[Michael Bruno recently finished his undergraduate degree at West Chester University of Pennsylvania. He is currently in the Coaching Mentorship Program at Athletic Lab]
Post Activation Potentiation (PAP) is a phenomenon by which muscular performance is temporarily enhanced as a result of the subsequent conditioning activity. PAP can be used to improve short-term performance in sprinting, throwing, swimming, and jumping capabilities. This is the underlying mechanism that training methods such as complex, contrast, and French contrast all seem to improve. Complex training involves a heavy compound exercise, followed by plyometric exercise with similar movement pattern (i.e. half squat and vertical jump), aimed at improving rate of force development or the ability to put force into the ground over a short period of time. Whereas contrast training is a heavy set followed by a relatively lighter set over a period of time, aimed at improving maximum strength with use of submaximal drop sets. Although there are many ways to implement PAP into workouts, we are still unclear as to the underlying physiology of PAP.
In the past decade, there has been a significant amount of research done on PAP and rightly so because of its wide range of performance improvements. The research has shown that there are three proposed mechanisms behind PAP. The phosphorylation of regulatory light chains, increased recruitment of higher order motor units, and changes in pennation angle of the muscle fibers. Phosphorylation or the adding of a phosphate molecule is done through catalyzation of an enzyme called myosin light chain kinase. This kinase is activated when calcium molecules are released from sarcoplasmic reticulum during muscle contraction. After being released, they then bind to calmodulin. This phosphorylation is thought to potentiate subsequent contractions by altering the structure of myosin head and moving it away from thick filament backbone. Traditional thought would say that this helps increase the turnover rate and thus, in turn, could shift the force-velocity curve to the right, meaning faster movements with higher loads. Although this is thought to be the main proposed mechanism, more research is still needed as most of the research is done with animals. The human-based research has inconsistent findings.
The second mechanism is increased recruitment of higher order motor units. The maximum contraction is thought to stimulate specific afferent neural fibers, which activate adjacent alpha motor neurons via afferent neural volley. In other words, the max contraction increases the synaptic excitation within the spinal cord, which in turn results in increased post-synaptic potentials and subsequently increases the force generating capacity of the involved muscle groups. Allowing the muscles used in the conditioning activity to produce more force in a shorter amount of time.
The last proposed mechanism is probably not the main driving mechanism behind potentiation, but any changes in muscle architecture should be noted. Pennation angle changes refer to the orientation of muscle fibers in relation to connective tissue or tendons. The smaller the angle of orientation the more mechanical advantageous the lever is. PAP has been reported to change pennation angles up to .9%. Although this is not a large change, the increase in force transmission to tendons could allow for a more forceful contraction. The underlying physiological mechanisms involved in PAP are important, but understanding the factors that affect the potentiation response of an athlete is paramount in designing and implementing this type of training.
With the complex nature of PAP, it should be no surprise that there are many factors that influence the magnitude of potentiation following conditioning activity (CA). These factors include fitness-fatigue relationship, training level of athlete, types of CA used, athlete muscular characteristics, and CA intensity and volume. The window of opportunity is the recovery window in which a delicate balancing act between the decay rate of PAP and dissipation of fatigue occur. The coach should be aware that the rest intervals are crucial in implementing this style of training. According to “Factors Modulating Post Activation Potentiation and Its Effect on Performance of Subsequent Explosive Activities” there are two possible windows where the second exercise would be performed in the potentiated state. The first window would be immediately following the low volume high-intensity contraction. The second potentiated window would be for high volume high-intensity contraction. While this theory makes sense, it is not a representation of what recent studies are showing.
In a landmark study, “The Effects of Three Different Conditioning Activity Volumes on the Optimal Recovery Time for Potentiation in College Athletes,” they wanted to measure optimal potentiation state time in college trained athletes. The study kept intensity the same but manipulated squat volume. They had three volume groups – low volume (LV), moderate volume (MV), and high volume (HV) group, all performing parallel squats with 80%. After they were all tested CMJ at predetermined time intervals (15s, 1, 2, 3, 5, 8, 12-minute intervals). The first part was that their window was very individual leading to a large window. The potentiation window ranged from 1-8 minutes for both MV and HV groups. The LV group was thought to not be enough to elicit potentiation because of the low volume. The second part was that those that did have a potentiation effect were only found in MV and HV protocols. In other similar studies looking for optimal potential window, there had been more consistent potentiation responses between 8-12 minutes in over 80% of participants. Although comparing these two studies is a bit unfair as the training status of participants was different. When comparing recreationally trained athletes and college athletes, it has been found that recreationally athletes have a more consistent potentiation window when compared to college athletes. Collegiate athletes have a more individualized potentiation window. Individual response to PAP is based on the research regarding individual’s muscle fiber type and prerequisite strength levels.
According to the Journal of Physical Education and Sport, because of the trained nature of collegiate athletes, when compared to recreationally trained athletes there was a higher response to potentiated exercise. This would make sense considering college athletes undergo a year-round regimented strength and conditioning program. Most well-designed programs utilize all components of the force-velocity curve at some point during the training year. A benefit of utilizing these components is the increase in both intramuscular and intermuscular coordination. Higher levels of strength allow for more intramuscular coordination. One component of intramuscular coordination is synchronization or the ability to recruit motor units. Higher intramuscular coordination allows for increased synchronization and decreased latency period allowing a greater number of muscle fibers to contract. If the athlete can squat double bodyweight, it is regarded in some research as the litmus test that would dictate whether the athlete will be in a potentiated state on the subsequent exercise. In addition to strength level, we’ve also found that those with a greater type II fiber type will have a higher rate of potentiating than those that do not. It is thought that fast twitch fibers undergo greater phosphorylation of myosin regulatory light chains in response to a conditioning activity than slow twitch fiber. This would make those with a greater ratio of type II to type I to increase likelihood of having a response to complex style training. Although there are many factors behind PAP there are many benefits of implementing this style of training.
The benefits of using workouts with PAP components are that it can increase both workout density and subsequently work capacity. Combined training allows for more activity with less rest between exercises, which increase training economy in a single session. Time is a precious commodity in all training sectors, especially the collegiate sector. Another benefit, when programmed correctly, would be an increase in dynamic correspondence. Dynamic correspondence is the transfer effect an exercise or training program will have on sporting performance. Complex training could enhance required sport motor qualities and movement patterns. In sports where jumping is a key part of success utilizing complex training can be beneficial. PAP can be used prior to short duration athletic competitions to temporarily enhance performance prior to competition. Components of sports such as swinging a bat, short course swimming events, and track and field events, where marginal enhancements could make the difference between winning and losing.
Although there has a been a lot of research done to this point on PAP, its inconsistency in potentiation windows would make it hard to truly get the potentiation correctly for acute increases in athletic performance. There are no definitive guidelines on the acute usages of PAP, but the long-term effects are being researched more. The legendary Yuri Verkhoshansky remains one of the few to demonstrate long-term effectiveness of a resistance training method underpinned by PAP. In 2016, The International Journal of Sports Science & Coaching conducted a nine-week study with 20 recreationally trained males split into two groups. The conventional training group completed jump squats prior to half squats, whereas the complex training group completed half squats before jump squats. At the end of nine weeks, both groups improved significantly, but complex training improved running vertical jump performance when compared to conventional. Sprint performance was not significantly improved in either group. Properly synchronized periodization schemes can create a sum greater than the individual parts. Hence the reason being able to have research on the long-term effects of implementing complex training cycles.
Verkhoshansky, one of the few people who has done research on the long-term effects of complex training, recommends utilizing sequential blocks of 4 to 6 week with strength, complex and plyometric being the emphasis respectively. The order is important as each block builds on the prior. We’ve learned that having a large prerequisite of strength is paramount in reaping the benefits of complex training, so it is ideally put prior to the complex block. And that complex training can have a high dynamic correspondence leading into the plyometric block, which would be more specific to the sport demands.
In conclusion, post-activation potentiation can be a great tool when used correctly. Not all athletes need to use exercises with underlying mechanisms of PAP when other means would be more justified for their needs and training background. I think coaches get caught up in what looks more aesthetically pleasing and not what could be the most beneficial for the athlete. Using the least amount of training to elicit the most amount of adaptation. The weight room is a tool to enhance athletic prowess by increasing biomotor abilities applicable to that sport, not forgetting that athletes are not powerlifters or Olympic lifters and that the more time spent in the weight room is time away from developing sport related skills.
Naclerio, F., Chapman, M., Larumbe-Zabala, E., Massey, B., Neil, A., & Triplett, T. N. (2015). Effects of Three Different Conditioning Activity Volumes on the Optimal Recovery Time for Potentiation in College Athletes. Journal of Strength Conditioning Research.
Talpey, Scott w, et al. “Is Nine Weeks of Complex Training Effective for Improving Lower Body Strength, explosive muscle function, sprint and jumping performance?.” International Journal of Sports Science & Coaching, Sept. 2016.
Tillin, Neale Anthony, and David Bishop. “Factors Modulating Post-Activation Potentiation and Its Effect on Performance of Subsequent Explosive Activities.” Sports Medicine, vol. 39, no. 2, 2009, pp. 147–166., doi:10.2165/00007256-200939020-00004.
Xenofonos, A., et al. “Post- Activation Potentiation: Factors Affecting It and the Effect on Performance.” Journal of Physical Education and Sport, vol. 28, no. 3, 20 Sept. 2010.