The purpose of this study is t to quantify the changes in early (t < 0.1s) and late phase (t < 0.1s) rate of force development as a result of post- activation potentiation. The phenomenon in which the force exerted by a muscle is increased following a previous contraction is known as post-activation potentiation (PAP) (Robbins, 2005). Two proposed mechanisms of PAP are an improved contractile environment and a neuromuscular response to potentiation. The first of which is a local response. Increased sensitivity of actin-myosin to calcium due to the phosphorylation of myosin regulatory light chains (R-LC) (Vandenboom, 1995). The second proposed mechanism is a systemic response of the nervous system. Recent studies have proposed that increased recruitment of higher order motor units result in the increase in force of subsequent muscle contractions (Tillin, 2009). The rate at which contractile force is produced following the onset of muscle contraction is commonly referred to as rate of force development (RFD) (Andersen, 2009). RFD can be divided into early (t < 0.1s) and late phase (t < 0.1s) (de Oliveria et al., 2013). Early phase RFD is primarily influenced by the central nervous system response to the stimulus whilst the late phase is influenced by contractile force and muscle cross sectional area (Aagaard, 2002). For this study a sample size 20 NCAA Division I athletes comprising of 10 males and 10 females performed two explosive plyometric exercises on a force plate to gather a baseline reading. Then a heavy resistance exercise (80% 1RM) that mimicked the same motor pattern of the corresponding plyometric was performed prior to the second test to elicit PAP. Differences in early and late- phase RFD pre- and post- intervention were then analyzed using Pearson’s correlation coefficient (r). Both groups showed statistically significant improvements in both the inertial vertical jump (VJ) and inertial standing broad jump (BJ) following the conditioning stimulus (p = 0.05). The greatest differences were seen in early- phase RFD of both plyometric exercises. The greatest of which occurred in the VJ following a barbell back squat (r = 0.78)(p = 0.01). No statistically significant differences were observed in late- phase RFD under either condition. These findings would suggest that changes in RFD due to PAP are a result of a systemic response of the central nervous system.

1. The effects of post-activation potentiation
on rate of force development in NCAA
Division I athletes.
Patrick Peterson
University of Denver
Denver, Colorado

2. What is PAP?
Post- Activation Potentiation (PAP)-
an increase in force production following a previous
contraction(Robbins, 2005).
•Commonly used in strength training
– Conditioning stimulus paired with explosive plyometric
•Has been shown to improve performance in
subsequent explosive activities
(Seitz et al., 2017; Martínez-Valencia et al., 2015)

3. Mechanisms of PAP
• Increased Ca2+
sensitivity (Vandenboom, 1995)
– Local response
– Caused by phosphorylation of myosin R-LC
• Recruitment of higher order motor neurons
(Tillin, 2009)
– Systemic Response
– Henneman’s (1957) Size Principle

4. Mitchell, C. J., & Sale, D. G. (2011).
PAP resulted in a 2.9% (P < 0.05) increase in CMJ when compared to control
(48.1 ± 5.6 to 49.5 ± 5.9 cm).
Twitch-torque also improved by 10.7% (P < 0.05) when compared to control
(49.5 ± 7.8 to 54.8 ± 11.9 N m).

5. What is RFD?
Rate of Force Development (RFD)-
The rate at which contractile force is produced
following the onset of muscle contraction
(Andersen, 2009).
RFD is essential to explosive plyometrics and
thus athletic performance (Zaras et al., 2016)

6. Rate of Force Development (RFD)

7. Mechanisms of RFD
Early Phase (t > 0.1s)
- Systemic “Neural Drive”
- Efferent motor outflow (Aagaard, 2002).
Late Phase (t < 0.1s)
- Local
- Cross-sectional area & peak force
(Farup et al., 2010)

8. Purpose Statement
The purpose of this study is to quantify
the changes in early (t < 0.1s) and late
phase (t < 0.1s) RFD as a result of PAP

9. Methods
• Participants
– 20 NCAA Division I athletes
male (n =10) and female (n = 10)
– Minimum training age of 1 year
• Measures
– Inertial vertical jump (VJ) height
– Inertial standing broad jump (BJ) distance
– RFD attained from force plates

10. Design
• Plyometrics will be paired with 5 repetitions of a
heavy conditioning exercise (85% 1-RM) to elicit
PAP (Mitchell & Sale, 2011).
• Subjects will be given 60 seconds rest between
exercises to limit fatigue whilst still preserving
PAP (Tobin & Delahunt, 2014).
• explosive exercises were performed with no
countermovement to eliminate the stretch-reflex
(Gerodimos et al., 2008)

11. Barbell Back Squat & VJ

12. Feet- Elevated Glute Bar Lift & BJ

13. Statistics
• Pearson’s correlation coefficient (r) used to
analyze differences in pre- and post- test
performance.
– VJ pre- and post- jump height
– BJ pre- and post- distance
– Both early and late phase RFD
• The level of statistical significance to be set at
(p <0.05, r > 0.444)

14. Contact Information
Patrick Peterson
B.S. Kinesiology
Sports Performance Intern
University of Denver Sports Performance
ppetersonsc@gmail.com
Cell: (774) 766 – 9144

15. References
Aagaard, P., Simonsen, E., Andersen, J., Magnusson, S., Dyhre-Poulsen, P. (2002). Increased rate of force development and neural
drive of human skeletal muscle following resistance training. Journal of Applied Physiology, 93(4), 1318-1326.
Farup, J., & Sorensen, H. (2010). Postactivation Potentiation: Upper Body Force Development Changes after Maximal Force
Intervention. Journal of Strength and Conditioning Research, 24, 1874–1879.
Gerodimos, V., Zafeiridis, A., Perkos, S., Dipla, K., Manou, V., & Kellis, S. (2008). The contribution of stretch-shortening cycle and
arm-swing to vertical jumping performance in children, adolescents, and adult basketball players. Pediatric Exercise
Science, 20(4), 379–389.
Henneman, E. (1957). Relation between size of neurons and their susceptibility to discharge. Science, 126(3287), 1345–1347.
Martínez-Valencia, M. A., Romero-Arenas, S., Elvira, J. L. L., González-Ravé, J. M., Navarro-Valdivielso, F., & Alcaraz, P. E.
(2015). Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the
Acceleration Phase. Journal of Human Kinetics, 46, 139–148.
Mitchell, C. J., & Sale, D. G. (2011). Enhancement of jump performance after a 5-RM squat is associated with postactivation
potentiation. European Journal of Applied Physiology, 111(8), 1957–1963.
Robbins, D. W. (2005). Postactivation potentiation and its practical applicability: a brief review. Journal of Strength and
Conditioning Research, 19(2), 453–458.

16. References
Seitz, L. B., Mina, M. A., & Haff, G. G. (2017). A sled push stimulus potentiates subsequent 20-m sprint performance. Journal of
Science and Medicine in Sport, 20(8), 781–785.
Tobin, D. P., & Delahunt, E. (2014). The acute effect of a plyometric stimulus on jump performance in professional rugby players.
Journal of Strength and Conditioning Research, 28(2), 367–372.
Vandenboom, R., Grange, R. W., & Houston, M. E. (1995). Myosin phosphorylation enhances rate of force development in fast-
twitch skeletal muscle. The American Journal of Physiology, 268(3), 596-603.
Zaras, N. D., Stasinaki, A.-N. E., Methenitis, S. K., Krase, A. A., Karampatsos, G. P., Georgiadis, G. V., … Terzis, G. D. (2016). Rate
of Force Development, Muscle Architecture, and Performance in Young Competitive Track and Field Throwers. Journal of
Strength and Conditioning Research, 30(1), 81–92.