANICS OF AGILITY SKILL EXECUTION.................................. 67
ASSESSMENT OF AGILITY PERFORMANCE ........................................... 111
CHAPTER III NOTATIONAL ANALYSIS............................................................ 129
INTRODUCTION ............................................................................................ 129
METHODS AND PROCEDURES................................................................... 131
RESULTS ......................................................................................................... 145
DISCUSSION ................................................................................................... 158
x
CHAPTER IV KINEMATIC ANALYSIS ...............................................................174
INTRODUCTION ............................................................................................174
METHODS AND PROCEDURES...................................................................176
RESULTS .........................................................................................................193
DISCUSSION ...................................................................................................243
CHAPTER V CONCLUSION ...................................................................................260
FUTURE DIRECTIONS ..................................................................................261
REFERENCES............................................................................................................263
APPENDICES .............................................................................................................306
APPENDIX A PROCEDURAL DOCUMENTS ............................................307
APPENDIX B SUMMARY OF LOGISTIC REGRESSION..........................312
APPENDIX C INDIVIDUAL SUBJECT CHARACTERISTICS ..................321
APPENDIX D SUMMARY OF MULTIVARIATE ANALYSIS ..................322
xi
LIST OF FIGURES
Figure 2.1: Representation of Chelladurai’s agility skill classification. ........................... 5
Figure 2.2: Representation of Gentile’s continuum of skill classification........................ 6
Figure 2.3: Model of agility performance with emphasis on change of direction
speed and decision-making abilities.......................................................... 7
Figure 2.4: Model of agility performance with the addition of anthropometry as
a key component of change of direction speed. ........................................ 8
Figure 2.5: Model of agility performance with emphasis on dynamic stability in
a sport specific context. ........................................................................... 10
Figure 2.6: Frontal plane representation of a side-stepping strategy in rugby
union........................................................................................................ 13
Figure 2.7: Frontal plane representation of a crossover-stepping strategy in
rugby union.............................................................................................. 13
Figure 2.8: Physiological energy systems relationship with agility performance. ......... 18
Figure 2.9: Sports specific demands as a determinant of agility performance. .............. 20
Figure 2.10: Dynamic stability as a determinant of agility performance........................ 29
Figure 2.11: Cognitive function as a determinant of agility performance. ..................... 34
Figure 2.12: Muscular capacity as a determinant of agility performance....................... 39
Figure 2.15: Representation of the integrated hamstring activation patterns
during the CD stance. .............................................................................. 71
Figure 2.16: Transverse plane representation of the complete agility gait cycle............ 73
Figure 2.17: Transverse plane representation of a single direction change
agility gait cycle. ..................................................................................... 74
Figure 2.18: Sagittal plane representation of PRECD-LDHORZ. ....................................... 76
Figure 2.19: Transverse plane representation of the agility CD phase. .......................... 80
Figure 2.20: Frontal plane representation of CD-LDLAT. ............................................... 82
Figure 2.21: Representation of GRFVERT and GRFHORZ during CD stance. ................... 85
Figure 2.22: Representation of GRFVERT and GRFHORZ during CD stance. ................... 88
xii
Figure 2.23: Representation of GRFVERT and GRFLAT during CD stance. .....................90
Figure 2.24: Representation of knee flexion angles comparing side-stepping
CD stance to the stance phase of straight-line running stance. ...............93
Figure 2.25: Representation of quadricep activation patterns comparing sidestepping CD stance to the stance phase of straight-line running.............94
Figure 2.26: Representation of GRFVERT and GRFHORZ during CD stance from
foot-strike to toe-off. ...............................................................................96
Figure 2.27: Transverse plane representation of the attacking running line
during an agility manoeuvre with a TRANS phase...............................101
Figure 2.28: Transverse plane representation of the attacking running line
during an agility manoeuvre without a TRANS phase..........................101
Figure 2.29: Representation of the sagittal plane ankle angular displacement
during the stance phase of side-shuffle and side-step. ..........................103
Figure 2.30: Frontal plane representation of an athlete displaying double
support during the TRANS phase..........................................................105
Figure 2.31: Frontal plane representation of an athlete in flight during the
TRANS phase........................................................................................105
Figure 2.32: Transverse plane representation of the agility ST phase. .........................107
Figure 2.33: Frontal plane representation of ST-LDLAT. ..............................................108
Figure 2.34: Representation of agility side-stepping tasks involving multiple
changes of direction...............................................................................118
Figure 2.35: Representation of agility side-stepping tasks with a single change
of direction.............................................................................................119
Figure 2.36: Transverse view representation of a shuttle running agility task. ............120
Figure 2.37: Transverse view representation of the 505 agility test. ............................121
Figure 2.38: Transverse view representation of the Illinois agility run. .......................123
Figure 2.39: Transverse view representation of the SEMO agility run. .......................124
Figure 2.40: Transverse view representation of the agility dot-drills...........................125
Figure 2.41: Transverse view representation of the figure of eight agility run.............125
xiii
Figure 2.42: Transverse view representation of the Diamond agility run. ................... 126
Figure 2.43: Transverse view representation of the agility T- test. .............................. 127
Figure 4.1: Distribution of running movement patterns in rugby union....................... 145
Figure 4.2: Representation of the components of match-play and the percent
prediction of tackle-break...................................................................... 151
Figure 4.3: Representation of the components of match-play and the percent
prediction of poor defensive position at contact. .................................. 153
Figure 4.4: Percentage of tackle-breaks with respect to team ranking. ........................ 155
Figure 4.5: Percentage of tackle-breaks with respect to playing position. ................... 156
Figure 4.6: Transverse plane representation of an indirect (lateral) running line......... 162
Figure 4.7: Transverse plane representation of direct and straight running line........... 162
Figure 4.8: Transverse plane representation of direct and inside running line. ............ 162
Figure 4.9: Transverse plane representation of initial direction change sidestepping manoeuvre............................................................................... 164
Figure 4.10: Transverse plane representation of initial direction change and
subsequent straightening side-stepping manoeuvre. ............................. 165
Figure 4.11: Transverse plane representation of agility course design based on
the findings of notational analysis presented in the current study. ....... 171
Figure 5.1: Representation of the biomechanical model achieved by linking the
anatomical landmarks............................................................................ 178
Figure 5.2: Schematic diagram of the agility course design included in
performance assessment procedures. .................................................... 180
Figure 5.3: Representation of the evasive running lines displayed during right
change of direction agility manoeuvres................................................. 184
Figure 5.4: Representation of the evasive running lines displayed during left
change of direction agility manoeuvres................................................. 185
Figure 5.5: Representation of unplanned agility performance trials with the
inclusion of a contact condition ensuing the straighten step. ................ 187
Figure 5.6: Mean performance times recorded for the agility conditions..................... 194
xiv
Figure 5.7: Transverse plane representation of the side-step angle during agility
testing. ...................................................................................................196
Figure 5.8: Relative agility phase percentages with respect to agility condition..........201
Figure 5.9: Relative agility phase percentages during PLAN conditions with
respect to speed group. ..........................................................................203
Figure 5.10: Frontal plane representation of PRECD-LDLAT
(a) slow
performances (b) moderate performances (c) fast performances. .........204
Figure 5.11: Frontal plane representation of POSTCD-LDLAT
(a) slow
performances (b) fast performances. .....................................................206
Figure 5.12: Relative agility phase percentages during UNPLAN conditions
with respect to speed group. ..................................................................207
Figure 5.13: Sagittal plane representation of LDHORZ at PRECD-FS (a) slow
performances (b) fast performances. .....................................................208
Figure 5.14: Transverse plane representation of VELLAT at CD-FS (a) slow
performances (b) fast performances. .....................................................210
Figure 5.15: Transverse plane representation of the CD-FS relative to the
direction
change
line
(a)
slow
performances
(b)
fast
performances. ........................................................................................211
Figure 5.16: Representation of mean lower limb segmental timings during CD
stance (a) Lower limb angular displacement (b) Lower limb
angular velocity. ....................................................................................212
Figure 5.17: Representation of mean lower limb segmental timings during ST
stance (a) Lower limb angular displacement (b) Lower limb
angular velocity. ....................................................................................214
Figure 5.18: Relative agility phase percentages during CONTACT conditions
with respect to speed group. ..................................................................216
Figure 5.19: Representation of the CGVERT oscillations during the TRANS
phase with respect to grouped speed and TRANS steps. ......................219
Figure 5.20: Transverse plane representation of ST-FS relative to the straighten
line (a) slow performances (b) moderate performances (c) fast
performances. ........................................................................................221
xv
Figure 5.21: Relative agility phase percentages during FEND conditions with
respect to speed group. .......................................................................... 223
Figure 5.22: Sagittal plane representation of LDHORZ (a) SLR-FS (b) PRECDFS of PLAN........................................................................................... 227
Figure 2.23: Sagittal plane representation of TDHORZ (a) SLR-TO (b) PRECDTO of PLAN. ......................................................................................... 228
Figure 5.24: Transverse plane representation of LDHORZ and LDLAT (a) SLRFS (b) CD-FS of PLAN......................................................................... 229
Figure 5.25: Transverse plane representation of TDHORZ and TDLAT (a) SLRTO (b) CD-TO of PLAN. ...................................................................... 229
Figure 5.26: Transverse plane representation of LDHORZ and LDLAT (a) SLRFS (b) ST-FS of PLAN.......................................................................... 230
Figure 5.27: Transverse plane representation of TDHORZ and TDLAT (a) SLRTO (b) ST-TO of PLAN. ....................................................................... 231
Figure 5.28: Transverse plane representation of LDHORZ and LDLAT (a) SLRFS (b) POSTCD-FS of PLAN................................................................. 232
Figure 5.29: Transverse plane representation of TDHORZ and TDLAT (a) SLRTO (b) POSTCD-TO of PLAN. .............................................................. 232
Figure 5.30: Sagittal plane representation of LDHORZ (a) PLAN (b) UNPLAN........... 233
Figure 5.31: Transverse plane representation of CD-FS relative to the direction
change line (a) PLAN (b) UNPLAN. .................................................... 235
Figure 5.32: Sagittal plane representation of body position at ST-TO
(a)
UNPLAN (b) CONTACT. .................................................................... 238
Figure 5.33: Sagittal plane representation of body position at POSTCD-TO (a)
UNPLAN (b) CONTACT. .................................................................... 239
Figure 5.34: Representation of TRUNKANT at POSTCD-FS for agility
conditions. ............................................................................................. 242
xvi
LIST OF TABLES
Table 2.1: Summary of the correlation between agility and muscular strength..............41
Table 2.2: Summary of the correlation between agility and measures of
functional power. .....................................................................................51
Table 2.3: Summary of the correlation between agility and drop jumping
power. ......................................................................................................52
Table 2.4: Summary of the correlation between agility and squat jumping
power. ......................................................................................................53
Table 2.5: Summary of the correlation between agility and straight-line running
speed. .......................................................................................................60
Table 4.1: Intra-tester Kappa measurement of agreement. ...........................................132
Table 5.1: Intra-tester TEM and CV reliability scores for randomly selected
landmark raw positions..........................................................................181
Table 5.2: Intra-tester TEM and CV reliability scores for randomly selected
joint angular displacement.....................................................................182
Table 5.3: Independent variables used in analysis ........................................................188
Table 5.4: Dependant variables used in analysis ..........................................................189
Table 5.5: Characteristics of sampled athletes (N = 8) .................................................193
Table 5.6: Performance time (s) with respect to speed grouping for each
condition. ...............................................................................................195
Table 5.7: Side-step distance (m) with respect to speed grouping for each
condition. ...............................................................................................198
Table 5.8: Side-step distance (m) with respect to TRANS steps for each
condition. ...............................................................................................199
Table 5.9: Correlation between %CD phase and %TRANS phase for each
condition. ...............................................................................................200
Table 5.10: Correlation between %ST phase and %TRANS phase for each
condition. ...............................................................................................200
xvii
GLOSSARY
Ability
Performance measured using qualitative descriptions
Backs
Rugby union positional role consisting halves, centres, wingers
and fullbacks
Bilateral
Two sided performance or movement
Capacity
Performance measured using quantitative descriptions
Crossover-step
Step taken sideways by planting the same foot as the intended
change of direction
Effective
Qualitative measures of performance
Efficient
Quantitative measure of performance
Forwards
Rugby union positional role consisting props, hooker, second
row, flankers and number eight
Impulse
Product of force and the time interval over which force acts
Kinematic
Form, pattern or sequencing of movement
Mechanism
Biomechanical execution or technique
Moment
Expression of force creating corresponding torque
Momentum
Quantity of motion of a moving body
Performance
The manner or quality of carrying out an activity
Side-step
Step taken sideways by planting the foot opposite to the
intended change of direction
Sprint
Running performance of maximal effort
Torque
System of forces tending to cause rotation
Unilateral
One-side performance or movement
xviii
ABBREVIATIONS
1RM
One repetition maximum
CD
Change of direction phase
CGVERT
Centre of gravity vertical displacement
FS
Foot-strike
GRFHORZ
Horizontal ground reaction force
GRFVERT
Vertical ground reaction force
LDHORZ
Horizontal landing distance
LDLAT
Lateral landing distance
m.s-1
Metres per second
ml.kg-1.min-1
Milliliters per kilogram per minute
N.kg-1
Newtons per kilogram
POSTCD
Re-acceleration phase
PRECD
Pre-change of direction phase
SAQ
Speed, agility and quickness
ST
Straighten phase
TDHORZ
Horizontal take-off distance
TDLAT
Lateral take-off distance
TO
Toe-off
TRANS
Transition phase
TRUNKANT
Anterior trunk lean angle
VELHORZ
Horizontal linear velocity
VELLAT
Lateral linear velocity
∆
Change in respective measure
°.s-1
Degrees per second
xix
PUBLICATIONS
Wheeler, K. W., Askew, C. D. and Sayers, M. G. L., Effective Attacking Strategies in
Rugby Union. European Journal of Sports Sciences. (in press).
Wheeler, K. W., (2009) Transfer of straight-line speed to agility in rugby union: a
review. Journal of Australian Strength and Conditioning. 17(2): 46 – 50.
Wheeler, K. W., and Sayers, M. G. L., (2009) Contact skills predicting tackle-breaks in
rugby union. International Journal of Sports Science and Coaching. 4(4): 535 – 544
Wheeler, K. W., Askew, C. D. and Sayers M. G. L., Agility Skill Execution in Rugby
Union. Asia Pacific Conference on Biomechanics. University of Christchurch,
Christchurch. 2009
Wheeler, K. W., Askew, C. D. and Sayers, M. G. L., The use of notational analysis to
examine agility skill execution in rugby union. International Association of Sport
Information World Congress. Australian Institute of Sport, Canberra. 2009.
Wheeler, K. W., Askew, C. D. and Sayers, M. G. L., Breaking the tackle in rugby
union. Evolution of the Athlete Conference, University of Queensland, Brisbane, 2008.
xx
CHAPTER I
INTRODUCTION
BACKGROUND
Agility is a complex skill of rapid multidirectional movement incorporating
variations to velocity, and the manipulation of momentum
30, 118, 149, 150, 319
.
It is a crucial component in sports, especially team field sports where movements are
conducted through several planes and where rapid changes of direction are a
feature of performance
63, 340, 348, 349
. The expression of agility skill execution varies
considerably between sports and is dependent on the specific attributes and performance
conditions
16, 118, 291, 329, 370
. The manifestations of agility can include such activities as
vertical jumping in volleyball, change of direction swimming manoeuvres in water polo,
aerobatics in gymnastics and board manoeuvres in snowboarding. Agility is also a vital
skill in team field sports such as rugby union, rugby league and hockey.
This
project
focused
on
agility
skill
execution
as
an
expression
of
side-stepping movement patterns observed in rugby union. Rugby union is a
collision team sport that features an invasive style of competitive match-play with great
emphasis on repeat bouts of high-intensity activity
76,
119,
173,
193,
291,
329
.
The ability to outmanoeuvre opponents through the expression of superior skills such as
agility, is a fundamental component of successful performance in rugby union
193
.
Despite the importance of agility in rugby union, there is a lack of comprehensive
scientific research examining the key determinants of performance
97, 206, 243
. This
paucity of published research has no doubt lead to confusion regarding the specific
requirements of agility skill execution as part of performance in rugby union. This is
evident where running ability is trained commonly using inappropriate models of
performance sourced from athletics and derived from straight-line sprinting 348, 349. This
is an important consideration as previous research has shown little transfer between
straight-line
running
speed
and
agility
1
performance
in
Australian
Rules
AGILITY
football
430
IN RUGBY UNION
.Conversely, the multi-directional nature of rugby union means that athletes
need to display running techniques adapted specifically to meet the requirements of the
sport 348.
Agility is a complex skill consisting of a variety of interrelated mechanisms that
combine physiological capacities, biomechanical abilities and advanced cognitive
strategies
180, 430, 433
. Previous research has demonstrated the complex nature of agility,
whereby physical capacities associated with muscular strength, power and straight-line
running speed have demonstrated limited transfer with performance 214, 228, 249, 285, 370, 430,
432
. Accordingly, it is crucial that agility assessment procedures reflect the
sport specific nature of skill execution. Despite this, the assessment of agility
performance is undertaken frequently using non-specific methods and procedures, such
as conducting testing within an indoor laboratory and assessing performances of low
athletic level participants
13, 57, 90, 96, 141, 142, 154, 188, 238, 239, 246, 250, 273, 284, 300, 302, 325, 397, 432
.
Consequently, research that has examined generic expressions of agility performance
has limited application for sports specific contexts and high performance athletes.
The
published
research
that
has
investigated
agility
performance
has
been confounded often by poor methodological approaches and operational definitions
of performance. Typically, agility testing procedures have assessed performance
through simple quantitative measures, such as the time to completion of an agility task
13, 29, 42, 55, 57, 69, 87, 99, 105, 118, 133, 143, 144, 162, 163, 165, 179, 180, 212, 223, 227, 228, 232, 234, 235, 249, 261, 274,
276, 284, 302, 306, 309, 313, 327, 361, 391, 397, 423, 430, 432, 433
. Measures of agility performance based
on expressions of time fail to acknowledge the quality of skill execution and associated
decision-making strategies
319
. A number of research projects have considered the
biomechanics of agility performance, however, generally these studies have examined
the potential for injury 16, 39, 43, 90, 102, 137, 175, 199, 259, 260, 287, 293, 294, 373. In contrast, there is
an apparent lack of published research examining agility skill execution in relation to
athletic performance enhancement. Consequently, there is a critical need to investigate
the key determinants of agility skill execution within specific sporting contexts, such as
those observed during evasive attacking manoeuvres in rugby union.
2
INTRODUCTION
AIM AND OBJECTIVES
The overall aim of this research project was to examine running based expressions of
lateral side-stepping agility performance during evasive attacking manoeuvres in rugby
union. The objectives were to:
1. Design a valid and reliable notational analysis system relating to attacking ball
carries in rugby union.
2. Determine the contribution of agility skill execution to the outcome of attacking ball
carries in rugby union using notional analysis.
3. Design an appropriate assessment protocol of agility skill execution with respect to
evasive attacking manoeuvres in rugby union.
4. Determine the kinematic determinants of agility skill execution in rugby union.
RESEARCH OVERVIEW
A review of the published scientific literature and associated coaching articles
examining agility performance was conducted to address the objective of this research
project. From this review a notational analysis system was designed to examine agility
skill execution in rugby union. This notational analysis system was used to examine the
movement patterns executed during attacking ball carries observed in high-level
competitive rugby union match-play. The findings of notational analysis formed the
basis for the design of a rugby union specific agility assessment task. Three-dimensional
kinematic analyses were employed to examine agility skill execution observed in a
sample of high-level rugby union players. Kinematic analysis was conducted during
five performance conditions including straight-line running, planned and unplanned
agility side-stepping as well as contact and fending conditions. The observations
presented through kinematic analysis provided in-depth comparisons of agility
performance based on temporal measures of speed combined with the qualities of skill
execution.
3
CHAPTER II
LITERATURE REVIEW
OVERVIEW
This literature review explores definitions of agility with respect to skill classification
systems and the relationship with sport specific performance. The review then considers
the notational analysis research examining agility performance throughout sport and
within rugby union. Following this, the literature review explores the determinants of
agility performance based on attributes of dynamic stability and also the advanced
cognitive functions associated with decision-making strategies and anticipation. To add
to this, the relationship between agility performance and functional capacities consisting
muscular strength, power and straight-line running speed will then be considered.
The biomechanical determinants of agility performance will be evaluated based on the
findings of previous scientific research and with reference to coaching resources.
Finally, the literature review evaluates critically the existing agility performance
assessment procedures and the application of such methods to rugby union.
The current review will not consider the relationship between agility and the potential
for injury, as this has been investigated extensively. It has been demonstrated that the
moments associated with agility tasks place the lower extremity at an increased risk of
injury 39, 43, 45, 90, 102, 137, 175, 199, 259, 260, 287, 293, 294. In addition, this study will not consider
the affects of prophylactic joint stabilising, which has been shown not to alter agility
performance
55, 62, 69, 162, 235, 306
. The current project accepts these limitations but notes
that the respective measures used to assess agility performance throughout the
aforementioned studies will be examined as a component of athletic assessment
procedures.
4
LITERATURE
REVIEW
CLASSIFICATION OF AGILITY
PERFORMANCE
The need for a conventional definition of agility performance is necessary, with a
number of authors attempting to define agility performance but abandoning the accepted
classification structures of sporting skills and motor programs
360, 432
. A conventional
agility classification model would provide the basis for establishing the development
of appropriate training methods and performance assessment protocols
Research conducted by Chelladurai
agility
performance
based
81
on
236
.
presented a generalised classification system for
movement
patterns
and
environmental
characteristics (Figure 2.1). Similarly, the skill classification model presented by
Gentile
152
considered the interaction between environmental and movement
characteristics represented through a progressive continuum ranging between closed and
open skill classifications (Figure 2.2). Using these models, agility in rugby union is
shown to be a complex / open skill that involves considerable environmental and
movement variability.
Spatial
Simple
Planned movement
Planned environment
Unplanned movement
Planned environment
Universal
Temporal
Planned movement
Unplanned environment
Unplanned movement
Unplanned environment
Figure 2.1: Representation of Chelladurai’s agility skill classification.
5
AGILITY
IN RUGBY UNION
It has been acknowledged that open skilled movements are more difficult to analyse
than closed skills
193
. This may be the reason that research examining agility has been
conducted typically under conditions characteristic of closed skill execution such as
within a laboratory 13, 39, 43, 45, 57, 90, 96, 102, 105, 118, 137, 141, 154, 165, 175, 179, 188, 190, 208, 238, 239, 246,
249, 256, 259, 276, 287, 300, 302, 307, 309, 315, 356, 361, 410, 432, 433
. However, expressions of laboratory
based agility performance are in contrast to the often open skill nature of agility within
sport. Clearly, it is important that scientific research addresses this gap in the research
and considers open skill based agility.
Closed Skills
Open Skills
Stationary environment
Dynamic environment
No inertial variability
Inertial variability
Stationary movement
Dynamic movement
No object manipulation
Object manipulation
Figure 2.2: Representation of Gentile’s continuum of skill classification.
Sport specific measurement procedures should be a feature when assessing agility
performance. Young, James and Montgomery
432
considered the factors that determine
agility performance and that should be represented as part of measurement procedures
(Figure 2.3). Cognitive function and functional capacities relating to speed were
identified as key determinants of agility skill execution. This model of agility
performance was then modified by Sheppard and Young
360
, who de-emphasised the
specific role of technique and highlighted anthropometry as an additional component in
the determination of agility performance (Figure 2.4). These models both identified a
running speed-based capacity termed change of direction speed as well as decisionmaking ability as the pivotal components when determining agility performance 360, 432.
6
LITERATURE
REVIEW
Agility
Perceptual and decision-making
Change of direction speed
Visual scanning
Technique
Anticipation
Foot placement
Adjustments of
strides to accelerate
Pattern recognition
and decelerate
Body lean and
Prior knowledge
posture
Straight-sprint speed
Leg muscle qualities
Strength
Power
Reactive strength
Figure 2.3: Model of agility performance with emphasis on change of direction speed
and decision-making abilities.
(Source: Adapted from Young, James and Montgomery 432)
7
AGILITY
IN RUGBY UNION
Agility
Perceptual and decision-making
Change of direction speed
Visual scanning
Technique
Anticipation
Anthropometry
Pattern recognition
Straight-sprint speed
Prior knowledge
Leg muscle qualities
Reactive strength
Concentric strength
and power
Left-right muscle
imbalance
Figure 2.4: Model of agility performance with the addition of anthropometry as a key
component of change of direction speed.
(Source: Adapted from Sheppard and Young 360 )
8
LITERATURE
REVIEW
Change of direction speed has been identified as the physical capacity to undertake
planned movements requiring at least one change of direction 360, 432. Young James and
Montgomery 432 stated that the presence of decision-making elements provides a means
to differentiate between agility and the purportedly separate physical capacity of change
of direction speed. The premise that this exists is that change of direction speed
describes movements where no reaction to an external stimulus is required. On the other
hand, agility movements involve a reaction to an external stimulus and therefore are
unrelated to change of direction speed
432
. This classification is inaccurate as the level
of decision-making stimulus (or lack there of) merely changes the requirements of
agility, rather than re-classify the skill as change of direction speed.
The agility model outlined by Young James and Montgomery
432
can be misleading
when applied to sport (e.g. batsmen running between wickets in cricket). Applying this
agility model, if a batsman played a shot and immediately realised that two runs were
available, then the process of running between wickets is change of direction speed
(planned movement)
432
. If the batsman then decided to turn a planned single into two
runs then this would be agility
432
. Alternatively, running between wickets (planned or
unplanned) is an excellent example of running based agility skill execution comprising
a change of direction angle of 180° at maximal effort. Agility can involve a decision or
no decision. Therefore, the model of agility outlined by Young James and Montgomery
432
is not a means to differentiate between change of direction speed and agility skill
execution, but rather a description of contributing factors to agility performance.
The level of decision-making strategies required of agility performances provides an
accurate means of skill classification rather than a differentiation of separate skills.
There exists an interrelationship between factors determining agility performance,
such that decision-making strategies determine the performance parameters.
Physiological capacities and technical proficiencies then combine to manifest as an
expression of dynamic stability (Figure 2.5), which coaches have acknowledged
as a key determinant of agility performance 39, 425. It should be noted that the research by
Lemmink, Elferink-Gemser and Visscher
223
represent the only published scientific
project that refers to the importance of dynamic stability to agility. Clearly, further
research considering the role of dynamic stability in agility performance is warranted.
9
AGILITY
IN RUGBY UNION
Agility
Sport specific demands
Environment
Tactical
Game
elements
requirements
Context
Variability
Dynamic stability
Cognition
Physiology
Decision-making
Anthropometry
Anticipation
Muscular capacity
Biomechanics
Kinematics
Stride
interaction
Visual
Speed
tracking
Game sense
Neuromuscular
interaction
Strength
Kinetics
Power
Force
coordination
Anaerobic
Motivation
Intelligence
Stance
capacity
Aerobic capacity
interaction
Muscle
activation
Prior knowledge
Figure 2.5: Model of agility performance with emphasis on dynamic stability in a sport
specific context.
10
LITERATURE
REVIEW
A precise and accurate definition of agility facilitates the development of appropriate
research paradigms and establishes the external validity of findings. The parameters
needed to form such a definition include the locomotion pattern and the directional
characteristics of movement, as well as the type of agility manoeuvre. The locomotion
pattern of agility performance can vary considerably between sports, and is determined
by the fluid environment in which sporting performance is observed. For example, in
water polo agility movement patterns are observed within a water-based environment
and as such, rely on swimming based locomotor patterns. Alternatively, agility
movement patterns in rugby union are observed within a field-based environment which
consists of a predominately running based motion. Hence, the locomotor descriptors of
agility performance are dependant on the environmental and match-play characteristics
of the sport.
It is also common for agility to be defined in the literature as a rapid movement
223,
284,
294,
309,
430,
432
.
However,
the
distinction
between
118, 143,
rapid
and non-rapid movement is subjective. Perhaps rapid describes movements that are
performed at maximal effort or more simply, as fast as possible. This would mean that
many agility manoeuvres throughout sport demonstrate characteristics of rapid
movement. However, many published studies of running based agility performance
have controlled velocity to sub-maximal efforts prior to direction change 43, 45, 208, 239, 256,
259, 315
. Similarly, other studies have measured the ability to execute a change of
direction during expressions of walking based agility
141, 142, 154, 188, 190, 238, 307, 308
.
It could be inferred that change of direction manoeuvres performed during sub-maximal
running and walking based locomotion patterns cannot be described as rapid and as a
result, should not be considered an expression of agility skill execution.
However, it would be a mistake to assume that expressions of agility cannot be
observed at sub-maximal velocities. Therefore when defining agility, it is important to
acknowledge the specific properties relating to the speed of agility movement.
11
AGILITY
IN RUGBY UNION
Definitions of agility have also included the ability to accelerate and decelerate
118 294
.
Undoubtedly, the multi-directional nature of agility skill execution indicates that the
manipulation of velocity is a key determinant of agility performance. In addition,
velocity can be exhibited through a range of directions during agility manoeuvres.
Consequently, it is important that definitions of agility performance note the directional
characteristics observed during the execution of agility manoeuvres. Draper and
Lancaster 118 proposed that the gross movement characteristics of agility skill execution
be described through horizontal (dodging) and vertical (jumping) plane motions
118
.
However, this only provides descriptions of two-dimensional motion. Building on this,
the movement characteristics of agility skill execution can be described according to
vertical, horizontal and lateral patterns of motion. Hence, running based agility in rugby
union would be considered a lateral movement whilst seeking to control horizontal and
vertical motion.
The type of agility manoeuvre should also be considered a fundamental component of
agility performance definitions. During expressions of lateral running based agility skill
execution, the types of agility manoeuvres have been described typically as either a
side-stepping or crossover-stepping strategy. The side-stepping strategy describes lateral
movement produced when stepping with the contralateral leg in reference to the
intended directional alignment (Figure 2.6). On the other hand, the crossover-stepping
strategy describes lateral movement produced when stepping with the ipsilateral leg in
reference to the intended directional alignment (Figure 2.7).
The terminology used to describe the respective agility stepping strategies varies
throughout the published research. For example, Rand and Ohtsuki
325
described
side-stepping strategies as an open step and crossover-stepping strategies as a closed
step. Similarly, the review of the literature revealed that the term cutting has often been
used to describe expression of lateral running based agility skill execution
96, 102, 126, 137, 175, 188, 190, 199, 208, 239, 256, 257, 259, 287, 293-295, 315, 325, 356
16, 39, 43, 45, 90,
. Essentially, the differing
terms reported between studies describe equivalent agility stepping strategies, and
simply represent variations in terminology.
12
LITERATURE
REVIEW
Figure 2.6: Frontal plane representation of a side-stepping strategy in rugby union
Figure 2.7: Frontal plane representation of a crossover-stepping strategy in rugby union.
13
AGILITY
IN RUGBY UNION
In summary, the lack of agreement regarding the definition of agility has no doubt
contributed to the disjointed nature of scientific research. Conventional definitions of
agility performance are necessary to provide guidance to future research projects and to
enhance the external validity of research findings as part of athletic development.
Definitions of agility should be sports specific and consider the activity patterns and
environmental context in which performance is observed. The current project discusses
the components of agility skill execution relating to rugby union and as such, agility is
defined in detail as a rapid multi-directional movement involving predominant lateral
side-stepping manoeuvres observed during running based locomotion patterns in rugby
union.
14
LITERATURE
REVIEW
PHYSIOLOGICAL REQUIREMENTS OF
RUGBY UNION
The game of rugby union is classified as an invasive ball sport based around concepts of
attack and defence 193. Rugby union is described also as a collision sport, where athletes
are required to make contact with their respective opponents during match-play. Success
in rugby union is decided ultimately by the number of points scored during a game
197
.
The fundamental elements contributing to this success are determined by the abilities of
individual athletes and team combinations acting to outmanoeuvre respective
opponents. The essential requirements of rugby union performance comprise a
combination of multifaceted physiological capacitates, advanced technical abilities and
complex tactical decision-making.
Rugby union is played on a rectangular, grassed playing surface that measures
approximately 100 m in length between try-lines and 70 m in width between
side-lines. A single game of rugby union is played over a period of 80 min of elapsed
time which is divided into two 40 min halves. It should be noted that a period of extra
time (two 10 min halves) may also be available during selected matches such as finals at
the Rugby World Cup. Notational analysis has shown the ball to be in play for
approximately 30 min during an 80 min game of rugby union
Williams, Hughes and O’Donoghue
415
125, 255, 415
. Similarly,
observed the ball to be in play for between 28
min and 34 min during match-play. Boddington and Lambert
56
found the mean
duration of team possession during attacking patterns of play was 25.52 ± 6.5 s during
the first half and 18.34 ± 8.8 s during the second half
Lambert and Noakes
394
56
. In addition, Van Rooyen,
demonstrated that the mean duration of possession during
attacking patterns of play that resulted in points being scored was 21.9 ± 14.5 s and
14.8 ± 5.2 s when no points were scored. Importantly, the match-play characteristics of
rugby union determine that repeat efforts of high intensity activity are a fundamental
component of individual athletic performance and team patterns of play 320, 371.
During rugby union match-play, previous research has found that the mean duration of
physical activity is less than 10 s for individual athletic performances
Nicholas
291
112, 121
.
stated that rugby union is an interval sport where individual players must
15
AGILITY
IN RUGBY UNION
perform a large number of intensive efforts between 5 and 15 s duration and with
approximately 40 s of lower intensity active recovery. Subsequently, the performance
characteristics of rugby union comprise frequent bouts of high-intensity activity, which
places high demands on the anaerobic energy system
76, 119, 121, 173, 291, 329
.
Notably, the activity patterns of rugby union athletes have been measured
between 1 : 1 and 1 : 1.9 work to rest ratios
255
. In comparison, previous research has
found that competitive field hockey displays a 1 : 5.7 work to rest ratio
209
. Hence, the
short duration of both high intensity activity and the associated intervals of active
recovery observed in rugby union are characteristics of intensive exercise
93
. The
considerable anaerobic energy demands of rugby union are also consistent with the
nature of invasive style team ball sports
371
. Further insight regarding the physiological
requirements of rugby can be gained from Reilly
329
and Nicholas
291
who both
conducted broad literature reviews of the associated literature.
In rugby union, distinctions exist between the specialised positional roles and the
physiological requirements that relate to the activity patterns observed during matchplay
254, 333
. Doutreloux et al.
116
found that the forward positional roles spent
significantly more time involved in intense activity when compared to the back-line
positional roles. It should be noted that Doutreloux et al. 116 classified intense activity as
heart rates greater than 85 % maximum, with expressions of high intensity exercise
including competing for the ball during rucks (a ruck is formed when one or more
players from each team, who are on their feet, in physical contact, close around the ball
on the ground
198
) and also maximal effort attacking ball carries. To add to this, time-
motion analysis conducted by Docherty, Wenger and Neary
112
reported that rugby
union players were involved in intense non-running activities, such as competing for the
ball at the breakdown for 9 % of total activity time.
Furthermore, forwards have been shown to spend approximately 16 % of total activity
time involved in non-running intensive activity, compared to approximately 3 % for
backs
112
. Importantly, Docherty, Wenger and Neary 112 found that rugby union players
were involved in maximal effort running activities for 6 % of total activity time during
match-play, with backs exhibiting the greatest percentage of maximal effort running.
These findings indicate that maximal effort running based locomotion contributes a
small portion to total activity time during rugby union match-play. However, it would
16
LITERATURE
REVIEW
be a mistake to assume that maximal effort running is not a fundamental determinant of
performance in rugby union. Alternatively, the intensive running patterns displayed by
rugby union athletes would likely be key determinants of performance, especially
during attacking ball carries. Therefore, the predominant energy contributions through
anaerobic metabolism facilitate expressions of agility skill execution that is vital to
success in rugby union (Figure 2.8).
The introduction of professionalism to rugby union has seen an alteration to the pattern
of high intensity activity during match-play. A study conducted by Eaves, Hughes and
Lamb
125
observed that the average number of rucks per game increased
to 123 during the professional playing period (1997 to 2002) when compared to 54
rucks per game recorded during the amateur playing period (1988 to 1995)
125
.
Similarly, Quarrie and Hopkins 320 demonstrated a 63 % increase to the number of ruck
contests with the introduction of professionalism in rugby union. The increase to the
number of ruck occurrences observed in rugby union would no doubt require a
concurrent increase to the number of attacking ball carriers that challenge the defensive
line. Hence, rugby union has evolved to require a great number of repeat bouts of
maximal effort activity that includes running based locomotion as represented through
attacking ball carries. To add to this, the match-play characteristics of invasive style
team sports such as rugby union are unpredictable and as a result players often display
non-linear running patterns. Therefore, heavy emphasis is placed (particularly during
recovery periods) on the energy systems (both aerobic and anaerobic) that support
agility skill execution during the repeat bouts of high intensity running patterns in rugby
union match-play.
17
AGILITY
IN RUGBY UNION
Agility
Sport specific demands
Environment
Tactical
Game
elements
requirements
Context
Variability
Dynamic stability
Cognition
Physiology
Decision-making
Anthropometry
Anticipation
Muscular capacity
Biomechanics
Kinematics
Stride
interaction
Visual
Speed
tracking
Game sense
Neuromuscular
interaction
Strength
Kinetics
Power
Force
coordination
Anaerobic
Motivation
Intelligence
Stance
capacity
Aerobic capacity
interaction
Muscle
activation
Prior knowledge
Figure 2.8: Physiological energy systems relationship with agility performance.
18
LITERATURE
REVIEW
NOTATIONAL ANALYSIS OF
AGILITY PERFORMANCE
Notational analysis provides a comprehensive tool for assessing the performances of
athletes in individual and team sports
369
. It provides critical support to the coaching
process through the integration of competitive performance assessments together with
monitoring
the
training
environment
and
athletic
development
50,
59,
200
.
In a coaching context, notational analysis is used also to identify tactical and technical
areas for improvement, as well as profiling the performance attributes of opposition
teams and players 297. Hence, it is possible to provide a comprehensive understanding as
to the expressions of agility skill execution during sporting performance using
notational analysis (Figure 2.9).
Despite the extensive use of notational analysis in high performance sport, few
published scientific studies have examined advanced sporting skills using notational
analysis. This lack of published research is no doubt due to the direct relationship
between notational analysis and competitive performance during match-play, whereby
the observations of professional and elite level athletes often remain confidential.
Consequently, the findings of notational analysis and also the extent to which notational
analysis is utilised throughout sport is largely unknown 200. This is reflected throughout
the available literature, whereby notational analysis has been limited typically to
generalised descriptions of motion, such as work-rate profiling during match-play
50
.
However, the popularity of this form of analysis as a research tool has increased rapidly
throughout recent scientific publications in recent years
380
. This increase in available
research can be attributed to the development of more advanced computer information
systems and the availability of public broadcast match footage 24, 200, 297.
19
AGILITY
IN RUGBY UNION
Agility
Sport specific demands
Environment
Tactical
Game
elements
requirements
Context
Variability
Dynamic stability
Cognition
Physiology
Decision-making
Anthropometry
Anticipation
Muscular capacity
Biomechanics
Kinematics
Stride
interaction
Visual
Speed
tracking
Game sense
Neuromuscular
interaction
Strength
Kinetics
Power
Force
coordination
Anaerobic
Motivation
Intelligence
Stance
capacity
Aerobic capacity
interaction
Muscle
activation
Prior knowledge
Figure 2.9: Sports specific demands as a determinant of agility performance.
20
LITERATURE
REVIEW
This review of published scientific literature suggests that there are three fundamental
areas of notational analysis research consisting; time-motion analysis, pattern (tactical)
analysis and movement (technical) analysis. Time-motion analysis refers to the
description of performance using physiological based variables, such as the percentage
of time spent sprinting during match-play
366
. This form of notational analysis
represents that the majority of published projects, and has been used in field based team
sports such as rugby league 265 and hockey 58, 209, 371 as well as other team sports such as
netball
233
. Time-motion analysis has also been reported extensively with reference to
the physiological requirements of rugby union match-play
112, 114, 119, 120, 123, 255, 332, 333
and including the activity profiles of rugby union referees
248
. The findings from
time-motion analysis facilitates the development and implementation of athletic training
programs based on an understanding of the physiological requirements of performance
within the competitive environment
50, 112
. However, descriptions of skill execution are
limited due to the quantitative measures characteristic of time-motion analyses.
Therefore, time-motion analysis provides an inappropriate assessment of agility skill
execution throughout sport.
Notational pattern analysis describes the process of modelling team patterns of play and
tactical decision-making and is used typically to explore the differences in playing
structures between successful and unsuccessful teams (dynamical systems)
388
.
Dynamical systems approach has been used widely to examine the key determinants of
performance based on measures of team tactics in field based team sports such as
soccer
381, 384, 426
and hockey
380
. In addition, tactical analysis has been employed in
other team sports such as basketball
17, 34, 35, 372
well as individual sports such as squash
192
, volleyball
and tennis
129, 436
299, 383
, and waterpolo
382
as
. To add to this, numerous
articles have analysed the patterns of play observed during rugby union
match-play 56, 65, 124, 220, 318, 328, 392-394, 415. In rugby union, notational pattern analysis can
provide valuable insight into the strategies associated with agility skill execution and
successful performance. However, notional pattern analysis research throughout the
scientific literature has been conducted commonly with reference to generalised
outcome measures, such as winning a game of rugby union 56, 65, 124, 220, 318, 328, 392-394, 415.
This method of analysis provides limited insight into the processes that are associated
with successful team performances, such as observed when exploring the patterns of
21
AGILITY
IN RUGBY UNION
attacking play that are associated with penetrating the defensive line during rugby
union.
Notational movement analysis describes skill execution during competitive match-play.
The fundamental application of notational movement analysis consists of identifying the
key determinants of performance based on a model of technique
254
. An association
exists between notational movement analysis and those kinematic observations
presented through biomechanical analysis. Accordingly, notional movement analysis
provides a valuable insight into the skills required during sport specific performances,
building on traditional biomechanical observations. Therefore, notational movement
analysis provides an effective tool to differentiate athletic performances, as well as
identifying areas of improvement in skill execution within the competitive sporting
environment 200, 369.
In conducting notational movement analysis, it would be a mistake to describe skill
execution through simple quantitative measures such as event frequency. Despite this,
the small number of research projects including qualitative variables have been limited
to the description of running intensity 119, 121. In contrast, previous research has outlined
the need for comprehensive qualitative descriptors to be implemented as part of
notational analyses
372
. To add to this, coaches and athletes require not only a
quantitative analysis of performance, but also a qualitative evaluation regarding the
determinants of successful skill execution
191
. This is consistent when considering
agility as a research paradigm, whereby reporting the frequency of agility manoeuvres
provides trivial information with regards to the determination of performance.
Alternatively, the description of agility performance based on a combination of
quantitative and qualitative measures provides a comprehensive model of skill
execution. Consequently, recent authors have offered notational analysis tools that
purportedly provide an assessment of sports specific movement patterns and with
particular reference to the description of agility skill execution.
Bloomfield, Polman and O’Donoghue
50
proposed a notational movement analysis
instrument, termed the Bloomfield Movement Classification (BMC) that described the
characteristics of motion, movement and playing actions observed during competitive
sporting performances 50. The development of the BMC was due to the lack of available
22
LITERATURE
REVIEW
research describing the interrelationship between patterns of motion and movement
throughout sport, and especially invasive sports such as rugby union 50. Subsequently, it
was then stated that the BMC provided a detailed system of movement classification
associated with the speed, agility and quickness demands of sporting performance 52.
The BMC described eight running based (ranging from standing to sprinting) and seven
non-running based motions, as well as seven sport specific actions 50. Movements were
then described using modifiers of performance intensity (12 classifications) and
directional characteristics (4 classifications). The description of running based
motion also combined timed events with subjective classifications of skill
execution (running direction and intensity). For example, the motion of sub-maximal
running was described using performance time combined with nine available directional
descriptors and two available descriptors of intensity. This broad nature of the BMC
meant that a generalised model of sporting performance was presented through a
complex system of modifiers. Following on from this, it is a mistake to assume that
every motion, movement and action must be coded during notational analysis.
Alternatively, coding systems should focus on describing specific motions, movement
or actions in relation to the outcome of skill execution and the result of relevant
performances.
In order to describe agility performance using the BMC, Bloomfield, Polman and
O’Donoghue
50
applied movement characteristics to the categorisation of motion.
The classification of swerving and turning was defined with directional characteristics
consisting of right or left movements. It should be noted that Bloomfield, Polman
and O’Donoghue 50 described a swerve as a rapid change of direction in one movement
without turning the body, but did not describe the differences between swerving and
turning direction change movements. In addition, the authors did not describe the
fundamental stepping strategies observed during agility skill execution, namely
side-stepping and crossover-stepping manoeuvres. The BMC was limited also to the
frequency of directional change instances associated with agility during match-play 170.
Furthermore, the change of direction angles (0 - 90°, 90° - 180°, 180° - 270°,
270° - 360° and > 360°) described by Bloomfield, Polman and O’Donoghue
50
were
arbitrary and displayed no consideration of running patterns during competitive sporting
23
AGILITY
IN RUGBY UNION
performance. For example, using the BMC it was shown that approximately 86 % of
turning movements in soccer occurred through a change of direction angle of less
than 90°
51
. In contrast, approximately 1 % of turning movements were found to be
greater than 180°. It should be noted also that the observations gathered by Bloomfield,
Polman and O’Donoghue
51
included instances where the sampled athletes were
engaged in low intensity activities such as walking and jogging. Therefore, the
description of agility using the BMC is too broad and does not reflect the running
patterns observed in sports such as soccer
The BMC has been used also o assess agility in sports such as netball, where it was
found that netball players executing an agility manoeuvre when jogging or running
rarely exhibited a change of direction angle greater than 90° (observed in approximately
2 % of the total number of jogging and running movements)
417
. Conversely, it was
demonstrated that players executing an agility manoeuvre when jogging or running
commonly exhibited a change of direction angle less than 90°, comprising
approximately 44 % of jogging and running movements. Similarly, a study conducted
by Hale and O’Donoghue
170
employing the BMC observed that 66 % of agility
manoeuvres displayed a change of direction angle of less than 90° during forward
running movements in netball. Clearly research needs to consider categories associated
with change of direction angles less than 90° when examining agility skill execution
during sporting performance.
Duthie et al. 122 investigated running patterns during rugby union match-play, recording
the duration of sprinting performances as well as any changes in direction observed
when running. It was demonstrated that 16 % of sprinting patterns during rugby union
involved a change of direction agility manoeuvre (15 % for forwards and 22 % for
backs (p = .03)). However, the research conducted by Duthie et al.
122
focused on
straight-line running patterns and as such, change of direction agility manoeuvres were
excluded from the discussion of implications and practical applications. Instead,
Duthie et al.
122
outlined the importance of straight-line running components to the
determination of success in rugby union. For example, straight-line maximal speed
capacity was highlighted as an important factor when attempting to evade a defensive
opponent during attacking ball carries. In contrast, Sayers and Washington-King
351
demonstrated that straight-line running patterns during attacking ball carries were
24
LITERATURE
REVIEW
associated with negative phase outcomes, such as losing the ball at the subsequent
breakdown. Instead, evasive movement patterns during attacking ball carries were
associated with positive phase outcomes such as breaking the attempted tackle of the
defensive opponent and advancing the ball beyond the advantage line. This suggests
that straight-line running patterns provide limited determination of running ability in
rugby union.
The research conducted by Sayers and Washington-King
351
coded factors associated
with attacking running patterns (evasive agility and straight-line running) with reference
to the tackle outcome (whether the attacking ball carrier advanced beyond the advantage
line and maintained possession of the ball) in rugby union. It was observed that players
who received the ball at higher running speed and then ran with greater intensity, whilst
using evasive stepping patterns were likely to dominate the tackle contest. It was then
shown that attacking ball carriers who used a side-stepping pattern that involved
predominately forward motion (change of direction angle less than 90°) were more
likely to advance the ball beyond the advantage line, which lead to more positive phase
outcomes (retain possession of the ball). It should be noted also that side-stepping
patterns displaying predominately lateral motion (change of direction angles greater
than 90°) where effective in advancing the ball beyond the advantage line, but were not
associated with retaining possession of the ball at the tackle contest. This research
demonstrated that the specific nature of an attacking ball carry has a distinct impact on
the tackle outcome and that evasive agility is an effective attacking strategy to dominate
the tackle contest in rugby union. It should be noted also that Sayers and WashingtonKing
351
highlighted the need for further research to discover the best techniques to
achieve the most effective ball carry in rugby union.
The ability to score tries is considered a key determinant of successful performance in
rugby union197. This would no doubt be associated with breaking the tackle of defensive
opponents and advancing the ball beyond the advantage line
201, 220, 318, 393
.
Clearly, it is important to understand the factors associated with dominating the tackle
contest in order to implement effective attacking strategies in rugby union
351
.
It should be noted also that researchers have divided the various aspects of the tackle
contest into four components; contact, ball carrier going to ground, support play and the
availability of the ball after the tackle
318
. Notational analysis of the tackle contest in
25
AGILITY
IN RUGBY UNION
rugby union has focused on the availability of the ball after the tackle
318, 351
.
McKenzie et al. 254 outlined the importance of support players and the actions of the ball
carrier to the determination of tackle outcome. Moreover, attacking ball carriers have
been found to be more likely to dominate the tackle contest when advanced beyond the
advantage line
254, 351
. Beyond this, the technical attributes combining evasive running
patterns (agility) and contact skills in resistance of defensive opponents (e.g. strong leg
drive, low body positions and active fending strategies), and how these influence
defensive positions and the tackle outcome have not been reported previously in the
scientific literature.
In addition, previous research has tended to describe the domination of the tackle
contest in relation to whether the ball carrier advanced the ball beyond the advantage
line 254, 351. This approach fails to consider the distinct tackle outcomes observed during
an instance when a ball carrier has advanced beyond the advantage line, such as
offloading the ball in the tackle, tackle-breaks and line-breaks. There is no doubt that a
greater understanding would be gained when exploring the influence that contact skills
have on promoting specific tackle outcomes such breaking the tackle (tackle-breaks).
It should be noted that the contact skills described by McKenzie et al.
254
have
supported coaching theory and practice, where low body height and strong leg drive are
considered effective techniques to dominate the tackle contest
important to note that the research by McKenzie et al.
254
23
. However, it is
was conducted when rugby
union was an amateur sport. The introduction of professionalism to rugby union has
altered the match-play characteristics such that the number of tackle contests has
increased by over 50 % 320. Subsequently, greater emphasis has been placed on power in
contact and as such, athletes have evolved to be greater in body mass
320
. There is no
doubt that the strong contact skills relating to running ability and promoting positive
tackle outcomes reported by McKenzie et al.
254
remain an important component of
current-day rugby union. However, there is considerable scope to explore running
ability in rugby union using more contemporary samples of match-play.
In summary, agility skill execution is fundamental to the determination of try scoring
ability and overall success in rugby union. In contrast, the relationship between
individual running ability and the capacity to score tries has received limited
26
LITERATURE
REVIEW
consideration throughout the published literature. Alternatively, the review of the
published research revealed a number of articles examining team patterns of play
associated with phases of possession and the relationship with scoring tries and overall
success in rugby union
56, 318, 392, 394
. Despite this, James, Mellalieu and Jones
201
identified the percentage of attacking ball carries resulting in positive phases outcomes
as a key performance indicator relating to success in rugby union. Therefore, it is
necessary that future notational movement analysis considers the relationship between
running ability and scoring tries with respect to an evaluation of overall team
performance.
27
AGILITY
IN RUGBY UNION
AGILITY SKILL EXECUTION AND
DYNAMIC STABILITY
Dynamic stability represents an expression of the balance mechanisms observed in the
body
72
. The maintenance of balance is regulated by the central nervous system based
on a combination of afferent visual and tactile impulses combined with proprioceptive
and vestibular feedback 30, 48. Expressions of balance consist of both static and dynamic
components, with static balance referring to the maintenance of stability with a fixed
based of support (e.g. standing)
48, 390
. Dynamic balance then refers to the maintenance
of stability with a changing base of support (e.g. running) 48, 73, 343, 390. The maintenance
of dynamic stability is a key component of performance during the execution of open
skills in sport 72, 390. Unfortunately, the extent of published research has focussed on the
dynamic instability of movement patterns observed in older adults rather than sport
339, 363
109,
.
Dynamic stability is crucial to athletic performances displaying multi-directional
activity patterns, such as observed during agility skill execution
215, 336
. To add to this,
enhanced dynamic stability can be achieved with modifications of foot placement
patterns as well as increases in stride rates and decreases in flight times during agility
skill execution
40
. In addition, the lowering of the body’s centre of gravity achieved
through mechanisms such as increasing the forward trunk lean angle and adopting lower
leg recovery heights also facilitates enhanced dynamic stability
348, 349
. It should be
noted that leg recovery is in direct reference to the range of movement about the knee
and hip during the swing phase of running. Decreasing the knee flexion angle during the
swing phase of running reduces the moment of inertia about the hip and increases the
angular velocity of the swing leg, promoting faster leg recovery 171. However, deep knee
flexion and exaggerated hip flexion during the swing phase of running would increase
the height of the centre of gravity and as a result, promote dynamic instability.
Contraindications are observed in contact sports such as rugby union, where gait
modifications that decrease dynamic stability are not associated with successful athletic
performance
348, 349
. Therefore, the interaction between skill execution and elements of
dynamic stability present as a key determinant of agility performance in rugby union
(Figure 2.10).
28
LITERATURE
REVIEW
Agility
Sport specific demands
Environment
Tactical
Game
elements
requirements
Context
Variability
Dynamic stability
Cognition
Physiology
Decision-making
Anthropometry
Anticipation
Muscular capacity
Biomechanics
Kinematics
Stride
interaction
Visual
Speed
tracking
Game sense
Neuromuscular
interaction
Strength
Kinetics
Power
Force
coordination
Anaerobic
Motivation
Intelligence
Stance
interaction
capacity
Aerobic capacity
Muscle
activation
Prior knowledge
Figure 2.10: Dynamic stability as a determinant of agility performance.
29
AGILITY
IN RUGBY UNION
The relationship between dynamic stability and agility skill execution has been outlined
within coaching resources
348, 349
. In support of this, published research has shown that
dynamic balance training can improve biological feedback systems associated
with
maintaining
equilibrium
during
dynamic
movement
185,
224,
240,
337
.
Similarly, improvements to dynamic stability have been observed following
intervention programs involving specific proprioceptive balance tasks
48, 61
. It has been
shown also that neuromuscular training protocols that combine dynamic stability
exercises with plyometric power development can enhance athletic performance 282, 283.
Other studies have shown that combined balance and functional capacity training can
improve neuromuscular coordination, whereby enhanced muscle capacity is associated
with a greater ability to promote joint stability during dynamic movement
48, 83
.
Specific dynamic balance training programs have been shown also to promote increased
muscular strength as well as providing equalisation of muscular imbalances and the
adaptation of movement patterns
176, 367
. Therefore, specific balance training can
improve the dynamic stability properties that facilitate enhanced athletic performances
involving complex skill execution.
The adaptations observed with dynamic balance training have demonstrated concurrent
improvements to agility performance. A study conducted by Bencke et al.39
demonstrated improvements to agility performance following dynamic balance training.
The intervention program included exercises associated with the development of
multi-directional dynamic balance stability, such as single leg side jumps and agility
dot-drills. The results presented by Bencke et al.39 showed that the dynamic stability
training group displayed shorter stance times during initial direction change of a
side-stepping agility manoeuvre. Further analysis revealed that the shorter stance times
were observed during the propulsive phase of the initial change of direction side-step of
the agility manoeuvre
39
. Bencke et al.39 suggested that the dynamic stability training
group improved neuromuscular coordination associated with the rate of force
development through the initial direction change propulsive phase. This has been shown
previously to be a significant contributor to the execution of dynamic movement
patterns 267, 270, 277.
30
LITERATURE
REVIEW
A study conducted by Yaggie and Campbell 425 examined the affects of balance training
on measures of dynamic stability, agility performance and other functional capacities.
The intervention program consisted of balance exercises that involved standing on an
unstable apparatus. Following the balance training program, results demonstrated
improvements to measures of dynamic balance and postural sway but not vertical
jumping performance. Interestingly, results observed improvements to the speed of
agility (measured in times) following the balance intervention. The findings from
Yaggie and Campbell
425
indicate that balance training can improve athletic
performances that require the maintenance of dynamic stability during patterns of multidirectional movement. However, it should be noted that the improvements to agility
performance following balance training were not retained during subsequent testing 425.
This finding suggests that enhanced dynamic stability is not retained and as such,
supports the training principle of reversibility as part of athletic development.
Therefore, balance training may only improve agility performance when conducted as
part of the regular athletic development program.
Balance training is considered to be an important part of sport specific athletic training
programs
155
. Indeed, the findings from previous research suggest that balance training
can improve athletic performances, including agility
Malliou et al.
240
39, 425
. A study conducted by
examined the improvements to skiing based agility performance
following an intervention program with training groups consisting of exclusive sports
specific training and a combination of sports specific and generalised balance
training. Malliou et al.
240
demonstrated that the combined sports specific and balance
training group displayed greater improvements to skiing agility performance when
compared to the exclusive sport specific training group. This adds weight to the notion
that balance training should form an important part of athletic development programs.
Extant research suggests that balance training should contribute an important part of
athletic development programs in rugby union. Balance training could form a central
component of ancillary training methods that consist of muscular strength, power and
speed development. In addition, it may be beneficial in rugby union for ancillary
training methods to consist of activities with high demand on dynamic stability, such as
observed in the martial arts and dance sports. A study conducted by Perrin et al.
31
310
AGILITY
IN RUGBY UNION
found that participation in activities that place great demand on dynamic stability
resulted in a positive training adaptation. It was shown that both judo and dance based
athletic development programs improved measures of dynamic stability and postural
control, and with judo training also improving proprioceptive balance control. Athletic
development programs associated with martial arts and dance sports require participants
to maintain balance and postural control during complex skill execution. Consequently,
adaptations to the somatosensory afferences are represented through enhanced
properties of dynamic stability, which then promote improved skill execution
310
.
Therefore, martial arts and dance sport activities can be considered appropriate ancillary
training methods of dynamic stability during the execution of multi-directional complex
skills, and as part of athletic development programs in sports such as rugby union.
In summary, dynamic stability represents a key determinant of agility skill execution.
Despite this, there is a lack of research examining the relationship between agility
performance and measures of dynamic balance and postural control in running based
team field sports such as rugby union. On the other hand, improvements to agility
performance have been observed following dynamic stability intervention programs
other sports such as skiing
240
Hence, dynamic stability training may represent an
appropriate means of agility performance enhancement as part of sports specific athletic
development. It is necessary that future research examines the relationship between
agility skill execution and manifestations of dynamic stability during multi-directional
sports such as rugby union.
32
LITERATURE
REVIEW
AGILITY SKILL EXECUTION AND
COGNITIVE FUNCTION
Decision-making strategies (associated with advanced cognitive functions) represent a
central component of successful performance during open skilled sports such as rugby
union
5, 264
(Figure 2.11). The review of the published scientific literature revealed that
agility performances that require athletes to display reactive decision-making strategies
are unrelated to those agility performances that do not required reactive decisions. For
example, a study conducted by Sheppard et al. 361 found that a positive weak correlation
existed between reactive and planned agility manoeuvres (r = .32). Interestingly, a
comparable relationship was observed between reactive agility manoeuvres and 10 m
acceleration speed (r = .33). The limited relationship between reactive and planned
agility manoeuvres suggests that skill execution is unique between the performance
conditions. This finding is supported by Farrow, Young and Bruce
133
who
demonstrated less than 50 % common variance between reactive and planned
agility conditions. The low common variance between reactive agility and
planned agility performances indicates that the inclusion of decision-making
elements alters the performance properties associated with agility skill execution.
Therefore, decision-making elements represent key determinants of agility performance
during the execution of open skilled manoeuvres.
33
AGILITY
IN RUGBY UNION
Agility
Sport specific demands
Environment
Tactical
Game
elements
requirements
Context
Variability
Dynamic stability
Cognition
Physiology
Decision-making
Anthropometry
Anticipation
Muscular capacity
Biomechanics
Kinematics
Stride
interaction
Visual
Speed
tracking
Game sense
Neuromuscular
interaction
Strength
Kinetics
Power
Force
coordination
Anaerobic
Motivation
Intelligence
Stance
capacity
Aerobic capacity
interaction
Muscle
activation
Prior knowledge
Figure 2.11: Cognitive function as a determinant of agility performance.
34
LITERATURE
REVIEW
It has been shown that planned agility assessment protocols do not distinguish between
levels of rugby league athletes
27, 148
. Conversely, the inclusion of decision-making
elements as part of agility assessment procedures has been shown to differentiate
between performance levels of athletes. Sheppard et al.
361
found that during
reactive agility performance conditions, high performance athletes displayed faster
agility performance times (1.55 ± 0.07 s) when compared to athletes of lower athletic
performance levels (1.64
±
performance
high
assessments,
0.08 s). In contrast, during planned agility
performance
athletes
displayed
comparable
agility performance times (1.64 ± 0.09 s) when compared to athletes of lower athletic
performance
levels
(1.61
±
0.09
s).
Notably,
it
was
revealed
that
high performance athletes improved agility performance times with the inclusion of a
decision-making element (1.55 ± 0.07 s) when compared to planned agility
performance conditions (1.64 ± 0.09 s). The decision-making condition employed by
Sheppard et al. 361 required athletes to react to the directional movements of a simulated
opponent and execute an appropriate agility movement response. Sheppard et al.
361
noted that anecdotal observations suggested that high performance athletes completed
the required decision-making processes earlier during the stimulus presentation than
athletes of lower performance levels. This indicates that the high performance athletes
were able to anticipate the directional movements of the simulated opponent and
execute the required agility movement strategy.
In another study conducted by Farrow, Young and Bruce 133, high performance athletes
displayed superior decision-making strategies during agility skill execution.
Farrow, Young and Bruce
133
examined agility performances with decision-making
elements represented through a video display of simulated match-play in netball.
It was demonstrated that high performance athletes displayed faster agility
performance times (3.57 ± 0.14 s) when compared to athletes of a lesser performance
level (3.83
±
0.11 s). Further analysis revealed significant differences in
decision-making times between high performance athletes and lower performance
athletes. It was apparent that the lower performance athletes displayed a positive
decision-making time (0.02 ± 0.09 s), indicating that the presentation of the stimulus
was completed prior to executing the appropriate agility movement strategy.
On the other hand, high performance athletes possessed superior anticipation strategies
as evidenced with negative decision-making times (-0.15 ± 0.13 s). The negative
35
AGILITY
IN RUGBY UNION
decision-making time indicated that the high performance athletes anticipated the
performance attributes of the simulated match-play activities and predicted the
appropriate movement strategy required of agility skill execution.
Abernathy
4
identified the ability to extract precise information based on subtle
movement patterns of opponents and then to predict performance is observed commonly
of highly skilled performers within open skilled sports. Highly skilled athletes display
accurate visual search strategies that fixate on relevant stimuli and facilitate the
prediction of movement
5, 31, 346, 359
. Notably, a number of research articles have shown
that anticipation strategies associated with the identification of movement patterns and
postural cues, predict skill execution and the associated factors of performance in sports
such as tennis
135, 414
, volleyball
178
and soccer
317, 346, 411
. Notably, Meir
264
highlighted
the importance of anticipatory strategies in determining the ability to penetrate the
defensive line and advance the ball beyond the advantage line during attacking ball
carries in rugby union. Hence, anticipation strategies based on advance cue recognition
and visual search strategies present an important component of agility skill execution in
rugby union.
The execution of complex motor skills such as agility is dependant on selective
attention and advance cue recognition of the contextual environment, such that this
information offers predictive event sequencing and crucial decision-making
capabilities 5. During the execution of open skilled motor programs it has been shown
that advance cue recognition can lead to the modification of gait patterns to enhance
subsequent skill execution
66, 80, 88, 437, 438
. A study conducted by Besier et al.
44
investigated the affects of anticipated versus unanticipated agility manoeuvres and
found that anticipation strategies allowed for more effective foot placement patterns
during the initial direction change side-step. Therefore, accurate anticipatory strategies
can promote enhanced agility skill execution. The elements of decision-making
associated with anticipatory advance cue recognition clearly contribute a central
component in the kinematic determinants of agility skill execution in rugby union.
A study conducted by Besier et al.44 identified the importance of including reactive
performance conditions as part of agility skill development programs. In addition, the
inclusion of reactive performance conditions as part of athletic development programs
36
LITERATURE
REVIEW
improves the ability to implement anticipatory postural adjustments during the
execution of open skills such as agility 20, 437, 438. Similarly, it has been noted that sports
specific skill development under reactive performance conditions result in considerable
improvements to the visual information processing systems that facilitate enhanced
decision-making strategies and improved accuracy of skill execution
347,
399
.
Hence, athletic training programs should emphasise visual search strategies and advance
cue recognition to improve decision-making strategies
368
. It should be noted also that
training programs focusing on improved decision-making and anticipation strategies
should be conducted under sports specific conditions
166, 167, 412, 413
. Previous research
has observed little transfer between sports specific anticipatory strategies and clinically
based decision-making performance conditions
362, 405
. The use of sports specific
training activities combined with video analysis and feedback is recommended for
developing perceptual and decision-making strategies associated with the execution of
open skills such as agility 28, 183.
In summary, anticipation and the associated decision-making strategies are critical
factors in the determination of agility performance in rugby union. Previous research
suggests that the more agile athletes combine advanced cognitive strategies with
physiological capacities and technical abilities to produce rapid changes of direction and
superior performances. It has been shown also that improvements to decision-making
and anticipation strategies facilitate enhanced agility performance. It is concluded that
sport specific decision-making and anticipatory strategies should be included as part of
agility skill development in rugby union.
37
AGILITY
IN RUGBY UNION
AGILITY PERFORMANCE AND
FUNCTIONAL CAPACITIES
BACKGROUND
The functional capacities incorporate attributes of muscular strength, power and speed.
Strength and power refer to the muscular forces and torques generated during sporting
activities 7. Speed can possess many definitions; however this literature review will
refer to speed with reference to the properties of straight-line running capacity.
It is accepted that the functional capacities of muscular strength, power and speed
contribute to overall athletic performance in team sports such as rugby
union
18, 106, 379, 428
. However, debate exists over the specific contribution of strength,
power and speed to athletic performances observed within the competitive sporting
environment
429
. It is common that measures of the functional capacity demonstrate
acceptable levels of reliability, but possess limited external validity when applied to
sports specific athletic performance and skill execution
214,
216,
249,
430,
432
.
The limited application of functional capacity measures is illustrated when considering
agility performance, where review of the published scientific literature observed poor
correlations between agility performance times and the functional capacities of strength,
power and speed.
The scope of the current literature review will consider the physiological and technical
transfer between the speed of agility performance and functional capacities of muscular
strength, power and speed. More specifically, the following discussion will explore the
published scientific literature investigating the relationships between the speed of agility
performance and factors of strength, power and speed (Figure 2.12). In addition, this
study will review the published literature that has conducted functional capacity
intervention programs and observed the associations with the speed of agility
performance.
38
LITERATURE
REVIEW
Agility
Sport specific demands
Environment
Tactical
Game
elements
requirements
Context
Variability
Dynamic stability
Cognition
Physiology
Decision-making
Anthropometry
Anticipation
Muscular capacity
Biomechanics
Kinematics
Stride
interaction
Visual
Speed
tracking
Game sense
Neuromuscular
interaction
Strength
Kinetics
Power
Force
coordination
Anaerobic
Motivation
Intelligence
Stance
interaction
capacity
Aerobic capacity
Muscle
activation
Prior knowledge
Figure 2.12: Muscular capacity as a determinant of agility performance.
39
AGILITY
IN RUGBY UNION
AGILITY AND MUSCULAR STRENGTH CAPACITY
Strength refers to the maximum force that can be generated by a muscle group or
groups
428
. Muscular strength contributes an important component of athletic
performance in sports displaying anaerobic activity patterns
379
. In rugby union, the
physical contact displayed during match-play suggests that athletes are required to
possess substantial amounts of muscular strength. Despite this, published scientific
research has indicated a limited relationship exists between strength indices and sport
specific performance, such as agility skill execution
38, 214, 246, 249, 285, 430
. Measures of
strength provide a popular assessment method of athletic muscle function throughout
sport and as a scientific research paradigm
204
. Commonly, strength testing is used to
evaluate performance adaptations during the athletic development cycle and also to
assess the effects of an intervention program in quantitative research 49.
Conventional strength assessment procedures consists of isometric, isokinetic and
isoinertial dynamometry 7. In addition, speed-strength dynamometry is a popular
method of strength assessment throughout the published literature. There are a number
of published scientific research projects that have investigated the relationship between
agility performance and muscular strength capacities. Table 2.1 displays an outline of
previous scientific research that has examined the correlation between measures of
agility performance and factors of muscular strength. Literature review also revealed a
number of scientific articles investigating the affects of strength intervention on agility
performance. It should be noted that the nature of strength expression means that the
various muscular strength indices must be dealt with separately as part of the current
literature review.
40
LITERATURE
REVIEW
Table 2.1: Summary of the correlation between agility and muscular strength.
Study
Results
Agility Performance
430
Strength Capacity
r
3 x 90° side-step
Loaded CMJ
.01
3 x 90° side-step with ball
Loaded CMJ
.27
3 x 120° side-step
Loaded CMJ
-.04
249
SEMO agility test
1RM bench press
.35
214
Shuttle run agility test
Isokinetic leg press
-.49
Shuttle run agility test
Isokinetic leg extensions
-.51
Diamond agility test
Isokinetic leg press
-.47
Diamond agility test
Isokinetic knee extension
-.54
Diamond agility test
Isokinetic single leg squat
-.59
Side-step
Isoinertial squat
-.17
Shuttle run agility test
Isoinertial squat
-.31
Slalom run agility test
Isoinertial squat
-.21
Ice-skating agility test
Isoinertial 1RM leg press
-.29
285
246
38
CMJ – Counter movement jump
SEMO – Southeast Missouri State
1RM – One-repetition maximum
41
AGILITY
IN RUGBY UNION
It is important to note that previous research investigating the relationship between
agility performance and muscular strength has inferred a significant level
of association between these two variables 430. Young, Hawken and McDonald 430 noted
that during agility change of direction manoeuvres, a powerful contraction of the lower
extremity muscles facilitated the initial absorption of the associated forces, and followed
by an explosive contraction providing propulsion. Young, Hawken and McDonald
430
then inferred that a significant association existed between muscular strength properties
and the muscle contraction characteristics observed during agility manoeuvres. This
assumed association between agility performance and muscular strength is then
represented by the number of related published scientific research projects. However,
the overall findings of previous research suggests that generality does not exist between
agility performance and measures of muscular strength capacity 38, 214, 246, 249, 285, 430.
ISOMETRIC STENGTH CAPACITY
Isometric strength refers to the maximal voluntary muscular contraction developed
against an immovable object and with no change to the respective joint angle
7, 419
.
It is has been noted that isometric strength testing demonstrates high reliability for both
single-joint and multi-joint protocols
419
. However, the external validity of isometric
assessment procedures and training programs is limited with respect to dynamic
movement
418, 419
. For example, research in rugby union has shown isometric strength
capacity to be unrelated to the production of force in the scrum, and rather that
individual technique combined with anthropometry were the most important factors
when determining the summation of forces during scrums in rugby union 321.
Measures of isometric contraction types seem poor determinants of athletic performance
throughout sport. The review of the literature revealed a single published project
investigating the relationship between agility performance and measures of isometric
strength
246
. Markovic
246
observed an extremely weak relationship between isometric
squat strength and side-stepping (r = -.25), shuttle running (r = .03) and slalom running
(r = .08) agility tests. This reinforces the notion that isometric strength has a limited
relationship with dynamic sporting performance. Indeed, previous studies have
42
LITERATURE
REVIEW
observed a weak relationship between isometric strength and other muscular strength
indices such as isokinetic strength, as well as measures of muscular power and straightline running speed
216, 305, 324, 341
. Hence, the mechanical differences observed between
isometric contraction types and dynamic movements indicates that isometric strength
testing is an inappropriate measure of athletic attributes, including agility performance.
ISOKINETIC STENGTH CAPACITY
Isokinetic muscular strength assessment involves the measurement of torque through a
range of motion in which the limb is moving at constant angular velocity 7. It has been
suggested that isokinetic testing offers greater reliability than other forms of strength
assessment, such as isoinertial and dynamic 134, 187, 226, 252, 385, 395, 406. However, the use of
isokinetic strength assessment in sport is contentious. It is argued that isokinetic testing
demonstrates poor external validity because movements observed during competitive
sporting performance are rarely performed at constant velocity, as is required during
isokinetic strength testing 19, 237, 281, 400. Rapid joint and whole body acceleration during
dynamic movements is a fundamental component of athletic performance in sports such
as rugby union. Hence, applying the observations of strength assessment within a
functional sporting context is questionable when acceleration is not possible
25, 216, 281
.
Therefore, it is not surprising that previous published research has demonstrated poor
relationships between isokinetic strength and agility performance 214, 285.
Isokinetic dynamometry is a popular assessment method of dynamic muscle function in
scientific research and sporting contexts
157, 285
. It is believed that isokinetic
dynamometry is more closely related to performance within a sport specific
environment compared to isometric
by Perry et al.
311
214,
285
. Despite this, a study conducted
found that an increase in isokinetic strength negatively affected the
accuracy of ball placement during tennis match-play. To add to this, previous research
indicates that there is a limited relationship between isokinetic chain dynamometry and
agility performance 214, 285.
43
AGILITY
IN RUGBY UNION
In general, weak relationships have been observed between agility performance and
isokinetic strength. A study conducted by Kovaleski et al.214 demonstrated weak
correlations between agility performance as measured through shuttle running, and
isokinetic leg press (r = -.49). In addition, isokinetic knee extension strength at a speed
of 60°.s-1 displayed a weak to moderate negative correlation with agility (r = -.51).
This suggests that there is little difference in the relationship with agility performance
between open and closed kinetic chain exercises. Notably, the coefficient of
determination was less than 50 %, which indicates that isokinetic strength is poorly
related to agility performance.
The findings presented by Kovaleski et al.214 are supported by a similar study conducted
by Negrete and Brophy
285
who found weak correlations between and isokinetic leg
press and agility performance as measured using a diamond run (r = -.47). To add to
this, single leg isokinetic squat strength held a negative moderate correlation with
agility (r = -.59). Considering closed chain exercises, moderate to weak correlations
between agility performance and isokinetic knee extension at 180°.s-1 were also
observed (r = -.54). Importantly, the relationship between agility performance and
isokinetic strength was considerably weaker when measures of isokinetic strength were
normalised to body weight. It was shown that agility performance displayed extremely
weak correlations with isokinetic leg press (r = -.11), single leg squat (r = -.12) and leg
extension (r = -.17) when normalised to body weight.
The weak relationships between agility performance and isokinetic strength
demonstrated by Kovaleski et al.
214
and Negrete and Brophy
285
are consistent with
similar studies investigating the relationship between such measures of strength and
other functional performances such as vertical jumping
Karunakara
distance
at 60°.s
314
and
-1
47, 314
. Pincivero, Lephart and
observed weak to moderate relationships between single leg hop for
measures
of
isokinetic
(r = .33 to .69) and 180°.s
-1
knee
extension/flexion
strength
(r = .33 to .67). It is apparent that little
transfer exists between measures of isokinetic strength and functional performance.
Additionally, Gleeson and Mercer
157
questioned the external validity of isokinetic leg
strength measures when applied to functional sporting performance. Therefore, it can be
concluded that isokinetic strength is poorly related to generalised athletic sporting
performance and more specifically to agility performance.
44
LITERATURE
REVIEW
ISOINERTIAL STRENGTH CAPACITY
Isoinertial strength is described as the muscle contraction types associated with
traditional weightlifting exercises 7. Isoinertial strength employs constant external loads,
and overcoming this resistance results in variations to the angular joint velocities
associated with the exercise movement patterns
7
. Testing for one repetition
maximum (1RM) isoinertial strength is a common form of athletic assessment.
It has been suggested that the more dynamic nature of isoinertial strength testing may
present greater external validity than that of isokinetic assessment
386
. However, the
specific nature and skills involved during isoinertial strength exercises can decrease
reliability and present bias towards skilled performers
7, 211
. Despite this, isoinertial
strength testing is a common part of athletic assessment procedures within a coaching
context. Certainly, the popularity of isoinertial testing as part of athlete development
programs is due to the inexpensive nature of isoinertial testing relative to isokinetic
dynamometry. Notably, isoinertial exercises are employed commonly within both a
functional context and scientific interventions.
Previous research has demonstrated a limited relationship isoinertial strength and
functional dynamic performance
407
. This is supported by Baker and Nance
25
who
demonstrated weak correlations between a number of measures of isoinertial strength
and straight-line running speed over 10 m and 40 m. Results showed that the strongest
correlation was between 3RM power clean from hang and both 10 m (r = -.36) and
40 m (r = -.24) sprint times. Interestingly, the relationship between measures of
isoinertial strength and running speed displayed significance when strength indices
where expressed with reference to body weight. Overall, results showed a moderate
association
between
strength
and
speed.
For
example,
the
coefficient
of
determination of 3RM power clean from hang was 31 % for 10 m and
52 % for 40 m sprint times. It should be noted that previous authors have stated that
normalisation to body weight confounds measures of muscular strength
3,
21
.
Hence, it is recommended that further research considers relative strength and the
association to other functional capacities and also sporting performance. Despite this,
the transfer of absolute isoinertial strength to running based functional performance
capacities seems limited.
45
AGILITY
IN RUGBY UNION
The relationship between measures of isoinertial strength and agility performance has
demonstrated weak correlations throughout the published literature. A study conducted
by Mayhew et al.
249
reported the relationship between agility performance and
isoinertial strength measured through 1RM bench press. Predictably, results observed a
weak
relationship
between
agility performance
and
muscular
strength
249
.
It is questionable whether specific expressions of upper body muscular strength such as
the 1RM bench press would ever hold relevance to the determination of running based
agility performance. Hence, the results offered by Mayhew et al. 249 presented no insight
in the determination of running based agility performance in sport. Conversely, a study
conducted by Behm et al.
38
examined the relationship between ice-hockey agility
performance and measures of lower extremity functional capacity measured through
isoinertial 1RM leg press strength. Behm et al.
38
observed a negative weak correlation
between ice-skating based agility performance and absolute 1RM leg press
strength (r = -.27). It should also be noted that the correlation between ice-skating based
agility performance and 1RM leg press strength remained consistent with strength
normalised to body weight (r = -.29). Therefore, the relationship between isoinertial
strength and sport specific agility performance seems limited and as a result, the transfer
between traditional weightlifting exercises and sport specific athletic skill execution
should not be assumed.
SPEED-STRENGTH CAPACITY
Speed-strength refers to the development of muscular force at high speeds and includes
factors of joint and whole body acceleration capacities 169, 278, 387, 401, 418. Throughout the
published scientific literature, weighted or resisted vertical jumping was a
common method of speed-strength assessment
between
traditional
strength
dynamometry
280, 418, 427, 431
and
. Discrepancies exist
sporting
performance
7
.
Accordingly, speed-strength testing is considered to possess the highest values of
external validity compared to other forms of strength assessment and with reference to
46
LITERATURE
REVIEW
sport specific athletic performance. Indeed, previous research has little relationship
between speed-strength and other forms of strength dynamometry
26
. Despite this,
loaded counter movement jumping has been shown to display a negative weak
correlation with 20 m straight-line running speed (r = -.47). It should be noted also that
the correlation between running speed and loaded counter movement jumping was
considerably lower than the correlation between running speed and counter
movement jumping without resistance (r = -.66). Hence, it would seem that dynamic
strength dynamometry presents limited transfer to other functional capacities.
Furthermore, the complex movement patterns and muscle contraction types required
during speed-strength exercises means that acceptable levels of measurement error can
be difficult to achieve.
The relationship between agility performance and speed-strength exhibits limited
association throughout the published research. A study conducted by Young et al.430
investigated the relationship between dynamic strength, as measured through loaded
counter movement jumping and agility performance. Measures of agility performance
were observed for side-stepping manoeuvres that required three changes of direction at
either 90° or 120° angles with reference to the directional running line
430
.
To add to this, selected agility measures also included generalised Australian Rules ball
skills as part of athletic assessment procedures. Overall, Young et al.430 demonstrated
almost no relationship between speed-strength indices and measures of agility
performance. The relationship between speed-strength and agility manoeuvres displayed
a very weak correlation at a change of direction angle of 90° (r = .01) and at a change of
direction angle of 120° (r = -.04). Interestingly, an increased correlation between
speed-strength and agility performance was observed with the inclusion of ball skills
when testing at an agility change of direction angle of 90° (r = .27), however this
correlation was low with the coefficient of determination at approximately 7 %.
The movement patterns and muscle contraction types associated with agility skill
execution differ greatly from those displayed during speed-strength exercises 99. Hence,
speed-strength measurements are poorly related to running based agility performance.
47
AGILITY
IN RUGBY UNION
MUSCULAR STRENGTH CAPACITY TRAINING
McBride et al.250 observed improvements to agility performance times following a
speed-strength intervention program. The speed-strength intervention consisted of
training groups performing weighted jump squats at either 60 % 1RM (JS30) or
80 % 1RM (JS80) squat strength. Following intervention, McBride et al.250 observed
improvements in the time to completion of an agility T-pattern test. Notably, the
improvements to agility performance times were observed with both jump squat training
groups, but not the control group. Speed-strength testing with jump squats
weighted at 30 % 1RM squat strength found that the JS30 training group significantly
increased peak power and peak velocity, whilst the JS80 training group significantly
improved peak force only. Furthermore, speed-strength testing with jump squats
weighted at 55 % 1RM and 80 % 1RM squat strength found that the JS30
significantly increased peak power, peak force, and peak velocity whereas both the
JS80 group and the control group significantly increased peak power and peak
force only. However, there were no significant differences between training groups with
respect to measures of peak power, peak force or peak velocity during speed-strength
testing protocols. It must be acknowledged that McBride et al.250 failed to provide an
appropriate explanation as to why jump squat training improved agility performances.
However, previous studies have found that neuromuscular coordination such as the
muscle contractile properties, improves expressly with the training of speed-strength
capacities
15, 37, 60, 83, 108, 168, 222, 404, 410
. Despite the poor relationships demonstrated
between speed-strength measurements and agility
430
, the improvements in
neuromuscular coordination with speed-strength training may explain the enhanced
agility performance times 250.
Conversely, Cronin, McNair and Marshall 99 found that an enhanced functional capacity
following speed-strength training did not transfer to improvements in agility
performance. The speed-strength intervention consisted of supine jump squat training
over a period of 10 weeks. Following intervention, the speed-strength training group
displayed significant improvements to measures of peak velocity, peak force, mean
power and peak power when compared to the control group. However, no differences in
agility performance times were recorded between training and control groups. Similarly,
no significant improvements in agility performance times were recorded following the
48
LITERATURE
speed-strength intervention program. Cronin, McNair and Marshall
99
REVIEW
concluded
that speed-strength training cannot improve agility performance and as such, it is
important to consider the expression of speed-strength in relation to sport specific skill
execution.
A study conducted by Deane et al.
105
provided a speed-strength training program with
consideration of the specific motor skills associated with running based locomotion.
The speed-strength training program used resisted hip flexion exercises that were
intended to replicate the recovery phase observed when running. Following
intervention, the speed-strength training group improved agility performance times as
well as straight-line sprinting speed, hip flexion strength and vertical jump
height. Furthermore, the improvements to athletic performance observed in the
speed-strength training group were significantly different to the control group.
Deane et al. 105 concluded that improvements to dynamic hip flexion can enhance sprint
and agility performances times. However, it should be noted that Deane et al.
105
sampled an untrained heterogeneous population, and also the training and control
groups did not participate concurrently in the study. Clearly, further research
investigating the affects of speed-strength training on agility performance in highly
trained athletes and rugby union players is necessary.
McBride et al.250 observed no difference between speed-strength training groups and a
control group, with respect to the time to completion of the agility assessment task.
McBride et al.250 allowed the control group to continue habitual sports specific training
programs during the intervention period. Thus, it is evident that the resistance exercises
performed by the speed-strength training groups did not improve athletic performance
beyond the adaptations observed with continued sports specific training activities. This
findings is supported by Wroble and Moxley
423
who observed no differences between
strength training and sports specific training groups with respect to measures of agility
performance time. Therefore, it is important that strength training programs consider the
application within a sports specific context and incorporate strength development
programs relating to the requirements of the sport.
49
AGILITY
IN RUGBY UNION
AGILITY AND MUSCULAR POWER CAPACITY
Power refers to the rate at which an athlete may perform work, where work is equivalent
to the speed of force application
428
. Muscular power is commonly considered as a
combination of both muscular strength and speed indices and forms a fundamental
component of performance in rugby union 249, 340. In rugby union, expressions of power
include jumping when receiving the ball from the restart, and the intense muscle
contractions of the leg musculature when tackling an opponent. The nature of power
seems to demonstrate greater external validity to sports specific athletic performance
when compared to strength.
FUNCTIONAL MUSCULAR POWER CAPACITY
Measures of power vary considerably throughout the published scientific literature,
ranging from laboratory based dynamometry to more functional sport specific
expressions of power, such as jumping exercises
38,
101,
214,
246,
285,
398,
430
.
Overall, the results from previous research suggest that a limited relationship exists
between agility performance and measures of functional power
38, 101, 214, 246, 285, 398, 430
.
Table 2.2 displays an outline of the relationship between agility performance and
measures of functional power including CMJ and broad jumping. Table 2.3 and 2.4
display an outline of the correlation between agility performance and commonly used
measures of functional power consisting drop jumping and squat jumping, respectively.
50
LITERATURE
REVIEW
Table 2.2: Summary of the correlation between agility and measures of functional
power.
Study
Results
Agility Performance
430
285
246
249
Power Capacity
r
3 x 90° side-step
CMJ
-.10
3 x 90° side-step with ball
CMJ
.30
3 x 120° side-step
CMJ
-.20
Diamond agility test
Vertical jump (dominant)
-.38
Diamond agility test
Broad jump (dominant)
-.65
Side-step
Broad jump
-.19
Shuttle run agility test
Broad jump
-.27
Slalom run agility test
Broad jump
-.12
SEMO Agility
Margaria-Kalamen Stairs
.22
CMJ – Counter movement jump
SEMO – Southeast Missouri State
51
AGILITY
IN RUGBY UNION
Table 2.3: Summary of the correlation between agility and drop jumping power.
Study
Results
Agility Performance
Drop Jump
Bilateral
r
430
432
38
Unilateral
Right
Left
r
r
3 x 90° side-step
.30
3 x 90° side-step with ball
.37
3 x 120° side-step
.15
20° side-step to left
-.50
-.51
-.29
20° side-step to right
-.65
-.71
.50
40° side-step to left
-.40
-.51
-.29
40° side-step to right
-.53
-.44
-.28
60° side-step to left
-.31
-.46
-.23
60° side-step to right
-.35
-.43
-.39
4 x 60° side-step
-.54
-.59
-.54
Time (s)
Height (m)
Ratio
-.13
-.1
-.13
Ice-skating agility test
52
LITERATURE
REVIEW
Table 2.4: Summary of the correlation between agility and squat jumping power.
Study
Results
Agility Performance
Squat Jump
Bilateral
432
246
38
Unilateral
Right
Left
r
r
r
20° side-step to left
.38
.10
-.22
20° side-step to right
.10
-.24
-.45
40° side-step to left
.33
.06
-.15
40° side-step to right
.54
.10
-.18
60° side-step to left
.30
.26
-.07
60° side-step to right
.46
.07
-.19
4 x 60° side-step
.29
.04
-.22
Side-step
-.15
Shuttle run agility test
-.35
Slalom run agility test
-.33
Ice-skating agility test
53
Height (m)
Power (W)
-.30
-.25
AGILITY
IN RUGBY UNION
A study conducted by Young, Hawken and McDonald
430
investigated the relationship
between agility performance and muscular power as measured through counter
movement jumping and drop jumping. It should be noted that measures of agility
included side-stepping manoeuvres at change of direction angles of 90° and 120° and
with three direction changes. Overall, results demonstrated a weak correlation between
agility performance and power capacity. It was shown that a negative weak correlation
existed between counter movement jumping and measures of agility performance at
both 90° (r = -.10) and 120° (r = -.20) change of direction manoeuvres.
In addition, positive weak correlations were observed between drop jumping and
measures of agility performance at both 90° (r = .30) and 120° (r = .15) change of
direction manoeuvres. Hence, muscular power as measured through jumping exercises
contributes little to the determination of agility performance.
It should be noted that Young, Hawken and McDonald
430
observed a stronger
relationship between measures of jumping power and agility performance with the
inclusion of ball skills as part of testing procedures. The addition of ball skills as part of
agility testing at 90° changes of direction brought an increase in the correlation with
counter movement jumping (r = .30). Similarly, the relationship between drop jumping
and agility performance at 90° changes of direction with ball skills observed an
increased correlation (r = .37). Hence, the addition of ball skills in agility testing seems
to enhance the relationship with muscular power indices (although the correlation is still
weak).
It was apparent also from the results presented by Young, Hawken and McDonald
430
there was a trend that as the change of direction angle decreased during agility
performance then concurrent increases were observed in the correlation with power.
For example, the coefficient of determination between drop jumping and agility
side-stepping manoeuvres at 90° changes of direction (9 %) was higher than
agility side-stepping manoeuvres at 120° changes of direction (2.25 %). In support of
this finding, Young, James and Montgomery 432 observed a coefficient of determination
of 12.25 % between drop jumping and agility side-stepping manoeuvres at a 60° change
of direction angle. It was apparent that the relationship between power and agility
performance with 60° changes of direction
432
was stronger when compared to agility
manoeuvres at 90° and 120° change of direction angles
54
430
. This supports the notion of
LITERATURE
REVIEW
an increased relationship between power and agility performance with decreases in the
change of direction angle required of skill execution. Despite this, it was evident that a
positive correlation was observed between power and agility at 60° (r = -.54) change of
direction angles, whilst negative correlations were observed between power and agility
at 90° (r = .30) and 120° (r = .15) changes of direction 430, 432.
The findings from previous research suggest a stronger relationship exists between
muscular power capacity and agility performance, with a decrease in the change of
direction angle. This notion is further supported by Young, James and Montgomery 432
who observed consistently an increased correlation between power and agility with a
decrease in the change of direction angle of a side-stepping manoeuvre. For example,
the correlations between drop jumping measures of power and agility side-stepping
performance were shown to increase between right directional change agility
side-stepping manoeuvres at 60° (r = -.35) to 40° (r = -.53) and 20° (r = -.65) change of
direction angles. However, the relationship trend between agility performance and
power as measured through drop jumping (bilateral) was not consistent when employing
single legged (unilateral) drop jumping power assessment.
In consideration of the aforementioned example, it would be logical to assume that a
direction change to the right would require a side-step off the left foot and as such,
the correlation between left foot drop jumping (unilateral) and agility performance
should increase with decreases in the side-stepping change of direction angle.
To the contrary, the relationship between agility performance and left leg power
(unilateral drop jumping) displayed inconsistent correlations when compared to the
correlation patterns observed with bilateral drop jumping. For example the correlation
between agility side-stepping manoeuvres to the right directional alignment at 60° (r = .39) decreased at 40° (r = -.28) but increased at 20° (r = -.50) change of direction
angles. These findings indicate that measures of unilateral power demonstrate an
inconsistent relationship with agility performance, when compared to measures of
bilateral power.
55
AGILITY
IN RUGBY UNION
The limited relationship between agility performance and muscular power capacity is
supported by previous research conducted by Mayhew et al.249 who examined the
relationship between agility performance and power as measured through the
Margaria-Kalamen stair run. It should be noted that the Margaria-Kalamen stair run is a
specifically designed measure of muscular power capacity where participants are
required to traverse a pre-determined flight of stairs at maximal effort
36, 267
.
Muscular power capacity is estimated as the product of body weight acting through the
vertical distance, with respect to the recorded performance time. It has been implied that
factors of speed and agility contribute to the production of muscular power during the
Margaria-Kalamen stair run
267
. In contrast, the results presented by Mayhew et al.249
observed a weak correlation between agility performance and muscular power capacity
(r = .22). In addition, an increased relationship between agility performance and
muscular power capacity was observed when power was expressed relative to body
weight (r = -.43). However the coefficient of determination was 18.49 %, indicating that
muscular power capacity holds a limited association with agility performance.
This signified that even with the consideration of body weight applied to expressions of
power capacity, the relationship between muscular power and agility performance
remained weak. It was concluded that agility performance is distinct from the physical
attributes associated with muscular power production and as such, agility is a unique
component of athletic performance 249.
MUSCULAR POWER CAPACITY TRAINING
Review of the published literature revealed a number of articles outlining methods of
muscular power training. It has been suggested that the key components of power
training should consist of the development of neuromuscular activation through high
intensity training exercises associated with improving muscle contractile properties and
skill execution
12, 37, 60, 131
. To add to this, traditional resistance training is no longer
thought to be the best method for improving functional power capacity
276
.
Consequently, training programs comprising plyometric exercises are considered the
best method of muscular power development
131
. Plyometric exercises employ the
attributes associated with the stretch-shorten muscle cycle and promotes skill
56
LITERATURE
REVIEW
development through high intensity change of direction movements
274,
409
.
Throughout the published literature, plyometric exercises are used commonly as part of
functional power training methods. Similarly, a number of studies have investigated the
affects of plyometric training and the associated development of muscular power
capacity on agility performance 132, 274. Notably, Miller et al. 274 implied that the balance
and control of body positioning associated with plyometric exercises results in
improvements to agility performance.
Miller et al. 274 examined the affects of a jumping based plyometric training program on
measures of agility performance. It should be noted that agility assessment procedures
comprised the agility T-test, the Illinois agility assessment protocol and the agility
dot-drill. The findings presented by Miller et al.
274
recorded significant improvements
in all agility assessment protocols following the muscular power intervention program.
The plyometric training group improved agility performance times by approximately
5 % for the agility T-test, approximately 3 % for the Illinois agility test and
over 10 % for the agility dot-drill. Miller et al.
274
concluded that plyometric training
improves agility performances through neuromuscular adaptations associated with high
intensity muscular power exercises.
It should be noted that Miller et al.
274
reported a trend at pre-intervention testing,
whereby the control group displayed superior agility performance times when compared
to the plyometric training group. For example, pre-intervention times for the agility
dot-drill
were
0.26
±
0.28
s
for
the
plyometric
training
group
and 0.23 ± 0.20 s for the control group. Following intervention, the plyometric training
group were shown to display significant improvements to agility performance.
However, it was apparent that the measures of agility performance recorded postintervention were similar between the plyometric training and control groups.
For example, post-intervention times to completion of the Illinois agility
were 16.6 ± 1.6 s for the plyometric training group and 16.5 ± 0.9 s for the control
group. It is suggested that differences existed in relation to athletic performance
between the plyometric training and control groups prior to the implementation of the
intervention program. Therefore, the results presented by Miller et al.
274
indicated that
plyometric training may enhance agility performance within heterogeneous samples or
untrained individuals.
57
AGILITY
IN RUGBY UNION
It is questionable whether generalised power training such as demonstrated with
plyometric exercises would improve agility performance in homogenous samples of
trained athletes. This notion is supported by Wilkerson et al.
410
who found no
improvement to measures of agility performance following plyometric training.
The lack of improvement to agility performance was in contrast to concurrent
improvements to measures associated with lower extremity muscular power capacity
following the plyometric intervention program. The contribution of the muscular power
capacity to athletic performance is highly specific to the physiological and
biomechanical components associated with skill execution
131
. Previous research has
noted that the association between complex expressions of power and athletic
performance capacity vary among athletes because of deviating physiological and
biomechanical interactions during skill execution
378
. Hence, training programs
involving complex skill execution such as plyometric jumping exercises improve
muscular power capacity but do not facilitate the specific development of
neuromuscular activation and muscle contractile properties important during agility skill
execution.
AGILITY AND SPEED CAPACITY
Speed refers to measures of displacement with respect to time during running based
locomotion. The functional capacity of speed is a fundamental component of sports
displaying high-intensity activity patterns
25
. Similarly, straight-line running speed is
vital to effective performance in team field sports such as rugby union
40, 348, 349, 402
.
There are two specific distinctions relating to the expression of straight-line running
speed, namely acceleration and maximum speed. Straight-line acceleration capacity
refers to the change in velocity over a set period
228
, while maximum speed capacity
refers to the highest running velocity that an athlete may reach (sprinting)
228, 428
.
Little and Williams 228 noted that the mechanical and physiological similarities between
running based agility performance and the running speed capacities of acceleration and
maximum speed have lead to assumptions of generality. However, the review of the
literature revealed limited transfer between measures of agility performance and the
58
LITERATURE
REVIEW
straight-line running speed capacities. Table 2.5 presents an outline of the correlation
between agility performance and speed consisting of acceleration and maximum
running speed capacity.
There are distinct modifications observed when comparing technique during the
acceleration and maximum speed phases of straight-line running. The biomechanics
associated with acceleration are characterised by the athlete displaying considerable
forward trunk lean
355
. The position of the upper body during the acceleration phase
promotes anterior instability with reference to the foot placement patterns and as such,
assists in the forward running motion
68, 267, 343
. To add to this, rapid stride rates and
swift arm swing actions also occur during the acceleration phase when running
268, 340
.
In comparison, athletes running at maximum velocity typically demonstrate
characteristics of longer stride lengths resulting in increased relative ground contact
times
340
. In addition, an upright posture is associated with maximum speed running
technique. Importantly, during both the acceleration and maximum speed phases of
straight-line running, lateral movements of the body segments are considered to be
inefficient 130.
It is important to note the fundamental differences between running skill execution in
rugby union and straight-line sprinting performance. Straight-line sprinting is
considered a closed skill involving predictable and planned movements as observed
during athletic events
433
. It is well documented that 100 m track sprinters take
between 40 m and 70 m to reach maximum running velocity
9, 107
. In contrast, the
average sprinting distance for rugby union athletes during a single bout of running
based activity is approximately 30 m, with athletes needing to maximise velocity within
this distance 40, 130, 149, 206, 319, 348, 349. In addition, the demands of rugby union match-play
such as defensive patterns and the movements of the ball mean that athletes frequently
display non-linear running patterns during acceleration and maximum speed running
bouts. Evidently, expressions of speed are unique to the observed sporting situation and
as such, universal models of running performance are impractical.
59
AGILITY
IN RUGBY UNION
Table 2.5: Summary of the correlation between agility and straight-line running speed.
Study
Results
Agility Performance
Speed Capacity
Acceleration
Maximum Speed
r
r
.50
.46
249
SEMO Agility
38
Ice-skating agility test
-
.32
430
3 x 90° side-step
-
.27
3 x 90° side-step with ball
-
-.02
3 x 120° side-step
-
.19
3 x 100° side-step
.35
.46
228
SEMO – Southeast Missouri State
Agility skill execution requires significant alterations to straight-line running gait such
that the running mechanics are dissimilar
433
. Despite this, running speed is
fundamentally determined fundamentally by the interaction between various
physiological and biomechanical factors. Conventions outline that running speed is a
product of stride length and stride rate and is also based on the interaction between
intricate stance kinematics
115, 343, 358
. Previous research has observed an inverse
relationship between stride length and stride rate 194. During sprinting efforts, elite track
sprinters have been shown to demonstrate large increases to stride length and concurrent
decreases
in
60
LITERATURE
REVIEW
stride rate 9. In contrast, it has been documented in rugby union that excessively long
strides reduce the effectiveness of agility skill execution 40, 348, 349. Therefore, stride rate
is an important component of running ability in team sports and especially agility skill
execution. It is recommended that athletic training programs aim to increase stride
frequency in athletes competing in multidirectional team sports such as rugby union.
MAXIMUM RUNNING SPEED CAPACITY
Maximum speed running activity has been shown to contribute a small portion of the
total distance covered during rugby union match-play 122. Despite this, maximum speed
running activity can contribute to crucial phases of play that result in scoring
opportunities. In team sports, maximum speed is typically measured over distances
25, 82, 108, 216, 305
between 20 m and 40 m
. It has been noted that the dynamic movements
of sprinting resemble the high muscular activity required of power exercises
216
.
However, measures of maximum speed capacity have demonstrated non-significant
weak correlations with both muscular strength and functional power indices
25, 216, 305
.
This finding supports the notion that running ability is specific to the exercise and
sporting context.
The review of literature examining the relationship between maximum straight-line
running speed and agility performance observed little transfer between the
two skills
228, 249, 370, 430
. A study conducted by Little and Williams
228
measured the
relationship between maximum straight-line running speed using a 20 m sprint and
agility
performance.
Agility
performance
was
measured
using
a
zigzag
running protocol which required four 100° changes of direction over 20 m.
Little and Williams
228
observed a weak correlation between agility performance and
maximum straight-line running speed (r = .45). Similarly, Mayhew et al.249
demonstrated weak correlations between agility performance and straight-line running
speed over 40 yards (36.58 m) (r = .46). This was supported by Young, Hawken and
McDonald
430
who found weak correlations between 20 m straight-line running speed
and agility performance under two conditions consisting three 90° changes of
direction (r = .27) and three 120° changes of direction (r = .19). The published research
61
AGILITY
IN RUGBY UNION
has been observed consistently poor relationships between agility performance and
maximum straight-line running speed and as such, adds weight to the notion that agility
is a unique skill, somewhat independent to running speed.
The inclusion of sport specific factors as part of agility testing diminished the
relationship with straight-line maximum running speed. Young, Hawken and
McDonald
430
included Australian Rules ball skills as part of agility testing procedures
consisting three 90° changes of direction. Results demonstrated almost no relationship
between straight-line maximum running speed and agility performance with ball
skills (r = -.02). Behm et al.
38
also demonstrated the distinction between straight-line
maximum running speed and sports specific agility performance. Behm et al.
38
observed a weak correlation between 40 yards (36.58 m) running speed (not held on ice)
and an agility assessment protocol held on ice (ice-hockey agility) (r = .32).
Therefore, the inclusion of sport specific performance parameters as part of agility
assessment procedures means that almost no relationship exists with straight-line
maximum running speed.
In addition, athletic performance is modified with the inclusion of sport specific skill
execution as part of athletic assessment procedures. Young, Hawken and McDonald
430
observed that the relationship between straight-line sprinting with and without the
execution of sports specific ball skills demonstrated a 36 % coefficient of determination.
Similarly, the relationship between agility performance with and without the execution
of sports specific ball skills demonstrated a 41 % coefficient of determination.
Hence, carrying a ball when running appears to be a different skill to running without a
ball. This notion is supported by Grant et al.161 who examined how three methods of
ball
carrying
influenced
20
m
sprinting
speed
in
rugby union
athletes.
It was demonstrated that running with a rugby ball in both hands (2.62 ± 0.16 s) lead to
the greatest decrement in maximum speed capacity, when compared to running without
a ball (2.58 ± 0.16 s) and running with a ball under either the right
arm (2.60 ± 0.16 s) or the left arm (2.61 ± 0.17 s) 161.
To add to this, a study conducted by McLean et al.
258
examined the affects on agility
performance with the inclusion of sports specific demands, expressed with the inclusion
of a simulated defensive opponent. Overall, results observed significant differences in
62
LITERATURE
REVIEW
lower extremity biomechanics with the addition of a simulated defensive opponent
during agility testing, when compared to trials without an opponent
258
. These findings
hold important implications with regards to the specificity of athletic performance
assessment protocols involving measures of agility performance. In rugby union,
running based agility performance contributes an imperative component during
match-play conditions. Therefore, it is important that agility assessment protocols
reflect the specific nature of athletic performance within the competitive sporting
environment.
ACCELERATION CAPACITY
Running capacities associated with acceleration speed are thought to contribute more to
the determination of athletic performance in multi-directional sports than maximum
running speed
25, 100
. Running based acceleration speed was typically over 10 m
distances throughout the published scientific literature 25, 82, 106, 216. In general, measures
of acceleration have demonstrated weak correlation with muscular strength
and power
25, 216
. To add to this, Baker and Nance
25
observed a common
variance of 52 % between acceleration and maximum speed running. This suggests that
there are unique physiological and biomechanical factors that contribute to acceleration
and maximum speed running performances. This finding supports the notion that
running ability is specific to activity patterns and sporting context. In addition, it would
be expected that the relationship between acceleration capacities and agility
performance would reflect the specificity of skill execution.
The literature review observed poor relationships between running based straight-line
acceleration and agility performance 228, 249, 370, 430. Little and Williams 228 measured the
interrelationships between acceleration speed over 10m and agility performance
measured with the zigzag test. The relationship between agility performance and
acceleration speed demonstrated a weak correlation (r = .35). In support of this finding,
Mayhew et al.249 observed a weak correlation between agility performance and
straight-line acceleration over 10 yards (9.14 m) (r = .50). The correlation between
agility performance and acceleration are slightly stronger than those observed
63
AGILITY
IN RUGBY UNION
between agility and maximum running speed. However, the common variance between
agility performance and acceleration speed remains limited. Therefore, the relationship
between running based acceleration speed and agility seems limited and as a result,
it can be concluded that different physiological and biomechanical factors contribute to
the determination of athletic performances involving these expressions of running based
locomotion.
SPEED CAPACITY TRAINING
Training programs designed to enhance running speed capacities are a common
component of many athletic development programs. In rugby union, speed development
programs typically involve repeat-efforts of straight-line sprinting through a range of
distances that elicit both acceleration and maximum speed capacities. To add to this,
speed training exercises involving external loading are used commonly to increase
acceleration capacities and represent the resistance that may be observed when in
contact with a defensive opponent during attacking ball carries in rugby union.
Similarly, the review of the published literature observed that straight-line running
interventions commonly compared unresisted and resisted speed development
programs
107, 157, 249, 314, 410
. It is important to note that the majority of sports
development programs as well as the published scientific literature utilised generalised
straight-line speed development programs. It would be a mistake to assume transfer to
improved sports specific performance as a result of the adaptations observed through
generalised speed training, such as the increase in stride rate when performing resisted
straight-line sprints
231, 434
. Notably, there is a lack of published research that has
considered sport specific running ability as part of speed development programs.
Despite this, it has been outlined previously that speed training programs should be
implemented with consideration of the sports specific activity patterns 340.
Running based agility performance involves rapid bursts of high intensity activity and
as such, utilises anaerobic capacities similar to maximal effort straight-line running
speed
46, 58, 94, 206, 265, 296, 329
. The apparent relationship between the anaerobic energy
system and both agility performance and straight-line running speed has resulted in
64
LITERATURE
REVIEW
inaccurate assumptions, whereby straight-line speed training is associated frequently
with the training of agility performance
30, 153, 296
. It is true that the utilisation of
anaerobic capacities during straight-line speed training often contain elements common
to agility performance
275
. However straight-line speed training should not assume to
develop athletic performances associated with agility skill execution. In support of this
notion, Young, McDowell and Scarlett
433
observed no improvements to agility
performance following a period of straight-line speed training. Similarly, Young,
McDowell and Scarlett 433 found that agility training programs do not improve straightline running speed. Therefore, the implementation of running based agility and straightline speed training programs observes unique physiological and biomechanical
adaptations.
Speed, agility and quickness (SAQ) intervention programs have now become a popular
training method throughout sport
53
. Agility training methods and the associated
equipment has now become a commercial product as observed with the promotion of
the SAQ® program. Existing agility training methods regularly incorporate numerous
apparatus and drills, including; ladder drills, cone hops, hurdle runs and
pattern running
160, 334
. Whilst it has been found that the implementation of specific
SAQ training programs can enhance agility performance 316, these programs (especially
the commercial products) can present generalised models of agility performance and fail
to consider the sport specific nature of agility skill execution 53. Although SAQ training
methods may increase the general ability to perform required athletic tasks, they do not
allow for motor skill development relating to the expression of agility performance
within specific sporting contexts 244.
SUMMARY: AGILITY PERFORMANCE AND
FUNCTIONAL CAPACITIES
The review of the literature revealed that the physiological factors associated with
muscular strength, functional power and straight-line running speed have limited
transfer of agility. The evidence presented throughout the published scientific literature
also suggest that whilst the training of muscular strength, functional power and straight65
AGILITY
IN RUGBY UNION
line running speed has benefits for the competitive athlete, the premise that training
such capacities will directly transfer to improvements in specific sporting performance
is misconceived. Handcock173 noted that many rugby union athletes often become
entranced with straight-line sprinting drills, weight-room strength exercises and
non-specific power training, with little consideration given to the transfer of such
activities to athletic performance in rugby union. It is accepted that the training of
strength, power and straight-line speed, should contribute an essential portion of athletic
development during a training cycle
428
, but should not precede the training of crucial
skills such as agility.
66
LITERATURE
REVIEW
BIOMECHANICS OF
AGILITY SKILL EXECUTION
BIOMECHANICAL ASSESSMENT
The lack of research that has considered the key determinants of agility in open skilled
sports is emphasised when considering the biomechanics of agility skill execution in
rugby union. To date, no published scientific studies have explored the biomechanical
determinants of agility performance in rugby union. This is despite coaches outlining
the fundamental nature of agility skill execution contributing to effective running ability
in rugby union
348
. Alternatively, the available scientific literature examining the
biomechanics of rugby union has focused on quantifying relatively closed skills, such as
the forces associated with the scrum
321, 424
or the technique of lineout throwing
350, 389
.
This focus on closed skill quantification has meant that the biomechanical determinants
of skills associated with successful performance in sports such as rugby union have
remained speculative
32
. Consequently, it is critical that future research examines the
open skills relating to the determination of performance in rugby union.
CLASSIFICATION OF STEPPING STRATEGIES
To achieve a change in direction during agility manoeuvres, a certain amount of existing
momentum is combined with a lateral impulse to alter the pattern motion
215
.
Hence, the kinetic interaction between the stance limb applying force (centrifugal force)
to the ground (centripetal force) produces a change in the directional alignment (lateral
movement). Further consideration of the interaction between movements and the
associated ground reaction forces highlights the various techniques that can generate
lateral movement (e.g. side-stepping and crossover-stepping strategies).
67
AGILITY
IN RUGBY UNION
A number of studies have examined the difference between side-stepping and
crossover-stepping strategies. Notably, temporal parameters demonstrated during
reactive agility testing conditions showed that the mean change of direction angle
when using a crossover-step (11.6 ±
side-step (25.5 ± 5.2˚)
325
6.1˚) was considerably less than the
. This was supported by Ohtsuki, Yanase and Aoki
300
who
found that employing a side-stepping strategy allowed for a greater change of direction
angle during agility manoeuvres, compared to the crossover-step. It should be noted that
the change of direction angle was limited to 45˚ when measuring the crossover-step
during agility assessment procedures reported throughout the published literature
43, 96
.
In contrast, change of direction angles greater than 90˚ were employed commonly when
measuring side-stepping agility performances
228, 430, 433
. This implies that the
crossover-stepping strategy limits the change of direction angles that may be achieved
during agility skill execution. In rugby union, it is possible that the crossover-step
is executed away from congested play, such as when counter-attacking an unstructured
defensive line following an opposition kick. In contrast, the side-stepping strategy may
provide a flexible method of evasive attack during several circumstances in rugby
union, especially when attacking a structured defensive line.
It is also possible that the greater direction change angles observed during side-stepping
performances are associated with a concurrent reduction to running speed. Investigation
of the change in running speed demonstrated that the side-stepping strategy allowed for
less overall speed
crossover-step
300
reduction during agility manoeuvres,
compared to the
. It was revealed that the mean running speed at change of direction
foot contact was greater when side-stepping (4.99 ±
crossover-stepping (4.57 ± 0.41 m.s-1)
325
0.70 m.s-1) compared
. However, despite comparable running
speeds at the step prior to direction change (side-stepping 4.69 ± 0.45 m.s-1 and
crossover-stepping 4.64 ± 0.39 m.s-1), the running speed following the change of
direction step was found to be less when side-stepping (4.85 ± 0.53 m.s-1) compared to
crossover-stepping
(5.03 ± 0.67 m.s-1)
325
. A study of agility manoeuvres under
walking conditions observed significant increases in both braking forces and
mediolateral forces when side-stepping compared to crossover-stepping
188
. It is
accepted that agility skill execution observed when walking holds little relevance to
high speed manoeuvres. However, the available literature has indicated that the
execution of a side-step agility manoeuvre demands greater manipulation of running
68
LITERATURE
speed when compared to the crossover-stepping strategy
325
REVIEW
. Clearly, further research
should examine measures of running speed with respect to the associated ground
reaction forces during side-stepping and crossover-stepping agility manoeuvres.
The directional change characteristics of side-stepping and crossover-stepping indicate
that the rotational components of the lower limb will differ between the respective
stepping strategies. For example, a study conducted by Andrews et al.16 noted that the
pelvis internally rotated and the femur externally rotated during the direction change
step of a side-stepping manoeuvre. Conversely, external rotation of the pelvis and
internal rotation of femur were observed during the direction change step of a
crossover-stepping manoeuvre
16
. The kinematic components exhibited through the
respective stepping strategies would no doubt contribute to the determination of agility
performance. However, a lack of published research has discussed the kinematic
components of the agility stepping strategies with reference to athletic performance
enhancement. In general, the research examining the kinematics of agility manoeuvres
has focused on the potential for injury as a result of lower limb rotational moments
when changing directions 39, 43, 45, 90, 96, 102, 175, 188, 199, 239, 256, 257, 259, 287, 295, 315, 325, 356, 364.
The functional movements of the knee has been identified as an important factor in both
side-stepping and crossover-stepping strategies, whereby the knee absorbs the ground
reaction forces and torsional moments associated with directional change
189, 195, 241
.
Notably, EMG studies have found that side-stepping displayed greater integrated
quadricep muscle activation despite comparable knee angles during stance, compared to
the crossover-stepping
239
. In addition, quadricep activation has been found to decline
earlier during stance when crossover-stepping compared to side-stepping. It was also
shown that quadricep activation declined during the early stages of stance when
crossover-stepping and during the latter stages of stance when side-stepping.
The increase in quadricep activation during stance when side-stepping suggests that the
ground reaction forces and joint moments associated with directional change requires
greater stabilisation when compared to crossover-stepping.
In addition, hamstring activation has been found to be greater during the latter stages of
stance when side-stepping, compared to crossover-stepping
239
. The magnitude of the
peak integrated hamstring activation was approximately 60 % maximal voluntary
69
AGILITY
IN RUGBY UNION
contraction (MVC) when crossover-stepping. In comparison, a greater magnitude of
peak integrated hamstring activation (~ 80 % MVC) was observed when
side-stepping (Figure 2.15). Also, the peak hamstring muscle activation observed when
side-stepping was comparable to the respective measure reported during straight-line
running conditions. Research has emphasised the importance of the hamstring muscle
group in facilitating propulsion when running
195, 196, 242, 354
. It is possible that the high
hamstring activation during the latter stages of stance when side-stepping suggests a
desire to accelerate. In rugby union, a greater acceleration capacity when side-stepping
may promote the ability to penetrate the defensive line and advance the ball beyond the
advantage line during attacking ball carries in rugby union.
The lower limb biomechanics associated with the agility stepping strategies are an
important
consideration
when
examining
running
ability
in
rugby
union.
The side-stepping strategy involves an increase to lateral foot placement during stance
and with the swing leg moving laterally to the subsequent step
16
. The movements
associated with the side-stepping strategy function to increase the base of support and as
a result, would enhance the properties of dynamic stability
348
. Conversely, the
crossover-stepping strategy involves a decrease in lateral foot placement during stance
and with the swing leg moving medially to the subsequent step
16
, and would diminish
the properties of dynamic stability 348. In rugby union, dynamic stability is an important
consideration when resisting contact with an opponent, as increases to dynamic stability
improves running ability
348
. However, crossover-stepping should not be overlooked as
a valuable evasive strategy in rugby union when executed under appropriate conditions.
Importantly, side-stepping provides a critical component of effective performance
during evasive attacking manoeuvres in rugby union. Accordingly, the current literature
review will focus on the biomechanical components of agility performance with
reference to agility side-stepping manoeuvres. The current literature review will discuss
the mechanics of the side-step in comparison to straight-line running and
crossover-stepping. There is no doubt that agility is a fundamental element of
performance in sports such as rugby union. It is recommended that future research
considers the specific nature of agility movement strategies, and then describes the key
biomechanical determinants of performance.
70
LITERATURE
REVIEW
90
80
Muscle Activation (%MVC)
70
60
50
40
Straight-line
Side-step
Crossover-step
30
0
50
100
Stance Time (%)
Figure 2.15: Representation of the integrated hamstring activation patterns during the
CD stance.
(Adapted from Malinzak et al. 239)
71
AGILITY
IN RUGBY UNION
AGILITY GAIT CYCLE
The execution of an agility manoeuvre requires significant alterations to conventional
straight-line running gait
325
. It has been suggested that gait patterns exhibited during
the execution of an agility manoeuvre possess unique characteristics to other forms of
running based locomotion
259
. Despite this, frequently the published scientific research
investigating the biomechanics of agility performance has presented a limited view of
the
agility
gait
direction step
cycle,
focusing
exclusively
on
the
initial
change
of
16, 43, 90, 96, 102, 126, 190, 199, 208, 239, 256, 259, 287, 294, 300, 308, 315, 325, 356
.
Accordingly, there is a lack of in-depth scientific research expressly describing the
events prior to and following the initial change of direction step. This lack of
comprehensive research has meant that the complete agility gait cycle has remained
undefined.
The complexity of movement patterns required during agility skill execution means that
it is important to divide the skill into the respective performance phases.
Common naming conventions exist in straight-line running such that a definitive
definition of the gait cycle and the associated stride and stance phase characteristics has
been outlined 77, 78, 304. In contrast, no common naming conventions exist with regards to
the gait parameters constituting agility skill execution. In defining the generalised
characteristics of the agility gait cycle it is possible that similarities may exist with
straight-line running. However, it would be a mistake to assume that the gait
components of straight-line running would directly transfer to running based agility skill
execution.
In straight-line running, the fundamental components of the stride phase consist
of contact (stance phase) and non-contact (swing phase) descriptors
304,
352
.
It should be noted that despite inter- and intra-subject variability during straight-line
stride phases
33, 420
, the naming structure of the stride components remains consistent
due to the common characteristics of motion
304
. In comparison, agility skill execution
requires the manipulation of momentum to produce a change in direction and as such,
considerable variations to motion as well as modifications to movement patterns would
be observed during the agility gait cycle. A comprehensive model of agility
performance would need to consider the events before, during and after direction
72
LITERATURE
REVIEW
change (Figure 2.16). Accordingly, it is proposed that the agility gait cycle displays
five distinct stride phases, consisting of the pre-change of direction (PRECD),
change
of
direction
(CD),
transition
(TRANS),
straighten
(ST)
re-acceleration (POSTCD) phases.
POSTCD PHASE
ST PHASE
TRANS PHASE
CD PHASE
PRECD PHASE
Figure 2.16: Transverse plane representation of the complete agility gait cycle.
73
and
AGILITY
IN RUGBY UNION
Importantly, the proposed model of the agility gait cycle can be modified to represent
various characteristics of skill execution. For example, agility manoeuvres may display
a pattern of initial direction change followed by a subsequent straightening of the
directional alignment (Figure 2.16). In this case the complete agility gait cycle will be
observed as part of skill execution. Conversely, a modified agility gait cycle without the
TRANS and ST phases, would be observed in the case of a single direction change with
a continuation through the adjusted running alignment (Figure 2.17). It was apparent
throughout literature review that the biomechanical analyses of agility performance
were limited to a direction change and continuation through the adjusted running line.
POSTCD PHASE
CD PHASE
PRECD PHASE
Figure 2.17: Transverse plane representation of a single direction change agility gait
cycle.
74
LITERATURE
REVIEW
AGILITY PRE-CHANGE OF DIRECTION PHASE
The PRECD phase represents the initial modifications of typical straight-line running
patterns in the events leading up to the agility CD step 16. The role of the PRECD phase
is to reduce running speed in preparation for a change in running direction and as such,
the PRECD phase presents as a central component in facilitating a controlled CD step 16.
Examination of the scientific literature revealed that Rand and Ohtsuki 325 was the only
published study to have considered stride components of the PRECD phase.
The remaining published studies that considered the biomechanics of the PRECD phase
have described preliminary joint positioning during the swing phase preceding CD-FS,
whereby it has been shown that the knee will extend during the later stages of the swing
phase until CD-FS
16, 325
. There is no doubt that the PRECD phase provides preliminary
gait alterations that present as crucial components of agility skill execution.
Andrews et al.
16
noted that the PRECD phase is characterised by preliminary
deceleration of VELHORZ in preparation for the CD step. This necessary reduction to
running
speed
running gait
16
requires
considerable
alteration
of
conventional
straight-line
. The deceleration of VELHORZ is possibly linked with an increase
to LDHORZ (foot positioned anterior to the centre of gravity) at PRECD-FS (Figure 2.18).
It has been demonstrated previously that horizontal braking forces that reduce running
speed are associated with increases to LDHORZ
54, 89, 196, 218, 267, 271
. In conventional
straight-line running, over-striding (increases in positive LDHORZ) is discouraged
because of the associated negative affects on running speed
270,
345,
416
.
In contrast, preliminary deceleration of VELHORZ is a desirable feature of the PRECD
phase to facilitate controlled movements during subsequent phases of the gait cycle.
This may also explain the increase in LDHORZ presented commonly by many team sport
athletes
348, 349
. Consequently, an increase in positive PRECD-LDHORZ represents
purposeful movement adjustments that results in the necessary reduction to running
speed.
75
AGILITY
IN RUGBY UNION
PRECD-LDHORZ
Figure 2.18: Sagittal plane representation of PRECD-LDHORZ.
It is important to note that an investigation conducted by Ohtsuki, Yanase and Aoki
300
found that those participants displaying faster performance capacities did so with less
reduction to running speed through an agility manoeuvre. Therefore, it is reasonable to
assume that faster agility performances are achieved with less reduction to running
speed during the PRECD phase. In the same sense, faster agility performers may possess
superior attributes associated with dynamic stability observed with greater initial
running speeds during the PRECD and CD phases. Despite this, there is a lack of
published research examining velocity change in the events preceding the CD phase and
the relationship with measures of agility skill execution.
Inter- and intra-subject variability of step patterns may exist during the PRECD phase,
such that comparable temporal and biomechanical outcomes are observed with different
stepping strategies. For example, a number of steps with short stance duration
(representing an alteration of conventional straight-line running gait) may be utilised
during the PRECD phase. Training rapid-multiple step patterns is common practise in
rugby union, where development programs aim to increase the reactive propulsive
properties of athletes prior to direction change and in response to the movements of
76
LITERATURE
opponents
23
REVIEW
. Alternatively, a single step may be employed during the PRECD phase,
whilst still achieving a similar PRECD phase outcome when compared to applying many
steps. In comparison to multiple PRECD steps, the single PRECD step pattern would no
doubt present less propulsive options in reaction to the movements of opponents.
Consequently, training programs focusing on rapid step patterns would improve agility
skill execution such that athletes would display shorter and more rapid step patterns
prior to changing directions.
It is important to consider the step patterns of agility skill execution with reference to
the requirements of sporting performance. Rand and Ohtsuki
325
examined the stance
times exhibited during agility manoeuvres performed at maximal effort and at angle of
approximately 45˚. During planned side-stepping agility manoeuvres, an increase in the
PRECD stance time (0.17 ±
0.20 s) was observed when compared to the
respective step during straight-line running (0.16 ± 0.17 s). This increase in
stance
time
was
also
associated
with
a
decrease
in
running
speed
during the PRECD phase (4.64 ± 0.36 m.s-1), when compared to straight-line
running (4.83 ± 0.58 m.s-1). It is proposed that the reductions to running speed
observed during the PRECD phase are a result of an enhanced capacity to apply braking
forces, which is promoted with increases to PRECD stance times 325.
Interestingly, during the PRECD phase of unplanned side-stepping agility manoeuvres a
decrease in stance time (0.16 ± 0.22 s) has been observed when compared to planned
side-stepping (0.17 ± 0.20 s), whilst displaying comparable measures in running
speed (4.69 ± 0.45 m.s-1 and 4.64 ± 0.36 m.s-1, respectively)
325
. The stance times
during the PRECD phase of unplanned side-stepping manoeuvres were also shown to be
comparable to the respective stance times of straight-line running (0.16 ± 0.22 s
and 0.16 ± 0.17 s, respectively). This finding suggests that during unplanned
side-stepping manoeuvres a reduction to running speed occurs during the PRECD phase
that may be independent of stance time. It is concluded that the reductions in running
speed during unplanned agility manoeuvres occur as a result of increased horizontal foot
displacements during the PRECD phase.
The increase in PRECD stance times during side-stepping agility manoeuvres as
observed by Rand and Ohtsuki 325, seem unrelated to reductions in VELHORZ during the
77
AGILITY
IN RUGBY UNION
PRECD phase. Alternatively, it is proposed that side-stepping performances with
increased PRECD stance times demonstrate altered properties of lateral movement prior
to the CD step. Undoubtedly, prior knowledge as to the intended directional
re-alignment
permits
enhanced
properties
of
lateral
movement
during
the PRECD phase. Despite this, an increase in PRECD stance time when side-stepping
would allow for an enhanced capability for preliminary motion redirection. This notion
is supported by research that has shown during the PRECD phase the trunk and
hips
will
rotate
towards
the
intended
side-stepping
direction
16,
325
.
Therefore, it would seem that a central component of the PRECD phase consists
of the ability to generate lateral movement in anticipation of the CD step.
Moreover, it is proposed that the speed of agility performance is enhanced with an
increase to lateral movement during the PRECD phase.
It would be expected that increases in lateral foot placement patterns would facilitate
greater
rates
of
preliminary
lateral
movement
during
the
PRECD
phase.
Unfortunately, no published studies have reported the interaction between lateral
velocity profiles and lateral foot displacement. Notably, changes in movement are
caused by an external impulse whereby the resultant ground reaction force will be a
vector sum of the existing velocity and the imparted velocity 215. In should be noted that
an increase to lateral foot position has been observed during side-stepping manoeuvres
when compared to straight-line running
208
. In addition, previous research has
demonstrated an increase in ground reaction forces with an increase to foot
displacement patterns during the stance phase of running
54, 89, 196, 218, 267, 271
.
Therefore, variations in foot placement patterns can be used to manipulate ground
reaction forces and produce a redirection of movement. It is proposed that during the
PRECD phase, greater lateral movement is associated with an increase to lateral foot
displacement during stance.
It is also important to discuss the biomechanics of deceptive movement patterns relating
to factors associated with the psychological refractory period, observed during the
PRECD phase of agility manoeuvres in rugby union. The psychological refractory period
refers to the limited capacity of the central nervous system to process rapidly several
stimuli presented in succession
262
. During attacking manoeuvres in rugby union,
ball carriers will often exhibit faking movements that provide additional stimuli to
78
LITERATURE
REVIEW
deceive defensive opponents as to the intended direction change. It has been
demonstrated that accurate visual search strategies and advance cue recognition can
predict movements and determine performance in field sports such as soccer 177, racquet
sports such as badminton and tennis
6, 159, 365
and hitting sports such as baseball
359
.
In presenting deceptive movements patterns during the PRECD phase of an agility
manoeuvre, an attacking ball carrier attempts to limit the visual cues offered to the
defence prior to initiating an evasive CD step. PRECD faking actions are intended to
disrupt opponent decision-making and present flaws in defensive strategies, thus
enhancing the ability to evade defensive opponents. There is no doubt that the
movements associated with PRECD faking would alter kinematic observations.
Accordingly, it is recommended that future research examine the variations in agility
performance when attacking ball runners attempt to deceive defensive opponents prior
to changing directions.
AGILITY CHANGE OF DIRECTION PHASE
The CD phase represents the critical stance component of the agility gait cycle.
It is apparent that the CD phase presents as the primary component of movement
redirection during the agility gait cycle, producing a shift from horizontal to lateral
movement (Figure 2.19). To achieve movement redirection the CD stance times
will increase when compared to conventional straight-line running gait
325
.
Increases to the lateral displacement of the stance foot will promote the development of
lateral movement during the CD phase (Figure 2.20). This will be associated with an
increase to CD-LDHORZ to decrease VELHORZ and facilitate a controlled side-stepping
agility manoeuvre.
79
AGILITY
IN RUGBY UNION
CD Step
Figure 2.19: Transverse plane representation of the agility CD phase.
80
LITERATURE
REVIEW
It has been shown that the mean CD stance times (0.29 ± 0.34 s) during a 45˚ side- step
are
greater
than
the
sprinting (0.12 ± 0.10 s)
stance
194, 287
times
observed
when
straight-line
. Notably, in national representative female track
sprinters, mean stance times have been reported as low as 0.11 ± 0.11 s
A study conducted by Rand and Ohtsuki
325
89
.
compared stance times between
side-stepping, straight-line running and running and stopping tasks. The CD stance
time (0.19 ± 0.20 s) was observed to increase by approximately 20 % when compared
to straight-line running (0.15 ± 0.15 s)
325
. In addition, greater stance times were
observed during the final stance phase when running and stopping (0.21 ± 0.60 s)
compared
to
both
side-stepping
manoeuvres
and
straight-line
running
325
.
The manipulation of linear velocity to produce a redirection of movement no doubt
results in a considerable increase to stance times associated with direction change
during running based locomotion.
The agility CD phase represents the primary focus of research throughout the published
literature. However, it is necessary to sub-divide the CD stance phase to gain a
comprehensive understanding of the kinematic variations that promote lateral
displacement during the agility gait cycle. Previous research has attempted to sub-divide
the CD stance phase of the agility gait cycle, but has been confounded by insufficient
definitions that have disregarded the total CD stance time 43. For example, Besier, Lloyd
and Ackland
43
stated that the CD stance phase components consisted of weight
acceptance from CD-FS to the first peak GRFVERT, peak push-off measured
10 % either side of the second peak GRFVERT, and final push-off during the final 0.35 s
of CD stance. In straight-line running, conventions outline that the stance phase be
divided into three components, consisting of initial impact at foot contact and
absorption through midstance followed by propulsion until toe-off
103, 304, 402
.
It is proposed that the CD stance phase be defined with respect to the stance model
presented within straight-line running conventions.
81
AGILITY
IN RUGBY UNION
CD-LDLAT
Figure 2.20: Frontal plane representation of CD-LDLAT.
AGILITY CHANGE OF DIRECTION IMPACT PHASE
The impact stance phase refers to the events associated with initial foot contact during
the agility CD step. It has been suggested that the impact stance phase constitutes
approximately 20 % of the agility CD stance time
356
. In straight-line running,
the impact phase is measured from the point of initial ground contact until
the first vertical ground reaction force peak
304
. Similarly, the CD impact
stance phase has been measured from the point of initial ground contact until the first
vertical force peak (Figure 2.21)
356
. The first vertical impact peak has been shown to
occur between 0.38 s and 0.44 s after initial ground contact during side-stepping agility
manoeuvres 39. Associated peak vertical forces (GRFVERT) during the impact phase have
been observed to be greater than 20 N.kg-1
39, 356
. This represents a ground reaction of
force of between 2 and 3 body weights (BW) occurring during the CD impact
82
LITERATURE
stance phase
39, 96
REVIEW
. Compared to other functional movements, the magnitude of the
reported CD impact forces are greater than those experienced at impact of a vertical
drop-jump
96
, but comparable to impact from a standing broad jump for distance
10
.
Interestingly, the vertical forces during CD impact stance are less than dynamic
landings in netball, where the vertical impact forces have been reported to range
between 3.53 and 5.74 BW
303
. Hence, the forces associated with the CD impact phase
represent a considerable pattern of loading.
A number of studies have utilised in-shoe pressure measurements to quantify the
patterns of pressure distribution over the stance foot during the CD phase of agility
side-stepping manoeuvres
126, 322, 323, 364, 422
. Eils et al
126
demonstrated that the mean
peak pressure at the medial heel was 655 ± 145 kPa and 489 ± 489 kPa at the lateral
heel during CD impact stance phase. This represents 15.9 ± 3.6 % and 11.3 ± 3.0 %
of the total loads experienced through the CD stance phase, respectively.
An increase to load experienced at the heel during agility manoeuvres was apparent
when compared to straight-line running (medial heel 268
±
59 kPa and
lateral heel 294 ± 58 kPa). There was also a greater ratio of pressure distribution
between the medial and lateral heel during CD stance, such that greater loads through
the medial heel were observed. This indicates that during the CD impact stance phase,
kinematic adjustments transfer load through the medial portion of the stance foot and
likely promoted the development of lateral movement.
Strong braking forces (GRFHORZ) are also associated with the CD impact phase
269, 325
.
Peak braking forces have been reported at 4.23 ± 0.73 N.kg-1 during the CD impact
phase of a side-stepping task involving stepping down off a 0.21 m high platform and
changing directions at a 45˚ angle
forces
during
the
188
side-stepping
. It was found that the magnitude of peak braking
task
were
greater
non-direction change conditions (3.57 ± 0.70 N.kg-1)
188
when
compared
to
. The measures of agility
performance involving a step down off a platform and change directions employed by
Houck
188
, and the associated findings hold limited application when considering
running based lateral agility performance under sport specific conditions.
83
AGILITY
IN RUGBY UNION
Schot, Dart and Schuh
356
examined the braking forces when side-stepping at maximal
effort running speeds. It was shown that the mean braking forces during the CD phase
were 4.9 ± 0.94 N.kg-1 for a side-step at 45˚ and 6.8 ± 1.25 N.kg-1 for a side-step at
a 90˚ angle
356
. It was concluded that greater direction change angles coincide with an
increase to the mean braking forces observed during the CD phase. It should be noted
that the braking forces reported by Schot, Dart and Schuh
356
were averaged through
the CD stance phase, and as a result do not represent the magnitude of forces experience
during the specific CD impact phase. Despite this, case study examination illustrated
that
the
magnitude
of
the
peak
braking
forces
CD impact stance phase was greater than 9 N.kg-1
356
experienced
during
the
. It can be concluded that
the CD impact stance phase is characterised by extensive braking forces.
The extensive braking forces observed at CD-FS are representative of an increased
horizontal displacement of the foot, when compared to conventional straight-line
running patterns. The presence of positive CD-LDHORZ promotes the deceleration of
VELHORZ in order for the intended direction change to occur as a controlled
movement 174. However, the interaction between rates of VELHORZ deceleration and foot
placement patterns during the CD impact stance phase remains unreported within the
literature. It should be noted that Rand and Ohtsuki
325
examined the mean VELHORZ
during the respective stance phases of an agility side-stepping manoeuvre. It was shown
that the mean VELHORZ demonstrated an approximate reduction of 3 % from the
CD stance (4.99 ± 0.70 m.s-1) to the subsequent stance phase in the agility movement
pattern (4.85 ± 0.53 m.s-1). In contrast, examination of the corresponding stance phases
during straight-line running exhibited an approximate increase of 10 % to
VELHORZ (5.21 ± 0.58 m.s-1 to 5.79 ± 0.63 m.s-1) 325. The deceleration of VELHORZ is
required to achieve successful agility skill execution 174. Further research examining the
velocity profiles through the agility gait cycle would no doubt enhance the
understanding of agility skill execution and improve athletic training programs in sports
such as rugby union.
84
LITERATURE
REVIEW
IMPACT
30
Vertical
Horizontal
20
-1
Force (N.kg )
10
0
0
50
100
-10
-20
Stance Time (%)
Figure 2.21: Representation of GRFVERT and GRFHORZ during CD stance.
(Adapted from Schot et al.356)
85
AGILITY
IN RUGBY UNION
The knee is an important factor in the determination of agility skill execution, absorbing
the forces associated with direction change during the CD impact stance
phase
189, 195, 241
. It has been shown that at CD-FS the knee will be slightly flexed, at
approximately 17° to 22° of the relative knee angle
90, 239, 315
. The slight knee flexion
observed at CD-FS facilitates an increased capacity to absorb the associative ground
reaction forces and crucially, assists in maintaining joint integrity under the effects of
such moments
189, 195, 241
. Notably, EMG studies have outlined the central role of
quadricep and hamstring co-activation in maintaining knee joint integrity during agility
skill execution 230.
It should be noted that Malinzak et al.
239
illustrated the mean integrated quadricep
activation at foot contact was comparable between side-stepping (~ 125 % MVC) and
straight-line running (~ 125 % MVC). Notably, the mean integrated hamstring
activation
was
lower
when
side-stepping
(~
50
%
MVC)
compared
to
straight-line running (~ 80 % MVC). Propulsive properties are no doubt inhibited
during the CD impact phase due to considerable CD-LDHORZ and as a result, lower
hamstring activation patterns would be expected compared to straight-line running.
However, the magnitude of integrated hamstring activation patterns during the
CD impact phase suggested that the hamstring muscle group assists the knee in
absorbing the forces associated with direction change
239
. In support of this notion, the
primary role of the hamstring muscle group during the CD impact phase has been
identified as a mechanism by which to decelerate the downward motion of the centre of
gravity through the stabilisation of the knee 251, 287.
86
LITERATURE
REVIEW
AGILITY CHANGE OF DIRECTION MIDSTANCE PHASE
The midstance phase refers to the intermediate events between absorption at CD-FS and
propulsion through CD-TO. It has been suggested that the midstance phase constitutes
approximately 30 % of the CD stance time
356
. The midstance phase of an agility
manoeuvre is measured from the end point of the impact phase until the point of the
second vertical force peak (Figure 2.22). In straight-line running, the kinematic
indicators of the midstance phase has been described from the point of fore-foot loading
until the first sign of the heel lifting off the ground
292, 304
. It is proposed that the
kinematic characteristics of CD midstance phase of the agility gait cycle be consistent
with the respective indicators presented in straight-line running.
In straight-line running, previous authors have noted that the end point of midstance is
characterised
by
the
termed zero fore-aft shear
shift
111, 304
from
braking
to
propulsive
impulse,
. This point of zero fore-aft shear has been shown to
occur between 43 % to 50 % of stance 79, 111, 172, 279. In contrast, continued deceleration
of VELHORZ during the CD midstance phase means that zero fore-aft shear would
occurs during the late stages of the total CD stance phase
16, 356
. To add to this, the
maximal point of braking impulse has been shown to occur during the CD midstance
phase
356
. Therefore, it would seem that the point of zero fore-aft shear does not
represent the transition from midstance to propulsive stance phases during the agility
CD phase. It can be concluded that the characteristics of GRFHORZ do not provide an
appropriate indicator of the CD midstance phase of the agility gait cycle and that the
GRFLAT characteristics may provide a more accurate indicator of this phase.
87
AGILITY
IN RUGBY UNION
MIDSTANCE
30
Vertical
Horizontal
20
-1
Force (N.kg )
10
0
0
50
100
-10
-20
Stance Time (%)
Figure 2.22: Representation of GRFVERT and GRFHORZ during CD stance.
(Adapted from Schot et al.356)
88
LITERATURE
REVIEW
The characteristics of GRFLAT coincide with the identification of the CD midstance
phase
356
GRFVERT
. Notably, Schot, Dart and Schuh
and
GRFLAT
observed
356
during
illustrated that the profiles of both
the
CD
midstance
phase
were
similar (Figure 2.23). The start and end-points of the CD midstance phase were shown
to be consistent with the presence of the first and second lateral impulse peaks during
CD stance. To add to this, the magnitude of the GRFLAT associated with directional
change has demonstrated an initial peak of 6.9 ±2 N.kg-1 and 7 ±2 N.kg-1, which would
be linked with the development of lateral movement during the early stages of
the CD midstance phase 293. Despite this, there is an apparent lack of in-depth published
research that has examined the profiles of GRFLAT during the CD stance phase, and
more generally the agility gait cycle.
The CD midstance stance phase has demonstrated unique loading patterns of the stance
foot when shifting from horizontal to lateral movement
126
. The mean peak
pressure at the medial mid-foot has been observed at 233 ± 73 kPa and at
the lateral mid-foot 175
±
57 kPa during the CD midstance phase
126
.
This represented 5.3 ± 1.6 % and 3.5 ± 1.1 % of the total load experienced
through the CD stance phase, respectively. In addition, an increase to the load
experienced at the medial mid-foot occurred during agility manoeuvres when compared
to straight-line running (140 ± 30 kPa). Notably, there was a trend for the loading
patterns of the lateral mid-foot to be greater during straight-line running (191 ± 33 kPa)
when compared to side-stepping. This indicates that the transfer of loads through the
medial portion of the stance foot enhances the properties of lateral movement during the
CD midstance phase.
89
AGILITY
IN RUGBY UNION
MIDSTANCE
30
Vertical
Lateral
-1
Force (N.kg )
20
10
0
0
50
100
-10
Stance Time (%)
Figure 2.23: Representation of GRFVERT and GRFLAT during CD stance.
(Adapted from Schot et al.356)
90
LITERATURE
REVIEW
It has been illustrated that the magnitude of the second peak GRFVERT will be slightly
less than the impact peak of the CD step
39
. In straight-line running, the second
GRFVERT peak has been termed the thrust maximum
111
. The mean thrust maximum
during agility side-stepping manoeuvres has been reported at 25.4 ±2.02 N.kg-1
James et al.
199
356
.
reported that the mean magnitude of the thrust maximum
-1
was 6.9 ±1.0 N.kg
during agility side-stepping manoeuvres. In another study, the
thrust maximum observed during agility manoeuvres was reported at 2.75 ±.28 BW 39.
In comparison, the magnitude of the thrust maximum has been reported
between 2.5 BW and 3.0 BW during straight-line running
79,
172,
279,
338
.
Therefore, the magnitude of thrust maximum observed during the CD midstance phase
of the agility gait cycle seems comparable to straight-line running.
Peak range of knee flexion has been observed in conjunction with thrust maximum,
during the CD midstance phase
45, 259, 287
. Andrews et al.
16
found that the peak knee
displacement angle during the CD step would exhibit approximately 60˚ of flexion
during CD stance. Pollard, Davis and Hamill
occurred
during
the
latter
stages
of
315
found the peak knee flexion angle
the
CD
midstance
phase,
with
approximately 50˚ of flexion during a 45˚ side-step at an approach speeds
between 5.5 m.s-1 and 6.5 m.s-1. McLean et al. 259 illustrated peak knee flexion angles of
just under 50˚ during the CD midstance phase, when side-stepping at angles
between 35˚ and 60˚ and at approach speeds between 5.5 m.s-1 and 7.0 m.s-1.
In straight-line running, peak knee angles less than 40˚ of flexion have been observed
during stance
111, 239
. The knee joint contributes an important component to the
189,
absorption of associated forces during running based locomotion
195,
241
.
Hence, the additional forces associated with directional change appears to require
subsequent increases to knee range of motion (ROM) when compared to straight-line
running.
It should be noted also that an increase to running speed is associated with greater
forces during the stance phase of running based locomotion
111
. James et al.
199
found
the knee moved through 18.4 ±4.79° of flexion during the CD stance phase of an agility
manoeuvre,
with
a
direction
change
-1
angle
of
60˚
at
an
approach
-1
speed of 3.28 ±.42 m.s . Notably, at increasing approach speeds (5.5 m.s to 7.0 m.s-1)
greater than 30° knee angular ROM has been observed during the CD stance
phase 315. The peak knee flexion angles observed during the CD stance phase of agility
91
AGILITY
IN RUGBY UNION
manoeuvres are greater than straight-line running (Figure 2.24)
that
the
absorption
of
associated
CD midstance phase of agility manoeuvres
forces
16
239
. It should be noted
continues
through
the
. It can be concluded that deep knee
flexion during the CD midstance phase of an agility manoeuvre absorbs the
multi-directional compound forces associated with directional change. Therefore,
the CD midstance phase features the body attempting to maintain stability whilst
pivoting and repositioning for the desired change in locomotion direction.
To promote the stability during the CD midstance phase, the quadricep muscle group
will exhibit peak muscle activation in the lead-up to maximum knee flexion.
Malinzak et al.
239
found peak quadricep muscle activation occurred at
approximately 40 % of the CD stance phase. Furthermore, the average magnitude of
quadricep activation during CD midstance phase was recorded above 200 % MVC
during a 45˚ side-step with an approach speed of 5.18 ±.38 m.s-1. In contrast, the mean
peak quadricep muscle activation when straight-line running was recorded
below 200 % MVC during stance (Figure 2.25). It has been demonstrated that the
integrated action of the quadriceps act to stabilise the knee joint during running based
locomotion
245,
421
. Therefore, the increased quadricep activation during the
CD midstance phase when side-stepping indicates the greater forces associated with
directional change compared to straight-line running. This emphasises the principle of
specificity when training the muscle contractile properties of athletes competing in
sports characterised by multi-directional movements.
92
LITERATURE
REVIEW
50
Straight-line
Side-step
45
Angular Displacement (°)-
40
35
30
25
20
0
20
40
60
80
100
Stance Time (%)
Figure 2.24: Representation of knee flexion angles comparing side-stepping CD stance
to the stance phase of straight-line running stance.
(Adapted from Malinzak et al. 239)
93
AGILITY
IN RUGBY UNION
250
Muscle Activation (%MVC)
200
150
100
Straight-line
Side-step
50
0
50
100
Stance Time (%)
Figure 2.25: Representation of quadricep activation patterns comparing side-stepping
CD stance to the stance phase of straight-line running.
(Adapted from Malinzak et al. 239)
94
LITERATURE
REVIEW
AGILITY CHANGE OF DIRECTION PROPULSION PHASE
The CD propulsive phase is measured from the end-point of midstance to the point of
CD-TO (Figure 2.26). The CD propulsive phase has been described as constituting
50 % of stance during agility manoeuvres
287
. Similarly, the propulsive phase has been
shown to represent approximately 50 % of stance during straight-line running
patterns
304
. Research examining the pressure distribution patterns of side-stepping
agility manoeuvres has found that the peak pressure at the medial forefoot
was 655 ± 131 kPa during the CD propulsive phase, representing 25.8 ± 3.6 % of the
relative load during CD stance
126
. It has been shown also that the peak pressure at the
hallux when side-stepping was 487 ± 98 kPa, representing 13.3 ± 3.4 % of the relative
load
126
. The load experience at the hallux when side-stepping was as great as the
respective load when straight-line sprinting (486 ± 130 kPa), yet greater compared to
straight-line sub-maximal running (348 ± 72 kPa)
126
. This emphasises the role of the
CD propulsive phase in the development of propulsion during the agility gait cycle.
In straight-line running, the propulsive phase is characterised by high magnitudes of
GRFHORZ that promote forward motion. The development of horizontal impulse during
propulsive
stance
performance
70, 408
phases
is
a
vital
contributor
to
straight-line
running
. However, this is not necessarily the case when considering the
CD stance phase of agility performance. The necessary lateral displacement during the
agility gait cycle suggests that it is desirable to limit momentum in the sagittal plane
during the CD stance phase 16. Schot, Dart and Schuh
356
found that positive GRFHORZ
(propulsive impulse) was only present during approximately the last 10 % of the agility
CD stance phase. Notably, the magnitude of propulsive force associated with
sagittal plane motion observed during agility performance was relatively low (less than
2 N.kg-1) when compared to the respective braking forces
356
. Comparably, the
magnitude of peak horizontal forces has been reported to be 2.37 ± 0.43 N.kg-1 during
the propulsive stance phase during a low velocity task such as walking
188
. Therefore,
the key biomechanical determinants of agility performance do not include the
development of high magnitudes of sagittal plane propulsive impulse during the CD
stance phase. Conversely, it is possible that the subtle control of sagittal plane
momentum (VELHORZ) during the CD stance phase presents as a key biomechanical
determinant of agility performance.
95
AGILITY
IN RUGBY UNION
PROPULSION
30
Vertical
Horizontal
20
Force (N.kg-1)
10
0
0
50
100
-10
-20
Stance Time (%)
Figure 2.26: Representation of GRFVERT and GRFHORZ during CD stance from
foot-strike to toe-off.
(Adapted from Schot et al.356)
96
LITERATURE
REVIEW
The velocity profiles during agility manoeuvres relating to performance enhancement
have been reported rarely within the published literature. Ohtsuki, Yanase, Aoki
300
conducted a basic analysis of running speed (VELHORZ) over a number of steps of an
agility manoeuvre. Participants were required to run at maximal effort and then change
directions in order to catch a designated target, such as a dropping basketball.
It was illustrated that during side-stepping performances, a reduction in VELHORZ of
approximately 30 % occurred during changes of direction. It should be noted that the
study conducted by Ohtsuki, Yanase, Aoki
300
measured running speed over a number
of steps during an agility manoeuvre. Therefore, it is recommended that future research
considers the specific velocity profiles presented during the distinct stance phases of the
agility gait cycle. It is proposed that an increased rate of VELHORZ deceleration during
agility CD phase results in greater running speed during the preceding agility phases.
Moreover, the subtle manipulation of VELHORZ during the propulsive phase of
the CD step may provide an important factor when considering the speed and
directional characteristics associated with displacement during the agility gait cycle.
In considering the kinematic properties of propulsion when side-stepping, it has been
found that the knee joint will display extensive sagittal plane ROM during
the
CD
propulsive
phase.
Pollard,
Davis
and
Hamill
315
observed
approximately 25˚ of extension during the CD propulsive phase. Moreover, it has been
demonstrated that the knee joint displays continuous extension during the
CD propulsive phase
239, 259, 315
. Notably, measures of GRFHORZ associated with
side-stepping manoeuvres have been shown to promote horizontal acceleration during
the CD propulsive phase
356
. These findings suggest that the motion of knee extension
during the CD propulsive phase promotes associated acceleration properties during the
agility manoeuvre.
It has been illustrated that the mean muscle activation of the hamstring group will be
greater than 95 % MVC, occurring at approximately 80 % CD stance. The activation of
the hamstring muscle group during the CD propulsive phase accelerates the respective
segments of the lower extremity following the preceding deceleration
90, 287, 314, 325
.
It should be noted that the muscles of the hamstring group are the prime movers of hip
extension
245
. In straight-line running, previous studies have found that the rate of hip
extension is a fundamental element of propulsion
97
195, 196, 242, 354
. Increasing the rate of
AGILITY
IN RUGBY UNION
hip extension is associated with an enhanced propulsive capacity during the stance
phase of running based locomotion
195, 196, 242, 354
. However, no published studies have
measured the rate of hip extension during running based agility manoeuvres. A study
conducted by Pollard, Davis and Hamill 315 examined the mean displacement of the hip
when side-stepping. It was illustrated that the hip extended from approximately 40 %
CD stance at a relative hip angle of 30˚ flexion until CD-TO to a relative hip angle of
10˚ extension. To add to this, the angular displacement of the hip was shown to become
extended at approximately 80 % CD stance. Notably, the transfer from a flexed to an
extended hip angle during CD stance
315
coincided with the peak muscle activation of
the hamstring group during agility manoeuvres
239
. Hence, there is an important
interaction between the hip joint ROM and the associated primary propulsive muscles
during agility skill execution.
During the CD propulsive phase, it is evident that the leg exhibits movement through
not only the sagittal plane as required in straight-line sprinting, but also demonstrates
extensive frontal plane motion. Examination of the associated published literature
revealed that few studies have considered the lateral movements of the hip during
agility manoeuvres and the relationship with properties of propulsion. It is possible that
combined rates of hip extension and abduction contribute a key component of
propulsion during the agility CD step. It has been shown that the range of lateral motion
about the hip during CD stance consists of approximately 5˚ when side-stepping
315
.
Interestingly these researchers found that the lateral displacement of the hip
demonstrated only slight abduction until the early stages of the CD propulsive phase,
upon which the hip began to adduct to approximately 5˚ at CD-TO. It is recommended
that further research considers the specific role of the hip joint in relation to the
propulsive properties exhibited when changing directions.
Considering the gross movement pattern when changing directions, the body has been
shown to rotate towards the intended path of locomotion, with the contact leg required
to rotate to facilitate this redirection of momentum
208
. Pollard, Davis and Hamill
315
showed that the hip joint displayed approximately 13˚ of external rotation ROM from
the point of CD-FS (~ 3˚ internal rotation) until approximately 80 %
CD stance (~ 10˚ external rotation)
315
. It was then shown that the hip joint internally
rotated during the later stages of the CD propulsive phase until CD-TO, reaching
98
LITERATURE
REVIEW
approximately 4˚ external rotation. Similarly, it was shown that the knee internally
rotated from the point of CD-FS (~ 5˚ external rotation) until approximately 60 %
CD stance (~ 10˚ internal rotation). The knee joint was then shown to externally rotate
until CD-TO (~ 2˚ external rotation). It is proposed that the pivoting action of the lower
limb when side-stepping enhances the associated lateral movement properties by
increasing stance times and providing additional rotary components to kinetic
chain force summation. Notably, research examining the rotational characteristics
of
lower
limb
motion
relationship with injury
during
agility
manoeuvres
has
focused
on
the
39, 43, 45, 90, 96, 102, 175, 188, 199, 239, 256, 257, 259, 287, 295, 315, 325, 356, 364
.
It is accepted that the torsional moments experienced by the lower limb during agility
manoeuvres is a valid research paradigm, however there is scope for examination of
lower movement patterns with respect to performance enhancement.
It is important to consider the motion of the ankle and the associated muscle activation
strategies of the ankle plantar flexors when considering propulsion during running based
locomotion. The muscle contractile properties of the plantar flexors have been shown to
provide a central component of propulsion during walking
based locomotion
217, 286
14, 158, 289, 292, 344
and running
. In addition, increased activation of the gastrocnemius muscle
(prime action of ankle plantar flexion) at toe-off has been associated with greater
running speeds
217
. Notably, the gastrocnemius has demonstrated increased activity
during the early stages of the CD propulsive phase when side-stepping
Similarly, Neptune, Wright and Van Den Bogert
287
188
.
found that the concentric action of
the muscles associated with plantar flexion provided propulsion during the stance phase
of agility manoeuvres. Therefore, the contraction of the plantar flexors during the CD
propulsive phase promotes the propulsive properties of agility performance.
99
AGILITY
IN RUGBY UNION
AGILITY TRANSITION PHASE
The TRANS phase of the agility performance cycle is measured from the point
of CD-TO until ST-FS. The agility TRANS phase is presented with a movement pattern
of initial direction change followed by a subsequent straightening of the directional
alignment. In rugby union, the presence of the TRANS phase is seen where an attacking
ball runner executes an initial side-step to outmanoeuvre an opponent and then
straightens the running direction to penetrate the defensive line (Figure 2.27).
It should be noted that the TRANS phase will not be observed in the case of
a single direction change with a continuation through the adjusted running
alignment (Figure 2.28). Unfortunately, there is a lack of published research exploring
the strategies associated with the transmission of lateral displacement following an
initial change of direction. It is proposed that the TRANS phase contributes the primary
component of lateral displacement during agility manoeuvres. Clearly, it is important
that future research describes the characteristics of lateral movement in rugby union,
with specific reference to the gait components of evasive attacking manoeuvres.
It is possible that the biomechanics associated with TRANS phase display similarities
with side-shuffling movements. In general, side-shuffling refers to running movements
that are performed perpendicular to the anteroposterior alignment of the body.
A study conducted by Neptune, Wright and Van Den Bogert
287
examined lower limb
muscle coordination and function during side-stepping and side-shuffling tasks.
It was found that the muscle activation strategies when side-shuffling were similar
compared to the respective measures when side-stepping. However, the stance phase
kinematics when side-shuffling displayed unique characteristics when compared to sidestepping.
100
LITERATURE
REVIEW
POSTCD STEP
ST STEP
TRANS PHASE
CD STEP
PRECD STEP
Figure 2.27: Transverse plane representation of the attacking running line during an
agility manoeuvre with a TRANS phase.
POSTCD STEP
CD STEP
PRECD STEP
Figure 2.28: Transverse plane representation of the attacking running line during an
agility manoeuvre without a TRANS phase.
101
AGILITY
IN RUGBY UNION
Neptune, Wright and Van Den Bogert 287 observed that the angular displacement of the
ankle exhibited approximately 20˚ of dorsi-flexion at CD-FS when side-stepping
287
.
It was shown that the movement of the ankle joint represented a sinusoidal pattern,
moving through plantar flexion during the impact phase, dorsi-flexion until
approximately 70 % stance and then plantar flexion until CD-TO. In contrast, it was
demonstrated that the ankle was in a neutral position (flat-foot) at foot contact when
side-shuffling. The ankle then dorsi-flexed until late midstance and then plantar flexed
during propulsion (Figure 2.29). Studies of straight-line running have shown that the
sagittal plane ankle motion is an important contributor to lower limb stabilisation and
forward progression during stance
288
. Hence, the lack of horizontal momentum
(forward progression) observed under the side-shuffling conditions represents the
differences in ankle motion when compared to side-stepping conditions
287
.
It is possible that a flat-foot position (neutral sagittal plane ankle joint displacement) at
foot contact may enhance the ability to maximise VELLAT. It is proposed that high rates
of VELLAT are a desirable feature during the TRANS phase and as such, the kinematic
characteristics of the ankle joint contribute an important component to the transmission
of lateral displacement during the TRANS phase of an agility manoeuvre.
It should be noted that the sagittal plane knee movements when side-shuffling were
comparable to the respective measures when side-stepping
287
. In contrast, the
movements of the hip joint when side-shuffling displayed unique characteristics
compare to side-stepping. The hip joint displayed continued extension from CD-FS
until CD-TO when side-stepping. In comparison, the hip continued to flex until
approximately 50 % of the stance phase when side-shuffling. In addition, the angular
displacement of the hip at toe-off was greater when side-shuffling (~ 20˚ flexion)
compared to side-stepping (~ 1˚ flexion). It has been found that hip extension is an
important component of sagittal plane propulsion
195, 196, 242, 354
. Undoubtedly, the
restriction of horizontal momentum when side-shuffling alters the propulsive function
of the hip. Neptune, Wright and Van Den Bogert 287 demonstrated that the activation of
the gluteus maximums was reduced when side-shuffling compared to side-stepping.
It has been shown that activation of the gluteus maximus is an important contributor to
forward propulsion in running 344. It is possible that the muscles of the hip joint provide
lateral stabilisation of the stance limb and assist in absorbing the associated rotational
forces when side-shuffling.
102
LITERATURE
REVIEW
30
Angular Displacement (°)
20
10
0
0
50
100
Side-shuffle
Side-step
-10
Stance Time (%)
Figure 2.29: Representation of the sagittal plane ankle angular displacement during the
stance phase of side-shuffle and side-step.
(Adapted from Neptune, Wright and Van Den Bogert 287)
103
AGILITY
IN RUGBY UNION
During the latter stages of the TRANS phase, preliminary kinematic adjustments would
no doubt occur in anticipation of the ST step. Accordingly, it is possible that the latter
stages of the TRANS phase would hold biomechanical similarities to those exhibited
during the PRECD phase 16. It would seem that the TRANS phase provides a means by
which to maintain the lateral movement created during the CD step, and then reposition
the body to transfer this force effectively during the ST step. Moreover, the TRANS
phase no doubt provides the primary component of lateral displacement during agility
manoeuvres. Consequently, extensive lateral moments will be observed during the
TRANS phase, which are not addressed within previous scientific studies regarding the
PRECD phase.
The TRANS phase stance properties are likely to contribute an important component to
lateral displacement during agility manoeuvres 171. It is apparent that propulsive abilities
are diminished with the absence of TRANS steps. Conversely, a greater number of
TRANS steps has the potential to promote subsequent increases to lateral propulsive
abilities. During evasive attacking manoeuvres in rugby union, it is necessary for an
athlete to accelerate away from a defensive opponent following the execution of an
initial side-stepping direction change. Accordingly, evasive attacking strategies in rugby
union are supported with additional steps during the TRANS phase of agility skill
execution.
It has been demonstrated that an increase in the number of steps when changing
directions is associated with a increase to dynamic stability 142. Notably, double support
stance times have been reported during change of direction walking conditions,
but have not been discussed with reference to lateral movement or dynamic stability 308.
The inclusion of additional steps during the TRANS phase no doubt enhances dynamic
stability and thus presents as a key kinematic component to markedly increase the
effectiveness of agility performance in rugby union (Figure 2.30). Conversely, if an
athlete were in flight during a contact situation in rugby union, the ability to maintain
stability and to resist an opponent would be greatly reduced, as the body is not provided
with a stable base of support (Figure 2.31). It is recommended that future research
examine the biomechanical determinants of the TRANS phase, with specific reference
to the relationship between the number of steps and the properties of dynamic stability
under sport specific conditions.
104
LITERATURE
REVIEW
Figure 2.30: Frontal plane representation of an athlete displaying double support during
the TRANS phase.
Figure 2.31: Frontal plane representation of an athlete in flight during the TRANS
phase.
105
AGILITY
IN RUGBY UNION
AGILITY STRAIGHTEN PHASE
The ST phase involves straightening the directional running line following preceding
lateral
displacement
observed
during
the
TRANS
phase
(Figure
2.32).
The required adjustment of the directional running line indicates that restricting lateral
movement and limiting the associated lateral excursions of the centre of gravity are
fundamental characteristics of the ST phase. The presence of excessive lateral forces
when attempting to maximise horizontal acceleration, results in considerable reductions
to performance capability when running
345
, this may then be overcome with increases
to lateral foot displacement during the ST phase (Figure 2.33) 208.
The redirection of predominant motion to the sagittal plane suggests that the application
of VELHORZ is a central characteristic of the ST phase. A primary mechanism to
promote forward propulsion is to decrease LDHORZ and as such, the ability to minimise
ST-LDHORZ seems a desirable feature of the ST phase
54, 89, 196, 218, 267, 271
.
In addition, increased hip extension velocity is associated with enhanced propulsion
when running
195, 241, 354
and this may also be a characteristic of enhanced ST phase
propulsion. In rugby union, the acceleration properties of the ST phase would be a
critical factor when attempting to exploit a break in the defensive line, created as a
result of an initial evasive side-step. Importantly, when an attacking player has
penetrated the defence and subsequently crossed the advantage line, the success of ball
retention increased to 66.7 %, as opposed to 43.9 % observed when an attacking player
did not gain the advantage line 254.
The direction change qualities of the ST step categorically resemble generalised sidestepping actions during agility manoeuvres but in the opposite direction. This indicates
that the ST step may demonstrate characteristics common with that of the CD step.
For example, the arms have been shown to assist in countering rotational
forces, preventing undesirable excursions of the centre of gravity during agility
manoeuvres
67, 181
. However, the distinctive characteristics of directional re-alignment
during ST phase indicate the existence of unique biomechanical components. It was
apparent that no published studies have examined the technical strategies employed
when attempting to shift from lateral to horizontal motion.
106
LITERATURE
ST Step
Figure 2.32: Transverse plane representation of the agility ST phase.
107
REVIEW
AGILITY
IN RUGBY UNION
ST-LDLAT
Figure 2.33: Frontal plane representation of ST-LDLAT.
AGILITY RE-ACCELERATION PHASE
The POSTCD phase refers to the concluding events of the agility gait cycle. There is no
doubt that the fundamental component of the POSTCD phase is the ability to reaccelerate
the centre of mass. Consequently, the POSTCD phase should hold biomechanical
characteristics similar to that of straight-line acceleration. Following the execution of an
evasive side-sep in rugby union, the POSTCD phase allows the attacking ball carrier to
advance the ball. Furthermore, the nature of rugby union match play suggests that the
attacking ball carrier will be required to position for subsequent actions during the
POSTCD phase in order to continue play (e.g. passing the ball or executing another
evasive manoeuvre). Hence, the POSTCD phase is a fundamental component of agility
manoeuvres executed under varying situational and performance conditions in rugby
union.
108
LITERATURE
Rand and Ohtsuki
325
REVIEW
found that measures of VELHORZ during the agility
POSTCD phase (4.85 ± 0.53 m.s-1) were greater than the respective measures in
straight-line acceleration (4.05 ± 0.46 m.s-1) at comparable stance times. The increased
velocity indicated that the combined ability to maintain horizontal momentum and
harness lateral movement during initial directional change increased running speed
during the POSTCD phase. In addition, Ohtsuki, Yanase and Aoki
300
observed faster
agility performance times with less variation to running speed. It is then proposed that
faster agility performances are supported with less change to VELHORZ ( ∆ VELHORZ)
through the agility gait cycle. However, no published articles have described the ability
to re-direct lateral movement in order to enhance horizontal running speed.
It is recommended that further research determine the relationship between measures of
velocity through the agility gait cycle, with specific reference to the redirections of
momentum occurring during performance.
Rand and Ohtsuki
325
also demonstrated that the mean stance time during the agility
POSTCD phase (176.5 ± 24.3 m.s-1) was greater when compared to straight-line
acceleration (156.1 ± 16.6 m.s-1) at comparable running speeds. The increased stance
time when side-stepping suggested that the required lateral displacement presented
additional performance requirements when attempting to maximise VELHORZ during the
POSTCD phase. There is no doubt that the increased POSTCD stance time was a product
of the considerable lateral moments experienced when changing directions.
This indicates that the agility POSTCD phase holds distinctive characteristics when
compared to straight-line acceleration running. Hence, it would beneficial for further
research to compare the biomechanical determinants of the agility POSTCD phase and
straight-line acceleration running.
It is important to consider foot placement patterns when exploring measures of velocity
during the agility POSTCD phase. The primary function of the POSTCD phase is to
provide VELHORZ acceleration. Accordingly, a reduction to POSTCD-LDHORZ would
minimise the negative ground reaction forces associated with positive horizontal foot
placements
196
. The POSTCD phase may also exhibit further reductions to the lateral
forces in residue following the preceding agility phases. Based on research in
straight-line running, the presence of lateral momentum may alter the speed of agility
109
AGILITY
IN RUGBY UNION
performance and seems an undesirable feature of skill execution
111
. Clearly, further
research should investigate the presence of lateral momentum during the POSTCD phase
and the associated affects on both the speed of performance as well as the effectiveness
of performance under sport specific conditions.
SUMMARY: BIOMECAHNICS OF AGILITY SKILL
EXECUTION
Review of the scientific literature demonstrated that agility is a unique skill consisting
of a number of interrelated kinematic mechanisms and kinetic components. The PRECD
phase is characterised by preliminary deceleration of VELHORZ in preparation for the
intended CD step. The CD phase provides a shift from horizontal to lateral movement
and presents as the central component of momentum redirection during the agility gait
cycle. The TRANS phase then promotes extensive lateral displacement as a
consequence of the lateral movement developed during the CD step. The ST phase then
transfers lateral movement to forward motion, with the POSTCD phase facilitating the
re-application of VELHORZ following lateral displacement. It is essential that future
research investigates the key biomechanical determinants of the agility gait cycle
throughout varied conditions and within an applied sporting context.
110
LITERATURE
REVIEW
ASSESSMENT OF AGILITY
PERFORMANCE
BACKGROUND
The assessment of agility performance has been conducted commonly with little
consideration of external validity and the application of findings within a sporting
context 13, 16, 29, 39, 42, 43, 45, 55, 57, 69, 90, 102, 104, 105, 118, 126, 133, 156, 162, 165, 175, 180, 188, 199, 223, 227, 232,
234, 235, 239, 249, 250, 256, 259, 276, 284, 293-295, 300, 306, 309, 313, 315, 325, 327, 397, 410, 423, 433
.
The reported agility testing procedures typically have demonstrated high reliability,
although often achieving this at the expense of external validity
249, 302, 309, 327, 361
13, 99, 141, 146, 232, 234, 235,
. The limitations of the published scientific literature are further
evidenced where many scientific research projects have relied on time as the single tool
for agility performance assessment 13, 29, 42, 55, 57, 69, 87, 99, 105, 113, 118, 133, 143, 144, 146, 151, 162, 163,
165, 179, 180, 212, 223, 227, 228, 232, 234, 235, 246, 249, 261, 274, 276, 284, 302, 306, 309, 313, 327, 361, 391, 396, 397, 423,
430, 432, 433
. The following discussion will explore the methodologies, as well and the
associated methods and procedures involved as part of the assessment of agility skill
execution reported throughout the published literature.
PARTICIPANTS
The review of the literature noted that many studies examining agility performance
involved subjects considered inappropriate for valid application to competitive athletes.
Commonly, generalised populations were sampled and included elderly participants as
well as young adults and children
13, 141, 142, 154, 238, 273, 284
. In clinical examinations of
agility performance, participants have included generalised population samples
recovering from lower extremity soft tissue injury, such as injury to the anterior cruciate
ligament 190, 290. In other studies, agility performance has been assessed with samples of
military personnel 261. To add to this, a number of scientific studies have utilised student
populations as part of agility assessment
180, 295, 410
111
. It has been outlined that the
AGILITY
IN RUGBY UNION
competitive sporting population demonstrates unique characteristics and performance
attributes
235, 259, 301
. Consequently, generalised population samples do not present an
accurate representation of agility skill execution within competitive athletic populations.
Many of the published studies that have examined agility have sampled a generalised
athletic population
Montgomery
432
57, 90, 96, 188, 239, 250, 300, 302, 325, 397, 432
. For example, Young, James and
assessed agility performance with a sample of athletes from soccer,
basketball and Australian Rules. In another study, Ohtsuki, Yanase and Aoki 300 utilised
a sample of basketball and rugby union athletes as well as university students as part of
agility assessment procedures. A combined athletic sampling technique represents a
contradiction to the sports specific nature of agility skill execution. Hence, agility
performance assessments with combined athletic sampling holds limited application to
sports specific agility performance.
The review of the literature noted a lack of published research directly examining agility
performance with sampled rugby union athletes. Alternatively, the assessment of
agility performance has been observed commonly in team sport athletic populations
such as soccer
field hockey
43, 45, 126, 156, 228, 276, 306, 315
118, 212, 223
, basketball
and Australian Rules
361, 430
29, 55, 137, 199, 234, 256, 313, 391, 410
,
. It is accepted that some research
projects have included rugby union athletes within the sampled cohort, however these
projects did not explore specifically the results of agility performance assessment with
reference to the application of findings in rugby union 53, 87, 147, 300, 325. Studies conducted
by Scott et al.
357
and Olds
301
have outlined the distinct anthropometric characteristics
of rugby union athletes. Therefore, there is scope for future research to examine agility
performance with specific consideration of rugby union.
It should be noted that a study conducted by McLean et al. 259 found experience level to
be a significant determinant of knee joint kinematics during side-stepping agility
manoeuvres, indicating less variation in knee movement patterns with increasing
athletic experience. In another study, Keogh, Weber and Dalton
212
demonstrated that
the speed of agility performance for state representative athletes was superior to club
level athletes through a number of agility assessment tasks. The skill level and unique
characteristics of high level competitive athletes 235, 259 means that applying the findings
of agility research based on unskilled performers will not provide consistent results and
112
LITERATURE
REVIEW
will be fraught with inaccurate assumptions. Unfortunately, the majority of research
examining agility performance has employed athletes not participating at high
performance levels, denoted with national and international level competition 42, 43, 69, 90,
104, 137, 162, 163, 179, 188, 199, 232, 235, 239, 249, 256, 276, 287, 293, 302, 313, 315, 356, 410, 423
.
Clearly further research is required with regards to agility performance attributes
observed high performance athletic populations.
STUDY DESIGN
The scientific assessment of agility performance has been conducted typically under
non-sport specific environmental conditions, such as testing within an indoor laboratory
13, 39, 43, 45, 57, 90, 96, 102, 105, 118, 137, 141, 154, 165, 175, 179, 188, 190, 208, 238, 239, 246, 249, 256, 259, 276, 287, 300,
302, 307, 309, 315, 356, 361, 410, 432, 433
. Limited research has incorporated sport specific
environmental conditions as part of agility performance assessment, particularly relating
to the field based football codes
126, 162, 235, 430
. Undoubtedly, the lack of field based
agility testing relating to the football codes is due to the variability of the sport specific
grassed playing surfaces
253
. In contrast, the measurement of agility performance under
sport specific environmental conditions has been observed commonly in sports that
retain greater ecological integrity between performances, such as basketball, netball and
tennis 29, 38, 55, 85, 133, 163, 212, 223, 234, 327, 391.
Sport specific environmental conditions are necessary to establish the validity of agility
performance assessment procedures. Consequently, grassed surfaces must be considered
a fundamental component of ecological validity during agility testing in rugby union.
Accordingly, consideration should be given to the footwear necessary to execute
successful agility manoeuvres on grassy surfaces
126, 430
. It is accepted that the
interaction between environmental conditions and equipment requirements can
confound agility assessment procedures
43
but replicating the sporting requirements
greatly promotes external validity. Therefore, sports specific requirements should be
considered a fundamental component regarding future assessments of agility skill
execution in rugby union.
113
AGILITY
IN RUGBY UNION
The absence of sport specific ball skills as part of agility testing procedures was a
fundamental factor confounding the validity of findings presented throughout the
published scientific literature. Absurdly, many of the studies claiming to have measured
agility performance as expressed throughout ball sports did not include ball skills within
testing protocols. In contrast, those studies that included sport specific ball skills as part
of agility assessment procedures indicated limited transfer with agility performance
29, 85, 126, 199, 212, 223, 227,
observed during assessment procedures not involving ball skills
391, 430
.
The presence of decision-making strategies should be given thorough consideration
when assessing the validity of agility assessment procedures. It should be noted that the
decision-making stimuli reported throughout the scientific literature have been
presented in forms unrelated to sports specific performance
227
. For example, the
published scientific literature typically used various light cues, such as in the form
of a directional
arrow to
the agility manoeuvre
indicate the
change of
43, 45, 154, 179, 208, 238, 307, 315, 325
direction
required
of
. Importantly, sport specific
decision-making strategies as part of agility performance assessment have been shown
to differentiate between respective athletic levels, that were not apparent with non-sport
specific visual cues such as directional light displays
342, 362, 405
. Therefore, it is
important that agility assessment protocols include elements of decision-making that
resembles athletic performance within a specific sporting context.
Athletic performance attributes relating to the velocities expressed during agility testing
procedures are an important consideration when attempting to apply the findings from
previous scientific studies to agility skill execution in rugby union. Rugby union
athletes have displayed horizontal velocities of greater than 8 m.s-1 prior to evasive
direction change
348
. The review of the scientific literature revealed that many studies
simply required participants to perform an agility task whilst walking or at similar
slow velocities
39, 43, 90, 137, 141, 142, 154, 175, 190, 238, 239, 258, 259, 287, 294, 307, 308
.
In other studies, the approach speed of participants has been limited to sub-maximal
velocities as low as 3m.s-1, purportedly representing the speed at which agility
manoeuvres are executed in sport
43, 45, 208, 239, 256, 259, 315
. Clearly, sub-maximal
performance parameters would hold limited application to maximal effort agility skill
execution during rapid match-play activities in rugby union.
114
LITERATURE
REVIEW
The majority of published scientific research merely reported that participants were
required to complete the respective agility assessment tasks at maximal effort 13, 29, 42, 55,
57, 69, 87, 102, 104, 105, 118, 126, 133, 143, 163, 180, 199, 212, 223, 227, 228, 232, 234, 235, 239, 249, 250, 302, 306, 309, 313,
316, 327, 356, 361, 391, 410, 423, 430, 432, 433
. However, these studies did not provide specific details
as to the velocities exhibited by participants during skill execution. In contrast, a study
conducted by Neptune, Wright and Van Den Bogert
287
requested that participants
complete the respective agility assessment tasks as quick as possible, but later reported
the speed at which performance was observed during testing. In another study,
Colby et al.90 asked participants to run at 75 % game speed during various agility
manoeuvres but did not provide details as to which sport this velocity had been
calculated or at what velocities participants were traveling during agility assessment
tasks. Notably, running velocity has been shown to alter kinematic variables and stride
patterns during dynamic activities
326
. Consequently, it is important to match the
required performance speeds during agility testing with the speeds expressed during the
specific sporting situation under investigation.
AGILITY COURSE DESIGN
The design of agility performance assessment tasks varied considerably throughout the
scientific literature. The tasks employed to measure agility performance commonly
consisted side-stepping agility tasks through a range of change of direction angles,
shuttle running over varied distances and other purposefully designed agility
performance assessment procedures. In reference to rugby union, perhaps the most
relevant assessment methods reported throughout the previous literature have involved
measures of side-stepping ability. The following discussion will outline the measures of
agility performance reported throughout the published scientific literature.
115
AGILITY
IN RUGBY UNION
SIDE-STEPPING AGILITY ASSESSMENT
Side-stepping tasks were the most common methods of agility performance assessment
reported throughout the published scientific literature
199,
223,
227,
228,
230,
239,
256-260,
287,
302,
313,
316,
13, 16, 43, 45, 90, 96, 102, 126, 143, 146, 180,
325,
356,
361,
422,
430,
432,
433
.
However, considerable variation to course design and respective performance
requirements were observed as part of agility side-stepping tasks reported throughout
the literature. The change of direction angles required of side-stepping agility
performances ranged between 20° and 120°, relative to sagittal plane locomotion
direction. Importantly, change of direction angles less than 90° were observed typically
throughout the literature. This is supported by previous notational analysis research that
has observed direction change angles occurring through less than 90° during the
majority of agility manoeuvres in sport
51, 170, 417
. The change of direction angles
employed as part of side-stepping agility assessment seemed arbitrary and presented
with limited sports specific evidence. Alternatively, other studies have not restricted the
change of direction angles required during side-stepping assessment tasks, instead
exploring the temporal parameters of agility skill execution as part of statistical
analysis
126, 325
. Clearly, further research is necessary in relation to the direction change
angles associated with agility manoeuvres executed during competitive sport, including
rugby union.
It was observed throughout the review that the change of direction patterns varied
considerably
between
agility
assessment
tasks.
Several
studies
required a number of changes of direction during a single side-stepping
assessment task
13, 45, 126, 180, 223, 227, 228, 361, 433
Young, McDowell and Scarlett
433
. For example, a study conducted by
required participants to perform multiple changes of
direction over a number of agility side-stepping tasks, ranging from two 20° changes of
direction to five 80° changes of direction (Figure 2.34). In contrast, a number
of
studies
required
assessment tasks
a
single
change
of
direction
during
43, 45, 90, 96, 133, 143, 199, 239, 256, 259, 287, 315, 325, 356, 361, 432
Young, James and Montgomery
432
side-stepping
. For example,
required participants to perform a single change
of direction through 20°, 40° and 60° during agility side-stepping assessment
tasks (Figure 2.35). Notably, studies incorporating a single change of direction during
side-stepping tasks were often limited to the measurement of either right
116
LITERATURE
or left
directional
running lines
For example, Schot, Dart and Schuh
43,
356
45,
90,
199,
239,
256,
287,
315,
REVIEW
325,
356
.
examined agility side-stepping performance
with a single change of direction through only left directional running lines.
Undoubtedly, measuring agility performance through only left running lines can present
inaccurate assumptions due to lower extremity dominance. Despite this, little is known
as to the change of direction patterns and running lines presented during agility skill
execution in sports, including rugby union.
117
AGILITY
IN RUGBY UNION
20°
50°
80°
80°
80°
80°
Figure 2.34: Representation of agility side-stepping tasks involving multiple changes of
direction.
(Adapted from Young, McDowell and Scarlett 433)
118
LITERATURE
REVIEW
20°
20°
40°
40°
60°
60°
Figure 2.35: Representation of agility side-stepping tasks with a single change of
direction.
(Adapted from Young, James and Montgomery 432)
119
AGILITY
IN RUGBY UNION
SHUTTLE RUNNING AGILITY ASSESSMENT
The shuttle run task was also a common method of agility performance assessment
reported throughout the published literature 29, 55, 57, 69, 105, 118, 132, 179, 180, 214, 223, 227, 232, 234,
235, 263, 284, 313, 391, 398, 423
. Shuttle running requires participants to run and touch a
designated line and then return in the opposite direction, representing a 180° direction
change angle (Figure 2.36). Typically, throughout the literature participants were
required to perform a number of direction changes during a single bout of a shuttle
running task
55, 105, 179, 214, 227, 235, 284
. To add to this, it was noted that the distances
traversed during a shuttle running agility assessment task varied considerably
between research projects, ranging between 5 and 30 m distances. For example,
Lemmink, Elferink-Gemser and Visscher
three
30
m
Nedeljkovic et al.
sprints
284
during
shuttle
223
required participants to complete
running
assessment.
Alternatively,
required participants to complete ten 5 m sprints during shuttle
running assessment. In another study, Burks et al.
69
measured agility shuttle running
performance over a total distance of only 10 yards (9.14 m).
Start / Finish Line
Turn Line
Figure 2.36: Transverse view representation of a shuttle running agility task.
120
LITERATURE
REVIEW
Notational analysis research has demonstrated that changes of directions greater
than 90° are observed rarely in team sports
51, 170, 417
. Hence, it is unlikely that
expressions of agility performance exhibiting multiple 180° direction changes as
observed during shuttle running tasks provide an accurate assessment of agility in most
team sports. Despite this, the Australian Institute of Sport (AIS) recommends the 505
shuttle run agility test (Figure 2.37) as an appropriate measure of agility performance
for rugby union
207
, basketball
Draper and Lancaster
118
376
, field hockey
221
, netball
128
and softball
127
.
presented the 505 agility test as a measure of agility
performance with valid applications to sport. This agility test has been used also as a
single predictor of muscular power, straight-line maximum running speed and
acceleration capacity, as well as agility skill execution 87. Clearly, shuttle running is not
an appropriate measure of agility for all team sports and it is questionable whether
the 505 agility test has the broad sporting applications as have been claimed
118
.
It is necessary for research to continue to examine sport specific methods of agility
assessment with relevant applications.
Turn Line
5m
505 Line
15 m
Start / Finish Line
Figure 2.37: Transverse view representation of the 505 agility test.
(Adapted from Draper and Lancaster 118)
121
AGILITY
IN RUGBY UNION
AGILITY ASSESSMENT VARIATIONS
Kirby
of
213
identified a number of distinct variations relating to the assessment
running
scientific
agility
based
agility
literature
observed
performance
as
performance.
that
expressed
a
The
number
during
review
of
249, 306
studies
purposefully
comprised commonly of the Illinois Agility run
the SEMO agility run
180,
(Figure 2.39), agility dot-drills
and the figure of eight agility run
of
165, 276, 397, 410
the
published
have
investigated
designed
procedures,
212,
398
(Figure 2.38),
162, 276, 410
(Figure 2.40)
(Figure 2.41). Furthermore, a study
conducted by Negrete and Brophy 285 required participants to traverse a diamond shaped
course (Figure 2.42), whilst other agility assessment protocols have included obstacles
that
required
stride patterns
evasive
manoeuvres
or
varied
surface
13, 42, 137, 154, 162, 163, 165, 175, 188, 238, 300, 313, 397
integrity
to
alter
. Typically, the purposefully
designed agility testing procedures have required participants to navigate around a
predetermined course that involved variations to the expression of running based
locomotion, such as the execution of forwards, backwards and sideways running and
through a range of change of direction angles.
The most commonly used of these agility assessment protocols reported throughout the
published scientific literature was the agility T-test
99, 113, 144, 250, 261, 274, 290, 309, 312, 410
.
Typically, the agility T-test required expressions of forward running as well as
side-shuffling
and
backwards
running,
with
changes
of
from 90° to 180° (Figure 2.43). Importantly, Pauole et al.
309
direction
ranging
demonstrated the
agility T-test to be a more valid measure of straight-line running speed than agility
performance. Despite this, authors of published scientific studies continue to promote
the validity of the agility T-test as a measure of agility performance for sport
99
.
The limitations of existing agility assessment protocols are represented in the
generalised skills that are required during performance. Clearly, it necessary to include
sport specific performance attributes in any measure of agility.
122
LITERATURE
REVIEW
Start / Finish line
Figure 2.38: Transverse view representation of the Illinois agility run.
(Adapted from Miller et al. 274)
123
AGILITY
IN RUGBY UNION
Start / Finish line
Figure 2.39: Transverse view representation of the SEMO agility run.
(Adapted from Mayhew et al. 249)
124
LITERATURE
REVIEW
Figure 2.40: Transverse view representation of the agility dot-drills.
(Adapted from Miller et al. 274 and Moore, Hickey and Reiser 276)
Start / Finish line
Figure 2.41: Transverse view representation of the figure of eight agility run.
(Adapted from Oritz et al. 302)
125
AGILITY
IN RUGBY UNION
Start / Finish line
Figure 2.42: Transverse view representation of the Diamond agility run.
(Adapted from Negrete and Brophy 285)
126
LITERATURE
REVIEW
Start / Finish line
Figure 2.43: Transverse view representation of the agility T- test.
(Adapted from Miller et al. 274 and Cronin, McNair and Marshall 99)
127
AGILITY
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SUMMARY: ASSESSMENT OF AGILITY
PERFORMANCE
Agility testing procedures reported throughout the scientific literature typically have
measured agility performance with limited consideration for sports specificity. Agility is
a sport specific skill and as a result, inaccurate methodologies and assessment
procedures
research
represent
180, 430, 433
confounding
factors
relating
to
the
application
of
. It is important to note that neither the International Rugby
Board (IRB) nor the Australian Rugby Union (ARU) offer any standardised procedures
in relation to the assessment of agility performance in rugby union. It is accepted that as
part of ARU coaching resources a basic outline of agility skill execution is provided,
however no specific resources are available in relation to agility testing in
rugby union 23.
A valid measure of agility in rugby union would consider the specific demands of the
sporting situation and incorporate multiple testing procedures. The assessment of agility
performance should involve a number of contributing factors relating to time based
speed assessments as well as kinetic and kinematic measures. It is also important that
agility assessment protocols incorporate sport specific physical capacities and activity
patterns, as well as cognitive abilities such as decision-making strategies and
anticipation. Fundamentally, agility assessment procedures must offer particular
consideration of the qualities of skill execution.
128
CHAPTER III
NOTATIONAL ANALYSIS
INTRODUCTION
BACKGROUND
Evasive changes of direction (agility skill execution) are an important attacking strategy
that promotes positive tackle outcomes (attacking ball carrier dominating the tackle
contest) in rugby union
351
. The ability of the attacking ball carrier to dominate the
tackle contest is enhanced further when displaying strong contact skills, such as
adopting low body height and strong leg drive in the tackle
254
. Beyond this, effective
attacking strategies in rugby union where attacking ball carriers combine evasive
running patterns and contact skills in resistance of defenders has not been described
previously in the scientific literature. Accordingly, the current study used notational
analysis to examine attacking strategies in rugby union, with a specific focus on the
attributes of agility skill execution associated with desirable tackle outcomes (e.g.
tackle-breaks and line-breaks).
129
AGILITY
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AIM AND OBJECTIVES
The overall aim of this study was to use notional performance analysis to examine
attacking strategies during ball carries in rugby union. The objectives consisted:
1. Design a valid and reliable notational analysis coding system relating to running
ability in rugby union, with particularly focus on agility skill execution during
evasive attacking manoeuvres.
2. Determine the attributes of evasive agility skill execution during attacking
manoeuvres in rugby union.
3. Determine the relationship between agility skill execution and phase outcome in
rugby union.
4. Determine the relationship between agility skill execution and overall team success.
5. Determine the relationship between running ability (agility and contact skills) and
attacking playing patterns in the prediction of desirable phase outcomes.
6. Design a rugby union specific assessment protocol of agility skill execution with
respect to evasive attacking manoeuvres in rugby union, based on the findings of
notational performance analysis.
130
NOTATIONAL
ANALYSIS
METHODS AND PROCEDURES
SUBJECTS
Notational analysis was conducted on seven international level provincial rugby union
games and consisted of randomly selected games played during the 2006
Super 14 rugby union competition. All Super 14 rugby union teams in the competition
were included in data collection. At the conclusion of the 2006 season, teams were
categorised into three groups based on the respective team ranking at the conclusion of
the competitive season. Three groups consisted:
1. Teams that finished the season ranked between first and fourth positions (N = 4)
2. Teams ranked between fifth and ninth positions (N = 5)
3. Teams that finished the season ranked outside of ninth place (N = 5)
STUDY DESIGN
DATA COLLECTION
The variables and the associated operational definitions coded as part of notational
analysis were compiled using available notational analysis publications and the
combined experience of the research team
210
. Lapsed-time notational coding was
completed by a single analyst consistent with previous protocols from Sayers and
Washington-King
351
. To assess intra-tester reliability, video footage of two
international rugby union matches was coded on two separate occasions. A one week
period between data collection sessions prevented measurement errors due to the
retention of results 328. The matches used to assess intra-tester reliability were Super 14
games but were not included as part of definitive notational analysis. In the current
study, variables were described using ordinal and nominal level data types and as such,
131
AGILITY
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non-parametric measures of relationship were used to assess reliability
203
. Kappa test
statistics were used to assess the intra-tester reliability of nominal and ordinal level data
types in accordance with Choi, O’Donoghue and Hughes 84. The reliability levels were
defined as complete with the Kappa measurement of agreement at 1.00, good above .81,
acceptable above .61 and poor below .61
84
. Overall, the intra-tester reliability
demonstrated appropriate levels of agreement (Table 4.1).
Table 4.1: Intra-tester Kappa measurement of agreement.
Variable
Kappa measurement of agreement
Attacking width
.97
Attacking depth
.85
Attacking velocity
.79
Attacking direction
.96
Defensive pattern
.92
Defensive position at contact
.79
Defensive numbers at contact
.95
Evasive step type
.94
Change of direction angle
.94
Proximity of defence at direction change
.88
Directional running line
.97
Resistive fend
.84
Contact intensity
.96
Phase outcome
1.00
Try outcome
1.00
Mean
.92
132
NOTATIONAL
ANALYSIS
The sampled rugby union matches included as part of notational analysis were recorded
by commercial
television
stations
and
distributed
on
the
public
domain.
The recorded footage was stored digitally and lapsed-time analysis was conducted with
video display software (Windows Media Player, Microsoft Corporation, Washington,
USA) capable of replaying footage. The notational analysis work-station was based in a
well-ventilated research laboratory with non-florescent lighting. The video match
footage was displayed on a 15-inch computer monitor (Samsung SyncMaster 710N,
Samsung Electronics, Sydney, Australia) that was set at seated eye level
219, 353
. To
reduce symptoms of eyestrain and potential errors due to fatigue, a maximum time of 2
hours restricted periods of observation and notational coding
50
. To add to this, active
recovery periods of 1 hour interspersed periods of notational coding. To reduce fatigue
further, regular short breaks during coding sessions were required and involved looking
away from the computer monitor and focusing on distant objects 219. During a period of
24 hours, notational coding was restricted to no more than a single rugby union game as
recommended by Eaves, Hughes and Lamb 125.
TESTING PROTOCOL
Notational analysis described and quantified the attacking and defending patterns of
team play and also the individual movement characteristics (evasive properties and
contact skills) of the attacking player in possession of the ball (N = 1372). For the
purposes of this study, a ball carry was defined as a motion where an attacking player
when in possession of the ball challenged the defensive line of the opposing team,
causing a reaction or commitment to this challenge by the defence
351
. During
assessment procedures, unforced handling errors observed when running in possession
of the ball were considered incomplete and not included as part of notational analysis.
However, those attacking ball carries where a handling error occurred when in contact
with the defence were considered a complete ball carry with a negative outcome and
was included as part of analysis.
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AGILITY
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The playing position of the attacking ball carriers was recorded and then categorised
according to the generalised positional grouping (forwards and backs). The forwards’
positional category consisted of tight forwards (loosehead and tighthead prop, hooker
and second row) and loose forwards (open-side and blind-side flankers and number 8).
The backs’ positional category consisted of inside backs (scrum half, fly half, and inside
centre) and outside backs (outside centre, wingers and fullback). In situations where
players were substituted, the replacement player was added to the data set for that
respective positional group.
The variables coded during notational analysis evaluated patterns of attacking play and
then the opposing response of the defensive team. Also, the movement characteristics of
the attacking ball carrier when attempting to penetrate the defensive line and advance
the ball were assessed. During those circumstances where the attacking ball carrier was
observed to make contact with an opposition defender, coded variables described the
characteristics of the contact (tackle contest) with consideration of both the attacking
ball carrier and the primary defensive opponent. A specific variable then examined the
quality of fend (upper body resistance) displayed by the attacking ball carrier in
resistance of the defence.
134
NOTATIONAL
ANALYSIS
PATTERNS OF PLAY: ATTACKING TEAM
The attacking team pattern of play examined the distribution of the ball through the
attacking line. Attacking team pattern of play also described the general locomotive
characteristics of the primary attacking ball carrier when receiving possession of the
ball. The respective variables measured attacking width and depth at ball reception, as
well as the speed at which the ball carrier was running at reception of the ball.
Attacking Width
The width of attack described the distribution of the ball along the attacking line
220
.
Attacking width described also those circumstances where the commencement of the
attacking ball carry was from a continuation of play, such as a pass in contact or a
turnover from the opposition. The width of attack variable sub-categories included:
1. Immediate attack – when the attacking ball carrier received possession of the ball
directly from the breakdown, such as those attacking situations commonly termed
pick and go.
2. Close attack –when the attacking ball carrier received possession of the ball through
no more than one pass from the breakdown.
3. Middle attack –when the attacking ball carrier received possession of the ball
through a pass from the first receiver.
4. Wide attack –when the attacking ball carrier received possession of the ball through
a pass from outside of the first receiver
5. Counter-attack –when the attacking ball carrier received possession of the ball
through an opposition turned over and play continued with counter-attacking
opportunities.
6. Phase continuation –when the attacking ball carrier received possession of the ball
through a continuation of the phase. An example of receiving the ball from a phase
continuation is when an attacking ball runner makes contact with the defence and
then offloads the ball to a team member in support, who then continues play.
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AGILITY
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Attacking Depth
The depth of attack described the distance to the defence when the attacking ball carrier
received possession of the ball. The depth of attack variable sub-categories included:
1. Close – when the attacking ball carrier received possession of the ball within 1 body
length (BL) of the nearest defensive opponent.
2. Moderate – when the attacking ball carrier received possession of the ball between
1 and 2 BL from the nearest defensive opponent.
3. Distant – when the attacking ball carrier received possession of the ball greater than
2 BL from the nearest defensive opponent.
Attacking Velocity
The attacking velocity described the running speed at which the attacking ball carrier
was moving when initially receiving possession of the ball
351
. The attacking velocity
variable sub-categories included:
1. Slow – when the attacking ball carrier was stationary or walking at ball reception.
2. Moderate – when the attacking ball carrier was jogging or cruising at ball reception.
3. Fast – when the attacking ball carrier was running or sprinting at ball reception.
Attacking Direction
The attacking direction described the general directional characteristics (in relation to
the side-line markings) of the attacking ball carry when challenging the defensive
line 351. The attacking direction variable sub-categories included:
1. Direct – when the attacking ball carrier ran directly at the defensive line.
2. Arcing – when the attacking ball carrier ran a curvilinear line at the defensive line.
3. Lateral – when the attacking ball carrier ran a lateral line from the defensive line and
in the general direction of the sideline.
136
NOTATIONAL
ANALYSIS
PATTERNS OF PLAY: DEFENSIVE TEAM
The defensive team pattern of play examined the defensive line movements in response
to the attacking ball carrier and also described the individual characteristics of the
primary defensive opponent when attempting to tackle the attacking ball carrier.
The respective variables measured the defensive line movement patterns and the
number of defenders attempting to tackle to attacking ball carrier. To add to this, the
body position of the primary defensive opponent when attempting to tackle the
attacking ball carrier was assessed.
Defensive Pattern
The defensive pattern described the general movement characteristics of the defensive
line in response to the attacking pattern of play and the ball carrier
23
. The defensive
pattern variable sub-categories included:
1. Static defensive line – when the defensive line was stationary on the advantage line
in response to the attacking pattern of play.
2. Rushed defensive line – when the defensive line moved forward off the advantage
line in response to the attacking pattern of play.
3. Lateral defensive line – when the defensive line moved laterally (across field) in
response to the attacking pattern of play.
Numbers at Contact
The numbers at contact described the number of defenders present during the attempted
tackle of the attacking ball carrier
65, 318
. It should be noted that no defenders were
present in the case of attacking line-break phase outcomes and as such, was not assessed
when line-breaks occurred. The number of defenders at contact variable sub-categories
included:
1. Single – when a single defensive opponent committed to tackling the attacking ball
carrier.
2. Double – when two defensive opponents committed to tackling the attacking ball
carrier.
3. Many – when more than two defensive opponents committed to tackling the
attacking ball carrier.
137
AGILITY
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Position at Contact
The position at contact described the body position of the primary defensive opponent
when attempting to tackle the attacking ball carrier 254. The defensive position at contact
variable sub-categories included:
1. Poor position – when the primary defensive opponent displayed high impact body
height, impacting the attacking ball carrier above abdomen height. Technical
indicators included where the primary defensive opponent attempted to tackle the
attacking ball carrier using the hands or dived in an attempt to tackle the attacking
ball carrier.
2. Moderate position – when the primary defensive opponent impacted the attacking
ball carrier above waist level. Technical indicators included where the defensive
opponent used predominately arms when attempting to tackle the attacking ball
carrier or reached with outstretched arms to tackle the attacking ball carrier.
3. Good position – when the primary defensive opponent displayed low impact body
height, impacting the attacking ball carrier below waist height. Technical indicators
included where the defensive opponent used the shoulders when attempting to tackle
the attacking ball carrier and with the feet close to the attacker at impact.
138
NOTATIONAL
ANALYSIS
EVASIVE PROPERTIES: ATTACKING BALL CARRIER
The evasive properties of the attacking ball carrier examined the movement patterns
exhibited by the attacking ball carrier when challenging the defensive line.
The respective variables measured evasive step type, direction change angles and
running lines. To add to this, the proximity to the nearest defensive opponent when
executing the initial change of direction was recorded.
Evasive Step Type
The evasive step type described the agility stepping patterns of the attacking ball
carrier when attempting to evade the defensive opponents
351
. The evasive step type
sub-categories include:
1. Straight –when the attacking ball carrier ran straight at the defence with no
execution of an evasive agility manoeuvre.
2. Side-step – when the attacking ball carrier attempted to evade the defence using a
side-stepping agility manoeuvre.
3. Crossover-step – when the attacking ball carrier attempted to evade the defence
using a crossover-stepping agility manoeuvre.
Change of Direction Angle
The change of direction angle described the angle at which the attacking ball carrier
changed directions in an attempt to evade the defence. It should be noted that the change
of direction angle was nullified with straight running patterns and as such, was not
assessed when a straight running pattern occurred. The change of direction angle
sub-categories included:
1. Slight – when the change of direction angle was between 0° and 20°.
2. Moderate – when the change of direction angle was between 20° and 60°.
3. Great – when the change of direction angle was greater than 60°.
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AGILITY
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Proximity of Defence at Direction Change
The proximity of defence at direction change described the distance to the defence at the
initial change of direction step. It should be noted that the proximity of the defence at
direction change was nullified with straight running patterns and as such, was not
assessed when straight running patterns occurred. The proximity of the defence at
direction change variable sub-categories included:
1. Near – when the primary defensive opponent was within 1 BL of the attacking ball
carrier at the change of direction step.
2. Moderate – when the primary defensive opponent was between 1 to 2 BL of the
attacking ball carrier at the change of direction step.
3. Distant – when the primary defensive opponent was greater than 2 BL from the
attacking ball carrier at the change of direction step.
Straighten Angle
The straighten angle described the angle that the attacking ball carrier straightened the
running direction following initial direction change. It should be noted that the
straighten angle was not assessed with straight running patterns. The straighten angle
variable sub-categories included:
1. Slight – when the straighten angle was between 0° and 20°.
2. Moderate – when the straighten angle was between 20° and 60°.
3. Great – when the straighten angle was greater than 60°.
Directional Running Line
The directional running line described the general running direction of the attacking ball
carrier in relation to the pattern of attacking play. The directional running line variable
sub-categories included:
1. Straight – when the attacking ball carrier ran straight at the defence.
2. Inside – when the attacking ball carrier ran an oblique line towards the direction of
the previous attacking phase of play.
3. Outside – when the attacking ball carrier ran an oblique line away from the direction
of the previous attacking phase of play.
140
NOTATIONAL
ANALYSIS
CONTACT SKILLS: ATTACKING BALL CARRIER
The contact skills of the attacking ball carrier examined the specific skill characteristics
of the attacking ball carrier when in contact with the defence. The respective variables
included measures of upper body resistance using fending strategies and also the
attacking intensity when in contact with the defence.
Resistive Fend
The resistive fend described the specific qualities of the fending strategies executed by
the attacking ball carrier in resistance of the defence. The resistive fend variable
sub-categories included:
1. Poor – when the attacking ball carrier provided no resistive fend.
2. Moderate – when the attacking ball carrier provided a light to moderate resistive
fend. An example of a light to moderate resistive fend is presented with swat or slap
techniques.
3. Good – when the attacking ball carrier provided a strong resistive fend using
techniques such as the push fend.
Contact Intensity
The contact intensity described the technical qualities of the attacking ball carrier when
in contact with the defence
23, 65, 254
. The contact intensity variable sub-categories
included:
1. Poor intensity – when the attacking ball carrier displayed high body height, above
the abdomen of the defence. Technical indicators included poor leg drive at contact,
submissive in contact and being driven behind the tackle-line by the defence.
2. Moderate intensity – when the attacking ball carrier impacted at abdomen level of
the defence. Technical indicators included an initial leg drive from the attacking ball
carrier but then submitting to the tackle of the defence and the attacking ball carrier
being tackled equal to the tackle-line.
3. Good intensity – when the attacking ball carrier displayed low body height, below
abdomen height of the defence. Technical indicators included strong leg drive with
the attacking ball carrier not submitting to the tackle and then advancing the ball
beyond the tackle-line during contact.
141
AGILITY
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ATTACKING OUTCOME
The attacking outcome examined the specific phase outcome as well as the relationship
between the attacking ball carry and the ability of the attacking team to score a try
within the subsequent period of possession. The respective variables included measures
of phase continuation or termination and also the number of phases between the
attacking ball carry and subsequently scoring a try.
Phase Outcome
The phase outcome described the general result of the attacking ball carry 65. The phase
outcome variable sub-categories included:
1. Breakdown loss – when the attacking team failed to retain possession of the ball at
the breakdown.
2. Breakdown win – when the attacking team successfully retained possession of the
ball at the breakdown.
3. Offload – when the attacking ball carrier was in contact with the defence and
successfully offloaded the ball to a supporting team member.
4. Tackle-break – when the attacking ball carrier successfully penetrated (broke free)
the attempted tackle from the defence.
5. Line-break – when the attacking ball carrier successfully evaded contact with the
defence and advanced the ball beyond the advantage line.
Try Outcome
The try outcome described the relationship between the attacking run of the ball carrier
and the immediacy of the attacking team scoring a try. It should be noted that an
indirect relationship was recorded when the attacking team did not a score a try
following the attacking ball carry. The try outcome variable sub-categories included:
1. Immediate – when the attacking team scored a try within 1 phase of the attacking
ball carry.
2. Direct – when the attacking team scored a try within 2 phases of the attacking ball
carry.
3. Indirect – when the attacking team scored a try after 2 phases following the
attacking ball carry.
142
NOTATIONAL
ANALYSIS
DATA ANALYSIS
Following notational analysis, the gathered observations were coded into an SPSS file
for statistical analysis. The SPSS software package (Version 12.01 for Windows, SPSS,
Inc., Chicago IL, USA) was used to present descriptive statistics (mean and standard
deviation) and measures of relationship using non-parametric tests
64
. Descriptive
statistics are presented as mean ( x ) and standard deviation (±SD) as normalised to the
total variable count. A significance level of p < .05 was used for all analyses.
Chi-squared (χ2) tests established significant dependencies between nominal and ordinal
data, with all data presented as chi-squared statistic, degrees of freedom and
significance figure (e.g. χ2 = 000, df = 0, p = 000) unless stated otherwise. These values
were representative of the relationship between all cells. Examination of the
standardised residuals (SR) then represented that magnitude by which the relationship
between two variables was above or below the expected. A value of ≥ 2.0 or ≤ -2.0
represented a value either significantly more or less (respectively) than expected for
that cell
164
. The current study will report the percentage of observed outcome from
Chi-squared analysis followed by the SR value.
Chi-squared analyses were conducted on the following categories:
o Evasive step type and attacking pattern of play
o Evasive step type and evasive properties of the attacking ball carrier
o Try outcome and phase outcome
o Phase outcome and attacking pattern of play
o Phase outcome and defensive pattern of play
o Defensive position at contact and defensive numbers at contact
o Phase outcome and evasive properties of the attacking ball carrier
o Phase outcome and the contact skills of the attacking ball carrier
Binary logistic regression analysis was performed and calculated the probability of a
tackle-break occurring when compared to winning the breakdown. The predictor
variable categories were attacking pattern of play, defending pattern of play, as well as
the evasive properties and contact skills of the attacking ball carrier. Further binary
logistic regression analysis examined the probability of poor defensive positioning
143
AGILITY
IN RUGBY UNION
occurring compared to moderate-good positioning, with predictor variables consisting
attacking pattern of play, defending pattern of play, as well as the evasive properties and
contact skills of the attacking ball carrier. Venn diagrams illustrated the prediction of
tackle-breaks and poor defensive positioning with a summary of the statistical results
outlined in Appendix B. These Venn diagrams also depicted the interrelationship
between variables when predicting tackle-breaks and poor defensive positions.
LIMITATIONS
In the current study, notational analysis coded specific variables relating to the
movement patterns associated with attacking ball carries in rugby union. The variables
used as part of notational analysis demonstrated high external validity with
consideration of rugby union. The variables used in this study may not be appropriate
when conducting notational performance analysis of movement patterns observed
within sports other than rugby union. Accordingly, the notational analysis presented in
this study is exclusive to rugby union and it is recommended that the external validity of
the variables used in the current study be evaluated prior to application within other
sporting contexts.
To add to this, the interpretation of events during data collection could have limited the
inter-tester reliability of the notational coding system. Previous authors have discussed
inter-tester agreement in performance analysis
95, 202, 298
but it was beyond the scope of
the current research project to conduct a comprehensive inter-tester reliability study.
Clearly, it is necessary that further research evaluates the inter-tester reliability of the
coding system used in the current study. The specific nature of the variables used in this
study meant that training another coder may have presented inherent inter-tester
reliability issues
202
. Despite this, the notational coding system used in this study
provides a sport specific examination of rugby union and emphasises the need to
develop notational analysis techniques that provide appropriate and meaningful
feedback to coaches and athletes.
144
NOTATIONAL
ANALYSIS
RESULTS
EVASIVE MOVEMENT PATTERNS
IN RUGBY UNION
Descriptive analysis of the general evasive qualities exhibited during rugby union
match-play revealed that 58 % of attacking ball carries displayed a straight running
pattern and 37 % a side-stepping strategy when challenging the defence. In contrast,
just 5 % of attacking ball carries used a crossover-stepping strategy when challenging
the defence (Figure 4.1). It was then shown that 54.3 % (SR = 2.4) of
crossover-stepping strategies were executed by the bottom 5 ranked teams (χ2 = 20.135,
df = 4, p < .001).
Straight-line
58 %
Crossover-step
5%
Side-step
37 %
Figure 4.1: Distribution of running movement patterns in rugby union.
145
AGILITY
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Straight runs (30.7 %, SR = 3.3) were associated with slow attacking velocity at ball
reception (χ2 = 43.841, df = 4, p < .001). In contrast, the majority of crossover-stepping
manoeuvres (72.9 %, SR = 2.5) were executed with fast attacking velocity at ball
reception. It should also be noted that a positive trend was observed between
side-stepping and moderate velocity (SR = 1.8). Further analysis showed that
straight runs (55.3 %, SR = 8.3) occurred typically with close depth at ball
reception (χ2 = 271.304, df = 4, p < .001). It was then demonstrated that the execution of
evasive
agility
manoeuvres
required
greater
depth
at
ball
reception,
with 54.3 % (SR = 2.9) of crossover-steps occurring at great depth, and over 85 % of
side-stepping movements occurring at moderate (35.9 %, SR = 3.0) and
great (50.8 %, SR = 6.6) attacking depth. In addition, the evasive change of direction
step when crossover-stepping and side-stepping was executed frequently at greater
than 1 BL from the defence (χ2 = 662.532, df = 4, p < .001). It was shown
that 47.1 % (SR = 4.7) and 20.0 % (SR = 3.4) of crossover-stepping strategies,
and 50.4 % (SR = 14.2) and 16.1 % (SR = 6.1) of side-stepping strategies occurred at a
moderate to distant proximity to the defence at direction change, respectively.
Preferred directional running lines varied depending on the evasive stepping strategy.
Attacking ball carriers using crossover-stepping strategies favoured outside running
lines (47.1 %, SR = 3.0), whereas those ball carriers using side-stepping typically
displayed an inside running line (66.7 %, SR = 12.6). Moderate change of
direction angles were found to be a common occurrence during agility skill
execution in rugby union, with both side-stepping (79.2 %, SR = 18.9) and
crossover-stepping (52.9 %, SR = 3.1) strongly associated with this component of
evasion (χ2 = 1268.543, df = 4, p < .001). There was also a significant associated
between great change of direction angles and both side-stepping (18.8 %, SR = 9.0) and
crossover-stepping (15.7 %, SR = 2.4). However, great change of direction angles were
observed in less than 20 % of evasive manoeuvres, compared to greater than 75 % of
evasive manoeuvres displaying a moderate angle.
A significant associated was observed between a moderate straighten angle and sidestepping (SR = 12.6), with 33.8 % of side-steps displaying a moderate
angle (χ2 = 357.250, df = 4, p < .001). Further analysis demonstrated that
27.4 % (SR = .8) of side-stepping manoeuvres involved a combination of a moderate
146
NOTATIONAL
ANALYSIS
change of direction angle followed by a moderate straighten angle (χ2 = 87.847, df = 4,
p < .001). It should be noted that 50.8 % (SR = .6) of side-stepping attacking runs
involved a combination of a moderate change of direction angle followed by a slight
straighten angle.
DETERMINATION OF TRY SCORING AND
PHASE OUTCOME
Tackle-breaks, line-breaks and offloading the ball in the tackle promoted try scoring
ability (χ2 = 68.111, df = 8, p < .001). It was shown that 33.3 % (SR = 3.8) of
tackle-breaks and 23.2 % (SR = 5.0) of line-breaks resulted in scoring a try within one
phase of the attacking ball carry. Also, 26.1 % (SR = 2.3) of successful offloads in the
tackle resulted in a try within two subsequent attacking phases.
PATTERNS OF PLAY: ATTACKING TEAM
Attacking width was not associated significantly with the tackle-breaks or offloading
the ball in the tackle. However, a significant association was observed with
73.3 % (SR = 2.9) of breakdown wins occurring with immediate attack
and 15.5 % (SR = 2.5) of breakdown losses associated with wide attack (χ2 = 93.576,
df = 20, p < .001). It should also be noted that 11.2 % (SR = 2.1) and 11.1 % (SR = 2.9)
of line-breaks occurring with counter-attack and phase continuation, respectively.
Following on from this, attacking ball carriers who achieved line-breaks (69.4 %,
SR = 6.1) typically received possession of the ball at distant depth of
attack (χ2 = 102.746, df = 8, p < .001). Also, results showed that 42.2 % (SR = 2.1) of
tackle-breaks were achieved with distant depth of attack at ball reception.
Fast attacking velocity at ball reception was shown to promote both tackle-breaks and
line-breaks (χ2 = 50.548, df = 8, p < .001). Greater than 61 % (SR = 2.0) of
147
AGILITY
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tackle-breaks and 72 % (SR = 2.8) of line-breaks occurred with fast velocity. It should
be noted that 61.8 % of side-stepping manoeuvres that resulted in a tackle-break
displayed fast attacking velocity but this was shown not to be a significant
association (χ2 = 14.888, df = 8, p = .061). Additional analysis observed that the
attacking direction was associated significantly with the determination of phase
outcome (χ2 = 27.547, df = 8, p = .001). However, this was associated only with losing
the ball at the breakdown, where 24.1 % (SR = 3.0) of breakdown losses occurred with
lateral attacking directions.
PATTERNS OF PLAY: DEFENSIVE TEAM
Analysis of the defensive patterns associated with the determination of phase outcome
showed that 36.7 % (SR = 2.6) and 37.8 % (SR = 2.9) of line-breaks occurred with
static and lateral defensive patterns, respectively (χ2 = 42.169, df = 8, p < .001).
Also, 57.6 % (SR = 2.1) of breakdown wins occurred with rush defence. Almost 95 %
of breakdown wins were associated with moderate 30.2 % (SR = 2.1) and
good 64.0 % (SR = 7.5) defensive positions at contact (χ2 = 975.993, df = 8, p < .001).
Similarly, 70.7 % (SR = 3.9) of breakdown losses occurred with good defensive
positions. It was shown that 50.7 % (SR = 5.7) of offloads in the tackle occurred with
moderate defensive positions. In contrast, 91.9 % (SR = 17.8) of tackle-breaks occurred
with poor defensive positions at contact.
The number of defenders committed to the tackle contest was associated with the
outcome of the tackle (χ2 = 329.906, df = 8, p < .001). Committing two or more
defenders to the tackle contest restricted the ability of the attacking team to continue the
phase of possession. For example, over 60 % of breakdown wins occurred with
double (54.0 % SR = 7.5) and many (6.5 % SR = 3.3) defensive opponents at contact.
In contrast, 90.1 % (SR = 5.0) of offloads in the tackle and 92.9 % (SR = 6.6) of
tackle-breaks occurred with a single defender at contact. Further analysis demonstrated
a significant association where 92.8 % of side-stepping manoeuvres that resulted in a
tackle-break involved a single defender (χ2 = 173.922, df = 8, p < .001).
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NOTATIONAL
ANALYSIS
In addition, it was shown that 88.4 % (SR = 7.7) of poor defensive positions occurred
with a single defensive opponent at contact (χ2 = 212.802, df = 4, p < .001).
On the other hand, 52.7 % (SR = 6.1) of good defensive positions occurred with
two or more defensive opponents at contact. A significant association was then
observed with 94.3 % (SR = .2) of attacking ball carries that resulted in a tackle-break,
created poor defensive positioning when displaying a side-stepping manoeuvre that
challenged a single defensive opponent (χ2 = 164.844, df = 8, p < .001).
EVASIVE PROPERTIES: ATTACKING BALL CARRIER
Straight running lines were shown to be associated with breakdown wins (47.1 %,
SR = 4.1) (χ2 = 153.476, df = 8, p < .001). In contrast, 42.9 % (SR = 2.8) of line-breaks
displayed an outside line and 60.7 % (SR = 6.7) of tackle-breaks displayed an inside
line. Further analysis showed that when ball carriers ran a direct inside running line then
this accounted for 62.2 % (SR = 6.7) of tackle-breaks (χ2 = 137.332, df = 8, p = .001).
It should be noted that 57.3 % (SR = 1.7) of breakdown losses occurred through a direct
and straight running line.
It was observed that 72.0 % (SR = 8.5) of tackle-breaks displayed patterns of
side-stepping evasive attacking strategies (χ2 = 153.254, df = 8, p < .001).
Moreover, 62.6 % (SR = 7.9) of tackle-breaks displayed a moderate change of direction
angle and 11.8 % (SR = 2.2) displayed a great change of direction angle.
Further analysis demonstrated a significant association where 83.6 % (SR = .6) of
side-stepping manoeuvres that resulted in a tackle-break exhibited a moderate change of
direction angle (χ2 = 50.226, df = 4, p < .001). Analysis showed that
59.2 % (SR = 1.5) of side-stepping manoeuvres that resulted in a tackle-break
displayed a moderate proximity to the defence at the change of direction evasive
step (χ2 = 39.435, df = 2, p < .001).
The
straighten
angle
during
agility
skill
execution
was
associated
with
tackle-breaks (χ2 = 146.908, df = 8, p < .001). It was shown that tackle-breaks typically
displayed a moderate straighten angle (32.7 %, SR = 8.0) or a great straighten
149
AGILITY
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angle (6.6 %, SR = 4.2). Furthermore, 42.1 % (SR = 2.1) of side-stepping manoeuvres
that resulted in a tackle-break phase outcome displayed a moderate straighten
angle (χ2 = 32.993, df = 2, p < .001).
CONTACT SKILLS: ATTACKING BALL CARRIER
The contact skills displayed by the attacking ball carrier represented a key determinant
of tackle outcome. Results demonstrated that 69.0 % (SR = 6.4) of breakdown
losses occurred with poor intensity, whilst greater than 70 % of breakdown wins
occurred with poor (42.9 %, SR = 4.3) and moderate (31.3 %, SR = 4.4) intensity.
In contrast, 95.7 % (SR = 12.0) of tackle-breaks occurred with good contact intensity.
Also, it was demonstrated that fending promoted tackle breaks, with almost 40 % of
tackle-breaks
occurring
with
a
moderate
(15.6
%,
SR
=
4.0)
and
good (23.7 %, SR = 10.4) resistive fend. It should be noted that good fending strategies
enhanced the ability of the attacking ball carrier to offload the ball in the tackle (10.6 %,
SR = 2.2).
The importance of active fending strategies was emphasised where attacking ball carries
that displayed no evasive step pattern but resulted in a tackle-break were shown to use a
moderate (25.5 %, SR = 4.8) or good (34.0 %, SR = 8.6) fend (χ2 = 145.723,
df = 8, p < .001). Similarly, 83.8 % (SR = 5.9) of attacking ball carries that
resulted in a tackle-break achieved through an evasive side-step exhibited a good
fend (χ2 = 65.280, df = 8, p < .001).
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NOTATIONAL
ANALYSIS
PREDICTION OF TACKLE-BREAK OUTCOME
Binary logistic regression was used to investigate models of predicting tackle-breaks
when compared to winning the breakdown. For the purposes of analyses, individual
variables were grouped according to the respective categories (attacking patterns of
play, defending patterns of play, evasive movement patterns of the attacking ball carrier
and the contact skills of the attacking ball carrier) and constituted the required predictor
variables. Appendix B.1 outlines the results from binary logistic regression predicting
tackle outcome. The percent predictions of tackle-break phase outcomes based on the
interrelationships between the components of play are represented in Figure 4.2.
Defensive Pattern
Evasive Properties
of play
17.1 %
86.7 %
Contact Skills
Attacking Pattern
38.9 %
of play
0%
Figure 4.2: Representation of the components of match-play and the percent prediction
of tackle-break.
The results demonstrated that the combined variables associated with attacking playing
pattern could not predict tackle-breaks reliably. It should be noted that the
attacking depth at ball reception as part of the pattern of play was associated
151
AGILITY
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significantly (p < .001) with tackle outcome; however the remaining variables were not
associated with the prediction of tackle-breaks and attacking pattern of play was a poor
predictor of tackle-breaks. Alternatively, the defensive pattern of play could predict
tackle-breaks with 86.7 % accuracy. It was shown that the defensive position at contact
and numbers at contact were significantly associated with tackle-breaks (p < .001).
Poor defensive positioning with less defenders at contact were factors associated with
the prediction of tackle-breaks. Conversely, the movement characteristics of the
defensive line in response to the attacking pattern of play and the ball carrier was not a
significant contributing factor associated to the prediction of tackle outcome (p = .639).
It was then shown that the evasive properties displayed by the attacking ball carrier
could predict 17.1 % of tackle-breaks. Moreover, the variables associated with evasion
(evasive step type, change of direction angle, proximity to the defence, straighten angle
and directional running line) were all significant (p < .05) factors contributing to the
prediction of tackle outcome. Further analysis demonstrated that 38.9 % of
tackle-breaks could be predicted using the variables that assessed the contact skills of
the attacking ball carrier. Active fending (p <. 001) and greater contact
intensity (p <. 001) were both factors associated significantly with tackle-breaks.
152
NOTATIONAL
ANALYSIS
PREDICTION OF POOR DEFENSIVE POSITION
Binary logistic regression then investigated models of predicting poor defensive
positioning at contact when compared to moderate-good positioning. Appendix B.2
outlines the results from binary logistic regression predicting defensive positioning at
contact. The percent predictions of poor defensive positions based on the
interrelationships between the components of play are represented in Figure 4.3.
Evasive Properties
Attacking Pattern
of play
26.6 %
0%
Contact Skills
Defensive Pattern
86.5 %
of play
0%
Figure 4.3: Representation of the components of match-play and the percent prediction
of poor defensive position at contact.
It was observed that neither attacking pattern of play nor defensive pattern of play
predicted reliably poor defensive positioning at contact. It should be noted that attacking
width (p = .011) and depth (p < .001) were significant contributors to the model of
attacking pattern of play but these combination of variables was unable to predict
defensive position accurately. Similarly, the variable assessing defensive numbers at
153
AGILITY
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contact was a significant contributor to the model of defensive pattern of play, but the
combination of defensive pattern (p = .792) and numbers at contact (p < .001) was not
an accurate predictor of poor defensive positions.
Alternatively, the individual skills of attacking ball carriers consisting the evasive
properties and contact skills were significant predictors of poor defensive positions at
contact. The variables associated with evasion predicted 26.6 % of poor defensive
positions, with the proximity of the defence at direction change the only variable not a
significant contributor (p = .615). To add to this, the qualities of contact skills displayed
by the ball carrier predicted 86.5 % of poor defensive positions. It was demonstrated
that strong fending and good contact intensity promoted poor defensive positions.
154
NOTATIONAL
ANALYSIS
ATTRIBUTES OF TEAM RANKING
The percentage of tackle-break phase outcomes tended to be higher in the top four
ranked teams (19 %, SR = 1.8) compared to the middle five (16 %, SR = .6) and
bottom five ranked teams (11 %, SR = -2.1) (χ2 = 15.582, df = 8, p = .049) (Figure 4.4).
It should be noted that the mean percentage of tackle-break phase outcomes
was 15 % of all attacking ball carries.
Tackle-breaks (%)
20
15
10
Top 4
Middle 5
Bottom 5
Team Ranking
Figure 4.4: Percentage of tackle-breaks with respect to team ranking.
Results showed that the 32.4 % (SR = 1.9) of attacking ball carries from the top 4 teams
created poor defensive positions (χ2 = 10.015, df = 4, p = .040). Further analysis
examined the number of defenders at contact between teams and demonstrated
that 64.8 % (SR = 1.7) of attacking ball carries from the top 4 teams were associated
with a single defensive opponent at contact (χ2 = 14.528, df = 4, p = .006). Analysis
then investigated the relationship between team ranking and contact intensity. It was
shown that 14.3 % (SR = 2.8) of the attacking ball carries from the bottom 5 ranked
teams were characterised by poor contact intensity (χ2 = 25.409, df = 4, p < .001).
155
AGILITY
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ATTRIBUTES OF PLAYING POSITION
The outside backs achieved the greatest percentage of tackle-breaks (56.4 %, SR = 3.7)
between the positional roles in rugby union (χ2 = 93.587, df = 12, p < .001) (Figure 4.5).
Although not significant, loose forwards also displayed a high percentage of
tackle-breaks (23.2 %) when compared to inside backs (15.6 %) and tight
forwards (4.7 %). It should also be noted that there was no significant difference in the
percentage of ball carries for each positional role between team rankings (χ2 = 7.280,
df = 15, p = .296). Higher ranked teams did not have a higher percentage of outside
backs as ball carriers.
60
*
Tackle-breaks (%)
50
40
30
20
10
0
Outside backs
Inside backs
Loose forwards
Tight forwards
Playing Position
*Significant (p < .001) association between outside backs and tackle-breaks
Figure 4.5: Percentage of tackle-breaks with respect to playing position.
A significant association was observed with tight forwards (6.9 %, SR = 2.0) commonly
encountering many defensive opponents when running with the ball (χ2 = 31.733, df = 6,
p < .001). The attacking width then reflected the typical positional roles,
with tight (33.9 %, SR = 6.0) and loose (28.4 %, SR = 5.6) forwards receiving the ball
156
NOTATIONAL
ANALYSIS
directly from the breakdown, whilst inside backs (36.1 %, SR = 4.6) received the ball
one pass from the breakdown and outside backs (14.5 %, SR = 6.0) running with wide
attacking width (χ2 = 335.274, df = 15, p < .001). Similarly, tight (53.7 %, SR = 3.9)
and loose forwards (49.0 %, SR = 3.9) received the ball typically in close proximity to
the defence, whilst outside backs (47.1 %, SR = 5.4) received the ball at distant
attacking depth (χ2 = 130.316, df = 6, p < .001). Analysis observed
that 40.4 % (SR = 4.6) of tight forwards and 36.0 % (SR = 4.7) of loose forwards
received the ball at slow velocity, whilst 69.6 % (SR = 5.8) of outside backs received
the ball at fast velocity (χ2 = 164.349, df = 6, p < .001). Furthermore, ball carries from
the loose forwards (12.7 %. SR = 2.1) were characterised by arcing runs, whilst inside
backs (25.4 %, SR = 5.1) were likely to run laterally (χ2 = 51.463, df = 6, p < .001).
Analysis of the evasive properties displayed by the respective positional roles revealed
that tight (78.9 %, SR = 4.2) and loose (69.1 %, SR = 3.0) forwards ran straight
at the defence with no evasion (χ2 = 118.824, df = 6, p < .001).
In contrast, both inside (46.7 %, SR = 2.1) and outside (50.0 %, SR = 5.1) backs
favoured the side-stepping evasive strategy when challenging the defence.
Moreover, 43.2 % (SR = 2.6) of inside backs and 43.8 % (SR = 5.0) of outside
backs
displayed
a
moderate
change
of
direction
angle
during
evasive
manoeuvres (χ2 = 127.967, df = 6, p < .001). Also, 28.4 % (SR = 2.0) of inside backs
displayed a moderate proximity to the defence at change of direction (χ2 = 91.610,
df = 6, p < .001). Similarly, 29.5 % (SR = 4.2) and 12.0 % (SR = 3.0) of outside backs
displayed moderate and distant proximity to the defence at change of direction.
Ball carries from the outside backs (20.3 %, SR = 4.8) were also associated with a
moderate straighten angle (χ2 = 65.743, df = 6, p < .001).
157
AGILITY
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DISCUSSION
RUNNING PATTERNS IN RUGBY UNION
The match-play characteristics of rugby union dictate that evasive agility skill execution
is an important component of running ability during attacking ball carries
122, 328
.
Notably, it was demonstrated that agility manoeuvres occur more frequently (42 % of
attacking ball carries exhibited an evasive agility manoeuvre) than has been reported in
previous notational analysis research (16 % of sprints exhibited an agility
manoeuvre)
122
. Importantly, the findings of the current study support Sayers and
Washington-King
351
who found that attacking ball carriers frequently exhibit evasive
agility manoeuvres when challenging the defensive line.
Agility skill execution during running based locomotion displays distinct stepping
strategies,
consisting
side-stepping
and
crossover-stepping.
In
rugby union,
side-stepping was found to be a common feature of ball carries, compared to
crossover-stepping.
Similarly,
Sayers
and
Washington-King
351
observed
that crossover-stepping strategies (swerves) were executed rarely during evasive agility
manoeuvres in rugby union. Building on this, the current study found that the crossoverstepping strategy was executed at high speeds with substantial attacking space, where
attacking ball carriers seemed to be attempting to outrun the defence through an outside
running line. In contrast, side-stepping strategies were associated with receiving the ball
at moderate and distant attacking depth and with no dependency on running speed.
This suggests that side-stepping is a more versatile method of evasive attack and that
attacking ball carriers need considerable depth to swerve in rugby union. This adds
weight to the notion that side-stepping is a more effective movement strategy than
crossover-stepping when considering the sport specific requirements of running ability
in rugby union 300, 325. It is recommended that attacking ball carriers use the side-step in
more congested situations on the field (defenders in close proximity) and use the
crossover-step when running with considerable depth (e.g. attacking from a kick).
158
NOTATIONAL
ANALYSIS
DETERMINATION OF PERFORMANCE
The capability to score tries is fundamental to success in rugby union
65, 201, 210, 220
.
The current study furthered this understanding in showing that tackle-breaks,
line-breaks and offloading the ball in the tackle were associated with scoring a try
within the subsequent phase of attacking play. Phase outcome has been identified by
coaches as a crucial factor contributing to scoring tries, whereby the ability to penetrate
the defensive line through tackle-breaks and line-breaks and also offloading the ball in
the tackle represent phase outcomes that promote try scoring capability 65, 210. Therefore,
the ability to penetrate the defensive line and advance the ball demonstrates an effective
strategy to maintain attacking continuity and as such, represents a highly desirable
phase outcome during attacking ball carries in rugby union.
The time in possession of the ball is believed to be a key determinant of team success in
rugby union 318, 394. However, it has been shown that the amount of attacking possession
does not predict successful team performances accurately in rugby union
393
.
An increased try scoring rate is associated with a decrease in the number of attacking
phases during a period of attacking possession (r = -.93, p < .01)
220
. In addition, the
total time an individual athlete is in possession of the ball has been shown to be as low
as 60 s during a game of rugby union, which emphasises the importance of penetrating
the defensive line during a ball carry
220
. Building on this, the findings of the current
study suggest that individual running ability relating to phase outcome is a critical
component to the determination of team success in rugby union.
It should be noted that the variables associated with penetrating the defensive line (linebreak and offloading in the tackle) were not associated with team success in Super 14
rugby union. However, the more successful teams displayed a greater percentage of
tackle-break phase outcomes. In support of this, previous research has noted the
importance of tackle-breaks to the determination of success in rugby union 65, 201, 210, 392.
This suggests that the percentage of tackle-break phase outcomes represents a key
determinant of try scoring capability and overall team success in rugby union. Clearly,
the percentage of tackle-breaks should be considered a key performance indicator for
rugby union teams. The results of this study suggest that teams should aim for 20 %
159
AGILITY
IN RUGBY UNION
tackle-breaks from all attacking ball carries (mean percentage of tackle-breaks from for
top 4 teams in Super 14).
The findings of this study indicate that a trade-off exists between tackle-breaks and the
ball distribution required to those positions more likely to break the tackle. For example,
outside backs were responsible for the majority of tackle-breaks, but the wide attacking
patterns that are often required to distribute the ball to these positions were associated
with loosing the ball at the subsequent breakdown
254
. It should be noted that previous
research has shown that 48 % of tries in rugby union are scored when the attacking ball
carrier receives possession of the ball within three passes from the breakdown
220
.
Therefore, wide attacking patterns seem counter productive to the continuity of
attacking phases and as such it is recommended that the running ability of the outside
backs be utilised through occasionally receiving possession of the ball through a pass
from the first receiver.
The demonstrated association between attacking depth and line-breaks in the current
study no doubt reflects the high percentage of line-breaks occurring through counterattacking and phase continuation opportunities where the defensive line is unstructured.
In contrast, the association between distant attacking depth and tackle-breaks suggests
that a period of time is required by the attacking ball runner to assess the defensive
pattern and manipulate individual defenders. Receiving the ball with greater depth also
means that the attacking ball carrier will likely be running at higher speed when
challenging the defensive line (greater distance to accelerate towards the defence).
This finding builds on coaching theories, where distant attacking depth is considered a
desirable feature of attacking patterns of play in rugby union 23.
The association between tackle-break phase outcomes and fast attacking velocity
when receiving possession of the ball reflects previous research by Sayers and
Washington-King
351
, who demonstrated that positive phase outcomes were associated
with the attacking ball carrier receiving possession of the ball at high running speeds.
To add to this, attacking ball carriers who ran with maximal intensity were shown to be
more likely to achieve positive phases outcomes
351
. To date, high intensity running
motions have been found to comprise a small percentage (2 %) of the total
running motions in rugby union
112
. Despite this, the current study demonstrated that
160
NOTATIONAL
ANALYSIS
tackle-break phase outcomes were achieved with high intensity running motions during
the attacking ball carry. Therefore, although high intensity running motions may
constitute a small proportion of the total running motion in a game of rugby union, they
represent an important factor in the determination of tackle-break phase outcomes.
This study demonstrated that the attacking direction relating to running motion was an
important factor in the determination of tackle-break phase outcomes. It was shown that
a lateral attacking direction (Figure 4.6) was associated with failing to retain the ball at
the subsequent breakdown. Similarly, the majority of breakdown losses (57.3 %)
occurred with a direct and straight running line (Figure 4.7). In support of this, Sayers
and Washington-King
351
found that direct and straight running lines were associated
with negative phase outcomes. In contrast, the results of the current study are consistent
with previous research in showing that tackle-breaks were achieved typically with a
direct inside running line (Figure 4.8), which increases the number of variables
associated with defensive decision-making and as a consequence, promotes skill
breakdown in the opposition 351. It is concluded that indirect attacking directions as well
as straight running lines are ineffective attacking strategies in rugby union.
161
AGILITY
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Figure 4.6: Transverse plane representation of an indirect (lateral) running line.
Figure 4.7: Transverse plane representation of direct and straight running line.
Figure 4.8: Transverse plane representation of direct and inside running line.
162
NOTATIONAL
ANALYSIS
This study demonstrated that side-stepping evasive manoeuvres represent the most
effective attacking strategy when attempting to penetrate the defensive line in
rugby union. Sayers and Washington-King
351
demonstrated that tackle-break phase
outcomes were more likely when the attacking ball carrier used an agility manoeuvre.
In addition, it was shown that side-stepping manoeuvres were the most common evasive
movement patterns observed during attacking ball carries. Importantly, this study
demonstrated that tackle-breaks (72.0 %) were achieved typically through a sidestepping evasive movement pattern. Biomechanics research has demonstrated that the
movements associated with the side-stepping strategy function to increase the base of
support and as a result, enhance the properties of dynamic stability during skill
execution
16, 348
. Consequently, the dynamic stability attributes associated with side-
stepping manoeuvres may improve running ability during contact situations in rugby
union, and would no doubt promote subsequent tackle-break phase outcomes.
The change of direction angle associated with side-stepping manoeuvres has been
shown to be an important factor in the determination of phase outcome
Washington-King
351
demonstrated
that
side-stepping
351
. Sayers and
manoeuvres
involving
predominately forward motion were associated with positive phase outcomes, such as
tackle-breaks. Building on this, the current study demonstrated that side-stepping
manoeuvres that resulted in tackle-breaks frequently displayed a moderate change of
direction angle (Figure 4.9). In addition, Sayers and Washington-King
351
found that
side-stepping manoeuvres involving predominately lateral motion were effective in
achieving positive phase outcomes such as tackle-breaks but were not associated with
advancing the ball beyond the advantage line. Similarly, the current study demonstrated
that just 11.8 % of agility manoeuvres resulting in a tackle-break exhibited a change of
direction angle greater than 60°. Analysis of the kinetics associated with side-stepping
has shown that greater braking forces are associated with greater change of direction
angles
356
. Therefore, side-stepping manoeuvres with a moderate change of direction
angle no doubt enable the ball carrier to maintain running speed that then enhances the
ability to penetrate the defensive line following the execution of the initial evasive
direction change 351.
163
AGILITY
IN RUGBY UNION
The proximity to the defence at the execution of the initial evasive side-step was also an
important factor determining tackle-breaks. Changing directions between 1 to 2 BL
from the defence was a common characteristic of ball carries resulting in
tackle-breaks (Figure 4.9). It should be noted that advance cue recognition can predict
movement patterns during sporting performance
6, 159, 177, 359, 365
. It is proposed
the execution of the initial evasive manoeuvre at a moderate distance from the
nearest defender limits the visual cues offered to the primary defensive opponents,
disrupting defensive decision-making and enhancing the ability of the attacking ball
carrier to penetrate the defensive line 262.
20° – 60 °
1 – 2 BL
Figure 4.9: Transverse plane representation of initial direction change side-stepping
manoeuvre.
164
NOTATIONAL
ANALYSIS
This study demonstrated that the presence of a moderate straighten angle
when side-stepping was an important component in the determination of
tackle-breaks (Figure 4.10). The ST phase involves straightening the directional running
line following preceding lateral displacement and as such, horizontal acceleration is no
doubt a fundamental characteristic of the ST phase. Hence, evasive manoeuvres
displaying a moderate straighten angle enable the ball carrier to overcome lateral
moments associated with direction change whilst maximising horizontal momentum 351.
Consequently, the relationship between the straighten angle and acceleration capacity
represents a critical factor when attempting to exploit a break in the defensive line
created from the initial evasive side-stepping manoeuvre.
20° – 60 °
20° – 60 °
1 – 2 BL
Figure 4.10: Transverse plane representation of initial direction change and subsequent
straightening side-stepping manoeuvre.
165
AGILITY
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The performance attributes displayed by the attacking ball runner when in contact
with defensive opponents has been shown to determine phase outcome
254, 318
.
Body height is an important factor in the retention of the ball when in contact with
defensive opponents
254
. Research conducted by McKenzie et al.
254
has shown that a
third of attacking ball carries are turned over at the breakdown when the attacking ball
carrier displays high body height at contact. However, it is important to note that the
research by McKenzie et al. 254 was conducted when rugby union was an amateur sport.
The introduction of professionalism to rugby union in 1995 has altered the match-play
characteristics such that the number of tackle contests has increased by over 50 %
320
.
Subsequently, greater emphasis has been placed on power in contact and as such,
athletes have evolved to be greater in body mass
320
. Building on the existing
knowledge, the current study demonstrated that over 95 % of tackle-breaks were
achieved with good contact intensity, characterised by low body height and strong leg
drive. In contrast, breakdown losses occurred typically with poor intensity, as
characterised by submissive contact and with high body height. The findings of this
study (based on contemporary rugby) provide support to coaching theory where
attributes of leg drive and body height are considered important technical indicators of
performance 23.
The fending strategies executed by the attacking ball carrier in resistance of the defence
were also shown to be a key determinant of phase outcome in rugby union. To add to
this, moderate-good fends were observed in the majority of tackle-breaks achieved
using direct and straight (no evasion) running patterns. The findings of the current
study emphasise the importance of resistive fending strategies in the determination of
tackle-break phase outcomes. Notably, there is a lack of published scientific research
considering resistive fending techniques in contact and collision sports such as rugby
union. Resistive fending represents a key determinant of running ability in rugby union
and as such, further investigation is warranted. It is recommended that fending
strategies should form a fundamental aspect of development programs in rugby union.
Strength and conditioning coaches should consider ways of improving fending capacity
through upper body resistive exercises (e.g. bench throws and medicine ball chest
press). The skill of fending could also be included in strength and conditioning
programs where players practice effective push technique on an opponent.
166
NOTATIONAL
ANALYSIS
The attacking patterns of play, evasive movement patterns and contact skills of the
attacking ball runner are strategies that combine to isolate defenders and manipulate
them to poor positioning. This study observed that tackle-breaks were likely when
attacking ball carriers isolated a defensive opponent and then exhibited evasive
movement patterns to manipulate the defender to poor positioning. In support of this,
previous research has shown that committing only a single defender to contact is
associated with positive attacking phase outcomes
318
. On the other hand, defensive
teams aiming to restrict attacking continuity and tackle-breaks should commit multiple
defenders to the tackle contest
65
. However, it should be noted in committing multiple
defenders to the tackle contest that this would leave less available defenders to be
positioned in the defensive line for the subsequent phases of attacking play, which may
then promote tackle-breaks during these phases. Clearly, research should continue to
examine the trade-off between the number of defenders at the tackle contest and the
immediate and subsequent phase outcomes.
The combination of evasive running patterns and strong contact skills represented
performance attributes that promoted poor defensive positions in rugby union.
Importantly, these poor defensive positions were created regardless of the defensive
pattern of play. This emphasises the importance of individual skill execution associated
with running ability and contact skills during attacking match-play in rugby
union
254, 351
. Therefore, the ability of attacking ball carriers to display evasive agility
manoeuvres combined with active resistance of defensive opponents no doubt
represents a measure of success in rugby union relevant to the effectiveness of skill
execution, phase outcome, try scoring ability and overall team success.
Investigation of positional running ability demonstrated that outside backs were the
primary ball carriers associated with tackle-break phase outcomes. Sayers and
Washington-King
351
observed a significant dependency between positive phase
outcomes and attacking ball carries executed by outside backs. The evasive attributes
displayed typically by ball carriers from the outside backs were consistent with those
that promoted tackle-breaks (side-stepping manoeuvres executed beyond 1 BL from the
defence at a moderate change of direction angle and then straightening the running line
through a moderate angle). It can be concluded that the evasive characteristics of
outside backs, promotes positive phase outcomes associated with penetrating the
167
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defensive line. It is recommended that research investigates further whether the specific
skills and training methods associated with outside backs promote tackle-breaks.
In contrast to outside backs, the current study demonstrated no significant
association between inside backs and tackle-break phase outcomes. Sayers and
Washington-King
351
also demonstrated no relationship between inside backs and the
outcome of attacking ball carries. The current study observed that the evasive attributes
displayed by inside backs were consistent to those achieving tackle-breaks. However,
the lateral attacking directions characteristic of inside backs no doubt reduced the
likelihood of tackle-breaks occurring
351
. Therefore, lateral attacking directions
characteristic of attacking ball carries observed from inside backs restricts their ability
to penetrate the defensive line.
The attributes exhibited when running with the ball make the back-line positions more
difficult to tackle when compared to forwards
351
. The current study demonstrated that
attacking ball carries observed in the forwards were characterised by running movement
patterns that were associated with an inability to penetrate the defensive line. Typically,
forwards received the ball immediately from the breakdown, in close proximity to the
defence and at slow attacking velocity. Sayers and Washington-King
351
stated that the
close proximity to the opposition when typically forwards received possession of the
ball resulted in less acceleration time and an inability to implement evasive strategies to
outmanoeuvre the defence.
The findings of this study suggest that the loose forwards are among the primary
attacking ball carriers in rugby union, but were not associated with tackle-breaks.
Importantly, it has been shown that the loose forwards display the least amount of
recovery with a work-to-rest ratio of 1 to 7.5 s during match-play
123
. In contrast,
outside backs have demonstrated the greatest recovery times with a 1 to 14.6 s work-torest ratio
123
. The exhaustive activity patterns required of the loose forwards would no
doubt limit high intensity running ability, such that it may be difficult to execute the
evasive movement patterns that are associated with tackle-break phase outcomes.
To add to this, loose forwards are required frequently to be involved in high intensity
non-running activities, such as competing for the ball at the breakdown
112
. It is
proposed that the concentrated breakdown skills required of loose forwards accounts for
168
NOTATIONAL
ANALYSIS
the significant association, where attacking ball carries from loose forwards were
commonly observed to have received possession of the ball through immediate
attacking width and in close proximity to the defence. Clearly, further research should
consider the association between match-play activities observed in loose forwards and
the respective ability to penetrate the defensive line during attacking ball carries.
PRACTICAL IMPLICATIONS AND APPLICATIONS
AGILITY ASSESSMENT PROCEDURES
Notational analysis of open skilled sports such as rugby union has been described as
difficult due to the complexity of interrelated match-play actions
65, 125, 184, 254
.
Consequently, notational analysis of open skilled sports have indexed performance
according to event frequency and time-motion
59
. Similarly, the notational research
considering agility skill execution has been limited to measures of event frequency and
time-motion
50-52, 417
. However, measures of event frequency and time-motion do not
capture the intricacy of skill execution and as a result, are inappropriate measures of
complex skills such as agility
59
. Alternatively, notational analysis examining
descriptors of skill execution relating to event outcome provide critical insight regarding
the specific role of agility to the determination of performance 351.
The current study examined agility skill execution with respect to the determination of
phase outcome, try scoring capability and overall team success. Sayers and
Washington-King 351 suggested that notational analysis of skill execution with reference
to outcome has the potential to provide a recipe for successful performance.
Accordingly, the findings of the current study provide critical insight regarding the
attributes of agility skill execution predicting effective attacking ball carries in rugby
union. In addition, the results of this study can be used to design appropriate
performance profiles and notational assessment procedures of effective attacking ball
carries in rugby union 392.
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AGILITY
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Performance profiles of skill execution and models of technique are presented through
notational movement analysis
254, 330
. Consequently, the observations of notational
movement analysis can be used to design testing protocols relating to scientific
assessments through biomechanical measures as well as sports specific technique
analysis as part of athletic development programs 50. Importantly, the direct relationship
with sporting performance means that the external validity of scientific research
is promoted when assessment protocols are based on the findings of notational
analysis
435
. Hence, the results of notational analysis described in the current study can
be used to design a valid measure of agility skill execution in rugby union to be
implemented as part of associated biomechanical assessment procedures.
The findings of notational analysis in this study illustrated a definitive model of agility
skill execution relating to the determination of phase outcome during attacking ball
carries in rugby union. This study demonstrated that tackle-break phase outcomes were
associated with evasive agility skill execution during attacking ball carries.
Therefore, the desirable features of evasive agility skill execution associated with
tackle-breaks facilitate the development of an agility course design that can be
implemented as part of sports specific biomechanical analyses (Figure 4.11).
To add to this, the results of this study demonstrated that attacking intensity and
resistive fending strategies were important components to the determination of effective
ball carries in rugby union. Accordingly, including measures of attacking intensity and
resistive fending strategies would be a desirable feature of evasive agility assessment
tasks in rugby union.
170
NOTATIONAL
ANALYSIS
20° – 60 °
20° – 60 °
1-2 BL
20° – 60 °
1-2 BL
Figure 4.11: Transverse plane representation of agility course design based on the
findings of notational analysis presented in the current study.
171
AGILITY
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AGILITY TRAINING PROGRAMS
The attributes of athletic development and training programs are based commonly on
the findings of notational analysis
50
. However, the lack of published notational
movement analysis research indicates that training methods examining skill execution
have been based on subjective observations and theoretical requirements
97, 244, 335, 377
.
The findings from the current study suggest training methods for the development of
running ability in rugby union should focus on high speed evasive manoeuvres
involving decision-making strategies. Side-stepping with a moderate change of
direction angle and then straightening to challenge the defence seems the best method of
attack when running with the ball. This ability can be trained in rugby union using
opposed sessions where individual players should be encouraged to evade defenders
(rather than run directly into contact with a defender). It is also important that coaches
design patterns of play and training games that get players in a position to receive the
ball with depth and running at high speed. In addition, the ability of ball carriers to
isolate defensive opponents should represent a central component of opposed training
sessions in rugby union, as this skill requires considerable decision-making before and
during attacking ball carries. To achieve this, sports specific games have been found to
improve
physiological
capacity
as
well
as
the
effectiveness
of
skill
execution 11, 143, 205, 229. Therefore, simulated rugby union games would no doubt provide
an appropriate training stimulus to improve evasive agility skill execution and
associated decision-making strategies for the development of running ability.
SUMMARY
Agility skill execution constitutes a fundamental component of performance in open
skilled sports that display multi-directional movement patterns, such as rugby union.
This study demonstrated that agility skill execution is a common feature of attacking
ball carries in rugby union. Evasive agility manoeuvres involving a side-step was found
to be the most frequently observed when challenging the defensive line. In contrast, the
crossover-stepping strategy was commonly observed when the attacking ball carrier
attempted to outrun the defence. It was concluded that the side-stepping strategy
172
NOTATIONAL
ANALYSIS
represented the most effective method of evasive agility skill execution when
challenging the defensive line during attacking ball carries in rugby union.
The ability to outmanoeuvre respective opponents through expressions of superior
agility skill execution is imperative to success in rugby union. This study demonstrated
that evasive agility skill execution was associated with positive phase outcomes of
attacking ball carries and specifically tackle-breaks. The features of evasive agility skill
execution promoting tackle-breaks consisted of executing a change of direction step
between 1 and 2 BL from the defence at a moderate CD angle and then straightening the
directional alignment through a moderate ST angle.
It is anticipated that the findings of the current study will stimulate the inclusion of
sports specific measures of agility skill execution as part of future athletic assessment
procedures. Importantly, this study proposed an agility course design based on the
features of evasive agility skill execution associated with tackle-breaks in rugby union.
The results of this study can be used to design specific training programs to improve
agility skill execution involving sports specific performance conditions. It is necessary
that future notational analysis research considers the sports specific movement patterns
associated with performance. It is important the sport specific movement patterns
described in this study be recognised within future athletic assessment procedures in
rugby union.
173
CHAPTER IV
KINEMATIC ANALYSIS
INTRODUCTION
BACKGROUND
The ability to evade defensive opponents through agility skill execution is
a fundamental attacking strategy that determines success in rugby union
193
.
The prevalence of the tackle contest (over 100 per game) in rugby union emphasises the
importance of evasive agility skill execution during attacking ball carries
125
. Despite
this, limited research has explored the biomechanics of agility skill execution with
reference to performance enhancement. In contrast, coaches have identified the
technical components of agility skill execution to improving running ability in rugby
union
348
. To address the gap in the scientific research, the current study examined the
kinematic determinants of agility skill execution during attacking ball carries in rugby
union.
174
KINEMATIC
ANALYSIS
AIM AND OBJECTIVES
The overall aim of this study was to use kinematic analysis to examine running based
expressions of side-stepping agility performance during evasive attacking manoeuvres
in rugby union. The objectives consisted:
1. Determine the kinematic modifications observed during agility skill execution when
compared to straight-line running.
2. Determine the kinematic determinants of agility skill execution with respect to the
interaction between stride and stance characteristics during the agility gait cycle.
3. Determine the relationship between agility skill execution and the speed of
performance.
4. Determine the kinematic modifications observed during reactive agility skill
execution when compared to planned performance conditions.
5. Determine the kinematic modifications observed during agility skill execution
involving sports specific contact conditions when compared to non-contact
conditions.
175
AGILITY
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METHODS AND PROCEDURES
SUBJECTS
A total of 8 male rugby union athletes volunteered to participate in the current study.
Subjects were highly trained and familiar with athletic performance assessment,
including the activities required as part of straight-line running and agility testing
procedures. The sampled participants included athletes from high level rugby union
teams, such as those competing in international provincial competitions (e.g. Super 14).
During testing, athletes were involved within the competitive training cycle, which
included one competitive rugby union game each week, daily sport specific training
sessions and additional ancillary training such as strength and power development.
Prior to testing, participants were informed of the potential injury risks associated with
the required performance assessment protocols. In addition, participants were provided
with information and instructions regarding the necessary straight-line running and
agility testing procedures. It was compulsory for all participants to sign a written
consent form prior to testing (Appendix A). Approval from the University of the
Sunshine Coast Human Research Ethics Committee was granted before any testing was
undertaken in the current study.
Performance speed for subjects was based on video footage and classified as fast,
moderate or slow. Speed groups were determined using a variation of one-half standard
deviation from the mean performance time of the respective conditions. The speed of
straight-line running trials was measured over four steps. The speed of agility trials was
measured from pre-change of direction foot-strike to re-acceleration foot-strike.
176
KINEMATIC
ANALYSIS
STUDY DESIGN
DATA COLLECTION
Anthropometric data was collected prior to testing and included standing height and
trunk length (recorded to the nearest 1 cm using a calibrated portable tape measure) as
well as body weight of each participant, dressed only in exercise shorts (recorded to the
nearest 1 kg using calibrated balance scales). Date of birth and the respective playing
positions of each participant were also noted.
Agility testing was conducted during one session and on a dry rugby union playing
surface consisting of couch grass sewn with rye grass. Air temperature during the
athletic testing session was measured at 12°C, atmospheric humidity was reported at 50
% and wind speed at 24 km.h-1 from the South-Southeast with the barometric pressure
at 1030 Hpa.
During testing, participants were required to wear sport specific rugby union equipment
as regulated by the International Rugby Board (IRB). This included approved rugby
union footwear (rugby boots) and any other protective equipment required by the
individual athlete, such as shoulder padding or ankle braces. Joint strapping was
available at the request of the participating athlete and was completed by a qualified
sports trainer. To increase the reliability of kinematic measurements athletes were
required to wear only tight exercise shorts or pants during performance testing.
This restriction was necessary, so that the respective anatomical landmarks could be
located clearly during the video digitising process (Figure 5.1).
177
AGILITY
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20
19
15
16
14
17
13
CG
6
7
18
5
8
9
4
10
3
2
1
11
12
1.
Right toes
11.
Left posterior calcaneal point
2.
Right posterior calcaneal point
12.
Left toes
3.
Right lateral malleolus of the fibula
13.
Right distal lateral radius
4.
Right femoral lateral epicondyle
14.
Right humoral lateral epicondyle
5.
Right femoral greater tronchanter
15.
Right acromion process
6.
Right iliac crest
16.
Left acromion process
7.
Left iliac crest
17.
Left humoral lateral epicondyle
8.
Left femoral greater tronchanter
18.
Left distal lateral radius
9.
Left femoral lateral epicondyle
19.
Anterior mandible
10.
Left lateral malleolus of the fibula
20.
Anterior frontal bone
Figure 5.1: Representation of the biomechanical model achieved by linking the
anatomical landmarks.
178
KINEMATIC
ANALYSIS
Straight-line running and agility performances were captured by four PAL digital video
cameras (Panasonic Nv-GS180GN, Matsushita Electric Industrial Co., Ltd., Kadoma,
Japan) operating at 50 Hz and with the shutter speed manually set to capture
at 1/2000ths. The cameras were fixed to stationary tripods and positioned with two
either side of the performance testing area and at oblique angles (Figure 5.2). Motion
analysis was calibrated using a specifically designed three-dimensional calibration
device with twenty-five stationary control points used for direct linear transfer (DLT)
calibration. Twenty anatomical landmarks marked prior to testing were then digitised
using the Ariel Performance Analysis System (APAS) (Ariel Dynamics, Inc., San Diego
CA, USA) forming a full body kinematic model (Figure 5.1). The time between each
digitised image was held at 0.02 s increments. A 5 Hz digital filter was passed through
the digitised data, and then processed to compute whole body centre of gravity and
segmental linear and angular velocities.
During the digitising process, the work-station was based in a well-ventilated research
laboratory with non-florescent lighting. The video footage was displayed on a 15-inch
computer monitor (Samsung SyncMaster 710N, Samsung Electronics, Sydney,
Australia) that was positioned at seated eye level
219, 353
. To reduce fatigue a maximum
time of two hours restricted periods of digitising with a recovery period of one hour 50.
To further reduce fatigue, regular short breaks were scheduled during digitising sessions
which involved looking away from the computer monitor and focusing on distant
objects 219.
179
AGILITY
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7.00 m
7.00 m
5.00 m
.93 m
1.86 m
1.86 m
Left direction change
Right direction change
3.72 m
7.70 m
7.70 m
Camcorder
3.72 m
Slalom pole
Marker cone
Start Point
1.00 m
1.86 m
4.80 m
Figure 5.2: Schematic diagram of the agility course design included in performance
assessment procedures.
180
KINEMATIC
ANALYSIS
RELIABILITY OF KINEMATIC MEASUREMENTS
All data collection and video digitising was completed by a single analyst.
To assess intra-tester reliability, video footage of a single agility performance
trial (that was not included in the definitive data) was digitised on two separate
occasions and one week apart to prevent measurement errors due to the retention of
results 328. Kinematic variables were described using scalar level data types and as such,
typical error of measurement (TEM) and coefficient of variation (CV) was used to
assess reliability
22, 186
. Excellent intra-tester reliability was observed for the raw
position of randomly selected landmarks (Table 5.1) as well as the angular displacement
of randomly selected joints (Table 5.2) 266.
Table 5.1: Intra-tester TEM and CV reliability scores for randomly selected landmark
raw positions.
TEM (m)
Landmark
CV (%)
x
y
z
x
y
z
Anterior mandible
.01
.01
.01
.40
2.80
.40
Left acromion process
.01
.01
.01
.50
3.20
.40
Right humoral lateral epicondyle
.01
.02
.01
.30
3.90
.50
Left femoral lateral epicondyle
.01
.01
.01
.50
3.90
1.20
Left femoral greater tronchanter
.01
.02
.01
.50
1.30
1.10
Right iliac crest
.01
.01
.01
.30
3.60
1.60
Mean
.01
.01
.01
.42
3.12
.87
181
AGILITY
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Table 5.2: Intra-tester TEM and CV reliability scores for randomly selected joint
angular displacement.
Landmark
TEM (°)
CV (%)
Right hip
4.97
3.8
Left hip
7.49
5.0
Right knee
1.29
1.4
Left knee
2.84
2.4
Right elbow
5.84
6.4
Left elbow
2.39
2.6
Mean
4.14
3.6
TESTING PROTOCOL
All participating athletes completed a generalised active warm-up prior to testing which
consisted of dynamic stretches interspersed with sub-maximal physical exercises.
Participants then completed specific warm-up activities which included performance
trials of the straight-line running and agility tasks used as part of performance testing
procedures. The combined generalised and specific warm-up activities were performed
in order to promote neuromuscular function and also to decrease any associated risk of
injury 136, 139.
During both straight-line running and agility testing conditions, participants
were required to carry a match-type, size 5 rugby union ball inflated to regulation
pressure recommended by the IRB
198
. Initial performance assessments required
participants to run at maximal effort (3 repetitions) over a 15 m straight-line running
182
KINEMATIC
ANALYSIS
(SLR) course with full recovery between trials (recovery time defined by athletes).
Agility testing then required participants to perform repeated trials at maximal effort of
four agility performance conditions with full recovery (Figure 5.2). Participants
complete 24 separate agility performance trials, over six successful side-stepping trials
(three right and three left directional running lines) for each of the four respective agility
testing conditions.
The agility testing conditions included:
1. Planned side-step without contact (PLAN) – this agility test was free from any
reactive, contact or fending conditions.
2. Unplanned side-step without contact (UNLPAN) – this agility test required a
reaction to a decision-making element and was free from any contact or fending
conditions.
3. Unplanned side-step with contact (CONTACT) – this agility test required the same
reactive condition as UNPLAN but with the presence of a contact situation ensuing
the straighten step.
4. Unplanned side-step with contact and fend (FEND) – this agility test required the
same reactive and contact condition as CONTACT, but upper body resistance (fend)
of the decision-making defensive opponent was also necessary during the initial
direction change step.
The decision-making element (reactive conditions) was presented in the form of a
simulated defensive opponent during the initial direction change. This consisted of an
individual stepping towards the performing athlete and at an oblique angle, thereby
determining the necessary evasive running line (the participating athlete was required to
traverse the contralateral running line to that of the defensive opponent).
Figure 5.3 demonstrates the right evasive running line in response to the movements of
the simulated defensive opponent. Figure 5.4 demonstrates the left evasive running
line in response to the movements of the simulated defensive opponent.
The opponent initiated movement when the performing athlete crossed a line 3.72 m
from the initial change of direction area indicated with slalom poles.
183
AGILITY
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Defensive movement pattern
Right direction change
Figure 5.3: Representation of the evasive running lines displayed during right change of
direction agility manoeuvres.
184
KINEMATIC
ANALYSIS
Defensive movement pattern
Left direction change
Figure 5.4: Representation of the evasive running lines displayed during left change of
direction agility manoeuvres.
185
AGILITY
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The addition of contact conditions as part of agility assessment procedures required
participants to traverse the agility course through reactive performance conditions and
with the presence of a contact situation ensuing the straighten step (Figure 5.5).
The contact situation included as part of agility testing procedures involved participants
running into a soft foam hit-shield (Profile Hit Shield, Silver Fern Australia Pty Ltd.,
Sydney, Australia), as used commonly within rugby union training environments.
The addition of the fending element required the performing athlete to provide upper
body resistance (fend) to the simulated defensive opponent during the initial change of
direction evasive manoeuvre. The execution of the upper body fend required performing
athletes to push a predetermined target of dense foam (circular in shape and measuring
0.18 m in diameter) that was located on the sternal region of the simulated defensive
opponent. The same individual was used as the simulated defensive opponent during
reactive conditions and did not impede the performing athlete through attempted
tackling, holding or similar restrictive activities.
186
ANALYSIS
SHIELD
SHIELD
KINEMATIC
Left direction change
Right direction change
Figure 5.5: Representation of unplanned agility performance trials with the inclusion of
a contact condition ensuing the straighten step.
187
AGILITY
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DATA ANALYSIS
The SPSS software package (Version 12.01 for Windows, SPSS, Inc., Chicago IL,
USA) was used to present descriptive statistics ( x
± SD) and compare
performances (t-test) and also to conduct analyses of variance (ANOVA and
MANOVA) and measures of relationships (Pearson’s Product Moment Correlation and
Chi-squared). Data was presented as mean ( x ) and standard deviation (±SD) for all
statistical analyses, and effect statistics reported the difference in performance times and
measure of body height between agility conditions. A significance level of p < .05 was
used for all analyses. Variables used in analysis are outlined in Table 5.3 and Table 5.4.
Table 5.3: Independent variables used in analysis
Variables
Categories
Side-step distance
Side-step Angle
Agility performance speed
Fast
Moderate
Slow
Performance condition
SLR
UNPLAN
PLAN
CONTACT
FEND
The number of TRANS steps
0
1
2
188
KINEMATIC
ANALYSIS
Table 5.4: Dependant variables used in analysis
Variables
Categories
Linear velocity of the centre of gravity
VELHORZ
VELLAT
Change in linear velocity of the centre of gravity
∆VELHORZ
∆VELLAT
Vertical displacement of the centre of gravity
CGVERT
Trunk angular displacement (forward trunk lean)
TRUNKANT
Horizontal foot displacements relative to the centre of gravity
LDHORZ
TDHORZ
Lateral foot displacements relative to the centre of gravity
LDLAT
TDLAT
Foot position at CD-FS relative to the direction change line
CD-FSHORZ
CD-FSLAT
Foot position at ST-FS relative to the straighten line
ST-FSHORZ
ST-FSLAT
Joint angular displacement of the hip, knee and ankle
Joint angular velocity of the hip, knee and ankle
Knee angular range of motion (ROM)
189
AGILITY
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One-way between subjects analysis of variance were performed and included Scheffe
post hoc comparisons to determine the difference in performance times between speed
groups for each condition. Also, one-way between subjects analysis of variance
examined the affect of agility condition on the dependant variables of side-step angle
and distance. One-way between subjects analysis of variance will be presented as the
degrees of freedom, the F-statistic and the significance level (e.g. F(0,
0)
= 0.000,
p = 000).
Pearson’s Product Moment Correlation then determined the degree to which scalar level
data was related. Analysis investigated the interrelationship between the percent agility
phases for each condition, as well as the relationship between the percent agility phases
and measures of velocity. Furthermore, correlation analyses established the relationship
between foot position and measures of velocity during the respective agility phases.
All correlation data will presented as the measure of relationship, the number of cases in
the data set and the significance level (e.g. r = .000, n = 0, p = .000).
The current study used multivariate analysis to determine the affect of an independent
variable on combined dependant variables. Follow up univariate analysis and Scheffe
post hoc contrasts explored the differences between independent variables with respect
to each individual dependant variable. All multivariate analysis is presented as the
degrees of freedom, the F-statistic, the significance level, the value of Wilks Lambda
and partial eta squared (F(0,
0)
= 0.000, p = .000; Wilks Lambda = .000; partial eta
squared = .000). It should be noted that a summary of statistical results from
multivariate analysis and follow up univariate analysis for each test performed is
outlined Appendix D. The associated Scheffe post hoc comparison will then be reported
as part of the primary findings of this study.
190
KINEMATIC
ANALYSIS
Multivariate analysis examined each agility condition and was used to determine the
affect of:
o
Speed on the combined dependant variable of the change in linear velocity
(∆VELHORZ and ∆VELLAT) during each agility phase
o
Speed on the combined dependant variable of linear velocity (VELHORZ and
VELLAT) during each agility phase
o
Speed on the combined dependant variable of foot position at foot-strike (LDHORZ
and LDLAT) during each agility phase
o
Speed on the combined dependant variable of foot position at take-off (TDHORZ
and TDLAT) during each agility phase
o
TRANS steps on the combined dependant variable of change in velocity
(∆VELHORZ and ∆VELLAT) during the TRANS phase
o
TRANS steps on the combined dependant variable of linear velocity (VELHORZ
and VELLAT) at ST-FS
o
TRANS steps on the combined dependant variable of body height (CGVERT at
ST –FS and CGVERT at ST-TO) during the ST phase
Analysis compared dependant variables between agility conditions. Independent
samples t-tests examined the variation to foot positions, linear velocities and body
height between conditions. All independent samples t-tests are presented as the t-value,
degrees of freedom and the significance level (e.g. t = .000, df = 0, p = .000, two-tailed).
It should be noted that Levene’s test of equal variance was assumed when comparing
performance conditions (SLR, PLAN, UNPLAN, CONTACT and FEND). However,
homogeneity was not assumed when comparing the straight-line running and PLAN
agility condition. Also, Levene’s test of equal variance was not assumed when
comparing the CGVERT between CONTACT and FEND agility conditions.
Finally, Chi-squared (χ2) tests established significant dependencies between nominal
and ordinal data such as TRANS steps, speed group and agility condition. All data is
presented
as
chi-squared
statistic,
degrees
of
freedom
and
significance
figure (e.g. χ2 = 000, df = 0, p = 000) with the standardised residuals (SR) indicting the
magnitude of relationship (SR ≥ 2.0 or ≤ -2.0 represented a value either significantly
more or less than the expected for that cell, respectively)
164
. Chi-squared analysis
examined the relationship between TRANS steps and the agility condition as well as
191
AGILITY
IN RUGBY UNION
agility performance speed. The percentage of observed outcome from Chi-squared
analysis will reported followed by the SR value.
LIMITATIONS
In the current study, athletic performance assessments were conducted on a grassed
outdoor playing surface. The variability of grassy surfaces has been noted previously by
McClements et al.253, however such variability was controlled in the current study by
means of ensuring a dry and consistently graded surface. Furthermore, the current study
requested that participating athletes execute the required performance assessment
procedures wearing habitual footwear used when playing rugby union. It is accepted
that footwear can alter both biomechanical observations and environmental surface
interactions
140, 272, 322, 422
. However, it was beyond the means of the current study to
control for footwear. Despite this, it is proposed that the performances of the sampled
athletes would be more reliable when wearing familiar footwear and participating on
accustomed rugby union surfaces.
Consideration of the aforementioned limitations and the presence of other factors
required as part of agility testing such as ball carrying skills and environmental
conditions, it is recognised that such factors would increase external validity. Increases
in external validity are substantial with the inclusion of sport specific environmental
conditions, equipment requirements and skill replication during performance
assessment. The inclusion of the decision-making and fending elements together with
the straighten step contact situation, as well as the sport specific performance conditions
(e.g. ball carrying, grassed surface and rugby union footwear) served to increase the
external validity of this study and thus provided a sport specific situation in which the
expression of agility was observed
192
KINEMATIC
ANALYSIS
RESULTS
SUBJECTS
Eight athletes completed successfully all agility assessment procedures and the
respective performances were subjected to kinematic analysis. Table 5.5 displays the
age, standing height, leg length and body mass for the sampled athletes involved in this
study. Individual data for each participant is presented in Appendix C.
Table 5.5: Characteristics of sampled athletes (N = 8)
x
±SD
Range
23
4
18 – 28
Standing height (m)
1.83
0.04
1.74 – 1.87
Leg length (m)
0.90
0.04
0.85 – 0.96
Body mass (kg)
98
11
80 – 110
Age (years)
193
AGILITY
IN RUGBY UNION
PERFORMANCE CONDITION
The
performance
times
varied
between
agility
conditions
with
significant
increases observed with the FEND agility condition (1.14 ± 0.13 s) compared
to PLAN (1.03 ± 0.13 s, p = .001) and CONTACT (1.07 ± 0.14 s, p = .047)
(F(3, 188) = 6.394, p < .001) (Figure 5.6). Analysis of the main effect statistics showed
that FEND times were 9.6 % and 6.14 % slower than PLAN and CONTACT,
respectively. For the purposes of further analysis, overall performance times were
divided into speed groups consisting of fast, moderate and slow performances for each
agility condition and the straight-line running (SLR) condition. Significant differences
in performance times were observed between speed groups for all conditions (Table 5.6)
(Appendix D.1).
1.35
*
1.25
Time (s)
1.15
1.05
0.95
0.85
PLAN
UNPLAN
CONTACT
FEND
Agility Condition
Figure 5.6: Mean performance times recorded for the agility conditions.
* Significant increase in time with FEND condition compared to PLAN and CONTACT (p < .05).
194
KINEMATIC
ANALYSIS
Table 5.6: Performance time (s) with respect to speed grouping for each condition.
x
±SD
N
Fast
0.87
0.05
15
Moderate
1.03
0.04
17
Slow
1.17
0.06
16
Fast
0.99
0.05
20
Moderate
1.10
0.03
14
Slow
1.24
0.06
14
Fast
0.92
0.05
18
Moderate
1.07
0.04
12
Slow
1.21
0.05
18
Fast
1.00
0.06
17
Moderate
1.15
0.03
16
Slow
1.29
0.07
15
Fast
0.80
0.01
10
Moderate
0.84
0.01
5
Slow
0.87
0.01
9
PLAN*
UNPLAN*
CONTACT*
FEND*
SLR*
* Significant difference between fast, moderate and slow speed groups for the condition (p < .05)
195
AGILITY
IN RUGBY UNION
SIDE-STEP ANGLE
It was demonstrated that the side-step angle did not vary significantly between agility
conditions (F(3,
188)
= 57.537, p = .675). Overall, the mean side-stepping angle was
calculated at 53.00 ±10.57° relative to the sagittal plane direction of locomotion
at CD-FS (Figure 5.7). In addition, no significant difference to the side-step angle was
observed between speed groups for each agility condition (Appendix D.2).
Side-step angle = 53.00 ± 10.57°
Figure 5.7: Transverse plane representation of the side-step angle during agility testing.
196
KINEMATIC
ANALYSIS
SIDE-STEP DISTANCE
Results
showed
significant
agility conditions (F(3,
188)
differences
to
the
side-step
distance
between
= 3.097, p = .004). The side-step distance was less
during PLAN (2.27 ±.77 m) and FEND (2.27 ±.85 m) conditions compared to
UNPLAN (2.77 ±.85 m). Further analysis showed a significant difference in side-step
distance between speed groups for each agility condition (Table 5.7) (Appendix D.3).
The side-step distance displayed by fast performances was less than both moderate and
slow for each agility condition.
Analysis then observed differing step strategies used during the TRANS phase of the
agility cycle, with athletes exhibiting no steps through the TRANS phase or one
TRANS step or two TRANS steps. It was shown that significant differences existed in
side-stepping distance depending on the TRANS step strategy (0, 1, 2) used for each of
the agility condition (Table 5.8) (Appendix D.4). Typically, the addition of TRANS
steps was found to increase the distance over which the side-step was performed.
197
AGILITY
IN RUGBY UNION
Table 5.7: Side-step distance (m) with respect to speed grouping for each condition.
x
±SD
N
Fast
1.51
0.14
15
Moderate
2.37
0.13
17
Slow
2.87
0.14
16
Fast
2.38
0.17
20
Moderate
2.79
0.21
14
Slow
3.33
0.21
14
Fast
1.73
0.15
18
Moderate
2.77
0.18
12
Slow
3.41
0.15
18
Fast
1.75
0.12
17
Moderate
2.26
0.12
16
Slow
2.88
0.13
15
PLAN*
UNPLAN**
CONTACT*
FEND*
* Significant difference between fast, moderate and slow for the agility condition (p < .05)
** Significant difference between fast and slow for the agility condition (p < .05)
198
KINEMATIC
ANALYSIS
Table 5.8: Side-step distance (m) with respect to TRANS steps for each condition.
x
±SD
N
0 TRANS steps
1.53
0.39
18
1 TRANS step
2.31
0.62
8
2 TRANS steps
2.85
0.52
22
0 TRANS steps
1.63
0.72
7
1 TRANS step
2.49
0.54
14
2 TRANS steps
3.22
0.67
27
0 TRANS steps
1.65
0.28
16
1 TRANS step
2.39
0.67
9
2 TRANS steps
3.39
0.67
23
0 TRANS steps
1.41
0.22
6
1 TRANS step
2.05
0.36
16
2 TRANS steps
2.61
0.66
28
PLAN*
UNPLAN*
CONTACT*
FEND*
* Significant difference between 0, 1 and 2 TRANS step groups for the agility condition (p < .05)
199
AGILITY
IN RUGBY UNION
AGILITY CYCLE
Results demonstrated that an increase to the CD and ST phase percent time occurred
typically with a decrease to TRANS percent time. A strong negative relationship existed
between the %CD phase and the %TRANS phase (Table 5.9) and between the %ST
phase and the %TRANS phase (Table 5.10) for each agility condition.
Table 5.9: Correlation between %CD phase and %TRANS phase for each condition.
PLAN
UNPLAN
CONTACT
FEND
r
n
p
-.840
48
< .001
-.673
48
< .001
-.732
48
< .001
-.791
48
< .001
Table 5.10: Correlation between %ST phase and %TRANS phase for each condition.
PLAN
UNPLAN
CONTACT
FEND
r
n
p
-.720
48
< .001
-.558
48
< .001
-.611
48
< .001
-.456
48
< .001
200
KINEMATIC
ANALYSIS
Analysis showed that the percent time for each phase of the agility cycle (except for the
CD phase) varied with the agility condition (Appendix D.5). There was no
significant difference in the %CD phase between agility conditions, with the overall
%CD phase 16.66 ±5.53 % across the agility conditions. It was then shown
that PRECD phase was greater during CONTACT (18.41 ±3.92 %, p = .042) and
FEND (17.86 ±3.47 %, p = .024) compared to UNPLAN (15.98 ±4.13 %).
The TRANS phase was then greater during UNPLAN (30.04 ±8.15 %) compared
to PLAN (22.76 ±10.99 %, p = .004) but the ST phase was greater during
PLAN (21.98 ±5.02 %) compared to UNPLAN (18.92 ±4.83 %, p = .028),
CONTACT (18.14 ±4.41 %, p = .003) and FEND (16.68 ±5.39 %, p < .001).
The POSTCD phase was greater during FEND (21.20 ±3.13 %) compared to
FEND
PRECD
17.86 %
CONTACT
PRECD
18.41 %
UNPLAN
PRECD
15.98 %
PLAN
Agility Condition
the UNPLAN (18.99 ±3.68 %, p < .001) (Figure 5.8).
PRECD
18.24 %
0%
CD
16.07 %
CD
17.00 %
CD
16.07 %
CD
17.51 %
TRANS
28.19 %
TRANS
25.69 %
TRANS
30.04 %
ST
16.68 %
POSTCD
21.20 %
ST
18.14 %
POSTCD
20.76 %
ST
18.92 %
TRANS
22.76 %
ST
21.98 %
50%
POSTCD
18.99 %
POSTCD
19.51 %
100%
Agility Cycle
Figure 5.8: Relative agility phase percentages with respect to agility condition.
201
AGILITY
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The relationship between agility condition and the number of steps present during the
TRANS phase was explored. It was shown that 37.5 % (SR = 1.8) of
agility manoeuvres performed during PLAN conditions exhibited no TRANS
steps (χ2 = 14.098, df = 6, p = .029). In contrast, 12.5 % (SR = -1.7) of agility
manoeuvres performed during FEND conditions exhibited no TRANS steps. It was then
found that fast performances (54.3 % SR = 5.0) favoured no steps through the
TRANS phase, whilst moderate performances (33.9 %, SR = 1.5) tended to
use a single TRANS step and slow performances (95.2 %, SR = 4.9) displayed
two steps through the TRANS phase (χ2 = 103.403, df = 4, p < .001).
Finally, it was shown that the percent TRANS flight decreased with the addition
of TRANS steps for each agility condition (Appendix D.6). Overall, the mean
percent TRANS flight was 31.43 ± 10.15 % for two TRANS steps and 69.87 ± 23.96 %
for one TRANS step. It should be noted that no TRANS steps meant that the
percent TRANS flight was 100 %.
202
KINEMATIC
ANALYSIS
PLANNED CONDITION
Analysis examining the variation to the agility cycle between speed groups showed
that %CD phase was less during slow performances (12.81 ±2.90 %) compared to fast
(22.26 ±5.61 %, p < .001) and moderate (17.73 ±6.16 %, p = .030) (Appendix D.7).
It
was
demonstrated
that
fast
performances
displayed
shorter
%TRANS
phase (12.72 ±7.27 %) compared to moderate (23.53 ±11.52 %, p = .002) and slow
performances (31.34 ±2.82 %, p < .001). Fast performances also displayed greater
%ST phase (25.98 ±3.89 %) compared to moderate (19.93 ±5.70 %, p = .001) and
slow (20.41 ±2.59 %, p = .003). Slow performances then displayed less %POSTCD
phase (17.42 ±2.10 %) compared to fast (21.00 ±2.30 %, p = .006) and
Slow
PRECD
18.02 %
CD
TRANS
12.81 % 31.34 %
Moderate
PRECD
18.63 %
CD
17.73 %
Fast
Performance Speed
moderate (20.18 ±3.92 %, p = .034) (Figure 5.9).
PRECD
18.04 %
CD
22.26 %
0%
ST
20.41 %
TRANS
23.53 %
ST
19.93 %
TRANS ST
12.72 %25.98 %
50%
POSTCD
17.42 %
POSTCD
20.18 %
POSTCD
21.00 %
100%
Agility Cycle
Figure 5.9: Relative agility phase percentages during PLAN conditions with respect to
speed group.
203
AGILITY
IN RUGBY UNION
PRE-CHANGE OF DIRECTION PHASE
Pearson’s correlation showed no significant relationship between the %PRECD phase
and ∆VELLAT (r = .034, n = 48, p = .817) or ∆VELHORZ (r = .090, n = 48, p = .545).
Despite this, fast performances exhibited greater increases to VELLAT during the PRECD
phase (0.54 ±0.28 m.s-1) compared to slow (0.06 ±0.29 m.s-1, p < .001) (Appendix D.8).
Pearson’s correlation then showed a significant negative weak to moderate relationship
between LDLAT and VELLAT (r = -.474, n = 48, p = .001). Further analysis demonstrated
that LDLAT of fast performances (-14.480 ±8.78 %) crossed the line of centre of gravity
further than moderate (-3.91 ±10.53 %, p = .010) and differed from the positive LDLAT
of slow performances (1.76 ±8.52 %, p < .001) (Appendix D.9) (Figure 5.10)
(b)
(a)
Figure
5.10:
Frontal
(c)
plane
representation
of
PRECD-LDLAT
(a) slow performances (b) moderate performances (c) fast performances.
CHANGE OF DIRECTION PHASE
Examination of velocity profiles during the CD phase showed that fast
performances displayed greater VELLAT at CD-FS (1.07 ±0.25 m.s-1) compared to
moderate (0.64 ±0.39 m.s-1, p = .002) and slow (0.37 ±0.31 m.s-1, p < .001)
(Appendix D.10). Pearson’s correlation then observed a significant moderate positive
relationship between the %CD phase and VELLAT at CD-TO (r = .569, n = 48,
p < .001). It was shown that fast performances displayed greater VELLAT at
CD-TO (2.76 ±0.20 m.s-1) compared to moderate (2.30 ±0.35 m.s-1, p < .001) and
204
KINEMATIC
ANALYSIS
slow (2.04 ±0.32 m.s-1, p < .001) (Appendix D.11). However, the foot positions
at CD-FS (LDHORZ and LDLAT) and CD-TO (TDHORZ and TDLAT) did not vary between
speed groups (Appendix D.12). Despite this, Pearson’s correlation showed a significant
moderate positive relationship between TDLAT and VELLAT at CD-TO (r = .679, n = 48,
p < .001). Also, there was a significant moderate negative relationship between LDHORZ
and ∆VELHORZ during the PRECD phase (r = -.559, n = 48, p < .001), indicating that
greater deceleration of VELHORZ was associated with increases to LDHORZ.
TRANSITION PHASE
Analysis examined the affect of the number of TRANS steps (0, 1 and 2) on the change
in linear velocity through the TRANS phase. A reduction to VELLAT occurred during
the TRANS phase with no TRANS steps (-0.08 ±0.10 m.s-1) compared to an increase in
VELLAT with two TRANS steps (0.22 ±0.41 m.s-1, p = .011) (Appendix D.13).
Further
with
analysis
no
demonstrated
TRANS
steps
significant
(2.65
±0.26
increases
m.s-1)
to
VELLAT
compared
to
at
using
ST-FS
two
-1
TRANS steps (2.26 ±0.33 m.s , p = .001) (F(2, 45) = 7.558, p < .001).
STRAIGHTEN PHASE
Pearson’s correlation showed no significant relationship between the %ST phase and
VELLAT at ST-FS (r = .210, n = 48, p = .152). However, fast performances displayed
greater VELLAT at ST-FS (2.73 ±0.26 m.s-1) compared to moderate (2.37 ±0.29 m.s-1,
p = .005) and slow (2.23 ±0.32 m.s-1, p < .001) (Appendix D.14). Further examination
observed no significant affect of speed group on the change in linear velocity during the
ST phase (VELHORZ and VELLAT) (F(4,
88)
= 1.606, p = .180; Wilks Lambda = .869;
partial eta squared = .068). Despite this, Pearson’s correlation showed a significant
strong negative relationship between ∆VELLAT during the ST phase and both
LDLAT (r = -.837, n = 48, p = 001) and TDLAT (r = -.894, n = 48, p < 001).
This indicates that an increase to lateral foot placement was associated with a greater
redirection of VELLAT during the ST phase.
Analysis explored the relationship between foot position and the speed of agility
performance. It was shown that foot positions at ST-FS (LDHORZ and LDLAT)
205
AGILITY
IN RUGBY UNION
were unaffected by speed (F(4,
88)
= .936, p = .447; Wilks Lambda = .920;
partial eta squared = .073). However, results showed that fast performances displayed
less TDLAT (18.90 ±16.27 %) compared to moderate (32.90 ±12.91 %, p = .032)
and slow (32.55 ±14.20 %, p = .040) at ST-TO (Appendix D.15).
RE-ACCELERATION PHASE
Fast performances displayed greater VELLAT at POSTCD-FS (2.73 ±0.26 m.s-1)
compared to moderate (2.37 ±0.29 m.s-1, p = .005) and slow (2.23 ±0.32 m.s-1, p < .001)
(Appendix D.16). It was shown that LDLAT of fast performances (-43.20 ±3.89 %)
crossed the line of centre of gravity further than slow (-34.70 ±11.98 %, p = .019)
(Appendix
D.17)
(Figure
5.11).
Despite
this,
fast
performances
exhibit greater VELLAT redirection during the POSTCD-FS (F(4,
88)
did
not
= 1.606, p = .180;
Wilks Lambda = .869; partial eta squared = .068)
(a)
Figure
(b)
5.11:
Frontal
plane
representation
(a) slow performances (b) fast performances.
206
of
POSTCD-LDLAT
KINEMATIC
ANALYSIS
UNPLANNED CONDITION
Results observed little variation to the percent contribution of agility phases during
unplanned performance (Appendix D.18) (Figure 5.12). However, it was shown that
the %CD phase was lower in slow performances (12.95 ±2.97 %) compared to
fast (17.88 ±5.82 %, p = .023). Similarly, slow performances (16.57 ±2.24 %) displayed
less %POSTCD phase compared to fast (12.95 ±2.97 %, p = .018) and
Slow
PRECD
17.19 %
Moderate
PRECD
CD
15.99 % 16.59 %
TRANS
29.88 %
Fast
Performance Speed
moderate (12.95 ±2.97 %, p = .048).
PRECD CD
15.14 % 17.88 %
TRANS
27.60 %
0%
CD
TRANS
12.95 % 33.70 %
ST
19.59 %
ST
17.70 %
ST
19.30 %
50%
POSTCD
16.57 %
POSTCD
19.84 %
POSTCD
20.08 %
100%
Agility Cycle
Figure 5.12: Relative agility phase percentages during UNPLAN conditions with
respect to speed group.
207
AGILITY
IN RUGBY UNION
PRE-CHANGE OF DIRECTION PHASE
It
was
found
that
fast
performances
displayed
greater
VELLAT
at
PRECD-FS (0.29 ±0.22 m.s-1) compared to moderate (0.05 ±0.23 m.s-1, p = .005) and
slow (-0.18 ±0.13 m.s-1, p < .001) (Appendix D.19). Also, slow performances
exhibited greater VELHORZ at PRECD-FS (5.93 ±0.29 m.s-1) compared to
fast (5.57 ±0.40 m.s-1, p = .022). Further analysis revealed that LDHORZ at
PRECD-FS
of
slow
performances
(40.33
±14.14
%)
was
greater
than
fast (26.49 ±17.89 %, p = .044) (Appendix D.20) (Figure 5.13).
(b)
(a)
Figure
5.13:
Sagittal
plane
representation
of
LDHORZ
at
PRECD-FS
(a) slow performances (b) fast performances.
CHANGE OF DIRECTION PHASE
Following on from the PRECD phase, fast performances displayed greater VELLAT at
CD-FS (0.52 ±0.34 m.s-1) compared to moderate (0.20 ±0.37 m.s-1, p = .034) and
slow (-0.08 ±0.31 m.s-1, p < .001) (Appendix D.21) (Figure 5.14). To add to this,
Pearson’s correlation showed a significant negative weak relationship between
the %CD phase and both VELHORZ (r = -.401, n = 48, p = .005) and
VELLAT (r = .406, n = 48, p = .004) at CD-TO. These findings suggest that a greater
%CD phase was associated with less VELHORZ and greater VELLAT at CD-TO.
Further analysis showed that fast performances exhibited greater increases to VELLAT
during the CD phase (1.83 ±0.37 m.s-1) compared to slow (1.50 ±0.41 m.s-1, p = .041)
(Appendix
D.22).
Pearson’s
correlation
208
observed
a
significant
positive
KINEMATIC
ANALYSIS
weak to moderate relationship between ∆VELLAT and LDLAT (r = .484, n = 48,
p
<
.001).
A
significant
negative
moderate
relationship
existed
between
∆VELHORZ and LDHORZ (r = -.696, n = 48, p < .001), indicating that greater
LDHORZ resulted in a greater deceleration of VELHORZ during the CD phase.
It should also be noted that fast performances (0.01 ±0.38 m) were shown to execute the
required side-step evasive manoeuvre earlier than slow (-0.53 ±0.43 m, p = .003)
(Appendix D.23) (Figure 5.15).
Analysis examined the joint segment contribution to the development of velocity during
the CD phase. Pearson’s correlation showed no significant relationship between VELLAT
at CD-TO and the angular velocity of the hip at CD-TO (r = -.097, n = 48,
p = .513). Angular hip velocity at CD-TO was shown not to vary with the
speed of performance (F(2,
45)
= .908, p = .410). In contrast, a significant positive
moderate relationship existed between VELLAT at CD-TO and the angular displacement
of the knee at CD-TO (r = .537, n = 48, p < .001). Greater knee extension was
associated
with
greater
VELLAT
at
significant difference between speed
at CD-TO (F(2,
45)
CD-TO.
Despite
this,
there
was
no
groups in angular knee displacement
= 2.406, p = .102) or the angular knee displacement ROM during
CD stance (F(2, 45) = 1.101, p = .341). Figure 5.16 illustrates the lower limb segmental
timings during CD stance based on the overall mean using the minimum, maximum and
median performance times for each speed group.
209
AGILITY
IN RUGBY UNION
CD-FS
CD-FS
VELLAT
VELLAT
(a)
Figure
(b)
5.14:
Transverse
plane
representation
(a) slow performances (b) fast performances.
210
of
VELLAT
at
CD-FS
KINEMATIC
ANALYSIS
(a)
(b)
Figure 5.15: Transverse plane representation of the CD-FS relative to the direction
change line (a) slow performances (b) fast performances.
211
AGILITY
IN RUGBY UNION
180
Angular Displacement (°)
160
140
120
Hip
Knee
Ankle
100
80
0
50
100
CD Stance (%)
(a)
600
-1
Angular Velocity (°.s )
400
200
0
0
50
100
-200
Hip
-400
Knee
Ankle
-600
(b)
CD Stance (%)
Figure 5.16: Representation of mean lower limb segmental timings during CD stance
(a) Lower limb angular displacement (b) Lower limb angular velocity.
212
KINEMATIC
ANALYSIS
TRANSITION PHASE
Analysis examined the affect of the number of TRANS steps on the change in linear
velocity during the TRANS phase. Greater decreases in VELHORZ occurred during the
TRANS phase with two TRANS steps (-0.55 ±0.36 m.s-1) compared to
one TRANS step (-0.05 ±0.47 m.s-1, p = .005) and an increase in VELHORZ
with no TRANS steps (0.02 ±0.36 m.s-1, p = .001) (Appendix D.24). It was shown that
reductions
to
VELLAT
occurred
during
the
TRANS
phase
with
no
TRANS steps (-0.02 ±0.25 m.s-1) compared to an increase with one TRANS
step (0.14 ±0.17 m.s-1, p = .010) and two TRANS steps (0.53 ±0.45 m.s-1, p = .004).
STRAIGHTEN PHASE
Analysis of the ST phase showed that fast performances displayed less LDHORZ at
ST-FS (-11.87 ±17.02 %) compared to slow (3.86 ±8.60 %, p = .015) (Appendix D.25).
Despite this, speed grouping did not have a significant affect on the change in linear
velocity during the ST phase (∆VELHORZ and ∆VELLAT) (F(4,
88)
= 1.975,
p = .105; Wilks Lambda = .842; partial eta squared = .082). Fast performances did
however display greater VELLAT at ST-FS (2.57 ±0.24 m.s-1) compared to
slow (2.26 ±0.29 m.s-1, p = .007) (Appendix D.26).
Further analysis of the factors associated with VELLAT during the ST phase found a
significant negative moderate relationship between TDLAT and ∆VELLAT (r = -.727,
n = 48, p < .001), indicating that greater TDLAT was associated with greater VELLAT
redirection. To add to this, Pearson’s correlation showed a significant negative
relationship between the angular knee displacement ROM during ST stance and
both VELLAT at ST-TO (r = -.503, n = 48, p < .001) and VELHORZ at ST-TO (r = -.395,
n = 48, p = .005). Less knee joint ROM during the ST phase was associated with
greater VELHORZ but an increase in residual lateral movement at ST-TO.
Despite this, the speed of performance had no significant affect on angular knee
displacement ROM (F(2,
during ST stance (F(2,
45)
45)
= 2.349, p = .107) or the maximum knee flexion angle
= 2.099, p = .134). Figure 5.17 illustrates the lower limb
segmental timings during ST stance based on the overall mean using the minimum,
maximum and median performance times for each speed group.
213
AGILITY
IN RUGBY UNION
Angular Displacement (°)
180
Hip
Knee
Ankle
160
140
120
100
0
50
100
ST Stance (%)
(a)
600
Hip
Knee
400
-1
Angular Velocity (°.s )
Ankle
200
0
0
50
100
-200
-400
-600
ST Stance (%)
(b)
Figure 5.17: Representation of mean lower limb segmental timings during ST stance
(a) Lower limb angular displacement (b) Lower limb angular velocity.
214
KINEMATIC
ANALYSIS
RE-ACCELERATION PHASE
A significant relationship was observed between the %POSTCD phase and
both VELHORZ (r = -.492, n = 48, p < .001) and VELLAT (r = .310, n = 48, p = .032) at
POSTCD-FS. It was shown that an increase to the POSTCD phase occurred with less
VELHORZ and greater VELLAT at POSTCD-FS. To add to this, slow performances
displayed less VELLAT at POSTCD-FS (0.55 ±0.46 m.s-1) compared to both
moderate (1.13 ±0.42 m.s-1, p = .012) and fast (1.20 ±0.55 m.s-1, p = .002)
(Appendix D.27). Despite this, no significant variations to foot position were
observed between speed groups at POSTCD-FS (LDHORZ and LDLAT) (F(4,
p
=
.188;
Wilks
Lambda
=
.871;
POSTCD-TO (TDHORZ and TDLAT) (F(4,
88)
partial
eta
squared
=
88)
= 1.576,
.067)
or
= .844, p = .501; Wilks Lambda = .927;
partial eta squared = .037). However, Pearson’s correlation showed a significant
positive moderate relationship between LDLAT and ∆VELLAT during the POSTCD
phase (r = .530, n = 48, p < .001), indicating an increased LDLAT was associated with
greater VELLAT redirection. Also, a significant negative weak relationship was observed
between LDHORZ and ∆VELHORZ during the POSTCD phase (r = -.377, n = 48, p = .008),
which suggests that a reduction to LDHORZ promoted VELHORZ acceleration.
215
AGILITY
IN RUGBY UNION
CONTACT CONDITION
The phases of the agility cycle (except the PRECD phase) during contact conditions
varied significantly with speed (Appendix D.28) (Figure 5.18). The %CD phase was
greater in fast performances (21.63 ±5.26 %) compared to moderate (15.50 ±4.40 %,
p = .001) and slow (13.37 ±2.66 %, p < .001). Fast performances also displayed
less %TRANS phase (14.89 ±8.24 %) compared to moderate (31.44 ±6.94 %, p<.001)
and
slow
(32.66
±2.94
%,
p
<
.001).
Fast
performances
exhibited
a
greater %ST phase (21.31 ±3.95 %) compared to moderate (15.15 ±2.56 %, p < .001)
and slow (16.95 ±3.93 %, p = .004) and greater %POSTCD phase (22.96 ±3.16 %)
compared to slow (18.69 ±2.43 %, p < .001). Figure 5.18 displays the mean phase
percentages relative to the complete agility cycle during CONTACT conditions for each
Slow
PRECD
18.34 %
CD
TRANS
13.37 % 32.66 %
ST
16.95 %
Moderate
PRECD
17.34 %
CD
TRANS
15.50 % 31.44 %
POSTCD
ST
15.15 % 20.57 %
Fast
Performance Speed
speed group.
PRECD
19.21 %
0%
CD
21.63 %
TRANS ST
14.89 % 21.31 %
50%
POSTCD
18.69 %
POSTCD
22.96 %
100%
Agility Cycle
Figure 5.18: Relative agility phase percentages during CONTACT conditions with
respect to speed group.
216
KINEMATIC
ANALYSIS
PRE-CHANGE OF DIRECTION PHASE
Pearson’s
correlation
showed
a
significant
weak
relationship
between
the %PRECD phase and both ∆VELHORZ (r = -.381, n = 48, p = .008) and
∆VELLAT (r = .406, n = 48, p = .004). This means that the development of greater
preliminary lateral movement combined with greater VELHORZ deceleration occurred
with an increase in %PRECD phase. Results showed that fast performances displayed
greater increases to VELLAT during the PRECD phase (0.60 ±0.19 m.s-1) compared to
moderate
(-0.05
±0.33
m.s-1,
p
=
.005)
and
slow
(-0.11
±0.32
m.s-1,
p < .001) (Appendix D.29). Fast performances exhibited greater reductions to VELHORZ
during
the
PRECD
phase
(-0.86
±0.35
m.s-1)
-1
compared
to
-1
moderate (-0.46 ±0.29 m.s , p = .005) and slow (-0.29 ±0.26 m.s , p < .001).
This greater reduction in VELHORZ for fast performance occurred with an
increase to LDHORZ (47.51 ±12.20 %), which was greater than moderate
performances (35.04 ±13.75 %, p = .040) (Appendix D.30). Also, it was found that
the LDLAT of fast performances (-12.63 ±6.21 %) crossed the line of centre of gravity
and was greater than both moderate (3.57 ±10.97 %, p < .001) and slow (.06 ±12.40 %,
p = .002)
CHANGE OF DIRECTION PHASE
Fast performances displayed
greater VELLAT (1.15 ±0.43 m.s-1) compared
to moderate (0.32 ±0.43 m.s-1, p < .001) and slow (0.07 ±0.32 m.s-1, p < .001)
at
CD-FS
(Appendix
D.31).
Also,
fast
performances
exhibited
less
VELHORZ at CD-FS (4.72 ±0.45 m.s-1) compared to moderate (5.28 ±0.47 m.s-1,
p = .009) and slow (5.62 ±0.48 m.s-1, p < .001). Pearson’s correlation showed a
significant moderate relationship between LDHORZ and VELHORZ at CD-FS (r = .608,
n = 48, p < .001) and also between LDHORZ and ∆VELHORZ during the
CD phase (r = -.655, n = 48, p < .001). Greater VELHORZ at CD-FS resulted in an
increase to LDHORZ, which subsequently promoted greater deceleration of VELHORZ
during the CD phase.
Further analysis showed that fast performances displayed greater VELLAT at
CD-TO (2.73 ±0.23 m.s-1) compared to moderate (2.21 ±0.53 m.s-1, p = .003) and
slow (1.77 ±0.40 m.s-1, p < .001) (Appendix D.32). Pearson’s correlation then observed
217
AGILITY
IN RUGBY UNION
a significant relationship between VELLAT at CD-TO and TDLAT (r = .759, n = 48,
p < .001). Accordingly, results then demonstrated that fast (76.25 ±.6.09 %) displayed
greater TDHORZ than slow (68.69 ±6.25 %, p = .009) (Appendix D.33).
TRANSITION PHASE
Results observed a significant affect of the number of TRANS steps (0, 1 and 2) on
CGVERT at ST-FS (F(2,
45)
= 10.057, p < .001). Increases to CGVERT at ST-FS
occurred with one TRANS step (49.33 % ±1.48 %) compared to two TRANS
steps (46.89 % ±1.63 %, p = .001) and no TRANS steps (46.48 % ±1.61 %, p < .001).
Descriptive statistics were used to illustrate the CGVERT oscillations through the TRANS
phase (Figure 5.19). This depicted the mean CGVERT values from three case study
groups in which the number of TRANS steps (0, 1 and 2) commonly observed for the
respective speed groups (fast, moderate and slow) were combined. The combined speed
and step groups consisted of grouping no TRANS steps with the fast speed group, one
TRANS step with the moderate speed group and two TRANS steps with the slow group.
The mean of each combined speed and step group was calculated using the minimum,
maximum and median performance times.
218
KINEMATIC
ANALYSIS
54
Fast (0 Steps)
Moderate (1 Step)
Slow (2 Steps)
CGVERT (% Standing Height)
52
50
48
46
44
0
50
100
TRANS Phase (%)
Figure 5.19: Representation of the CGVERT oscillations during the TRANS phase with
respect to grouped speed and TRANS steps.
219
AGILITY
IN RUGBY UNION
STRAIGHTEN PHASE
The foot placement patterns during the ST phase with reference to the straighten line
differed between speed groups (Appendix D.34) (Figure 5.20). The ST-FSHORZ of fast
performances (-0.77 ±0.23 m) occurred earlier compared to moderate (-0.49 ±0.20 m,
p = .004) and slow (-0.33 ±0.22 m, p < .001). Also, the ST-FSLAT of fast
performances
(0.31
±0.19
m)
occurred
with
less
width
compared
to
moderate (0.58 ±0.12 m, p < .001) and slow (.56 ±.11 m, p < .001). Despite this, further
analysis showed little notable differences in foot position relative to the centre of
gravity, where significant differences were only observed between the LDHORZ of
moderate performances (-17.10 ±10.38 %) which was less than slow (0.32 ±14.74 %,
p = .009) (Appendix D.35).
Analysis examined the difference in body height preceding contact between the speed
groups. It was revealed that the ∆TRUNKANT during the ST phase did not differ
significantly between speed groups (F(2, 45) = 2.093, p = .135). Similarly, speed had no
affect on the CGVERT during the ST phase (CGVERT at ST-FS and CGVERT at ST-TO)
(F(4,
88)
= 1.220, p = .308; Wilks Lambda = .898; partial eta squared = .053).
This suggests that the speed of performance did not alter measures of body height
during the ST phase.
220
KINEMATIC
ANALYSIS
(a)
(b)
(c)
Figure 5.20: Transverse plane representation of ST-FS relative to the straighten line
(a) slow performances (b) moderate performances (c) fast performances.
221
AGILITY
IN RUGBY UNION
RE-ACCELERATION PHASE
No differences to POSTCD change in linear velocity (∆VELHORZ and ∆VELLAT) were
observed between speed groups (F(4,
88)
= 1.333, p = .264; Wilks Lambda = .889;
partial eta squared = .057). However, further analysis demonstrated that fast
performances
displayed
greater
VELLAT
(1.37
±0.47
m.s-1)
compared
to
-1
slow (0.61 ±0.52 m.s , p < .001) (Appendix D.36). Following this, the LDLAT of fast
performances (-44.51 ±6.32 %) was shown to have crossed the line of the centre of
gravity further than slow performances (-36.65 ±6.26 %, p = .008) (Appendix D.37).
Then, Pearson’s correlation showed a significant positive moderate relationship
between LDLAT and ∆VELLAT during the POSTCD phase (r = .624, n = 48, p < .001).
This indicates that a greater redirection of lateral movement occurred with an increase
to the length that LDLAT crossed the line of the centre of gravity.
Analysis of body height showed similar results to the ST phase, where ∆TRUNKANT
during
the
POSTCD
phase
did
not
differ
significantly
between
speed
groups (F(2, 45) = 1.509, p = .600). Similarly, no significant difference was observed in
the TRUNKANT at contact initiation between speed groups (F(2, 45) = 1.676, p = .199).
Also, there was no significant affect of speed group on CGVERT during the POSTCD
phase (CGVERT at POSTCD-FS and CGVERT at POSTCD-TO) (F(4, 88) = 1.042, p = .390;
Wilks Lambda = .912; partial eta squared = .045).
222
KINEMATIC
ANALYSIS
FEND CONDITION
Analysis indicated that the phases of the agility cycle did not vary between speed
groups for the %PRECD or %ST phases (Appendix D.38) (Figure 5.21).
However, the %CD phase was greater for fast performances (18.88 ±6.23 %) compared
to slow (14.16 ±2.96 %, p = .020). Also, fast performances displayed less %TRANS
phase (22.42 ±10.34 %) compared to moderate (30.42 ±4.60 %, p = .001) and
slow (32.35 ±4.22 %, p = .001). It was shown that fast performances displayed greater
Slow
PRECD
17.73 %
CD
TRANS
14.16 % 32.35 %
ST
16.49 %
Moderate
PRECD
18.03 %
CD
TRANS
14.89 % 30.42 %
POSTCD
ST
15.48 % 21.18 %
Fast
Performance Speed
%POSTCD phase (22.92 ±3.19 %) compared to slow (19.27 ±2.25 %, p = .003).
PRECD
17.81 %
CD
18.88 %
0%
TRANS
22.42 %
50%
ST
17.97 %
POSTCD
19.27 %
POSTCD
22.92 %
100%
Agility Cycle
Figure 5.21: Relative agility phase percentages during FEND conditions with respect to
speed group.
223
AGILITY
IN RUGBY UNION
PRE-CHANGE OF DIRECTION PHASE
Pearson’s correlation showed no significant relationship between the %PRECD phase
and ∆VELHORZ (r = -.061, n = 48, p = .678) and ∆VELLAT (r = .057, n = 48, p = .698).
It was shown that fast performances displayed greater increases to VELLAT during the
PRECD phase (0.51 ±0.31 m.s-1) compared to moderate (0.01 ±0.30 m.s-1, p < .001) and
slow (-0.12 ±0.37 m.s-1, p < .001) (Appendix D.39).
CHANGE OF DIRECTION PHASE
Building on the greater VELLAT observed during the PRECD phase, fast performances
displayed
greater
VELLAT
at
CD-FS
(0.88
±0.58
m.s-1)
-1
compared
to
-1
moderate (0.28 ±0.35 m.s , p = .005) and slow (0.21 ±0.53 m.s , p = .002)
(Appendix D.40). However, Pearson’s correlation showed no significant relationship
between ∆VELLAT and LDLAT (r = .060, n = 48, p = .686). Despite this, a significant
negative moderate relationship existed between ∆VELHORZ and LDHORZ (r = -.699,
n = 48, p < .001), indicating that increases to LDHORZ were associated with greater
VELHORZ deceleration.
It
was
found
that
fast
performances
displayed
greater
VELLAT
at
CD-TO (2.66 ±0.29 m.s-1) compared to slow (2.10 ±0.45 m.s-1, p < .001)
(Appendix D.41). Further analysis examined the affect of speed group on the change in
linear velocity from the point of resistive fend initiation until termination (∆VELHORZ
and ∆VELLAT). Results showed that moderate performances exhibited greater increases
to VELLAT during the resistive fend execution (1.29 ±0.11 m.s-1) compared to
fast (0.83 ±0.10 m.s-1, p = .014) and slow (0.84 ±0.11 m.s-1, p = .019) (Appendix D.42).
TRANSITION PHASE
The number of TRANS steps affected the change in linear velocity through
the TRANS phase (∆VELHORZ and ∆VELLAT) (Appendix D.43). A decrease in
VELHORZ occurred with two TRANS steps (-0.36 ±0.49 m.s-1) compared to an increase
in VELHORZ with one TRANS step (0.03 ±0.31 m.s-1, p = .018) and no TRANS
steps (0.41 ±0.34 m.s-1, p = .001). In addition, a reduction to VELLAT occurred with
one TRANS step (-0.13 ±0.27 m.s-1) compared to an increase in VELLAT with
224
KINEMATIC
ANALYSIS
two TRANS steps (0.23 ±0.46 m.s-1, p = .011). Further analysis revealed a significant
affect of the number of TRANS steps (0, 1 and 2) on the percent resistive fend relative
to TRANS time (F(2,
45)
= 5.998, p = .005). An increase to the percent
resistive fend occurred with no TRANS steps (71.67 ±31.25 %) compared to
one TRANS step (48.74 ±12.65 %, p = .035) and two TRANS steps (43.73 ±16.72 %,
p = .005).
STRAIGHTEN PHASE
Analysis examined the affect of the speed of performance on the foot position of ST-FS
relative to the straighten line (ST-FSHORZ and ST-FSLAT) (Appendix D.44).
It was demonstrated that ST-FSHORZ of fast performances (-0.55 ±0.30 m) occurred
earlier compared to slow (-0.19 ±0.33 m, p = .004) and that ST-FSLAT of slow
performances (0.79 ±0.12 m) occurred wider compared to moderate (0.58 ±0.21 m,
p = .004) and fast (0.50 ±0.16 m, p < .001).
Results showed that slow performances displayed less VELLAT (2.23 ±0.31 m.s-1)
compared to moderate (2.56 ±0.30 m.s-1, p = .008) and fast (2.59 ±0.24 m.s-1, p = .003)
(Appendix D.45). In addition, Pearson’s correlation demonstrated a significant negative
moderate relationship between LDLAT and ∆VELLAT (r = -.680, n = 48, p = .026),
indicating that greater redirection of lateral movement occurred with an increase
to LDLAT. It was found that the LDLAT of slow performances (53.47 ±7.64 %) was
greater than moderate (40.81 ±9.87 %, p = .003) (Appendix D.46).
Analysis of body height demonstrated that ∆TRUNKANT during the ST phase did not
differ
significantly
between
speed
groups
(F(2,
45)
=
.949,
p
=
.395).
Similarly, no significant affect was observed for speed groups on CGVERT during
the ST phase (CGVERT at ST-FS and CGVERT at ST-TO) (F(4,
88)
= .981, p = .422;
Wilks Lambda = .916; partial eta squared = .043).
RE-ACCELERATION PHASE
Pearson’s
correlation
showed
a
significant
weak
relationship
between
the %POSTCD phase and both VELHORZ (r = -.406, n = 48, p = .002) and
225
AGILITY
IN RUGBY UNION
VELLAT (r = .435, n = 48, p = .002) at POSTCD-FS. Results observed no significant
affect of speed group on the change in linear velocity during the POSTCD
phase (∆VELHORZ and ∆VELLAT) (F(4,
88)
= 1.104, p = .360; Wilks Lambda = .907;
partial eta squared = .048). However, slow performances displayed less VELLAT at
POSTCD-FS (.39 ±.61 m.s-1) compared to moderate (1.06 ±.51 m.s-1, p = .005) and
fast (1.13 ±.51 m.s-1, p = .002) (Appendix D.47). Pearson’s correlation then found a
significant
negative
weak
relationship
between
LDLAT
and
VELLAT
at
POSTCD-FS (r = -.333, n = 48, p = .021). Finally, it was demonstrated that the LDLAT of
fast performances (-41.51 ±10.60 %) had crossed the line of the centre of gravity further
than moderate (-31.88 ±7.67 %, p = .027) (Appendix D.48).
The ∆TRUNKANT during the POSTCD phase did not differ significantly between speed
groups (F(2, 45) = .981, p = .383). Similarly, there was no significant difference in the
TRUNKANT at contact initiation between speed groups (F(2, 45) = .464, p = .632). To add
to this, the speed of performance had no significant affect on CGVERT during the
POSTCD phase (CGVERT at POSTCD-FS and CGVERT at POSTCD-TO) (F(4,
p = .555; Wilks Lambda = .934; partial eta squared = .033).
226
88)
= .759,
KINEMATIC
ANALYSIS
STRAIGHT-LINE RUNNING AND PLANNED
CONDITIONS
PRE-CHANGE OF DIRECTION PHASE
It was demonstrated that VELHORZ decreased during the PRECD phase of
PLAN (-.64 ±.43 m.s-1) compared to an increase during stance of SLR (.27 ±.17 m.s-1)
(t = 12.759, df = 67.79, p < .001, two-tailed). It was then shown that LDHORZ was greater
at PRECD-FS (41.68 ±14.78 %) compared to SLR-FS (14.90 ±8.90 %) (Figure 5.22)
(t = -9.556, df = 67.405, p < .001, two-tailed). Similarly, TDHORZ was less at
PRECD-TO (-6.82 ±15.85 %) compared to SLR-TO (-43.36 ±2.94 %) (Figure 5.23)
(t = -15.455, df = 53.183, p < .001, two-tailed).
(a)
Figure
(b)
5.22:
Sagittal
plane
representation
(b) PRECD-FS of PLAN.
227
of
LDHORZ
(a)
SLR-FS
AGILITY
IN RUGBY UNION
(a)
(b)
Figure
2.23:
Sagittal
plane
representation
of
TDHORZ
during
the
(a)
SLR-TO
(b) PRECD-TO of PLAN.
CHANGE OF DIRECTION PHASE
Results
showed
PLAN
(-1.18
that
±0.41
VELHORZ
m.s-1)
decreased
compared
to
an
CD
increase
phase
during
of
stance
-1
with SLR (0.27 ±0.17 m.s ) (t = 20.998, df = 68.586, p < .001, two-tailed).
Accordingly, LDHORZ was greater at CD-FS (46.24 ±11.19 %) compared to SLR-FS
(14.90 ±8.90 %) (Figure 5.24) (t = -11.944, df = 70, p < .001, two-tailed).
Further analysis revealed that TDHORZ was less at CD-TO (-22.92 ±15.52 %) compared
to SLR-TO (-43.36 ±2.94 %) (Figure 5.25) (t = -8.816, df = 53.430, p < .001, twotailed).
It
was
shown
that
VELLAT
increased
during
the
CD
phase
of
PLAN (1.64 ±0.28 m.s-1) compared to SLR (-0.43 ±0.29 m.s-1) (t = -28.835, df = 70,
p < .001, two-tailed). Accordingly, lateral foot positions then increased where it was
found
that
LDLAT
at
CD-FS
(41.35
±5.85
%)
was
greater
compared
to SLR-FS (8.06 ±3.17 %) (Figure 5.24) (t = -31.273, df = 56.451, p < .001, two-tailed).
Similarly, results observed that TDLAT was greater at CD-TO (74.69 ±8.34 %) compared
to SLR-TO (-17.69 ±2.82 %) (Figure 5.25) (t = -68.751, df = 64.134,
p < .001, two-tailed).
228
KINEMATIC
(a)
Figure
ANALYSIS
(b)
5.24:
Transverse
plane
representation
of
LDHORZ
and
LDLAT
of
TDHORZ
and
TDLAT
(a) SLR-FS (b) CD-FS of PLAN.
(b)
(a)
Figure
5.25:
Transverse
plane
representation
(a) SLR-TO (b) CD-TO of PLAN.
229
AGILITY
IN RUGBY UNION
STRAIGHTEN PHASE
Greater increases to VELHORZ occurred during the ST phase of PLAN (0.77 ±0.35 m.s-1)
compared to SLR (0.27 ±0.17 m.s-1) (t = -8.208, df = 69.996, p < .001, two-tailed).
This greater increase to running speed during agility skill execution meant that
variations to foot position were observed. It was found that LDHORZ was less
at ST-FS (-0.91 ±15.43 %) compared to SLR-FS (14.90 ±8.90 %) (Figure 5.26)
(t = 5.501, df = 68.426, p < .001, two-tailed). Also, TDHORZ was greater at
ST-TO (-81.02 ±7.35 %) compared to SLR-TO (-43.36 ±2.94 %) (Figure 5.27)
(t = 30.896, df = 67.773, p < .001, two-tailed).
Results showed that a greater redirection of VELLAT occurred during the ST phase of
PLAN (-1.51 ±0.57 m.s-1) compared to SLR (-.43 ±.29 m.s-1) (t = 10.660,
df = 69.934, p < .001, two-tailed). Accordingly, LDLAT was greater at
ST-FS (46.14 ±11.42 %) compared to SLR-FS (8.06 ±3.17 %) (Figure 5.26)
(t = -21.494, df = 59.722, p < .001, two-tailed). Also, TDLAT was greater
at ST-TO (28.40 ±15.56 %) compared to SLR-TO (-17.69 ±2.82 %) (Figure 5.27)
(t = -19.887, df = 52.926, p < .001, two-tailed).
(b)
(a)
Figure
5.26:
Transverse
plane
representation
(a) SLR-FS (b) ST-FS of PLAN.
230
of
LDHORZ
and
LDLAT
KINEMATIC
(a)
Figure
ANALYSIS
(b)
5.27:
Transverse
plane
representation
of
and
TDHORZ
TDLAT
(a) SLR-TO (b) ST-TO of PLAN.
RE-ACCELERATION PHASE
Greater
increases
to
VELHORZ
occurred
during
the
POSTCD
phase
of
PLAN (0.50 ±0.49 m.s-1) compared to SLR (0.27 ±0.17 m.s-1) (t = -2.910, df = 64.952,
p
=
.005,
two-tailed).
It
was
shown
that
LDHORZ
was
less
at
POSTCD-FS (11.84 ±11.22 %) compared to SLR-FS (14.90 ±8.90 %) (Figure 5.28)
(t = 5.501, df = 68.426, p = .214, two-tailed). However, TDHORZ was greater at
POSTCD-TO (-68.33 ±12.72 %) compared to SLR-TO (-43.36 ±2.94 %) (Figure 5.29)
(t = 12.923, df = 56.272, p < .001, two-tailed).
Greater redirection of VELLAT was also observed during the POSTCD phase of
PLAN (-0.97 ±0.32 m.s-1) compared to SLR (-0.43 ±0.29 m.s-1) (t = 6.871, df = 70,
p < .001, two-tailed). Furthermore, LDLAT at POSTCD-FS (-39.50 ±8.64 %) had crossed
the line of the centre of gravity and was greater compared to SLR-FS (8.06 ±3.17 %)
(Figure 5.28) (t = 33.840, df = 65.968, p < .001, two-tailed). It should be noted that
TDLAT
was
greater
at
POSTCD-TO
(-32.00
±10.52
%)
compared
SLR-TO (-17.69 ±2.82 %) (Figure 5.29) (t = 8.811, df = 59.012, p < .001, two-tailed).
231
to
AGILITY
IN RUGBY UNION
(a)
Figure
(b)
5.28:
Transverse
plane
representation
of
LDHORZ
and
LDLAT
of
TDHORZ
and
TDLAT
(a) SLR-FS (b) POSTCD-FS of PLAN.
(a)
Figure
(b)
5.29:
Transverse
plane
representation
(a) SLR-TO (b) POSTCD-TO of PLAN.
232
KINEMATIC
ANALYSIS
PLANNED AND UNPLANNED CONDITIONS
PRE-CHANGE OF DIRECTION PHASE
Results demonstrated that greater deceleration of VELHORZ occurred during
PLAN (-0.64 ±0.43 m.s-1) compared to UNPLAN (-0.43 ±0.41 m.s-1) (t = -2.495,
df = 94, p = .014, two-tailed). It was observed that LDHORZ was greater during PLAN
(41.68 ±14.78 %) compared to UNPLAN (31.52 ±16.12 %) (Figure 5.30)
(t = 3.218, df = 94, p = .002, two-tailed).
(a)
(b)
Figure 5.30: Sagittal plane representation of LDHORZ (a) PLAN (b) UNPLAN.
Results
showed
that
greater
increases
to
VELLAT
occurred
during
PLAN (0.29 ±0.35 m.s-1) compared to UNPLAN (0.02 ±0.39 m.s-1) (t = 3.476, df = 94,
p = .001, two-tailed). Also, greater VELLAT at PRECD-FS was observed for
PLAN (0.42 ±0.25 m.s-1) compared to UNPLAN (0.08 ±0.28 m.s-1) (t = 6.130, df = 94,
p < .001, two-tailed). It was found that LDLAT had crossed the line of the centre of
gravity
and
was
greater
during
PLAN
(-5.33
±11.33
%)
compared
to
UNPLAN (.02 ±10.71 %) (t = -2.376, df = 94, p = .020, two-tailed). Also, TDLAT had
233
AGILITY
crossed
IN RUGBY UNION
the
line
of
the
centre
of
gravity
and
was
greater
during
PLAN (-11.20 ±17.26 %) compared to UNPLAN (-1.60 ±15.98 %) (t = -2.826, df = 94,
p = .006, two-tailed).
CHANGE OF DIRECTION PHASE
No significant difference in ∆VELLAT was observed between PLAN and UNPLAN
conditions (t = -1.088, df = 94, p = .279, two-tailed). However, greater VELLAT at
CD-FS
was
observed
for
PLAN
(0.69
±0.43
m.s-1)
compared
to
UNPLAN (0.25 ±0.42 m.s-1) (t = 4.953, df = 94, p < .001, two-tailed).
This was shown to occur in conjunction with an increased LDLAT, which was greater
during UNPLAN (44.52 ±6.10 %) compared to PLAN (41.35 ±5.85 %)
(t = -2.601, df = 94, p = .011, two-tailed).
Results showed no significant difference in the VELHORZ at CD-FS between PLAN and
UNPLAN conditions (t = -.290, df = 94, p = .772, two-tailed). Similarly, no significant
difference
was
observed
in
the
LDHORZ
between
PLAN
and
UNPLAN
conditions (t = 3.307, df = 94, p = .001, two-tailed). However, the initial side-step
agility manoeuvre was executed earlier when participants were not required to react to
the defensive stimulus. It was demonstrated that the CD-FSHORZ occurred earlier during
PLAN (0.13 ±0.42 m) compared to UNPLAN (-0.24 ±0.48 m) (Figure 5.31) (t = 4.112,
df = 94, p < .001, two-tailed).
234
KINEMATIC
ANALYSIS
(a)
(b)
Figure 5.31: Transverse plane representation of CD-FS relative to the direction change
line (a) PLAN (b) UNPLAN.
235
AGILITY
IN RUGBY UNION
TRANSITION PHASE
It was found that greater increases to VELLAT occurred during the TRANS phase of
UNPLAN (0.33 ±0.42 m.s-1) compared to PLAN (0.08 ±0.32 m.s-1) (t = -3.272, df = 94,
p = .001, two-tailed). Chi-squared analysis examined the relationship between agility
condition (PLAN and UNPLAN) and the number of TRANS steps (0, 1 and 2).
Examination of the standardised residuals revealed no significant relationships, but a
trend was observed in which the no TRANS step strategy tended to be used during
PLAN (1.6) and not during UNPLAN (-1.6) conditions (χ2 = 6.987, df = 2, p = .030).
STRAIGHTEN PHASE
Results showed no significant difference between PLAN and UNPLAN conditions for
the
∆VELHORZ
(t
=
-.685,
df
=
94,
p
=
.495,
two-tailed)
and
∆VELLAT (t = .373, df = 94, p = .710, two-tailed). Accordingly, no significant
differences
were
observed
between
PLAN
and
UNPLAN
conditions
in
LDHORZ (t = 1.572, df = 94, p = .119, two-tailed) or LDLAT (t = -.036, df = 94,
p = .971, two-tailed).
RE-ACCELERATION PHASE
Similar to the ST phase, no significant difference were shown between PLAN and
UNPLAN conditions in VELHORZ at POSTCD-FS (t = .060, df = 94, p = .952, two-tailed)
or VELLAT (t = -.303, df = 87.858, p = .763, two-tailed). Results found no significant
difference between PLAN and UNPLAN conditions in LDHORZ (t = -1.642, df = 94, p =
.104, two-tailed) or LDLAT (t = .209, df = 94, p = .835, two-tailed).
236
KINEMATIC
ANALYSIS
UNPLANNED AND CONTACT CONDITIONS
PRE-CHANGE OF DIRECTION PHASE
Results showed little variation to measures of velocity between UNPLAN and
CONTACT conditions during the initial side-step direction change phases. Analysis
demonstrated that no significant differences existed between UNPLAN and CONTACT
conditions for ∆VELHORZ (t = 1.462, df = 94, p = .147, two-tailed) and ∆VELLAT
(t = -1.708, df = 94, p = .091, two-tailed).
CHANGE OF DIRECTION PHASE
It was shown that no significant difference in ∆VELHORZ existed between UNPLAN and
CONTACT conditions (t = -.520, df = 94, p = .604, two-tailed). Similarly, there was no
significant difference observed in ∆VELLAT between UNPLAN and CONTACT
conditions (t = 1.339, df = 94, p = .184, two-tailed).
TRANSITION PHASE
Despite the lack of variation to velocity during the initial side-step, results showed that a
smaller reduction to VELHORZ occurred during CONTACT (-0.11 ±0.39 m.s-1)
compared to UNPLAN (-0.32 ±0.47 m.s-1) (t = -2.425, df = 94, p = .017, two-tailed).
Further analysis explored the relationship between agility condition and the number of
TRANS steps. Chi-squared analysis observed no significant dependency between agility
condition (UNPLAN and CONTACT) and the number of TRANS steps (0, 1 and 2)
(χ2 = 4.929, df = 2, p = .085).
STRAIGHTEN PHASE
No significant difference were observed between UNPLAN and CONTACT conditions
for ∆VELHORZ (t = 1.882, df = 94, p = .063, two-tailed) and ∆VELLAT (t = -.005,
df
=
94,
p
=
.996,
two-tailed).
However,
TDHORZ
was
greater
during
CONTACT (-86.70 ±6.14 %) compared to UNPLAN (-83.29 ±5.91 %) (t = 2.766,
df = 94, p = .007, two-tailed).
237
AGILITY
IN RUGBY UNION
Analysis found that reductions to body height occurred preceding contact compared to
those performances not involving a contact situation. The CGVERT at ST-FS was show to
be
less
during
CONTACT
(47.21
±1.88
%)
compared
to
UNPLAN (49.14 ±1.82 %) (t = 5.098, df = 94, p < .001, two-tailed).
Moreover, CGVERT at ST-TO was less during CONTACT (43.97 ±2.15 %) compared
to UNPLAN (46.79 ±2.14 %) (t = 6.426, df = 94, p < .001, two-tailed) and greater
reductions to TRUNKANT were observed during CONTACT (-19.83 ±11.01°) compared
to UNPLAN (-10.47 ±8.86°) (t = 4.566, df = 94, p < .001, two-tailed).
Figure 5.32 represents the body position at ST-TO including TRUNKANT, CGVERT and
TDHORZ as observed during UNPLAN and CONTACT conditions.
(a)
Figure
(b)
5.32:
Sagittal
plane
representation
of
body
position
at
ST-TO
(a) UNPLAN (b) CONTACT.
RE-ACCELERATION PHASE
Results showed no significant difference in ∆VELLAT between UNPLAN and
CONTACT conditions (t = .000, df = 94, p = 1.00, two-tailed). Also, there was no
significant difference in ∆VELHORZ between UNPLAN and CONTACT conditions
(t = .889, df = 94, p = .376, two-tailed), despite LDHORZ being greater during
CONTACT (20.99 ±12.85 %) compared to UNPLAN (15.71 ±11.89 %)
(t = -2.087, df = 94, p = .040, two-tailed).
238
KINEMATIC
ANALYSIS
Analysis of body positions showed that CGVERT at POSTCD-FS was less during
CONTACT
(43.84
±2.24
%)
compared
to
UNPLAN
(46.70
±2.24
%)
(t = 6.416, df = 94, p < .001, two-tailed). To add to this, TRUNKANT at POSTCD-FS
was less during CONTACT (51.18 ±9.30°) compared to UNPLAN (65.48 ±7.39°)
(t = 8.337, df = 94, p < .001, two-tailed). Figure 5.33 illustrates the differences in body
position at POSTCD-TO between UNPLAN and CONTACT conditions.
(a)
(b)
Figure 5.33: Sagittal plane representation of body position at POSTCD-TO
(a) UNPLAN (b) CONTACT.
239
AGILITY
IN RUGBY UNION
CONTACT AND FEND CONDITIONS
PRE-CHANGE OF DIRECTION PHASE
No significant difference was observed for ∆VELHORZ between CONTACT and FEND
conditions (t = 1.903, df = 94, p = .060, two-tailed). However, a greater reduction to
running speed occurred during the initial side-stepping phases when participants were
required to execute a fend on the defensive opponent. It was shown that VELHORZ at
PRECD-TO
was
lower
during
FEND
(4.96
±0.54
m.s-1)
compared
to
CONTACT (5.29 ±0.62 m.s-1) (t = 2.706, df = 94, p = .008, two-tailed).
CHANGE OF DIRECTION PHASE
Following on from the PRECD phase, a greater reduction to VELHORZ was observed
during
CD
phase
FEND
(-1.55
±0.61
m.s-1)
compared
to
CONTACT
conditions (-1.03 ±0.45 m.s-1) (t = 4.773, df = 94, p < .001, two-tailed).
To add to this, VELHORZ at CD-TO was less during FEND (3.32 ±0.58 m.s-1) compared
to CONTACT (4.17 ±0.70 m.s-1) (t = 6.469, df = 91.104, p < .001, two-tailed).
However, no significant difference in LDHORZ between CONTACT and FEND
conditions was observed (t = -.209, df = 94, p = .835, two-tailed). Despite this,
TDHORZ
was
less
during
FEND
(-20.57
±14.80
%)
compared
to
CONTACT (-30.22 ±15.12 %) (t = -3.157, df = 94, p = .002, two-tailed).
TRANSITION PHASE
Results
showed
no
significant
difference
between
CONTACT
and
FEND
conditions in ∆VELHORZ (t = .260, df = 94, p = .795, two-tailed) or
∆VELLAT (t = 1.231, df = 94, p = .222, two-tailed). However, Chi-squared analysis
observed a significant dependency between agility conditions (CONTACT and FEND)
and the number of TRANS steps (0, 1 and 2) (χ2 = 6.689, df = 2, p = .035). Examination
of the standardised residuals revealed no significant relationships, but it was
shown that those participants completing the FEND agility condition were unlikely to
use the no TRANS step strategy (SR = -1.5).
240
KINEMATIC
ANALYSIS
STRAIGHTEN PHASE
No significant difference existed for VELLAT at ST-FS between CONTACT and FEND
conditions (t = -.494, df = 94, p = .622, two-tailed). Despite this, a greater redirection
of VELLAT was observed during FEND conditions (-1.78 ±0.46 m.s-1) compared to
CONTACT conditions (-1.55 ±0.43 m.s-1) (t = 2.527, df = 94, p = .013, two-tailed).
It was shown that CGVERT at ST-FS was greater during FEND (48.36 ±2.69 %)
compared to CONTACT conditions (47.21 ±1.88 %) (t = -2.431, df = 84.099, p = .017,
two-tailed).
RE-ACCELERATION PHASE
A reduction to VELHORZ at POSTCD-FS was observed during FEND (3.93 ±.46 m.s-1)
compared to CONTACT conditions (4.71 ±.54 m.s-1) (t = 7.531, df = 94, p < .001,
two-tailed). Accordingly, LDHORZ was less for FEND (13.27 ±13.37 %) compared to
CONTACT (20.99 ±12.85 %) (t = 2.882, df = 94, p = .005, two-tailed).
Further analysis demonstrated no significant difference in CGVERT at POSTCD-FS
between CONTACT and FEND conditions (t = -.537, df = 78.453, p = .592,
two-tailed). Similarly, CGVERT at contact initiation did not vary between CONTACT
and FEND conditions (t = -.839, df = 87.740, p = .403, two-tailed). Also, no significant
difference in TRUNKANT at contact initiation was observed between CONTACT and
FEND conditions (t = 1.278, df = 94, p = .205, two-tailed). However, a significant
reduction to TRUNKANT at POSTCD-FS occurred during CONTACT (51.18 ±9.30°) and
FEND
(51.20
±10.29°)
conditions
compared
to
PLAN
(64.50
±9.12°)
and UNPLAN (65.48 ±7.39°) as well as SLR (72.37 ±4.51°) (Figure 5.34)
(F(4, 211) = 44.564, p = .002). Analysis of main effect statistics showed that athletes at
contact initiation displayed a 41 % reduction to TRUNKANT during FEND conditions
and a 42 % reduction for CONTACT conditions when compared to the running posture
displayed for SLR. Further analysis of main effect statistics showed that athletes at
contact initiation displayed a 26 % reduction to TRUNKANT during both FEND and
CONTACT conditions compared to UNPLAN conditions.
241
AGILITY
IN RUGBY UNION
75.00
TRUNKANT (°)
65.00
55.00
*
*
CONTACT
FEND
45.00
SLR
PLAN
UNPLAN
Performance Condition
Figure 5.34: Representation of TRUNKANT at POSTCD-FS for agility conditions.
* Significant decrease in TRUNKANT with CONTACT and FEND compared to PLAN, UNPLAN and
SLR (p < .05).
242
KINEMATIC
ANALYSIS
DISCUSSION
AGILITY GAIT CYCLE
PRE-CHANGE OF DIRECTION PHASE
The PRECD phase was characterised by rapid VELHORZ deceleration achieved with
increases to horizontal foot placement patterns 54, 89, 196, 218, 267, 271. This finding builds on
the notion that the reduction to running speed during the PRECD phase improves
the control of movement and properties of dynamic stability during the subsequent
CD step
16
. It is proposed that a trade-off exist between running speed and dynamic
stability during agility skill execution, such that excess running speeds diminish the
ability to maintain movement control. In rugby union, less dynamic stability would
surely reduce the ability to react to the movements of defensive opponents prior to
agility skill execution.
This study found that lateral foot positions where the stance limb crossed the line of the
centre of gravity facilitated greater preliminary lateral movement during the PRECD
phase. In support of this, previous research has shown that greater foot displacement
patterns are associated with an increase in ground reaction forces acting in the opposite
direction
54, 89, 196, 218, 267, 271
. In addition, previous research has shown that preliminary
movements occur during the PRECD phase to increase lateral movement towards the
intended direction change when side-stepping
16
. It is concluded that the lateral foot
placement patterns during the PRECD phase can be used to promote lateral movement
towards the intended direction change.
The properties of lateral movement during the PRECD phase were shown to vary
between speeds of agility skill execution. The greater lateral movement during the
PRECD phase of fast performances was accompanied by increases to LDLAT, where the
foot crossed the line of the centre of gravity further than slow and moderate
243
AGILITY
IN RUGBY UNION
performances. The negative LDLAT at PRECD-FS meant that the stance limb was
no
doubt
change
providing
54, 89, 196, 218, 267, 271
lateral
propulsion
towards
the
intended
direction
. In contrast, slow performances displayed typically positive
LDLAT at PRECD-FS, where the stance limb contributed little to preliminary lateral
movement redirection
54, 89, 196, 218, 267, 271
. It is concluded that more negative lateral
foot positions promote the redirection of lateral movement and represent a mechanism
to enhance the speed of agility skill execution. In rugby union, greater lateral movement
during initial direction change would promote the ability to evade defensive opponents
and as such, represents a key determinant of agility skill execution.
It was found that the inclusion of the decision-making element in agility testing limited
the magnitude of preliminary lateral movement during the PRECD phase. However, fast
performances exhibited greater preliminary lateral movement across all agility
conditions including those with a decision-making element. In support of this,
previous research has shown that the inclusion of decision-making elements as part of
assessment procedures has been shown to differentiate between speeds of agility
performance
133, 361
. Faster performers display superior decision-making strategies
during agility skill execution
133
. Therefore, reactive agility conditions restrict
preliminary lateral movement redirection but fast performances posses superior
decision-making strategies that enhances the ability to generate preliminary lateral
movement towards the required running line. Therefore, the presence of sport specific
decision-making elements should be considered a desirable feature of agility skill
development programs.
CHANGE OF DIRECTION PHASE
The CD phase was characterised by further reductions to running speed following the
PRECD phase. Interestingly, greater running speeds at CD-FS meant the LDHORZ was
greater, which further supports the notion that LDHORZ reduces running speed in order
for the intended direction change to occur as a controlled movement
174
. There is no
doubt that the reduction to running speed with purposeful increases to LDHORZ
represents a fundamental element of the CD phase during agility skill execution.
244
KINEMATIC
ANALYSIS
However, the lack of variation between performance speeds suggests that the measures
associated with the reduction of running speed during the CD phase do not differentiate
between performance levels in relatively homogenous samples of rugby union athletes.
Investigation of the mechanisms that reduce running speed during agility skill execution
across a more diverse sample would provide critical understanding of the mechanisms
that vary between athletic performance levels.
This study observed a significant relationship between lateral foot position and the
development of lateral movement during the CD phase, such that increases to LDLAT
and TDLAT promoted increases to VELLAT. However, no variation to lateral foot position
was observed between speeds despite fast performances displaying greater lateral
movement during the CD phase. It should be noted that the greater CD phase percentage
exhibited by fast performances would no doubt allow for greater lateral force production
adding to the lateral movement produced during the PRECD phase. This builds on
previous research that identified the CD phase percentage as an important component in
the development of lateral movement when changing directions 325.
This study demonstrated that measures associated with lateral movement and the
relationship with lateral foot positions affected the speed of agility skill execution.
Fast performances were able to generate greater increases to VELLAT during the
CD phase when also displaying greater initial VELLAT at CD-FS. In rugby union, the
expression of lateral movement during agility skill execution represents a critical
attacking element when attempting to evade the defence. Advanced lateral evasive skills
would ultimately present breaks in the defensive line and promote the ability to advance
the ball. Therefore, proficient generation of lateral movement during the PRECD and
CD phases is a critical component of evasive agility skill execution in rugby union.
It is important to explore the joint segmental contributions to the development of lateral
movement during the CD phase. For example, hip extension velocity at toe-off
has been shown to be an important contributor to propulsion in straight-line
running
195, 196, 242, 354
. Similarly, research has suggested the activation of the hamstring
muscle group during the CD propulsive phase accelerates the respective segments of the
lower extremity to promote lateral movement 90, 287, 314, 325. In contrast, the current study
found that hip extension velocity made no significant contribution to the development
245
AGILITY
IN RUGBY UNION
of lateral movement and did not vary between speed groups. This suggests that the hip
joint may not be the primary propulsive segment during the CD phase, but rather
provide stabilisation during the pivoting action of the lower leg when side-stepping.
Clearly, further research should examine the role of the hip joint during agility
manoeuvres.
It has been shown that the knee plays an important role during agility skill execution,
absorbing the forces associated with direction change
189, 195, 241
. The current study
demonstrated that greater knee extension angles were associated with greater VELLAT
at CD-TO. This suggests that the knee joint flexes to help absorb the forces associated
with direction change during the CD impact and midstance phases, and then facilitates
increases to VELLAT during the CD propulsion phase. Despite this, neither knee
displacement at CD-TO or knee displacement ROM during the CD phase were shown to
vary between agility performance speeds. The lack of variation to foot placement
patterns between speed groups would no doubt be associated with the lack of variation
in knee displacement angles during the CD phase. It is possible that the combined joint
kinematics of the hip, knee and ankle contribute to the speed of agility skill execution.
Accordingly, it is recommended that further research explores the lower limb multisegmental timings during the CD phase with respect to enhancing agility skill execution
32
.
This study found that anticipation abilities during reactive agility conditions provided a
means to differentiate between speeds of agility skill execution. The anticipation
abilities of fast performance meant that the required side-step was executed earlier and
with greater VELLAT at CD-FS towards the direction of the required running
line. Interestingly, slow performances typically displayed negative VELLAT at CD-FS,
which indicates that lateral movement was towards the opposite direction.
Farrow, Young and Bruce
133
observed that slower performing athletes waited until the
presentation of a decision-making stimulus was complete prior to executing the
appropriate agility movement strategy. In contrast, faster performing athletes predicted
the appropriate movement strategy required of agility skill execution during the early
stages of stimulus presentation
133
. Agility skill execution within an open
environmental context is dependant on selective attention and advance cue
recognition to offer predictive event sequencing that enhances decision-making
246
KINEMATIC
abilities
4, 5, 31, 346, 359
. Meir
264
ANALYSIS
highlighted the importance of anticipatory strategies in
penetrating the defensive line and advancing the ball beyond the advantage line during
attacking ball carries in rugby union. Hence, anticipation strategies based on advance
cue recognition and visual search strategies represent an important component of
evasive agility skill execution in rugby union.
The anticipatory strategies of fast performances promoted increases to lateral movement
during agility skill execution. Interestingly, athletes who achieved moderate speed
agility performance times used the resistive fend execution to increase lateral movement
during the FEND agility condition. This indicates that although moderate performances
were less able to predict the movements of the defensive opponent, they used the fend
execution to provide vital increases to lateral movement. Notational analysis
demonstrated that strong fending strategies executed by the attacking ball carrier in
resistance of defensive opponents are a key determinant of tackle-break phase outcomes
in rugby union. It can then be concluded that the fend execution in rugby union
represents an important attacking strategy, as well as a mechanism to increase lateral
movement during evasive agility skill execution. Further research is warranted on this
key area as it is possible that patterns of movement and event timings not described in
this study when combining fending strategies with agility skill execution alter the
effectiveness of running ability in rugby union. Incorporating force transducers /
pressure sensors measuring the kinetics of fend impact regions would also provide
novel insight along with assessing the strength and power capacities of athletes and how
this affects fend execution. It would be beneficial for strength and conditioning research
to examine upper body strength (1RM bench press) and power (e.g. bench throw) and
the relationship with the effectiveness of fend execution (e.g. the velocity of elbow
extension when pushing the defender).
TRANSITION PHASE
This study demonstrated that the TRANS phase provides the primary component of
lateral displacement during agility skill execution. It was found that the TRANS phase
is characterised by the transmission of lateral movement whilst seeking to control
247
AGILITY
IN RUGBY UNION
horizontal
momentum.
Importantly,
the
step
patterns
exhibited
during
the
TRANS phase altered the properties of lateral movement and provided a means to
differentiate between speeds of agility skill execution. It was concluded that the inverse
relationship between the speed of performance and the number of TRANS steps
represents a key determinant of agility skill execution in rugby union.
The current study found that a decrease in TRANS-VELLAT occurred with no TRANS
steps, compared to an increase in TRANS-VELLAT with both one and two TRANS step
patterns. Clearly, the increase to periods of flight associated with the absence of
TRANS steps restricts lateral propulsion
171
. In rugby union, lateral movement during
the TRANS phase is an important component when attempting to evade the defence.
Hence, a greater number of TRANS steps promotes the lateral propulsive strategies
required to evade defensive opponents. Adding weight to this notion, it was observed
that the addition of TRANS steps was favoured during agility conditions involving the
decision-making element. In addition, the development of lateral movement during the
initial side-step was restricted with the inclusion of the decision-making element.
Therefore, additional TRANS steps enhances the transmission of lateral movement
during reactive agility skill execution and as such, represents an important evasive
strategy in rugby union.
The increase in ground contact time achieved with additional TRANS steps would
enhance dynamic stability
142
. In rugby union, periods of flight during agility skill
execution provides the body with no stable base of support. Consequently, the ability to
resist an opponent would be severely diminished and this would reduce the
effectiveness of agility skill execution. This study observed a trade-off between the
speed of performance and the TRANS step patterns that promote dynamic stability.
It is recommended that future research whether the improvements to dynamic
stability associated with additional TRANS steps outweighs the associated decrement to
the speed of agility skill execution in rugby union.
The findings of the current study support the notion that additional TRANS steps
promotes enhanced dynamic stability. The complexity of agility skill execution
combined with the fend execution in resistance of the defensive opponent no doubt
required greater dynamic stability and as a result the no TRANS step pattern was rarely
248
KINEMATIC
ANALYSIS
observed. Consequently, additional TRANS steps functioned to increase lateral
movement and provide a more stable base of support in order to improve movement
control and resistance of the defensive opponent. It should be noted that an increase in
fend time was observed with less TRANS steps. In rugby union, increased resistive fend
time whilst displaying no stable base of support would give the defensive opponent a
greater opportunity to successfully tackle the attacking ball carrier. It is proposed that
strong fend execution over a short period of time and with a stable base of support
would promote the effectiveness of running ability in rugby union. It is necessary that
further research examines the kinetic characteristics of fend execution with reference to
enhancing running ability in rugby union.
Body height is an important determinant of the effectiveness of running ability during
attacking manoeuvres in rugby union
254, 348, 349
. Increases to body height promote
instabilities that would reduce the effectiveness of agility skill execution in resistance of
defensive opponents
348
. Importantly, the current study observed that the one TRANS
step pattern is an ineffective strategy during agility skill execution in rugby union due to
the significant increases in body height prior to contact. Alternatively, lowering body
height preceding contact was better achieved when not displaying no TRANS steps or
utilising two steps through TRANS. Agility training for contact sports should focus on a
player’s ability to side-step and straighten with minimal flight time (when displaying no
transition steps) or side-step and straighten with two transition steps (shuffle
technique). Preferably, players should display the shuffle technique to maintain lower
body height and greater dynamic stability. There is scope for research to describe the
presence of double and transitional single support during the TRANS phase with
reference to the speed and effectiveness of performance within a sport specific context.
STRAIGHTEN PHASE
This study demonstrated that the ST phase involves the redirection of lateral movement
to promote forward motion. Accordingly, increases to VELHORZ in conjunction with a
reduction to VELLAT were observed during the ST phase. An increase to lateral foot
positions certainly assisted in the redirection of lateral movement. It was then shown
249
AGILITY
IN RUGBY UNION
that a decrease to LDHORZ and an increase in TDHORZ occurred during the ST phase of
agility manoeuvres, no doubt promoting VELHORZ acceleration
196
. Interestingly, the
presence of negative LDHORZ was observed at ST-FS, which would have facilitated
exclusive forward propulsion
54, 89, 196, 218, 267, 271
. In rugby union, rapid acceleration of
forward motion during the ST phase would enhance the ability to exploit breaks in the
defensive line created from the initial evasive direction change. The ability to penetrate
the defence and advance the ball beyond the advantage line is a fundamental component
of running ability in rugby union
254
. Therefore, the properties of forward propulsion
during the ST phase represent a key determinant of agility skill execution in ruby union.
Previous research has found that the presence of excessive lateral forces when
attempting to maximise forward propulsion results in considerable reductions to
performance capability when running
345
. It is possible that the desirable increases to
forward propulsion during the ST phase are restricted when experiencing extensive
residual lateral movement following initial direction change. The lack of difference
between speed groups in forward propulsion during the ST phase suggests that the
increased residual lateral movement associated with enhanced speeds inhibited forward
propulsive capacities during agility skill execution.
It should be noted that greater lateral movement has been associated with increased
lateral foot positions when running
208
. Similarly, the current study observed that
increases to lateral foot positions were associated with greater redirection of lateral
movement during the ST phase of agility skill execution. It would be expected that the
greater residual lateral movement experienced with faster performances would be
associated with an increase to lateral foot positions. Conversely, fast performance
displayed a reduction to lateral foot positions during the ST phase. Consequently, the
reduction to lateral foot positions meant that fast performances were unable to dissipate
the associated greater residual lateral movement, whilst attempting to increase forward
propulsion. It can then be concluded that the inability to reduce residual lateral
movement evident with fast performances limited forward propulsive abilities during
the ST phase. In rugby union, it is possible that restricted forward propulsion during the
ST phase may reduce the ability to penetrate the defensive line following evasive agility
skill execution.
250
KINEMATIC
ANALYSIS
The knee joint has been identified as an important mechanism to promote forward
progression when running by absorbing the internal destabilising forces
189, 195, 241
.
The findings of the current study suggest that a trade-off exists between the application
of forward propulsion and the ability of the knee to absorb residual lateral moments
during the ST phase. Despite this, fast performances seemed to be able to maintain
movement control whilst displaying comparable knee joint biomechanics and absorbing
greater lateral moments. In rugby union, the ability to maintain movement control when
experiencing greater destabilising forces would mean that agility skill execution can be
performed with more rapid lateral movement. Consequently, an attacking ball carrier
displaying more rapid lateral movement would no doubt posses an enhanced ability to
evade defensive opponents during agility skill execution.
Residual lateral movement during the ST phase could promote instability during evasive
manoeuvres in rugby union. For example, the effectiveness of agility skill execution
could be diminished when presented with an external force from an opponent whilst
overcoming the internal destabilising forces associated with residual lateral movement.
Moreover, the current study demonstrated that alterations to step patterns and body
height occurred during the ST phase with the presence of contact in agility testing.
This is supported by previous research that has observed kinematic modifications of
agility skill execution during contact conditions in rugby union
254
. The ability to
implement the postural adjustments required during contact conditions in rugby union
would likely be diminished with excessive residual lateral movement. The earlier
straighten step observed with fast performances no doubt allowed greater time
preceding contact, where postural adjustments could occur in the presence of greater
residual lateral movement. Clearly, further research should examine dynamic stability
during contact conditions in rugby union, with reference to the kinematic adjustments
occurring with lateral movement in residue following evasive direction change.
RE-ACCELERATION PHASE
The POSTCD phase refers to the concluding events of agility skill execution where a
considerable increase to VELHORZ is a desirable feature of performance. In rugby union,
251
AGILITY
IN RUGBY UNION
the POSTCD phase allows the attacking ball carrier to penetrate the defensive line and
advance the ball. This study demonstrated that the POSTCD phase is characterised by
high rates of VELHORZ acceleration and further dissipation of residual lateral movement.
A reduction to horizontal foot placement patterns no doubt promoted VELHORZ
acceleration during the POSTCD phase, where the LDHORZ at POSTCD-FS was positive
and more closely resembled straight-line running patterns when compared to the
negative LDHORZ at ST-FS
54, 89, 196, 218, 267, 271
. However, lateral foot placement patterns
during the POSTCD phase were distinctive to straight-line running and a unique
component of agility skill execution. The negative lateral foot positions observed during
the POSTCD phase indicate that residual lateral movement remained following the
ST phase. Similar to the ST phase, the presence of residual lateral movement during
the POSTCD phase would promote instability during agility skill execution in rugby
union.
Rand and Ohtuski
325
suggested that residual lateral movement presented additional
performance requirements when attempting to maximise forward propulsion during the
POSTCD phase. This is an important consideration as greater forward propulsion has
been associated with enhanced running speeds
70, 408
. The current study observed that
fast performances typically displayed greater residual lateral movement during the
POSTCD phase, which has been shown to be detrimental when attempting to maximise
straight-line sprinting speed
111
. This greater residual lateral movement no doubt
restricted the forward propulsive abilities of fast performances and as a result, measures
of VELHORZ demonstrated no variation between speed groups. It can be concluded that
the presence of residual lateral movement is an undesirable feature when attempting to
maximise forward propulsive capacities during the POSTCD phase of agility skill
execution.
In rugby union, the effectiveness of running ability into contact would no doubt
diminish with greater residual lateral movement during the POSTCD phase of agility
skill execution. The current study observed that fast performances displayed more
negative lateral foot positions in order to overcome the greater residual lateral
movement experienced during the POSTCD phase. To add to this, fast performances also
exhibited an increase to the percent contribution of the POSTCD phase to the agility
cycle. Consequently, fast performances improved resistance to defensive contact with
252
KINEMATIC
ANALYSIS
the lateral displacement of the stance limb providing a greater blocking force over an
increased period of ground contact time. It should be noted that an increase to LDHORZ
at POSTCD-FS was observed with the inclusion of contact in agility testing.
An increase to LDHORZ would no doubt promote movement control during contact
conditions. Despite this, variations to horizontal foot positions were not observed
between speed groups. It is concluded that a greater phase percent with a greater foot
displacement during the POSTCD phase represents a key determinant of agility skill
execution in rugby union. However, it is necessary that further research examines the
relationship between stance limb kinematics and attributes of dynamic stability during
contact in rugby union.
The current study demonstrated that extensive reductions to body height occurred with
the presence of contact during the POSTCD phase of agility skill execution. In rugby
union, reductions to body height improve the effectiveness of attacking ball carries
when in contact with the defence
254
. To add to this, significant variations to lower
extremity biomechanics have been observed with the inclusion of a simulated defensive
opponent during agility testing 258. It should be noted that the current study observed no
significant variations to body height between speed groups with the inclusion of contact
during agility skill execution. This suggests that the increased lateral moments
following direction change that was evident with fast performances did not affect the
ability to lower body height into contact. It is proposed that an earlier straighten step
and increased POSTCD phase allowed fast performances a greater period of time to
lower body height into contact, despite the magnitude of residual lateral movement.
PRACTICAL IMPLICATIONS AND APPLICATIONS
AGILITY ASSESSMENT PROCEDURES
It is anticipated that the current study will promote improvements to the measurement of
agility performance throughout sport and specifically rugby union. This study
demonstrated that modifications to agility skill execution occur with variation to
253
AGILITY
IN RUGBY UNION
performance requirements. This suggests that the components of agility assessment
procedures should reflect the specific requirements and performance attributes of the
respective sport. To add to this, it was shown that enhanced speed of performance was
not necessarily associated with effective agility skill execution. Hence, it is important
that assessments of agility describe the speed of performance relating to the qualities of
skill execution. For example, an appropriate measure of agility performance in rugby
union would describe the speed of performance with consideration to the kinematic
adjustments necessary to enhance dynamic stability and movement control in reaction to
defensive patterns and in contact with defensive opponents. It is essential that
assessment procedures observe agility skill execution within sports specific conditions.
The sports specific nature of agility assessment procedures establishes the high external
validity of the current study. This study observed agility skill execution within an
environment specific to rugby union and with participants required to wear sports
specific footwear. Agility assessment procedures also included sports specific skills
such as ball carrying techniques, decision-making strategies and contact conditions. In
contrast, previous assessments of agility performance have been conducted typically
within non-sport specific environmental conditions, such as testing within an indoor
laboratory 13, 39, 43, 45, 57, 90, 96, 102, 105, 118, 137, 141, 154, 165, 175, 179, 188, 190, 208, 238, 239, 246, 249, 256, 259,
276, 287, 300, 302, 307, 309, 315, 356, 361, 410, 432, 433
. The observations of agility skill execution in
the current study were conducted under sports specific conditions and as such, the
findings can be applied within a functional setting.
The patterns of lateral movement exhibited during agility skill execution further affirm
the external validity of the current study. The agility course used in kinematic analysis
reproduced the evasive running patterns observed during notational analysis of running
patterns in rugby union. For example, notational analysis showed that a side-stepping
angle between 20° and 60° was associated with evasive agility skill execution resulting
in tackle-break phase outcomes in rugby union. It was then shown that the mean
side-stepping angle was 53 ± 10.57° during the kinematic analysis of agility skill
execution in rugby union. Moreover, the current study also observed side-stepping
agility skill execution through both right and left running lines. In contrast, previous
studies have limited the measurement of agility performance to a single directional
running line
43, 45, 90, 199, 239, 256, 287, 315, 325, 356
. It is concluded that the patterns of lateral
254
KINEMATIC
ANALYSIS
movement required during agility assessment protocols reflect the multidirectional
side-stepping attributes associated with evasive agility skill execution in rugby union.
The velocity profiles observed in the current study are an important factor contributing
to the external validity of findings. The current study required athletes to perform at
maximal effort during assessment protocols. It was recorded that the overall running
speed was 5.19 ± .65 m.s-1 at PRECD-FS during agility manoeuvres and 7.19 ± .32 m.s-1
during the straight-line running protocol. It should be noted that high level rugby union
athletes have been observed at running speeds in excess of 8 m.s-1 prior to agility skill
execution
348
. The maximal effort performances of rugby union athletes combined with
the sports specific design of assessment tasks indicate that the velocity profiles observed
in the current study reflect accurately skill execution within rugby union match-play. In
other studies, the running speed of participants prior to agility skill execution has been
limited to sub-maximal velocities as low as 3m.s-1, purportedly representing the speed at
which agility manoeuvres are executed throughout many sports
43, 45, 208, 239, 256, 259, 315
.
The velocity profiles observed in the current study suggest that limiting performance to
sub-maximal efforts holds limited application to maximal effort skill execution during
rugby union. It is accepted that the running speeds displayed prior to agility skill
execution would vary with the attributes of sports specific performance. However, the
apparent variations to running speed indicate that further research should measure the
speed at which agility manoeuvres are executed throughout sports.
The athletic level of participants is also a critical consideration in the application of
findings within a sports specific context. The observation of highly trained athletes in
the current project indicates that results are relevant to performance enhancement in
competitive rugby union. Competitive high level athletes demonstrate unique
characteristics and performance attributes
235, 259, 301
and as such, the generalised
sampling techniques utilised typically by previous research presents limited applications
to performance enhancement in high level sport 13, 57, 90, 96, 141, 142, 154, 188, 238, 239, 250, 273, 284,
300, 302, 325, 397, 432
. The knowledge gained from this study can be applied to the
assessment and training of agility skills in populations of high-level competitive
athletes. However, it is necessary that future research expand on the sample size of the
current study in order to gain a more comprehensive understanding of agility in such
athletes.
255
AGILITY
IN RUGBY UNION
The omission of female athletes in the current project indicates that findings may be
limited to the male athletic population. Modifications to agility skill execution have
been observed in female athletes compared to males
137, 175, 239, 256, 259, 293, 315, 364, 403
.
It is recommended that future studies should examine agility skill execution relating
to performance enhancement of female athletes. It should be noted that the popularity
of women’s rugby union has grown considerably in recent times with the
establishment of international and national competitions as well as comprehensive
development programs 86, 182, 331. Unfortunately, previous scientific studies investigating
women’s rugby union have investigated exclusively the potential for injury with
participation in the sport
75,
91,
92,
117,
225
. There have been no published
studies examining expressions of agility skill execution with female rugby
union athletes.
AGILITY TRAINING PROGRAMS
Agility skill development programs should form a fundamental element of specific
training in many sports. In contrast, agility interventions are included as part of ancillary
strength and conditioning programs. Consequently, the resources allocated to agility
skill development are secondary to the development of popular generalised strength and
power capacities. For example, advocates of core strengthening and stability workouts
involving exercise balls claim direct improvements to athletic performance and as such,
attract vital strength and conditioning resources 1, 138. However, improvements to sports
specific performance using such alternative training methods are not supported by the
scientific literature
247, 374, 375
. It is accepted that appropriate strength, power and speed
training improves general sporting performance
2, 98, 311, 319
. However, the transfer of
weight room training and straight-line sprints seem less direct compared to agility skill
development programs in a sporting context
173
. A link no doubt exists between agility
skill development in a sport specific training environment and agility skill execution
within competition. Therefore, the resources allocated to weight room exercises and
straight-line running training should not detract from vital agility skill development
programs.
256
KINEMATIC
ANALYSIS
A lack of understanding has meant that the implementation of agility training in sports
such as rugby union has focused on inappropriate speed development techniques
sourced from straight-line sprinting (e.g. upright body positions and high knee
recovery 71). To add to this, the commercially available agility training products present
generalised models of performance and disregard the sports specific nature of agility
skill execution. It is anticipated that the findings of the current study will improve
agility skill development programs throughout sport and within rugby union.
This
study
presented
the
distinct
technical
attributes
of
agility
skill
execution with regards to the specific requirements of sporting performance.
For example, methods to enhance the speed of agility skill execution were described
with reference to the relationship between foot placement patterns and linear velocity,
and then with consideration of the reductions to body height required prior to contact in
rugby union. Therefore, it is important that future agility interventions focus on the
qualities of skill execution with reference to the specific requirements of sporting
performance.
Inappropriate agility training methods (aimed at improving technique and anaerobic
capacity concurrently) are commonly derived through the apparent relationship between
agility and the anaerobic energy system. For example, methods of anaerobic capacity
training such as repeat shuttle runs are often associated with agility skill
development 30, 296. Clearly, training repeat effort agility (an important capacity in rugby
union) will resemble those methods used to increase anaerobic capacity. However,
anaerobic capacity training should not assume to improve agility technique. It is also
likely that athletes in a fatigued state demonstrate different agility technique (compare
to unfatigued) and this is clearly an area for further investigation. Despite this, agility
skill development programs should emphasis rapid changes of direction at high
velocities and expressed within sport specific context 74, 119, 130, 243.
The proficiency of the athlete must be considered when designing appropriate agility
training programs. As a general guide, it important that agility technique training be
sequenced so that athletes are not experiencing intra or inter-session fatigue, particularly
in the early stages of development
377
. Agility training to fatigue or in a fatigued state
can then be used for more skilful athletes (e.g. elite athletes) to simulate the repeat
257
AGILITY
IN RUGBY UNION
efforts of high intensity activity during rugby union match-play. It is important that an
agility development program incorporate the training principles of overload, recovery,
specificity and individuality
41, 146, 147, 340
. In a functional setting, agility development
programs should incorporate game sense activities and modified drills, where athletes
are required to display advanced sensory processing and decision-making abilities using
visual, auditory and proprioceptive pathways 8, 145, 148.
In rugby union, agility training programs should describe measures of performance time
combined with the ability to react to opponents and maintain effective posture and
technique. For example, training agility during attacking ball carries could occur in a
one-on-one situation within a small grid (e.g. 10 x 10 m), where the ball carrier must
beat the defender with a rapid change of direction whilst displaying a stable and
balanced movement pattern. The technical coaching points would include the athlete
maintaining forward momentum during the change of direction (not excessively
reducing speed to change directions), the upper body not collapsing (maintaining strong
core) during direction change and the knee joint providing a quick rebound when
stepping (knee joint not collapsing under the direction change load). In addition,
training within an open skilled environment where athletes are chasing and reacting to
other players, such as counter-attacking games (e.g. attacking ball carrier attempting to
score a try with a defender chasing across-field) and speed training where attacking ball
carriers experience destabilising contact (e.g. running through a gauntlet of hit-shields)
improves running ability in rugby union. The concepts from the above training games
should form part of development programs, but coaches are encouraged to analyse
match-play performance and then use the information to design agility tests and games
that replicated sport specific performance.
SUMMARY
Kinematic analysis outlined the attributes of agility skill execution during conditions
specific to rugby union. The agility gait cycle was characterised by an initial reduction
to running speed and subsequent increase to lateral movement. The lateral movement
developed
through
the
PRECD
and
CD
258
phases
was
then
expressed
as
KINEMATIC
ANALYSIS
lateral displacement during the TRANS phase. Following initial direction change,
the agility gait cycle was characterised by considerable increases to forward
motion whilst dissipating residual lateral movement. It was shown that the
foot placement patterns were associated with changes to velocity and were
unique through each phase of the agility gait cycle. In addition, the inverse
relationship between the CD and TRANS phases represented an important
attribute of the agility gait cycle that altered the speed and effectiveness of
skill execution.
Kinematic analysis demonstrated significant gait modifications and associated
velocity profiles with variation to the speed of agility skill execution. It was
shown that the evasive properties of agility skill execution were enhanced with
increases to lateral movement during the initial side-step. The subsequent
redirection of lateral movement to forward propulsion following direction change then
represented an important component of agility skill execution with consideration
of
the requirements
of
rugby union.
Importantly,
this
study
found
that
enhanced speed of performance often presented contradictions to the effectiveness
of agility skill execution within sport specific conditions. This study also observed
significant
modifications
to
agility
skill
execution
with
variation
to
the
requirements of performance. The inclusion of the decision-making element,
contact condition and fend execution altered agility skill execution.
The findings of kinematic analysis can be included as part of future athletic
assessment protocols. The attributes of agility skill execution described in this study
can be used to measure specifically technical proficiency during evasive
attacking
manoeuvres
in
rugby
union.
The
relationship
between
linear
velocity and measures of stride pattern, foot position and segmental timings
contributes a critical understand to the mechanisms required during agility skill
execution. The results of kinematic analysis can be used to design specific
training programs to improve agility skill execution. It is necessary that future
scientific research considers external validity when assessing agility skill execution.
It is critical that testing protocols and training programs within a functional context
incorporate the sport specific nature of agility skill execution.
259
CHAPTER V
CONCLUSION
This project examined agility skill execution as an expression of side-stepping
movement patterns observed in rugby union. It was demonstrated that the ability to
outmanoeuvre opponents through agility skill execution is a fundamental component of
successful performance in rugby union. The findings of this project address a gap in the
literature where agility is not well understood within the scientific and coaching
contexts. In addition, the current project provides a necessary insight into how agility
relates to successful performance in rugby union. It was demonstrated that evasive
agility skill execution is associated with successful performance, but that enhanced
speed of agility skill execution was not necessarily associated with improved running
ability. There is no doubt that the sport specific findings of this project can be used to
enhance performance in rugby union.
The research methodology (notational and biomechanical analyses) established the
strength of the current investigation. The intricate combination of notational and
kinematic analysis provided a comprehensive understanding regarding the attributes of
technical proficiency relating to sports specific agility skill execution in rugby union. To
add to this, the strong ecological validity of the current project means that the findings
have clear practical applications in rugby union and can be incorporated within a sports
specific training environment. This information provides an in-depth understanding to
coaches and athletes of what is required when designing sport specific testing
procedures and training programs to be implemented within a functional setting. It is
anticipated that the research methodology employed in the current study will improve
those associated with future scientific investigations.
260
CONCLUSION
FUTURE DIRECTIONS
The findings of this project present exciting opportunities for further examination of
agility. It is necessary that future research considers agility skill execution with
reference to performance enhancement and the application of findings within a
functional context. Agility is a rapidly expanding scientific research area and
component of athletic performance enhancement. Accordingly, it is important that
notational analysis continues to describe expressions of agility skill execution within
rugby union and throughout other sports. Once these profiles have been established,
biomechanical analysis of agility skill execution can progress with precise assessment
protocols. This would facilitate the development of reliable, valid and easily
implemented assessment tools and training techniques.
Clearly, future research must evolve to consider the attributes of performance required
during agility skill execution within a sport specific context. The current project has
demonstrated
that
the
combination
of
notational
and
kinematic
analysis
presents a comprehensive understanding of sports specific agility skill execution.
However, it is recommended that research examines running ability during contact
conditions in rugby union with analysis focusing on fending strategies and full contact
game simulations. In addition, future studies should investigate the specific
manifestations of agility skill execution within a defensive context in rugby union.
There is the scope for research to expand the measurement of agility skill execution
through various sports and with modified environmental conditions.
There is an increasing demand for biomechanical and performance analysis in the
provision
of
scientific
support
to
athletes
and
sporting
teams
330,
388
.
However, traditional methods of assessing technical proficiency are labour intensive
and time consuming
65
. It is a requirement that future biomechanical and performance
analysis techniques present immediate and comprehensive feedback relating to the
determinants of sporting performance and skill execution 24. To date, video and motion
analysis has represented the most viable method of assessing technical proficiency,
providing measurements of sport specific performance without disruption to
competition
110
. Recently, automated player tracking systems such as ProZone® have
presented time-motion analysis of open skilled sports
261
110
. However, automated player
AGILITY
IN RUGBY UNION
tracking systems are expensive and currently unable to describe the qualitative measures
of performance achieved with notational movement analysis and kinematic assessments.
Therefore, it is necessary that the development of new and innovative technologies
examines methods of providing unobtrusive and immediate qualitative feedback relating
to skill execution.
262
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APPENDICES
APPENDIX A
Procedural documents
APPENDIX B
Summary of logistic regression
APPENDIX C
Individual subject characteristics
APPENDIX D
Summary of multivariate analysis
306
APPENDICES
APPENDIX A
PROCEDURAL DOCUMENTS
APPENDIX A.1
Research project description
APPENDIX A.2
Consent to participate in research
307
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APPENDIX A.1
RESEARCH PROJECT DESCRIPTION
AGILITY SKILL EXECUTION IN RUGBY UNION
You are invited to participate in a research project conducted by the University of the
Sunshine Coast (USC) that aims to determine the kinematic determinants of agility skill
execution in rugby union. This research has been granted clearance by the Human
Research Ethics Committee of USC (S/07/121). Your involvement in this study is
entirely voluntary and your choice to participate (or not participate) will not involve
penalty or loss of benefits to which you might otherwise be entitled. The information
below is provided to inform and help you decide about participation in this project.
RESEARCH BACKGROUND
This project involves human participation and contributes towards meeting the requirements of
the degree Doctor of Philosophy at the University of the Sunshine Coast. This study will
focus on agility as an expression of lateral movement during rugby union. The majority
of previous studies investigating agility performance have failed to consider the specific
nature of agility skill execution within sport specific context.
RESEARCH PURPOSE
• Define the key determinants of agility skill execution in rugby union.
STUDY DURATION
Preceding agility testing, a five minute warm-up period will be complete. Agility testing
procedures will then be completed within fifteen minutes. Single agility performance
bouts will be completed within ten seconds and participants allowed full recovery
between trials, which should be within three minutes. During periods of recovery,
participants will remain active through low intensity running and dynamic stretching.
STUDY DESCRIPTION
Three-dimensional video analysis will examine rugby union athletes performing agility
tasks. Prior to testing participants will complete the consent to participate and
background data. The required procedures will be explained in detail to each participant
prior to agility testing including verbal descriptions and performance demonstrations.
Participants will also be permitted to complete non-measurable performances of the
agility course. Testing will be conducted on a dry, grass covered oval with participants
required to wear rugby union footwear as provided by the participating athletes and any
other protective equipment necessary. Strapping will be available on request and will be
completed by a qualified sports trainer. Athletes will also be required to wear only tight
exercise shorts during testing so that the respective anatomical landmarks can be clearly
located during analysis.
308
APPENDICES
Preceding agility testing, participants will complete a warm-up consisting of dynamic
stretches and activities. During agility testing, participants will be asked to perform
repeated trials of an agility task at maximal effort and carrying a match-type rugby
union ball. Initial agility tasks will require participants to traverse an agility course
involving a change of direction side-step and then a straighten step, without the
presence of defence. Subsequent agility tasks will require participants to run through the
same agility course as in initial trials, but with the presence of defence. The defensive
conditions involved as part of agility testing will be of familiar occurrence to
participating athletes; as such methods are used commonly within rugby union training
environments.
AGILITY TESTING RISKS
The required testing procedures are of common occurrence within both the training and
competitive rugby union environments. Accordingly, the agility testing protocol holds
minimal risk of participants experiencing soft tissue or other injuries. However, because
agility testing does require participants to make light contact with a soft hit-shield there
will be first-aid staff present during testing. Participants who have recently sustained
musculoskeletal or soft tissue injuries will not take part in agility testing. Nor, will those
athletes who have not fully recovered from an acute illness or suffer from bleeding
disorders or respiratory problems participate.
RESEARCH BENEFITS
It is hoped that this study will present a specific measure of agility and an understanding
of technical proficiency in rugby union. Results from the current study are expected to
question present testing and training techniques of agility. The improvement and further
understanding of agility testing and training techniques will be promoted through the
findings from the current study.
CONFIDENTIALITY AND PARTICIPATION CONDITIONS
Your involvement in this study is voluntary and your choice to participate (or not
participate) will not involve penalty or loss of benefits to which you might otherwise be
entitled. If you chose to withdraw from the study any information received from you
over the course of the study will not be presented in the final report or subsequent
publications. If you participate in this study then an individual identification code that
will be used instead of your name on all data collected. All personal information will be
protected and your identity will remain anonymous. The results of this study will
be published as a research journal article and findings will also be presented at sport
science seminars. No personal information or information pertaining to you that may
possibly lead to your identification will be used in the final report or any publication
resulting from this research.
Please note that you are able to take your time to think about whether you wish to
participate in this study. If after having some time to think about it you decide you
would like to participate, please contact the Chief Investigator at the details provided.
Your response by 30/06/07 would be appreciated as it is planned to commence the study
shortly. No incentives or rewards will be offered to participants for participating in the
research. The research team and the University of the Sunshine Coast sincerely
appreciate your participation and assistance with this research project.
309
AGILITY
IN RUGBY UNION
PRINCIAPAL RESEARCH EXPERTISE
Dr Mark Sayers has an extensive background in the biomechanics of team sports
(especially the football codes), gait analysis, impact skills training and sports specific
training programs. Currently, he is the consultant biomechanist and specialist skills
coach for the New Zealand All Blacks rugby union team. Previously, Dr Sayers has
been consultant biomechanist for other Australian and New Zealand Super 12 rugby
sides and was the biomechanist and specialist skills coach for the Wallabies
in 2001-2002 and biomechanist and kicking coach for the Italian rugby team during
the 2003 Rugby World Cup.
INVESTIGATORS
Dr Mark Sayers (Principal Researcher)
BAppSci CCAE, MAppSci Canberra, PhD RMIT
Senior Lecturer in Sports Biomechanics
Faculty of Science, Health and Education
University of the Sunshine Coast
Ph: 07 5459 4703
Email: [email protected]
Dr Chris Askew (Associate Researcher)
BAppSc(Hons) RMIT, PhD Qld.UT
Lecturer in Exercise Physiology
Faculty of Science, Health and Education
University of the Sunshine Coast
Ph: 07 5430 1128
Email: [email protected]
Mr Keane Wheeler (Associate Researcher)
BAppSc(Hons) Canberra
PhD Candidate - Faculty of Science, Health and Education,
University of the Sunshine Coast
Ph: 0407 236 157
Email: [email protected]
If you have any complaints about the way this research project is being conducted you
can either raise them with the Chief Researcher or, if you prefer an independent person,
contact the Chairperson of the Human Research Ethics Committee at the University of
the Sunshine Coast: (c/- The Academic Administration Officer, Teaching and
Research Services, University of the Sunshine Coast, Maroochydore DC 4558;
telephone (07) 5459 4574; facsimile (07) 5459 4727; e-mail [email protected])
On behalf of the research team, and the University of the Sunshine Coast, thank you for
considering your involvement in this study.
310
APPENDICES
APPENDIX A.2
CONSENT TO PARTICPATE IN
RESEARCH
AGILITY SKILL EXECUTION IN RUGBY UNION
I give my consent to participate in the project outlined below on the following basis:
I understand that my participation in this study is voluntary. I can withdraw from the
study at any time and I do not have to give any reasons for withdrawing and any
information regarding me, obtained during the research will not be used. I will not be
penalised or treated less favourably or lose any benefit if I do withdraw from the study.
I understand that I will be provided with a summary of the results of the research.
I understand that all information regarding me will be kept confidential and that there
will be no means of identifying me personally as a participant through the research
findings.
I understand that the above procedures involve physical effort on my part.
I regularly take part in physical activity and consider myself physically fit and able to
participate in the required tasks of this research. I have not recently sustained
musculoskeletal or soft tissue injury. Nor, do I suffer from an acute illness, bleeding
disorder or respiratory problems.
I understand the contents of the Research Project Information Sheet for the research
study and this Consent to Participate in Research form. I agree to participate in this
research project and give my consent freely. I understand that the study will be carried
out as described on the Research Project Description, a copy of which I have kept.
Any questions I had about this research project and my participation in it have been
answered to my satisfaction
Signature………………………………………………….. Date……………………..
Participant
311
AGILITY
IN RUGBY UNION
APPENDIX B
SUMMARY OF LOGISTIC
REGRESSION
APPENDIX B.1
Prediction of tackle-breaks
APPENDIX B.2
Prediction of poor defensive positions
312
APPENDICES
APPENDIX B.1
PATTERNS OF PLAY: ATTACKING TEAM
A logistic regression analysis was performed with tackle outcome (tackle-break and
breakdown win) as the dependant variable and attacking width, attacking depth,
attacking
velocity
and
directional
running
line
as
predictor
variables.
A total of 1016 cases were analysed and the full model was significantly
reliable
(χ2 = 40.091,
df
= 4
<
p
.001).
This
model
accounted
for
between 3.9 % and 6.0 % of the variance in tackle outcome, with 100 % of breakdown
wins successfully predicted. However, 0 % of predictions for tackle-breaks
were accurate. Overall, 79.2 % of predictions were accurate. It should be noted that the
depth of attack reliably predicted tackle-breaks.
Variable
B
S.E.
Wald
df
p
Exp(B)
.066
.046
1.994
1
.158
1.068
Attacking depth
.446
.104
18.396
1
.000
1.563
Attacking velocity
.206
.113
3.3.19
1
.069
1.228
Attacking direction
-.062
.125
.244
1
.621
.940
Constant
-2.869
.336
73.074
1
.000
.057
Attacking width
313
AGILITY
IN RUGBY UNION
APPENDIX B.1
PATTERNS OF PLAY: DEFENSIVE TEAM
A logistic regression analysis was performed with tackle outcome (tackle-break and
breakdown win) as the dependant variable and defensive pattern, defensive position at
contact
and
the
defensive
numbers
at
contact
as
predictor
variables.
A total of 1016 cases were analysed and the full model was significantly
reliable (χ2 = 714.694, df = 3, p < .001). This model accounted for
between 50.5 % and 78.9 % of the variance in tackle outcome, with 96.8 % of
breakdown wins successfully predicted and with 86.7 % accuracy for predictions for
tackle-breaks. Overall, 94.7 % of predictions were accurate. It was shown that both the
defensive position and the number of defenders at contact reliably predicted tacklebreaks.
Variable
B
S.E.
Wald
df
p
Exp(B)
Defensive pattern
-.096
.205
.220
1
.639
.908
Position at contact
-3.843
.293
172.493
1
.000
.021
Numbers at contact
-2.147
.350
37.732
1
.000
.117
Constant
8.061
.774
108.429
1
.000
3168.379
314
APPENDICES
APPENDIX B.1
EVASIVE PROPERTIES: ATTACKING BALL CARRIER
A logistic regression analysis was performed with tackle outcome (tackle-break and
breakdown win) as the dependant variable and evasive step type, change of direction
angle, proximity of the defence at change of direction, running line and
straighten angle as predictor variables. A total of 1016 cases were analysed and the
full model was significantly reliable (χ2 = 178.043, df = 5, p < .001).
This model accounted for between 16.1 % and 25.1 % of the variance in tackle
outcome,
with
96.3
%
of
breakdown
wins
successfully
predicted
and
with 17.1 % accuracy for predictions for tackle-breaks. Overall, 79.8 % of predictions
were accurate. It was shown that evasive step type, change of direction angle, proximity
to the defence at change of direction, running line and straighten angle reliably
predicted tackle-breaks.
Variable
B
S.E.
Wald
df
p.
Exp(B)
Evasive step type
1.277
.187
46.738
1
.000
3.587
Change of direction angle
-.755
.261
8.377
1
.004
.470
Proximity of defence
-.474
.158
8.986
1
.003
.622
Straighten angle
.821
.179
21.063
1
.000
2.273
Directional running line
.424
.129
10.748
1
.001
1.528
-3.964
.357
123.245
1
.000
.019
Constant
315
AGILITY
IN RUGBY UNION
APPENDIX B.1
CONTACT SKILL: ATTACKING BALL CARRIER
A logistic regression analysis was performed with tackle outcome (tackle-break and
breakdown win) as the dependant variable and the quality of resistive fend and
contact intensity as predictor variables. A total of 1016 cases were analysed and
the full model was significantly reliable (χ2 = 422.615, df = 2, p < .001).
This model accounted for between 34.0 % and 53.2 % of the variance in tackle
outcome,
with
96.4
%
of
breakdown
wins
successfully
predicted
and
with 38.9 % accuracy for predictions for tackle-breaks. Overall, 84.4 % of predictions
were accurate. It was shown that both the quality of the attacking fend and attacker
intensity reliably predicted tackle-breaks.
Variable
B
S.E.
Wald
df
p
Exp(B)
Resistive fend
1.058
.161
43.118
1
.000
2.881
Contact intensity
2.971
.297
100.044
1
.000
19.514
-10.411
.898
134.570
1
.000
.000
Constant
316
APPENDICES
APPENDIX B.2
PATTERNS OF PLAY: ATTACKING TEAM
A logistic regression analysis was performed with defensive position (poor and
moderate-good) as the dependant variable and grouped position, attacking width,
attacking depth, attacking velocity and attacking direction as predictor variables.
A total of 1372 cases were analysed and the full model was significantly
reliable (χ2 = 83.914, df = 4, p < .001). This model accounted for between 5.9 % and
8.6 % of the variance in defensive position, with 100 % of moderate-good defensive
positions successfully predicted and 0 % of predictions for poor defensive
positions
were
accurate.
Overall,
72.4
%
of
predictions
were
accurate.
It should be noted that the depth of attack reliably predicted poor defensive positions.
Variable
B
S.E.
Wald
df
p
Exp(B)
.094
.037
6.544
1
.011
1.099
Attacking depth
.557
.082
46.540
1
.000
1.746
Attacking velocity
.114
.090
1.581
1
.209
1.120
Attacking direction
-.125
.095
1.756
1
.185
.882
Constant
-2.565
.266
92.661
1
.000
.077
Attacking width
317
AGILITY
IN RUGBY UNION
APPENDIX B.2
PATTERNS OF PLAY: DEFENDING TEAM
A logistic regression analysis was performed with defensive position (poor and
moderate-good) as the dependant variable and defensive pattern and the number of
defenders at contact as predictor variables. A total of 1372 cases were analysed and
the full model was significantly reliable (χ2 = 209.926, df = 2, p < .001).
This model accounted for between 14.2 % and 20.5 % of the variance in
defensive position, with 100 % of moderate-good defensive positions successfully
predicted and 0 % of predictions for poor defensive positions were accurate.
Overall, 72.4 % of predictions were accurate. It was shown that the number at contact
predicted poor defensive positions.
Variable
B
S.E.
Wald
df
p
Exp(B)
.024
.092
.070
1
.792
1.025
Numbers at contact
-1.954
.163
144.299
1
.000
.142
Constant
1.563
.272
32.900
1
.000
4.772
Defensive pattern
318
APPENDICES
APPENDIX B.2
EVASIVE PROPERTIES: ATTACKING BALL CARRIER
A logistic regression analysis was performed with defensive position (poor and
moderate-good) as the dependant variable and evasive step type, change of direction
angle, proximity to the defence at change of direction, running line and straighten angle
as predictor variables. A total of 1372 cases were analysed and the full model was
significantly reliable (χ2 = 166.400, df = 5, p < .001). This model accounted for between
11.4 % and 16.5 % of the variance in defensive position, with 92.6 % of moderate-good
defensive positions successfully predicted and with 26.6 % accuracy for predictions for
poor
defensive
position.
Overall,
74.4
%
of
predictions
were
accurate.
It was shown that evasive step type, change of direction angle, proximity of the defence
at change of direction, running line and straighten angle reliably predicted poor
defensive positions.
Variable
B
S.E.
Wald
df
p
Exp(B)
Evasive step type
.787
.142
30.790
1
.000
2.197
Change of direction angle
-.656
.206
10.119
1
.001
.519
Proximity of defence
.058
.115
.253
1
.615
1.060
Straighten angle
.693
.153
20.598
1
.000
1.999
Directional running line
.400
.089
20.386
1
.000
1.492
-3.182
.253
158.395
1
.000
.042
Constant
319
AGILITY
IN RUGBY UNION
APPENDIX B.2
CONTACT SKILLS: ATTACKING BALL CARRIER
A logistic regression analysis was performed with defensive position (poor and
moderate-good) as the dependant variable and the quality of attacking fend and
attacker intensity as predictor variables. A total of 1372 cases were analysed and
the full model was significantly reliable (χ2 = 449.028, df = 2, p < .001).
This model accounted for between 27.9 % and 40.3 % of the variance in defensive
position, with 74.7 % of moderate-good defensive positions successfully predicted
and with 86.5 % accuracy for predictions for poor defensive positions.
Overall, 78.0 % of predictions were accurate. It was shown that both the quality of the
attacking resistive fend and contact intensity reliably predicted poor defensive positions.
Variable
B
S.E.
Wald
df
p
Exp(B)
Resistive fend
.581
.122
22.664
1
.000
1.788
Contact intensity
1.822
.122
223.052
1
.000
6.183
Constant
-6.046
.356
287.664
1
.000
.002
320
APPENDICES
APPENDIX C
INDIVIDUAL SUBJECT
CHARACTERISTICS
Age
Standing
Leg Length
Body Mass
Playing
(years)
Height (m)
(m)
(kg)
Position
1
20
1.84
.96
82
Inside back
2
22
1.87
.94
101
Loose forward
3
18
1.83
.85
105
Outside back
4
19
1.84
.88
104
Tight forward
5
27
1.74
.88
80
Outside back
6
28
1.79
.89
86
Inside back
7
26
1.87
.91
107
Loose forward
8
25
1.83
.87
110
Tight forward
x
23
1.83
.90
98
±SD
4
.04
.04
11
Subject
321
AGILITY
IN RUGBY UNION
APPENDIX D
SUMMARY OF MULTIVARIATE
ANALYSIS
APPENDIX D.1
Performance times for speed groups
APPENDIX D.2
Side-step angles between agility conditions
APPENDIX D.3
Side-step distance between agility conditions
APPENDIX D.4
Side-step distance with respect to TRANS steps
APPENDIX D.5
Agility cycle with respect to agility condition
APPENDIX D.6
Agility condition and TRANS flight
APPENDIX D.7
PLAN - Speed and agility cycle
APPENDIX D.8
PLAN - Speed and PRECD change in velocity
APPENDIX D.9
PLAN - Speed and PRECD-FS
APPENDIX D.10
PLAN - Speed and CD-FS velocity
APPENDIX D.11
PLAN - Speed and CD-TO velocity
APPENDIX D.12
PLAN - Speed and foot position at CD-FS and CD-TO
APPENDIX D.13
PLAN – TRANS steps and change in velocity
APPENDIX D.14
PLAN – Speed and ST-FS velocity
APPENDIX D.15
PLAN – Speed and ST-FS velocity
APPENDIX D.16
PLAN – Speed and POSTCD-FS velocity
APPENDIX D.17
PLAN – Speed and foot position at POSTCD-FS
322
APPENDICES
APPENDIX D.18
UNPLAN - Speed and agility cycle
APPENDIX D.19
UNPLAN – Speed and PRECD-FS velocity
APPENDIX D.20
UNPLAN – Speed and foot position at PRECD-FS
APPENDIX D.21
UNPLAN – Speed and CD-FS velocity
APPENDIX D.22
UNPLAN – Speed and change in velocity during CD phase
APPENDIX D.23
UNPLAN – Speed and foot position at CD-FS relative to
direction change line
APPENDIX D.24
UNPLAN – Speed and change in velocity during TRANS phase
APPENDIX D.25
UNPLAN – Speed and foot position at ST-FS
APPENDIX D.26
UNPLAN – Speed and ST-FS velocity
APPENDIX D.27
UNPLAN – Speed and POSTCD-FS velocity
APPENDIX D.29
CONTACT - Speed and agility cycle
APPENDIX D.30
ONTACT – Speed and POSTCD-FS velocity
APPENDIX D.31
CONTACT – Speed and foot position at PRECD-FS
APPENDIX D.32
CONTACT – Speed and CD-FS velocity
APPENDIX D.33
CONTACT – Speed and CD-TO velocity
APPENDIX D.34
CONTACT – Speed and foot position at CD-TO
APPENDIX D.35
CONTACT – Speed and foot position at ST-FS relative to the
straighten line
APPENDIX D.36
CONTACT – Speed and foot position at ST-FS
APPENDIX D.37
CONTACT – Speed and POSTCD-FS velocity
APPENDIX D.38
CONTACT – Speed and foot position at POSTCD-FS
323
AGILITY
IN RUGBY UNION
APPENDIX D.39
FEND - Speed and agility cycle
APPENDIX D.40
FEND – Speed and the change in velocity during the PRECD
phase
APPENDIX D.41
FEND – Speed and CD-FS velocity
APPENDIX D.42
FEND – Speed and CD-TO velocity
APPENDIX D.43
FEND – Speed and change in velocity during resistive FEND
execution
APPENDIX D.44
FEND – TRANS steps and change in velocity during the
TRANS phase
APPENDIX D.45
FEND – Speed and foot position at ST-FS relative to the
straighten line
APPENDIX D.46
FEND – Speed and ST-FS velocity
APPENDIX D.47
FEND – Speed and foot position at ST-FS
APPENDIX D.48
FEND – Speed and POSTCD-FS velocity
324
APPENDICES
APPENDIX D.1
Performance times for speed groups
One-way between subjects analysis of variance with speed group (Fast, moderate and
slow) as the independent variable and performance time with respect to agility condition
(PLAN, UNPLAN, CONTACT and FEND) as the dependant variable.
df
F
p
PLAN
2,45
146.324
< .001
UNPLAN
2,45
115.690
.004
CONTACT
2,45
162.243
< .001
FEND
2,45
103.595
< .001
SLR
2,21
20.338
< .001
325
AGILITY
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APPENDIX D.2
Side-step angles between agility conditions
One-way between subjects analysis of variance with agility condition (PLAN,
UNPLAN, CONTACT and FEND) as the independent variable and side-step angle as
the dependant variable.
df
F
p
PLAN
2,45
402.196
.091
UNPLAN
2,45
217.477
.169
CONTACT
2,45
103.878
.344
FEND
2,45
121.158
.149
326
APPENDICES
APPENDIX D.3
Side-step distance between agility conditions
One-way between subjects analysis of variance with agility condition (PLAN,
UNPLAN, CONTACT and FEND) as the independent variable and side-step distance
as the dependant variable.
df
F
p
PLAN
2,45
24.122
< .001
UNPLAN
2,45
6.265
.004
CONTACT
2,45
32.508
< .001
FEND
2,45
21.086
< .001
327
AGILITY
IN RUGBY UNION
APPENDIX D.4
Side-step distance with respect to TRANS steps
One-way between subjects analysis of variance with agility condition (PLAN,
UNPLAN, CONTACT and FEND) as the independent variable and side-step distance
with respect to the number of TRANS steps as the dependant variable.
df
F
p
PLAN
2,45
34.981
< .001
UNPLAN
2,45
18.601
.004
CONTACT
2,45
45.067
< .001
FEND
2,45
14.428
< .001
328
APPENDICES
APPENDIX D.5
Agility cycle with respect to agility condition
Multivariate analysis with agility condition (PLAN, UNPLAN, CONTACT and FEND)
as the independent variable and agility cycle (PRECD, CD, TRANS, ST and POSTCD) as
the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
3, 188
4.379
< .001
.715
.106
df
F
p
PRECD
3, 188
4.109
< .001
CD
3, 188
.797
.497
TRANS
3, 188
.520
< .001
ST
3, 188
9.886
< .001
POSTCD
3, 188
4.532
< .001
Agility cycle
329
AGILITY
IN RUGBY UNION
APPENDIX D.6
Agility condition and TRANS flight
One-way between subjects analysis of variance with agility condition (PLAN,
UNPLAN, CONTACT and FEND) as the independent variable and the percent TRANS
flight as the dependant variable.
df
F
p
PLAN
2,45
126.085
< .001
UNPLAN
2,45
64.866
< .001
CONTACT
2,45
157.442
< .001
FEND
2,45
82.635
< .001
330
APPENDICES
APPENDIX D.7
PLAN - Speed and agility cycle
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and agility cycle (PRECD, CD, TRANS, ST and POSTCD) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
10, 82
4.425
< .001
.422
.350
df
F
p
PRECD
2, 45
.141
.869
CD
2, 45
13.270
< .001
TRANS
2, 45
.20.369
< .001
ST
2, 45
9.506
< .001
POSTCD
2, 45
6.442
< .001
Agility cycle
331
AGILITY
IN RUGBY UNION
APPENDIX D.8
PLAN - Speed and PRECD change in velocity
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and PRECD change in linear velocity (∆VELHORZ and ∆VELLAT) as the
dependant variable.
df
F
p
Wilks
Partial Eta Squared
Lambda
PRECD phase
4,88
5.279
.001
df
F
p
∆VELHORZ
2, 45
2.015
.145
∆VELLAT
2, 45
10.330
< .001
332
.650
.194
APPENDICES
APPENDIX D.9
PLAN - Speed and PRECD-FS
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and PRECD-FS (LDHORZ and LDLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
7.388
< .001
.560
.251
df
F
p
LDHORZ
2, 45
.905
.412
LDLAT
2, 45
11.960
< .001
PRECD-FS
333
AGILITY
IN RUGBY UNION
APPENDIX D.10
PLAN - Speed and CD-FS velocity
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and linear velocity at CD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
7.628
< .001
.551
.257
df
F
p
VELHORZ
2, 45
2.111
.133
VELLAT
2, 45
18.237
< .001
CD-FS
334
APPENDICES
APPENDIX D.11
PLAN - Speed and CD-TO velocity
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and linear velocity at CD-TO (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
12.116
< .001
.416
.355
df
F
p
VELHORZ
2, 45
.180
.836
VELLAT
2, 45
22.850
< .001
CD-TO
335
AGILITY
IN RUGBY UNION
APPENDIX D.12
PLAN - Speed and foot position at CD-FS and CD-TO
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and foot position at CD-FS (LDHORZ and LDLAT) and CD-TO (TDHORZ and
TDLAT).as the dependant variables.
df
F
p
Wilks Lambda
Partial Eta Squared
CD-FS
4,88
1.727
.151
.860
.073
CD-TO
4,88
1.967
.106
.843
.082
336
APPENDICES
APPENDIX D.13
PLAN – TRANS steps and change in velocity
Multivariate analysis with the number of TRANS steps (0, 1 and 2) as the independent
variable and change in linear velocity through the TRANS phase (∆VELHORZ and
∆VELLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
6.536
< .001
.601
.225
df
F
p
∆VELHORZ
2, 45
1.854
.168
∆VELLAT
2, 45
14.565
< .001
TRANS
337
AGILITY
IN RUGBY UNION
APPENDIX D.14
PLAN – Speed and ST-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at ST-FS (VELHORZ and VELLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
6.533
< .001
.595
.229
df
F
p
VELHORZ
2, 45
1.756
.184
VELLAT
2, 45
12.051
< .001
ST-FS
338
APPENDICES
APPENDIX D.15
PLAN – Speed and ST-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at ST-TO (TDHORZ and TDLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
3.227
.016
.761
.128
df
F
p
TDHORZ
2, 45
1.673
.199
TDLAT
2, 45
4.723
.014
ST-FS
339
AGILITY
IN RUGBY UNION
APPENDIX D.16
PLAN – Speed and POSTCD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at POSTCD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
3.532
.010
.742
.138
df
F
p
VELHORZ
2, 45
2.208
.122
VELLAT
2, 45
7.334
.002
POSTCD-FS
340
APPENDICES
APPENDIX D.17
PLAN – Speed and foot position at POSTCD-FS
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at POSTCD-FS (LDHORZ and LDLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
2.850
.028
.784
.115
df
F
p
LDHORZ
2, 45
2.349
.107
LDLAT
2, 45
4.639
.015
POSTCD-FS
341
AGILITY
IN RUGBY UNION
APPENDIX D.18
UNPLAN - Speed and agility cycle
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and agility cycle (PRECD, CD, TRANS, ST and POSTCD) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
10, 82
1.702
.094
.686
.172
df
F
p
PRECD
2, 45
1.013
.371
CD
2, 45
4.202
.021
TRANS
2, 45
2.454
.097
ST
2, 45
.636
.534
POSTCD
2, 45
5.024
.011
Agility cycle
342
APPENDICES
APPENDIX D.19
UNPLAN – Speed and PRECD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at PRECD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
9.846
< .001
.488
.301
df
F
p
VELHORZ
2, 45
4.227
.021
VELLAT
2, 45
22.858
< .001
PRECD-FS
343
AGILITY
IN RUGBY UNION
APPENDIX D.20
UNPLAN – Speed and foot position at PRECD-FS
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at PRECD-FS (LDHORZ and LDLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
4.243
.003
.703
.162
df
F
p
LDHORZ
2, 45
3.465
.040
LDLAT
2, 45
1.301
.282
PRECD-FS
344
APPENDICES
APPENDIX D.21
UNPLAN – Speed and CD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at CD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
5.849
< .001
.624
.210
df
F
p
VELHORZ
2, 45
2.462
.097
VELLAT
2, 45
13.017
< .001
CD-FS
345
AGILITY
IN RUGBY UNION
APPENDIX D.22
UNPLAN – Speed and change in velocity during CD phase
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and change in linear during the CD phase (∆VELHORZ and ∆VELLAT) as the
dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
3.121
.019
.767
.124
df
F
p
∆VELHORZ
2, 45
.889
.418
∆VELLAT
2, 45
3.634
.034
CD-FS
346
APPENDICES
APPENDIX D.23
UNPLAN – Speed and foot position at CD-FS relative to direction change line
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at CD-FS relative to the direction change line (CD-FSHORZ
and CD-FSLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
3.283
.015
.757
.130
df
F
p
CD-FSHORZ
2, 45
6.996
.002
CD-FSLAT
2, 45
2.829
.070
CD-FS
347
AGILITY
IN RUGBY UNION
APPENDIX D.24
UNPLAN – Speed and change in velocity during TRANS phase
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and change in linear during the TRANS phase (∆VELHORZ and ∆VELLAT) as
the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
6.048
< .001
.615
.216
df
F
p
∆VELHORZ
2, 45
10.686
< .001
∆VELLAT
2, 45
9.031
.001
TRANS
348
APPENDICES
APPENDIX D.25
UNPLAN – Speed and foot position at ST-FS
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at ST-FS (LDHORZ and LDLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
2.188
.077
.827
.090
df
F
p
LDHORZ
2, 45
4.689
.014
LDLAT
2, 45
.646
.529
ST-FS
349
AGILITY
IN RUGBY UNION
APPENDIX D.26
UNPLAN – Speed and ST-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at ST-FS (VELHORZ and VELLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
2.812
.030
.786
.113
df
F
p
VELHORZ
2, 45
.248
.781
VELLAT
2, 45
5.611
.007
ST-FS
350
APPENDICES
APPENDIX D.27
UNPLAN – Speed and POSTCD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at POSTCD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
4.103
.004
.710
.157
df
F
p
VELHORZ
2, 45
.528
.593
VELLAT
2, 45
8.114
.001
POSTCD-FS
351
AGILITY
IN RUGBY UNION
APPENDIX D.28
CONTACT - Speed and agility cycle
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and agility cycle (PRECD, CD, TRANS, ST and POSTCD) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
10, 82
7.359
< .001
.278
.473
df
F
p
PRECD
2, 45
.839
.439
CD
2, 45
18.172
< .001
TRANS
2, 45
41.469
< .001
ST
2, 45
11.773
< .001
POSTCD
2, 45
9.643
< .001
Agility cycle
352
APPENDICES
APPENDIX D.29
CONTACT – Speed and POSTCD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and the change in linear velocity during the PRECD-FS (∆VELHORZ and
∆VELLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
14.099
< .001
.371
.391
df
F
p
∆VELHORZ
2, 45
16.170
< .001
∆VELLAT
2, 45
13.576
< .001
POSTCD-FS
353
AGILITY
IN RUGBY UNION
APPENDIX D.30
CONTACT – Speed and foot position at PRECD-FS
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at PRECD-FS (LDHORZ and LDLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
5.106
.001
.659
.188
df
F
p
LDHORZ
2, 45
4.503
.016
LDLAT
2, 45
4.503
.016
POSTCD-FS
354
APPENDICES
APPENDIX D.31
CONTACT – Speed and CD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at CD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
14.381
< .001
.366
.395
df
F
p
VELHORZ
2, 45
17.134
< .001
VELLAT
2, 45
36.343
< .001
CD-FS
355
AGILITY
IN RUGBY UNION
APPENDIX D.32
CONTACT – Speed and CD-TO velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at CD-TO (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
11.880
< .001
.422
.351
df
F
p
VELHORZ
2, 45
8.152
.001
VELLAT
2, 45
27.629
< .001
CD-TO
356
APPENDICES
APPENDIX D.33
CONTACT – Speed and foot position at CD-TO
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at CD-TO (TDHORZ and TDLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
3.362
.013
.752
.133
df
F
p
TDHORZ
2, 45
5.658
.006
TDLAT
2, 45
5.654
.006
CD-TO
357
AGILITY
IN RUGBY UNION
APPENDIX D.34
CONTACT – Speed and foot position at ST-FS relative to the straighten line
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at ST-FS relative to the straighten line (ST-FSHORZ and STFSLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
11.417
< .001
.433
.342
df
F
p
ST-FSHORZ
2, 45
19.271
< .001
ST-FSLAT
2, 45
16.998
< .001
ST-FS
358
APPENDICES
APPENDIX D.35
CONTACT – Speed and foot position at ST-FS
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at ST-FS (LDHORZ and LDLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
3.050
.021
.771
.122
df
F
p
LDHORZ
2, 45
5.414
.008
LDLAT
2, 45
1.361
.267
ST-FS
359
AGILITY
IN RUGBY UNION
APPENDIX D.36
CONTACT – Speed and POSTCD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at POSTCD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
5.405
.001
.644
.197
df
F
p
VELHORZ
2, 45
1.144
.328
VELLAT
2, 45
10.493
< .001
POSTCD-FS
360
APPENDICES
APPENDIX D.37
CONTACT – Speed and foot position at POSTCD-FS
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at POSTCD-FS (LDHORZ and LDLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
4.313
.003
.699
.164
df
F
p
LDHORZ
2, 45
1.285
.287
LDLAT
2, 45
5.647
.006
POSTCD-FS
361
AGILITY
IN RUGBY UNION
APPENDIX D.38
FEND - Speed and agility cycle
Multivariate analysis with speed group (Fast, moderate and slow) as the independent
variable and agility cycle (PRECD, CD, TRANS, ST and POSTCD) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
10, 82
2.370
.016
.602
.224
df
F
p
PRECD
2, 45
.031
.969
CD
2, 45
5.11
.010
TRANS
2, 45
8.938
.001
ST
2, 45
.892
.417
POSTCD
2, 45
6.712
.003
Agility cycle
362
APPENDICES
APPENDIX D.39
FEND – Speed and the change in velocity during the PRECD phase
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and the change in linear velocity during the PRECD phase (∆VELHORZ and
∆VELLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
83727
< .001
.513
.284
df
F
p
∆VELHORZ
2, 45
.765
.471
∆VELLAT
2, 45
16.596
< .001
PRECD-FS
363
AGILITY
IN RUGBY UNION
APPENDIX D.40
FEND – Speed and CD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at CD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
4.492
<.002
.690
.170
df
F
p
VELHORZ
2, 45
2.877
.067
VELLAT
2, 45
8.845
< .001
CD-FS
364
APPENDICES
APPENDIX D.41
FEND – Speed and CD-TO velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at CD-TO (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
5.172
< .001
.656
.190
df
F
p
VELHORZ
2, 45
3.224
.049
VELLAT
2, 45
10.092
< .001
CD-TO
365
AGILITY
IN RUGBY UNION
APPENDIX D.42
FEND – Speed and change in velocity during resistive FEND execution
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and change in linear velocity from the point of resistive FEND initiation until
termination (∆VELHORZ and ∆VELLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
3.761
.007
.729
.146
df
F
p
∆VELHORZ
2, 45
.772
.468
∆VELLAT
2, 45
6.008
.005
CD-FS
366
APPENDICES
APPENDIX D.43
FEND – TRANS steps and change in velocity during the TRANS phase
Multivariate analysis with the number of TRANS steps (0, 1 and 2) as the independent
variable and change in linear velocity through the TRANS phase (∆VELHORZ and
∆VELLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
5.809
< .001
.626
.209
df
F
p
∆VELHORZ
2, 45
10.097
< .001
∆VELLAT
2, 45
5.417
.008
CD-FS
367
AGILITY
IN RUGBY UNION
APPENDIX D.44
FEND – Speed and foot position at ST-FS relative to the straighten line
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and foot position at ST-FS relative to the straighten line (ST-FSHORZ and STFSLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
5.682
< .001
.632
.205
df
F
p
ST-FSHORZ
2, 45
6.362
.004
ST-FSLAT
2, 45
12.853
< .001
ST-FS
368
APPENDICES
APPENDIX D.45
FEND – Speed and ST-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at ST-FS (VELHORZ and VELLAT) as the dependant variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
4.135
.004
.709
.158
df
F
p
VELHORZ
2, 45
.963
.390
VELLAT
2, 45
7.789
.001
ST-FS
369
AGILITY
IN RUGBY UNION
APPENDIX D.46
FEND – Speed and foot position at ST-FS
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear foot position at ST-FS (LDHORZ and LDLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
2.967
.024
.776
.119
df
F
p
LDHORZ
2, 45
1.975
.151
LDLAT
2, 45
6.447
.003
ST-FS
370
APPENDICES
APPENDIX D.47
FEND – Speed and POSTCD-FS velocity
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear velocity at POSTCD-FS (VELHORZ and VELLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4,88
4.381
.003
.695
.166
df
F
p
VELHORZ
2, 45
.351
.706
VELLAT
2, 45
8.785
.001
POSTCD-FS
371
AGILITY
IN RUGBY UNION
APPENDIX D.48
FEND – Speed and foot position at POSTCD-FS
Multivariate analysis with the speed group (Fast, moderate and slow) as the independent
variable and linear foot position at POSTCD-FS (LDHORZ and LDLAT) as the dependant
variable.
df
F
p
Wilks Lambda
Partial Eta Squared
4, 88
3.878
.006
.723
.150
df
F
p
LDHORZ
2, 45
1.833
.172
LDLAT
2, 45
4.704
.014
POSTCD-FS
372