Comparison between angles of kicking an AFL football from a standing start and a run up
By Steve Clogstoun and Paul Isaac
Introduction
When reviewing and analysing the football kick to improve performance the biomechanical analysis such as the
recording of values utilising angular and linear kinematics is important (Ball, 2008). This will go a long way to
refining aspects of the kick such as power, distance and accuracy. By taking into account the relevant landmarks
of the kicking leg, waist, knee, toe, malleolus, heel and greater trochanter researchers can acquire the relevant
information to make comparisons and changes if required. Analysing a subjects kick can be a long process
because it requires the break down of each stage of the kick, for instance the toe off, support base and ball
contact (Ball, 2008) will help break down the motion of each stage to pick up any issues that improvements can
be made to improve performance, such as the knee flexion and hip flexion in preparation phase of the kick
(Bach et .al, 2006). A comparative study by Hall and Scurr (2009) found that the approach angle could have an
effect on the kicking motion due to greater angle of the hip and knee allowing the foot to be placed further under
the ball. All these facts should be considered when analysing the kicking motion within any sport.
Methods
The experiment was completed in an indoor basketball court. One male subject (n=1) completed a series
of AFL style drop punts under two separate conditions. Kicking on the run and kicking off one step. The
subject was asked to kick with his preferred foot, this being the left. Two reflective markers were placed 7
metres away vertically from camera and 3 metres horizontally apart. The subject was asked to strike his
kick within the first 2 metres allowing 1 metre for follow through. Images were recorded on a Sony hybrid
Handy cam in sports mod with a capture rate of 25 Hz (0.02 sec capture rate). Videos were converted with
virtual dub and video converter software then analysed through the Image J software. Results for the two
variables were taken at the knee and hip joints. The angular velocity, recorded in degrees and radians was
then calculated between these two points.
Results and Discussion
Figure 1.a Preparation Phase
Figure 1.b Maximum Height
Table 1: Results of angles calculated performing kick on the run and off one step
Kicking off one step :
Knee Angle
Kicking on the run :
Knee Angle
Kicking off one step :
Hip Angle
Kicking on the run
:Hip Angle
Preparation Stage
90.10o
89.10o
53.14o
31.05o
Maximum Height
30.09o
41.80o
52.50o
88.96o
Angular
Velocity(Degree o s ) at
Maximum Height
35.43o s
-13.75o s
-133.68o s
22.45o s
Angular Velocity
(radian s -1)
0.62 rad s-1
-0.24 rad s-1
-2.33 rad s-1
0.40 rad s-1
Figure 2.a Preparation Phase of Kicking Motion
Figure 2.b Maximum height of kicking motion
Comparisons were made between the hip and knee and angles during preparation and follow through stages of
the kick (Table 1). Findings showed that there was an increased angle at the hip joint during running motion
(Figure 2.b) which allows for an increased force and distance when kicking. This is a direct result of an
increased step length and velocity and is supported by a comparative study conducted by Ball (2011). We can
see significant differences in angular velocity at the hip joint between the two variables, a difference of 36.46o.
Noticing the similar hip angle at the two stages recorded was another factor on the effect of kicking on the run,
which facilitates greater distance. Knee angles at both stages were similar with a greater knee flexion in
preparation stage as expected with a difference of between 48o and 57.8o.
Conclusion
When comparing the variables of distance and accuracy it is important to know the angles of the hip and knee in
analysing data at different stages of the kick. A study conducted by (Bach et.al, 2006) showed that increased
accuracy could be attributed to greater hip flexion in both limbs and greater knee flexion in the support limb
throughout the kicking movement. Other information that can be gathered from this information involving joint
angles is comparing the angular velocity between the different types of kicks. A Study by Millar (2004)
compared the hip angle and angular velocity in regard to kicking a drop punt on the run and hitting a target at
long distance. The study showed that accuracy was increased if the hip angle at preparation stage was increased,
therefore more chance of not hitting an intended target. Comparing this research to our findings, the hip angle
recorded was lower and we can assume from this information provided that the intended kick would not hit the
target. Another effect of the angle at these joints stated, hip and knee can influence other factors such as speed
of the foot contacting the ball, as a shorter foot-ball contact area can influence the ball speed over a distance (Ali
et al., 2010). Overall, using biomechanical theories to analyse the kicking motion will result in improved
performance and is an integral part of sport science.
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