This study investigated the effects of post-activation potentiation (PAP) using maximum isometric contractions on peak power output in college football players. Twelve players performed vertical jump and back squat tests both with and without preceding PAP. PAP involved a six-second maximum voluntary isometric contraction in the back squat position. Mean vertical jump and back squat peak powers were 8-12% higher with PAP but differences were not statistically significant. While PAP may provide small improvements in power, the study was underpowered and larger samples are needed to determine if PAP using maximum isometric contractions can effectively enhance athletic performance.

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SOUTHWESTM I N N E S O T A S T A T E U N I V E R S I T Y
The Effects of Post-Activation Potentiation Using Maximum Isometric Contractions on College Football Players ,
Alex Oliver, Blake Pennock & Jeffrey W. Bell
Southwest Minnesota State University 1501 State Street Marshall, MN 56258
Results/Discussion Conclusion
References
Introduction
Abstract Methods
Acknowledgement
1. Sale, D.G. (2002). Postactivation Potentiation: Role in
Human Performance. Exercise in sport science reviews,
Vol. 30, Issue (3): 138-143.
2. Babajic, F., Bradic, A., Klino, A., Kovanecevic, E. Effects
of Maximum Isometric Contraction on Explosive Power
of Lower Limbs (Jump Performance). Sport SPA, Vol. 7,
Issue (1): 69-75.
 Post-Activation Potentiation allows for the
potentiation of the neuromuscular system which may
improve power and performance of the athlete.
 A common theory for this improvement of power and
performance is the concept of myosin light chain
phosphorylation. Myosin light chain phosphorylation
causes the actin-myosin interaction to be more
sensitive when releasing the calcium ion from the
sarcoplasmic reticulum, thus allowing for faster
muscle twitch and contractions (Sale, 2002).
 PAP research has used dynamic contractions, but
few studies have investigated the effects of static
isometric contractions to potentiate muscular power
(Babajic, 2010).
 The primary goal of our research was to determine
whether maximal voluntary isometric contractions
improve performance and power.
Post-Activation Potentiation (PAP) has been reported to
increase force production through activating
neuromuscular systems. PAP is typically performed by
contracting skeletal muscle near maximum force
development. The objective of this investigation is to
determine if PAP using maximum voluntary isometric
contractions (MVC) influences instantaneous peak-power
output and performance in vertical jump and back squat.
In two separate sessions, twelve collegiate football
players performed either a dynamic warm-up or a dynamic
warm-up followed by a six second MVC before each test.
Vertical jump was similar with and without PAP (72.0±6.9
vs 72.8±7.2 vs cm, p=0.76). Back squat peak-power was
greater, but not significantly different, with PAP compared
to without (1864±315 vs. 1725±281 Watts, p=0.26) as
was instantaneous peak-power during vertical jump
(2528±390 vs. 2241±330 Watts, p=0.11. Additional
subject recruitment and testing is needed to determine
whether isometric PAP influences instantaneous peak
power but does not appear to improve vertical jump
height.
Participants
Ethical approval received from SMSU’s IRB and
participants were provided written informed consent.
12 collegiate football players participated.
Subject characteristics: age (20.8±1.37 years),
weight (93.3±9.68 kg), and height (185.7±3.98 cm).
Study Design
This study was performed in two sessions with each
session being a week apart.
Session 1 included a dynamic warm-up followed by
testing.
Session 2 included a dynamic warm-up and PAP
followed by testing. PAP was performed 30. seconds
before vertical jump tests and back squat tests.
Testing included a vertical jump and back squat.
Procedures
Vertical Jump- While standing on a vertical jump mat
(Just Jump) and connected to a power analyzer
(Tendo), subjects completed three trials of a maximal
jump for height.
Back Squat- The power analyzer (Tendo) was
connected to the barbell and configured to the weight
being lifted. Subjects performed three trials of 1
repetition at 50% of 1 Repetition Maximum as rapidly
as they could lift the weight.
Activation was performed by using the barbell to
push against the power rack in the back squat position.
The power rack was adjusted for about 90 degrees of
knee flexion for the isometric contraction position. The
subjects were then instructed and encouraged as they
pushed up against the power rack for six-seconds
(Figure 1B).
Thank you to those who volunteered as subjects for our
research, Dr. Jeffrey W. Bell for assisting us throughout our
study, and Caleb Heim for providing us with support and
data documentation that was used for the subjects’ one-
repetition maximums.
 Vertical jump height was similar in both
conditions.
 The mean vertical jump peak power was
12.8% better when the testing was
conducted following isometric contraction
activation, but did not reach significance.
 The mean back squat peak power was 8%
higher when the testing was conducted
following isometric contraction activation, but
did not reach significance.
Table 2A: The mean results obtained for the combined subjects for each
testing activity with and without activation.
Figure 1C: Comparison of mean peak power in the
vertical jump test among all subjects with activation
(2527.97 ± 389.6) and without activation (2240.65 ±
330.25).
Figure 1B: A photograph of the activation method used
to potentiate the individual’s neuromuscular system
prior to testing.
Maximum voluntary isometric contractions
may not effectively potentiate the
neuromuscular system and improve peak
power and performance.
Results of this study suggest only small,
non-significant improvements in peak power.
The study may have been underpowered
and additional recruitment and testing is
needed.
The power analyzer did not capture data for
vertical jump of three subjects and
contributed to the lack of study power.
Future studies should perform PAP prior to
each and every trial as previous trials may
moderate performance.
Recovery time increments may need to be
varied to determine the effect on potentiation
to ensure fatigue was not inhibiting
performance.
The joint angle of the maximum voluntary
isometric contractions may also be altered in
further research to determine the most
effective angle to properly potentiate the
neuromuscular system for each performance
task.
Overall, this study allowed us to gain insight
on the possibility of maximum voluntary
isometric contractions ability to potentiate
the neuromuscular system and will allow for
improvements during follow-up studies.
Warm-Up Exercise Distance
Warm-Up Jog 200 yards
Walking Knee up & Grab 15 yards
Walking Single Leg Toe Touch 15 yards
Walking Ankle Grab 15 yards
High Knee Run 20 yards
Butt-Kick Run 20 yards
Carioca (high knee over) 20 yards each way
High Knee Skip 20 yards
Figure 1A: The dynamic warm-up exercises and distances that were performed prior to each
session.
Test Without Activation With Activation
Vertical Jump Height (cm) 72.83 (± 7.16) 71.96 (± 6.82)
Vertical Jump Peak Power
(Watts)
2240.64 (± 330.25) 2527.97 (± 389.6)
Back Squat Peak Power
(Watts)
1725.4 (± 282) 1864 (± 314.6)
Figure 1D: Comparison of mean peak power in
the Back Squat test among all subjects with
activation(1864 ± 314.6) and without
activation(1725.4 ± 282).