ACUTE EFFECTS OF STATIC STRETCHING ON SQUAT
JUMP PERFORMANCE AT DIFFERENT KNEE
STARTING ANGLES
ANTONIO LA TORRE,1 CARLO CASTAGNA,2 ELISA GERVASONI,1 EMILIANO CÈ,1 SUSANNA RAMPICHINI,1
MAURIZIO FERRARIN,3 AND GIAMPIERO MERATI1,4
1
Department of Sport Sciences, Nutrition and Health, Faculty of Exercise Science, University of Milan, Italy;
School of Sport and Exercise Sciences, Faculty of Medicine and Surgery, University of Rome Tor Vergata,
Rome, Italy; 3Centre of Bioengineering, Don C. Gnocchi Foundation, Milan, Italy; and 4Centre of Sports
Medicine, Don C. Gnocchi Foundation, Milan, Italy
2
ABSTRACT
INTRODUCTION
La Torre, A, Castagna, C, Gervasoni, E, Cè, E, Rampichini, S,
Ferrarin, M, and Merati, G. Acute effects of static stretching on
squat jump performance at different knee starting angles.
J Strength Cond Res 24(x): 000–000, 2010—The purpose
of this study was to examine the effects of static stretching on
leg extensor muscles during squat jump (SJ) at different knee
starting angles. Seventeen male subjects (23 6 3 years, 179 6
5 cm, and 74 6 6 kg) performed on a force platform 2 series
(preceded or not [control condition] by 10-minute static
stretching of quadriceps and triceps surae muscles) of SJs
at different knee starting angles: 50°, 70°, 90°, and 110°. Squat
jump height, peak force, maximal acceleration, velocity, and
power were calculated for each jump. The angle that maximized
power development was obtained from the power–angle
relationship. The SJ height, peak force, and maximal velocity
increased according to angle amplitude in both control and
stretching conditions (p , 0.01), performance being significantly lower in the stretching condition (p , 0.01). Peak power
was obtained at 90° in both control and stretching conditions,
but was significantly lower (p , 0.01) after stretching. These
results suggest that an acute bout of static stretching reduces
power and force development during SJ, decrements being
significantly higher at lower knee starting angles. Therefore, the
use of static stretching may be questionable in those power
activities requiring maximal power output at knee angles near
full extension.
A
KEY WORDS muscle, power output, torque/length relationship,
concentric jump
Address correspondence to Prof. Antonio La Torre, antonio.latorre@
unimi.it
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lthough passive static stretching is commonly
used during the warm-up procedures of several
sports, the effects of this technique on subsequent
muscular performance are currently under debate
(3,21,22).
Indeed, recent studies showed that pre-exercise static
stretching may negatively affect force and power development (2,13,19,21,23). Additionally, an angle-specific effect of
pre-exercise static stretching was reported. Examining
isometric knee extension strength at different knee angles,
Nelson et al. (17) reported that the negative influence of
a pre-exercise bout of passive stretching was more evident at
working knee angles near full joint extension. From a practical
point of view, this means that in those sports requiring lower
limbs to perform maximally at working angles near full knee
extension (see, e.g., sprinting from starting block, fencing,
rugby, American Football) the negative effects of pre-exercise
stretching on muscle performance might be enhanced.
Several sports require athletes to perform from a semisquatted position to favorably exert explosive power during
competition (e.g., basketball, volleyball, soccer, and sprinting).
Therefore, it is of interest to study the possible detrimental
effects of stretching on power muscular performance during
sports activities requiring more complex movements (as
jumps) at different knee working angles and at various levels
of muscle preactivation (as those required to hold different
starting positions).
The squat jump (SJ) at different knee starting angles may be
a good model for these conditions, because the lower limbs
extensor muscles are preactivated to different levels to hold
the various starting positions and the jump performance is
strongly related to starting knee angle. Furthermore, the SJ
position is similar to those adopted by athletes as starting
posture prior explosive actions (power position) (11).
Currently available data on the effects of static stretching on
SJ were produced at standardized knee angles of 90°–100° and
reported conflicting results (4,5,12,19,23,25). This typically
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Stretching and Squat Jump Performance
Figure 1. Experimental procedure.
corresponds to the starting position maximizing force output
(18,20). However, we hypothesized that at other starting
angles of SJ, characterized by different state of muscle
preactivation and initial elongation, the effects of the
stretching on the subsequent power output may be different.
The purpose of this study was therefore to evaluate the
acute effects of a prior-exercise static-stretching routine on SJ
performance at different knee starting positions. This was
done to assess whether the possible acute detrimental effect of
stretching on explosive muscle performance is joint angle–
specific and dependent on the preactivation state of stretched
muscles.
muscle performance because of neuromuscular or central
inhibition. In addition, we studied the relationship between
SJ performance and 4 different knee starting angles by
a repeated measures analysis of variance (ANOVA; prestretching and poststretching). The starting position that
enabled maximal power development was estimated through
the analytically reconstructed relationship between maximal
power and starting angles. The preactivation state of the
quadriceps was estimated calculating the starting knee
moment by a biomechanical analysis applied to the images
of each starting position during the control session, photographed on the sagittal plane.
Subjects
METHODS
Seventeen male subjects (age 23 6 3 years; height 179 6 5 cm;
and body mass 74 6 6 kg) participated in this study. They
In the present investigation, we addressed the possible effects
were currently active in recreational or competitive sports
of static stretching on lower limbs explosive power with
(mainly track and field and soccer: None of them were
a pre–post assessments of SJ performance. The main outcome
involved in jumping sports, such as high jump, long jump, or
variables were vertical peak force (Fp), velocity (Vmax),
volleyball). All the subjects were actively training 3–4 times
acceleration (Amax), and maximal power (Pmax). Peak force
per week, for 90 6 30 minutes per training session. Testing
was chosen to evaluate the effects of stretching mainly on the
was performed during the 8th and the 11th weeks of the
cross bridges formation, and velocity and acceleration could
regular season in soccer players and during the indoor
reveal some possible additional effects of stretching on
precompetitive period in track and field athletes. Moreover,
they were free of recent lower
limbs injury, and they were
asked to maintain their normal
activity over the whole study
duration. Subjects were not
allowed to consume coffee,
tea, or other stimulants 2 hours
before the beginning of the
experimental procedure. Participants
were
preliminarily
informed about the possible
risks of the experimental procedures. A written informed
consent to participate in the
study was obtained from all
Figure 2. Stretching procedures applied to ankle plantar flexors and quadriceps muscles.
the enrolled subjects before
the beginning of the study,
Experimental Approach to the Problem
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and the experimental protocol was preliminarily approved by
the local Institutional Review Board. The staff of the soccer
and track and field teams also approved athletes’ participation
in this study.
Procedures
The experimental procedure is shown in Figure 1. Supervised
familiarization sessions with this study testing procedures
were undertaken before the study by all participants.
Control and stretching sessions were performed on different days in random order. After a standardized warm-up
(8-minute running on a motorized treadmill), subjects were
submitted to a control or intervention (i.e., static-stretching)
session. During the intervention condition (ca. 10 minutes),
subjects were requested to perform lower limbs staticstretching exercises (4 stretches of 30 seconds, with 30-second
rest for each muscle) after warm-up. Stretching exercises were
performed bilaterally with the end position considered as the
point of discomfort. The muscles stretched were the ankle
plantar flexors and quadriceps, because of their significant
contribution to SJ performance (14). The ankle plantar flexor
muscles were simultaneously stretched with the subject in
supine position by maintaining the dorsiflexion on the foot.
The quadriceps muscles were stretched in a standing position
with the dorsal side of the foot placed on a horizontal bar
approximately positioned at the buttocks level. The experimenter then pushed the knee backward until the point of
discomfort (Figure 2). During the control condition, subjects
observed 10-minute rest, before SJ.
Immediately after either the control or intervention
procedure, subjects performed a series of 2-legged unloaded
SJs on a force platform (4 Jump, Kistler, Zurich, Switzerland)
at each of 4 different knee starting angles (50°, 70°, 90°, and
110°). The full knee extension was assumed to be 0°, and
increasing of knee angle means moving toward full flexion. In
this protocol, we used the SJ to (a) avoid force potentiation
because of the stretch-shortening cycle (as in countermovement jump) and (b) minimize the contribution of muscle
elastic elements to jump performance (3).
Before each jump, the subjects held the selected static squat
position for about 1 second with each angle monitored by an
electrogoniometer (Biopac Systems Inc., Goleta, CA, USA).
For each starting angle were performed 5 SJs interspersed
with passive rest. Between the first 3 SJ bouts, subjects
recovered 40 seconds and thereafter 90 seconds to avoid
cumulative fatigue. The sequence of the different starting
angles was not randomized, to minimize the possible
confounding effect of the postactivation–potentiation
phenomenon (9).
To account for the difference in muscle preactivation
during the 4 SJ conditions (i.e., 50°, 70°, 90°, and 110°), the
quadriceps starting knee moment was calculated. This
assuming that, to maintain the static equilibrium of the
whole system, the internal knee moment (mainly because
of quadriceps activation) must equilibrate the external knee
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moment (because of the weight of the part of the body above
the knees [head–arms–trunk–thighs]).
Each starting position during the control session has been
photographed on the sagittal plane by a digital camera
(Coolpix 8400, Nikon, Tokyo, Japan), and the images were
then analyzed by an image-analysis software (NIH Scion
Image, version 4.0). Each image was calibrated by a known
length (the length of the force platform = 920 mm), which
was measured at the interception of the sagittal plane of the
subject with the horizontal plane of the platform. The
following parameters were then calculated:
Figure 3. Method to estimate starting knee moment. CoMHAT = center of
mass of head + arms + trunk; CoMHATT = center of mass of head + arms +
trunk + thighs; CoMT = center of mass of thigh; dW = arm of the gravity
force at the knee level; WHATT = gravity force of head + arms + trunk +
thighs; Mk = starting knee moment. The estimated position of CoMHAT on
the vertex-hip joint center segment were obtained from Dempster (7),
whereas the relative position of the CoMT and CoMHATT, and the relative
weight of the segment head + arms + trunk + thighs were obtained from
De Leva (6).
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of the force corresponding to subject weight recorded by the
force platform); (b) the maximal vertical height achieved in
the jumps without any recognized countermovement.
Curves of force–time, acceleration–time, velocity–time, and
power–time were calculated from the ground reaction force
records acquired from the force platform, by means of
a custom made software (National Instrument Inc., Austin,
TX, USA). Acceleration–time curves were calculated by
dividing the force–time record by the jumper’s body mass,
whereas the velocity–time curve was obtained by numerically
integrating the acceleration–time curve with respect to time.
The power–time curve was then calculated by multiplying
force and velocity. Peak values of each curve from time = 0 to
the beginning of the jump fly phase (where F = 0) were finally
calculated as peak force (Fp), maximal velocity (Vmax),
maximal acceleration (Amax), and maximal power (Pmax).
The optimal starting angle of SJ (OSASJ) was estimated for
each subject in both control and stretching conditions
as follows: (a) Pmax (average of the best 3 jumps) was plotted
as a function of knee starting angle; (b) a second-order
regression curve was calculated by the least-square method,
obtaining the coefficients a, b, and c of the following equation:
y = ax2 + bx + c (parabola); (c) the OSASJ was then calculated
as the abscissa of the parabola vertex as OSASJ = 2b/2a. An
OSASJ calculation in a representative subject is shown in
Figure 4.
Figure 4. Calculation method for optimal knee starting angle (OSASJ).
See text for explanations.
(a) the center of mass of the head–arms–trunk complex
(CoMHAT), which, according to Dempster (7) was
placed at 39.6% of the distance head vertex–hip
rotation center;
(b) the CoM of the thigh (CoMT), which was placed at
40.95% of the thigh length (6);
(c) the arm of the gravity force at the knee (dW), calculated as
the distance between the rotation center of the knee and
the gravitational force (WHATT) because of weight of the
complex head–arms–trunk–thighs (calculated as 88.6%
of the total body weight, according to De Leva ½6).
The CoM of the complex head–arms–trunk–thighs
(CoMHATT) was then positioned on the line linking the
CoMs of HAT and thighs, at a distance of 12.5% from
CoMHAT, according to the ratio of weights of those segments
(WT/WHATT = 0.125).
Finally, the starting knee moment was calculated as
Mk = ½WHATT 3 dW, assuming a symmetric distribution of
loads between the 2 legs. The method for starting knee
moment calculation is shown in Figure 3.
The best 3 jumps of each series were chosen, on the basis of
the following criteria: (a) the absence of a countermovement
at the beginning of the SJ (defined as a decrease of at least 3%
Statistical Analyses
If not otherwise stated, data are expressed as mean 6 SD.
All parameters were normally distributed (Kolmogorov–
Smirnov test). Sample size was calculated from the pooled
estimate of within-group standard deviations derived by
preliminary data. The detection of a 5% decrease in SJ
performance (SJ height and maximal muscular power, p =
0.05, 2 sided) because of stretching application (with b = 0.20
and a = 0.05) would require a sample of 7 and 10 subjects
for experimental group, respectively. A 2-way ANOVA for
repeated measures (followed by a Fisher Least Significant
Difference post hoc test) was used to test the null hypothesis
of no effects of stretching on performance parameters at each
TABLE 1. Body weight, estimated weight of head–arms–trunk–thighs (WHATT), DW, and estimated starting knee moment
in the 4 starting positions of SJ (control conditions) (n = 17).
Knee starting angle (deg)
Parameter
50
Body weight, N
Weight of head–arms–trunk–thighs (WHATT), N
DW (cm)
Estimated starting knee moment (Nm)
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735
651
9.9
34.5
6 64
6 57
6 4.1
6 11.0
70
90
110
—
—
14.3 6 4.8
49.8 6 10.6
—
—
17.5 6 3.0
57.4 6 12.7
—
—
17.8 6 6.3
62.6 6 14.4
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TABLE 2. SJH, Pf , and Amax calculated in control and stretching conditions at different knee starting angles (n = 17).
Knee starting angle (deg)
Parameter
Condition
50
70
90
110
SJH (cm) [cv, %]
Control
Stretching
10.6 6 4.3 [5.0]
8.4 6 3.6*
18.0 6 5.1 [3.4]
16.7 6 5.2
23.2 6 4.9 [4.0]
22.6 6 4.1
24.2 6 5.6 [2.3]
24.4 6 2.9
Peak force (Fp),
N [cv, %]
Control
2,373 6 350 [2.3] 2,189 6 227 [1.4] 1,962 6 190 [1.7] 1,653 6 179 [3.5]
Stretching 2,151 6 282*
2,167 6 207
1,849 6 150*
1,613 6 140
Maximal acceleration Control
(Amax) (m/s2)[cv, %] Stretching
22.0 6 4.5 [2.9]
18.6 6 3.0*
19.6 6 3.0 [1.7]
19.3 6 1.8
16.6 6 2.0 [2.5]
15.2 6 1.9
12.1 6 2.5 [2.3]
11.9 6 1.3
*SJH = squat jump height.
The coefficient of variation (calculated as [SD/mean]100) for each of the SJ series executed at the 4 different angles in the control
condition is reported in square brackets. *p , 0.05 vs. control condition.
different knee starting angle, with stretching and angles as
main factors. A 1-way ANOVA was used to test the null
hypothesis of no changes of starting knee moment with
respect to knee starting angles. A paired Student t test was
used to verify the hypothesis of no differences between
OSASJ in control and stretching conditions. The test
reliability for the dependent variables has been calculated
by evaluating the coefficient of variation (calculated as
[SD/mean]100) of each parameter in the 5 SJ series executed
at the 4 different angles in the control condition, according to
Hopkins et al. (10). The results have been added to Table 2.
Finally, 1 hour after the end of each control procedure, the
subjects were required to perform a last series of SJs at a 90°
knee starting angle. The Intraclass Correlation Coefficient
between the intraprotocol and the postprotocol 90° SJ series
was finally calculated.
The alpha level for significance was set at p # 0.05.
RESULTS
The estimated weight of head–arms–trunk–thighs (WHATT),
DW, and starting knee moment in the 4 starting positions of SJ
(control session) are shown in Table 1. Starting knee moment
significantly increased (p , 0.01) with knee starting angles.
The squat jump height (SJH) significantly increased with
knee starting angles in both control and stretching conditions
(p , 0.01). Squat jump height values were however
significantly lower in the stretching condition (p = 0.02)
(Table 2). The Fp significantly decreased with increasing knee
starting angles in both control and stretching conditions (p ,
0.01). However, Fp values were significantly lower in the
stretching condition (p , 0.01), especially at 50° and 90°
knee angles, with significant interaction between main factors
Figure 5. Vmax and Pmax in control and stretching conditions at different
knee starting angles (n = 17). Black circles = stretching condition, open
circles = control condition. *p , 0.05 vs. corresponding condition (Fisher
LSD post hoc test).
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Figure 6. Estimated optimal knee starting angle (OSAsj) to achieve
maximal power during a squat jump, calculated in both control and
stretching conditions. p , 0.05 between control and stretching sessions
(n = 17).
(p = 0.005) (Table 2). The Amax decreased with increasing
knee starting angles in both the control and stretching
conditions, being significantly lower after stretching at 50°
only (p , 0.001), with significant interaction between main
factors (p , 0.05) (Table 2).
The Vmax increased with knee starting angles in both the
control and stretching conditions (p , 0.01) and was
significantly lower in the stretching condition (p , 0.001)
especially at lower knee angles (50°, p , 0.01 and 70°, p =
0.02) (Figure 5A).
The Pmax was obtained at 90° knee starting angle in both
control and stretching conditions and was significantly lower
(p , 0.01) after stretching, especially at lower starting angles
(50°, p , 0.01, 70° and 90°, p = 0.06) (Figure 5B), with
significant interaction between main factors (p , 0.05).
The estimated OSASJ was significantly higher in the
stretching condition (p = 0.024, Figure 6). The coefficient of
variation calculated for each SJ series during the control
procedure never exceeded 5.0% (Table 2). The ICC between
interprotocol and postprotocol SJH (SJ series al 90° starting
angle) during the control procedure was 0.89.
DISCUSSION
The main finding of this study was the angle-dependent
detrimental effect of pre-exercise static stretching on all SJ
performance variables, such an effect being higher at lower
knee angles (50° and 70°).
This is similar to what was previously reported by McNeal
et al. and by Young et al., who showed a lower SJ performance
(3–4%) after static stretching (15,25). However, conflicting
results were reported by other authors, who found no effect
of pre-exercise routine on successive SJ performance
(3,12,19,24). Rubini et al. (21) in their review claimed that
differences in SJ performance were due to differences in the
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stretching routines used in those studies. Specifically in those
studies that reported post–static-stretching impairment in SJ
performance hamstring muscles were not exercised (21).
Therefore, it may be hypothesized that the stretching
applied to hamstring muscles caused a reflex activation of the
quadriceps, thus masking the possible detrimental effects of
stretching on subsequent force development. From a practical
point of view, this possible contribution of hamstring muscle
stretching to the global effects of stretching on jump
performance will deserve future experiments, as stretching
of both flexor and extensor muscles is commonly practiced in
many sports activities. However, to minimize this possible
confounding effect, in our protocol, we decided to stretch
only the quadriceps and the triceps surae, but not the
hamstrings.
In the 6 aforementioned studies, SJs were performed at 90°
(most papers) or 100° starting angles. In the present protocol,
we decided to perform SJs at other different knee starting
angles. Indeed, the conflicting results yielded in previous
studies might also depend on the choice of the 90° knee
starting angle selected in these experiments. In fact, it has been
proposed that the negative effects of stretching on muscle
performance is most apparent at knee working angles near full
extension (16). In this study, we found that at starting angles
near full extension of lower limbs, the detrimental effect
of stretching on jumping performance is more evident.
Conversely, at 90° knee angle, the differences between
stretched and nonstretched lower limb performance are less
relevant, being significant only for Fp. From a methodological
point of view, this suggests that the use of lower angles of
SJ (e.g., 50° and 70°) may help to emphasize the effects of
stretching on explosive muscular power output.
Starting knee moment increased with knee starting angles,
suggesting that the preactivation state of the quadriceps rises
with knee angles. Therefore, peak force, maximal velocity,
and power output during jumping performance are reduced
by stretching especially at those knee starting angles at which
the overall muscular activation, estimated by starting knee
moment, is lower. Thus, the inhibitory effects of stretching on
SJ performance not only appear to be knee angle-specific but
may also be related to the initial quadriceps moment. One
possible limitation of this study is that our model assumes that
all of the moment about the knee is due to quadriceps activity.
This is not completely true, because of a possible cocontraction of the hamstrings and other muscles. However,
from a practical viewpoint, we considered this assumption
sufficiently valid in the case of this static analysis, even though
it provides only an approximation of the real knee moment.
A possible hypothesis to explain these data is that the
increased compliance of the musculo-tendonous unit induced
by stretching may have effectively reduced force transmission
to the bones (14). If this was the case, such an effect may be
more apparent when the muscle and tendon complex is less
preactivated (i.e., the global tension of the whole musculotendonous system is lower), as in the case of lower knee
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starting angles. Accordingly, this also results in a change
of the optimal angle of power output development (OSAsj),
which was shifted toward higher angles (about +8°, Figure 6).
Overall, these data suggest that the stretched muscles need
to be more preactivated than nonstretched muscles to give
a similar maximal power output at the same working angle. A
possible practical application of this finding is that after
a stretching session, the knee might start from a more flexed
position to obtain the maximal power output. It is well
acknowledged that during the knee extension exercise, the
anterior cruciate ligament is loaded at low knee angles and
increases as the knee angle decreases. Thus, after stretching,
the more squatted position necessary to obtain the maximal
power output during knee extension could better preserve the
anterior cruciate ligament from elongation injuries.
Our results do not allow us to clarify the mechanisms
underlying the effects of stretching on jumping performance.
However, it may be hypothesized that the increased length of the
musculotendonous complex induced by the stretching technique may have caused the muscle fibers to work in the ascending
(i.e., in a suboptimal curve portion) rather than in plateau (i.e., in
the optimal curve portion) limb of the force–length curve (8). In
addition, this work did not investigate whether the stretchinduced decreases in force and power could be attributed to
impairments in neural output to the muscles. However, altered
torque/fascicle length relationship may also have influenced
the neural activation patterns. Avela et al. (1) suggested that the
increased compliance of the muscle could decrease the resting
discharge of the muscle spindles, leading to disfacilitation of the
a-motoneuron pool. Nevertheless, some studies provided
evidence that such an effect is not likely to be long lasting.
For example, Fowles et al. (8) reported a significant decrease in
the motor unit activation after static stretching that lasted 30
minutes, whereas the mechanical effects of stretching on
muscle power output persisted for 1 hour. As our experiment
lasted at least 45 minutes from the stretching bout application, it
is unlikely that our results may have been affected only by the
possible neuromuscular inhibition.
In conclusion, this study addressed the effects of stretching
on SJ performance in 4 different starting positions (corresponding to different initial quadriceps moments), to see
whether the effects of stretching on complex explosive muscle
performance (vertical jumps) depend on the starting position
and on the preactivation state of the extensor muscles. We
found that, at lower knee angles (50° and 70°), the effects of
stretching seem to be detrimental to performance, whereas at
higher angles (90° and 110), such effects are negligible.
PRACTICAL APPLICATIONS
This study has implications for all those complex sport tasks
requiring the knee joint to maximally perform at some critical
angles lower than 90°. This may be the case for leg movement
in swimming (e.g., front crawl), cycle sprinting, rugby union
(e.g., scrum position), fencing (e.g., lunge), and many positions
of Greco-Roman wrestling. From a practical viewpoint, this
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suggests that for certain power activities, the practice of static
stretching during the warm-up procedures may be detrimental for subsequent muscular performance.
ACKNOWLEDGMENTS
The authors sincerely thank Dr. Andrea Bosio, Dr. Eloisa
Limonta, and Ing. Massimiliano Sacchi for their valuable
technical assistance, and all the study participants.
The authors declare no professional relationships with
companies or manufacturers who will benefit from the results
of the present study and state that the results of the present
study do not constitute endorsement of the product by the
authors or the NSCA.
REFERENCES
1. Avela, J, Kyrolainen, H, and Komi, PV. Altered reflex sensitivity after
repeated and prolonged passive muscle stretching. J Appl Physiol
86: 1283–1291, 1999.
2. Behm, DG, Bambury, A, Cahill, F, and Power, K. Effect of acute
static stretching on force, balance, reaction time, and movement
time. Med Sci Sports Exerc 36: 1397–1402, 2004.
3. Church, JB, Wiggins, MS, Moode, FM, and Crist, R. Effect of warmup and flexibility treatments on vertical jump performance. J Strength
Cond Res 15: 332–336, 2001.
4. Cornwell A, Nelson AG, and Heise, P. Acute effects of passive
muscle stretching on vertical jump performance. J Hum Movement
Stud 40: 307–324, 2001.
5. Cornwell, A, Nelson, AG, and Sidaway, B. Acute effects of stretching
on the neuromechanical properties of the triceps surae muscle
complex. Eur J Appl Physiol 86: 428–434, 2002.
6. de Leva, P. Adjustments to Zatsiorsky–Seluyanov’s segment inertia
parameters. J Biomech 29: 1223–1230, 1996.
7. Dempster, WT. Free-body diagrams as an approach to the
mechanics of human posture and locomotion. In: Biomechanical
Studies of the Musculoskeletal system. E.F.G., eds. Springfield, IL:
Charles C. Thomas, 1961.
8. Fowles, JR, Sale, DG, and MacDougall, JD. Reduced strength after
passive stretch of the human plantarflexors. J Appl Physiol 89: 1179–
1188, 2000.
9. Hodgson, M, Docherty, D, and Robbins, D. Post-activation
potentiation: underlying physiology and implications for motor
performance. Sports Med 35: 585–595, 2005.
10. Hopkins, WG. Measures of reliability in sports medicine and science.
Sports Med. 30: 1–15, 2000.
11. Johnson, J. The Power Snatch: How to Use It and Why. NSCA J
5: 14–18, 1983.
12. Knudson, D, Bennett, K, Corn, R, Leick, D, and Smith, C. Acute
effects of stretching are not evident in the kinematics of the vertical
jump. J Strength Cond Res 15: 98–101, 2001.
13. Kokkonen, J, Nelson, AG, and Cornwell, A. Acute muscle stretching
inhibits maximal strength performance. Res Q Exerc Sport 69: 411–
415, 1998.
14. Luhtanen, P and Komi, RV. Segmental contribution to forces in
vertical jump. Eur J Appl Physiol Occup Physiol 38: 181–188, 1978.
15. McNeal, JR and Sands, WA. Static stretching reduced power
production in gymnasts. Technique (Nov/Dec): 5–6, 2001.
16. Nelson, AG, Allen, JD, Cornwell, A, and Kokkonen, J. Inhibition of
maximal voluntary isometric torque production by acute stretching
is joint-angle specific. Res Q Exerc Sport 72: 68–70, 2001.
17. Nelson, AG, Guillory, IK, Cornwell, C, and Kokkonen, J. Inhibition of
maximal voluntary isokinetic torque production following stretching
is velocity-specific. J Strength Cond Res 15: 241–246, 2001.
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Stretching and Squat Jump Performance
18. Pincivero, DM, Salfetnikov, Y, Campy, RM, and Coelho, AJ. Angleand gender-specific quadriceps femoris muscle recruitment and knee
extensor torque. J Biomech 37: 1689–1697, 2004.
19. Power, K, Behm, D, Cahill, F, Carroll, M, and Young, W. An acute
bout of static stretching: effects on force and jumping performance.
Med Sci Sports Exerc 36: 1389–1396, 2004.
20. Rassier, DE, MacIntosh, BR, and Herzog, W. Length dependence of
active force production in skeletal muscle. J Appl Physiol 86: 1445–
1457, 1999.
21. Rubini, EC, Costa, AL, and Gomes, PS. The effects of stretching on
strength performance. Sports Med 37: 213–224, 2007.
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the
TM
Journal of Strength and Conditioning Research
22. Smith, CA. The warm-up procedure: to stretch or not to stretch. A
brief review. J Orthop Sports Phys Ther 19: 12–17, 1994.
23. Taylor, DC, Brooks, DE, and Ryan, JB. Viscoelastic characteristics of
muscle: passive stretching versus muscular contractions. Med Sci
Sports Exerc 29: 1619–1624, 1997.
24. Unick, J, Kieffer, HS, Cheesman, W, and Feeney, A. The acute effects
of static and ballistic stretching on vertical jump performance in
trained women. J Strength Cond Res 19: 206–212, 2005.
25. Young, WB and Behm, DG. Effects of running, static stretching and
practice jumps on explosive force production and jumping
performance. J Sports Med Phys Fitness 43: 21–27, 2003.