Postactivation Potentiation (PAP)

For years there has been a gap between performance enhancement and injury management. Strength coaches fail to address rehabilitation  and injury prevention during performance training whereas health care practitioners (ATs, PTs, OTs) fail to address performance training during injury management. There are some who continually seek to merge the two disciplines, by utilizing the unique training principles from each side. I am not saying ALL fail to bridge the gap, but it certainly is the majority.  Health care practitioners could be a bit more boundaryless and integrate performance enhancement concepts and protocols into injury management programming. One method we can use is Postactivation Potentiation or (PAP).

Brief Overview of Postactivation Potentiation:

Postactivation Potentiation was described by Robbins in 2005. According to Robbins, PAP is the enhanced and immediate muscle force output of explosive movements after a heavy resistance exercise is performed (1). Over the past few years, it has gained popularity in the performance enhancement world because the approach significantly optimizes force and power production when compared to traditional training.   PAP operates on the principle that heavy muscle loading creates increased stimulation of the central nervous system, resulting in greater motor unit recruitment and subsequently force production (2, 3).

Physiologically there are two reasons for which PAP occurs. The first states that maximal muscle contraction yields an increased phosphorylation of myosin. The increased phosphorylation causes actin and myosin binding to be more responsive to  calcium ions released from the sarcoplasmic reticulum (4).  This enhances force muscle production at the structural level of muscle (5).  As a result, faster contraction rates develop (2). The second reason involves the Hoffmann Reflex (4). The Hoffman reflex is an excitation of  muscle spindle nerve fibers. Physiologically,  PAP increases the speed of H-reflex, thus increasing the firing rate to muscle, resulting in increased force production (6).

Exercise programming to elicit PAP is fairly simple. The exercises should be performed in a super-set fashion. The first set should be a maximal strength lift (85% -100% intensity, 1-6 repetitions) of a particular body part (bench press, chest; squat, legs). Super-set this maximal strength exercise with a power movement exercise (8 reps, as fast as possible, at 10% body weight) of the same body part (med ball chest pass, chest; box jumps, legs). By incorporating exercises that will elicit Postactivation Potentiation, health practitioners can improve patient outcomes for late phase rehab and return to play, or even prevent injury by optimizing function during power training.

The data supporting PAP certainly exists. Benefits from PAP training has been demonstrated in sprinters, throwers, and the vertical jump. Santos and Janiera found that PAP inducing training protocols significantly improved squat jump, countermovement jump, medicine ball throw, and agility in male basketball players (7). Mitchell and Sale observed significant jump performance enhancements (2.9% increase) using PAP protocols (7).

Postactivation Potentiation and Injury Prevention:

There are many causes for injury, but one common mechanism for injury is the inability of the neuromuscular system to sustain excessive eccentric loading, especially when combined with oblique movement patterns. For example, an Achilles tendon rupture in the racquetball player attempting to react to sprint forward, or a soccer player who is decelerating to make a cut. If the neuromuscular system is unable to sustain the force – injury will follow.

Health care practitioners often focus on altered functional movement patterns, to prevent injury. For example, a practitioner may focus on gluteus medius strengthening to correct unwanted knee valgus movement. This is obviously fantastic, but practitioners need to evaluate movement at full-speed, not in a clinic, under controlled settings. As acute variables (speed, power, force, direction, etc) are increased and movement patterns more advanced, the likely hood of biomechanical breakdown also increases.

High levels of stability through the full muscle contraction spectrum allows for more efficient responses (i.e power and force production) when movement is necessary (8). Improved proprioception can prevent the underutilization or overcompensation of joints and their supporting structures (9). Biomechanical efficiency will not only serve to prevent injury but also serves as an essential precursor to maximizing strength gains, power output, and speed production (10).

So to prevent injury we need stability and power with stability. While implementing corrective exercise strategies  and incorporating the PAP training concept will ensure power and stability optimization. This can create a phenomenal injury prevention program.

Postactivation Potentiation and Late Phase Rehabilitation:

One prime area health care practitioners can emphasize in order to shrink the gap between performance enhancement and injury is late phase rehabilitation. It is commonplace for a practitioner to turn previously injured athletes over to the strength and conditioning staff when functionally capable. But the transition between controlled clinical rehabilitation and performance enhancement can still be improved.

The integration of PAP during late phase rehabilitation can significantly improve power and optimally prepare the athlete for athletic competition or high-level performance training. An article done by Lorenz and published in International Journal of Sports Physical Therapy examined this quite well. Lorenz states physical therapist training the recovering athlete, the PAP concept may be most appropriately applied during functional training (7). This goes without saying, we do not want to perform such high-intensity training if the client is unable to tolerate these forces. That said, if utilized during functional rehabilitation phases the benefit could be outstanding.

To utilize this concept clinically, one possibility may be in helping to facilitate acute power increases in a unilateral lower extremity injury (7). This would prevent dominance by the uninjured limb. Postactivation Potentiation has shown promise in healthy, trained athletes to help improve acute increases in strength and power (7). This is certainly the goal of heath care practitioners during late phase rehabilitation.

Summary:

The primary objective of PAP integration is to optimize  power for athletic performance. Research has shown that PAP does in fact exist and can enhance performance. Although effects of PAP on performance does exist it is unknown if these benefits are short-term or if they do induce long-term changes (7). Following the theory of specificity, one would deduce that training with this intensity will elicit adaptation.

The relationship between the performance enhancement team and the care provider needs to be symbiotic. Strength coaches can become better at injury management protocols just as health care practitioners can become better at integrating performance training techniques into injury prevention or rehabilitation programs. Our goal is to help the clients achieve and do more. In order to do this, we need to be boundaryless in the techniques we implement. It’s time to stop being ignorant and learn from each other.   

 

References:

  1. Robbins DW. Postactivation potentiation and its practical applicability: a brief review. J Strength Cond Res. 2005; 19: 453–458.
  2. Chiu, L.Z., Fry, A.C., Weiss, L.W., Schilling, B.K., Brown, L.E., & Smith, S.L. (2003). Postactivation potentiation response in athletic and recreationally trained individuals. Journal of Strength and Conditioning Research. 17(4), 671-677.
  3. Rixon, K.P., Lamont, H.S., & Bemden, M.G. (2007). Influence of type of muscle contraction, gender, and lifting experience on postactivation potentiation performance. Journal of Strength and Conditioning Research, 21(2), 500-505.
  4. Kravitz
  5. Hamada, T., Sale, D.G., MacDougall, J.D., & Tarnopolsky, M.A. (2000a). Postactivation potentiation, muscle fiber type, and twitch contraction time in human knee extensor muscles. Journal of Applied Physiology, 88, 2131-2137.
  6. Hodgson, M., Docherty, D., & Robbins, D. (2005). Post-activation potentiation underlying physiology and implications for motor performance. Sports Medicine, 25 (7), 385-395.
  7. Lorenz, D. Postactivation Potentiation: An Introduction.  Int J Sports Phys Ther. 2011 September; 6(3): 234–240.
  8. Kovacs MS, Roetert EP, and Ellenbecker TS. Efficient deceleration: The forgotten factor in tennis-specific training. Strength Cond J 30: 58–68, 2008.
  9. Gillett, J., O’Brien, L., Ryan, M. & Rogowski, J. Strategic exercise prescription for baseball: Bridging the gap between injury prevention and power production. Strength and Cond J. 2009. 31(5):81-88.
  10. Maher CG, Latimer J, Hodges PW, Regshauge KM, Moseley GL, Herbert RD, Costa L, and McAuley J. The effect of motor control exercise versus placebo in patients with chronic low back pain. BMC  Musculoskelet Disord. 2005. 6: 54

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