Postactivation Potentiation

Geschatte leestijd: 9 minutenPostactivation Potentiation, roughly translated, means “the principle of acute improvement of explosively generated forces by muscles following heavy resistance training” (1). In other words, it refers to the “potency obtained after activation.” For instance, better performance in long or high jumps by doing squats, leg presses, or other heavy leg exercises beforehand. The principle of Postactivation Potentiation has been the subject of numerous studies over the last decade, although it has been described since 1996 (1-8). Movement scientists primarily research to determine if and how they can improve athlete performance using this principle.

Postactivation Potentiation tested on muscle fibers

Postactivation Potentiation has been successfully demonstrated by examining its effect on muscle fibers (13-18). These studies revealed that “potentiation” occurred after “activation” due to increased tension on the fibers and the speed at which this tension was produced. A study from 1989 also showed improved phosphorylation after activation, a way of supplying energy to the muscles described in the third part on energy systems.

Postactivation Potentiation: Different from a warm-up

Postactivation Potentiation should not be confused with a warm-up. A (general) warm-up mainly aims to prepare the body for the activities to follow by increasing body temperature, activating the sympathetic nervous system (9). This can be seen as the “action mode” of the body as opposed to the parasympathetic nervous system that puts the body at rest. In the “action mode,” heart rate and oxygen intake are increased. Exercises of moderate intensity are usually performed for this purpose. Additionally, there is the specific warm-up, which focuses more on the specific movements of the sport being trained for. For example, sharpening the hand-eye coordination of ball players. A warm-up is typically not very intense to prevent fatigue before the moment of performance.

In Postactivation Potentiation, heavy strength exercises are performed. High-intensity resistance training is done to bring the muscles into an “excited” or “sensitive” state, thereby enhancing performance:

“Loading of the neuromuscular system elicits an ‘‘excited’’ or ‘‘sensitive’’ state in which performance is enhanced.”
D. Robbins, University of Victoria

Postactivation Potentiation in practice

The above distinction is important because it has been difficult in practice to demonstrate the added value of Postactivation Potentiation by recording improved performance after activation. Several studies have attempted to demonstrate this in practice. Some were more successful than others. This can depend, among other things, on the protocol followed. Considerations include the execution of the resistance exercise (e.g., half or full squats), the required rest after the activation exercise, number of repetitions, resistance level, etc.

One of the studies that demonstrated the added value of Postactivation Potentiation was one of the earlier studies from 1996 (6). The researchers had their subjects perform the leg press (isometrically) 3 to 5 times followed by counter movement jumps (jumping straight up from a standing position). They observed a 3.3% increase in jump height after doing the leg press. They also observed an increase in upper body strength after doing bench presses, but the design of this test was unclear.

In another study, vertical jumps were made before and after performing five half squats. The jumps after the squats were 2.8% higher, even though jumping had already occurred beforehand, making fatigue a heavier factor than normal.

However, there are also several studies that did not observe improved performance after various Postactivation Potentiation protocols.

Potentiation vs. fatigue

This is the first challenge of Postactivation Potentiation. The heavy training that causes “potentiation” also results in fatigue that can detract from performance. Therefore, it is the balance between these two factors that determines whether the efforts beforehand lead to improved or worsened performance (10). This is why there is talk of “net potentiation,” which is the result of the added value of potentiation minus the negative influence of fatigue (1). The question that many researchers are trying to answer is how long one should train, how intensively, and how many repetitions and sets should be done. Factors such as how long to rest after activation, which exercise to do beforehand, and how to perform it also play a role.

In 2000, researchers had their subjects perform an isometric exercise for 10 seconds, maintaining tension in the muscles from the same position (11). This could be, for example, keeping the arms stretched horizontally. Fifteen seconds later, they had them do dynamic contractions, both concentrically (raising arms) and eccentrically (lowering arms). When they later measured maximum strength (the study involved exercises for the quadriceps), they saw no increase but a decrease in strength. They concluded that 15 seconds was too short. The effects of fatigue outweighed those of potentiation.

Other researchers found no difference in the performance of counter movement jumps when performed 1-4 minutes after doing 5 repetitions of squats (12).

Individual differences

I will not delve into all the different studies with various tested protocols but refer to one of the most important findings. There appear to be significant individual differences in the added value of Postactivation Potentiation. Some respond very well to it, while others see no difference or even a decline in performance under the same conditions (6,19). For example, it is suspected that stronger individuals benefit more from Postactivation Potentiation (8,20).

This may explain why studies show such different results. It can strongly depend on the subjects. If half of them respond well and the other half do not, it may seem as if there is no improvement with Postactivation Potentiation, whereas it may be the case for some. Therefore, no general standard seems to be found that yields the best results for everyone. Various personal factors must be taken into account in determining whether and how Postactivation Potentiation can improve performance.

“Assuming interindividual variability does exist, a multitude of categorical variables would also need to be considered. These include training status, training age, chronological age, genetics (e.g., fiber-type composition), anthropometrics, gender, relative strength, and absolute strength. Before any conclusions can be made as to the efficacy of exploiting PAP in a warm-up protocol designed to enhance performance, further scientific research is required.”
D. Robbins, University of Victoria

Conclusion: Only for the pros?

For now, I believe that the average athlete has little use for this knowledge unless they are willing to test the added value themselves. For example, as an individual basketball player, you can see if you can jump higher after doing squats. Two to three percent may not seem like much, but it can be the difference between being able to dunk or not. However, this requires a basic understanding of movement sciences to properly assess which “activation exercises” would fit the activities of the sport in question. Moreover, time must be taken to test different protocols in terms of intensity and duration of the activation exercise (number of sets and reps) and rest until the moment of performance. The coach of an average youth team may not have the means

or knowledge to do so. Testing the effect on performance of every individual player would be too time-consuming. And even if a coach knew the exact suitable protocol for each player, they probably could not implement it in practice. After all, not every location has the necessary facilities for Postactivation Potentiation. To jump higher by squatting first, you need the opportunity to squat. Facilities commonly found in most gyms are often absent on most sports fields. Try finding a squat rack on a soccer field. It will undoubtedly be there at the Amsterdam Arena, but it is unlikely at SV Ilpendam. Improvised squatting with balls or benches along the field may not always be effective either, as the difference between successful or performance-deteriorating Postactivation Potentiation is very subtle.

Summary

Postactivation Potentiation is the principle of acute improvement of explosively generated forces by muscles following heavy resistance training and should not be confused with a warm-up. Postactivation Potentiation has been successfully demonstrated by examining its effect on muscle fibers but has shown contradictory results in practice. This can depend on the protocol followed, aimed at achieving the highest possible “net potentiation,” which is the result of the added value of potentiation minus the negative influence of fatigue.

There also appear to be significant individual differences in the added value of Postactivation Potentiation. Some respond very well to it, while others see no difference or even a decline in performance under the same conditions. Therefore, no general standard seems to be found that yields the best results for everyone. It is necessary to individually determine if a protocol for Postactivation Potentiation works for someone and, if so, which protocol. This, combined with the necessary means to then apply it in practice, suggests that Postactivation Potentiation may only be of value to professionals.

“Assuming interindividual variability does exist, a multitude of categorical variables would also need to be considered. These include training status, training age, chronological age, genetics (e.g., fiber-type composition), anthropometrics, gender, relative strength, and absolute strength. Before any conclusions can be made as to the efficacy of exploiting PAP in a warm-up protocol designed to enhance performance, further scientific research is required”

D. Robbins, University of Victoria

Conclusion: Only for the pros?

For now, I think that the average athlete has little use for this knowledge unless he/she is willing to test the added value themselves. As an individual basketball player, for example, you can see if you can jump higher after doing squats. Two to three percent may not seem like much, but it can be the difference between being able to dunk or not. This, however, requires basic knowledge of movement sciences to properly assess which “activation exercises” would fit the activities of the sport in question. Moreover, time must be taken to test different protocols in terms of intensity and duration of the activation exercise (number of sets and reps) and rest until the moment of performance. The coach of an average Pupillen-D team may not have the means to test all players extensively.

More importantly, even if a coach knew the exact suitable protocol for each player, they probably could not implement it in practice. Not every location has the necessary facilities for Postactivation Potentiation. To jump higher by squatting first, you need the opportunity to squat. Facilities commonly found in most gyms are often absent on most sports fields. Try finding a squat rack on a soccer field. It will undoubtedly be there at the Amsterdam Arena, but it is unlikely at SV Ilpendam. Improvised squatting with balls or benches along the field may not always be effective either, as the difference between successful or performance-deteriorating Postactivation Potentiation is very subtle.

Summary

Postactivation Potentiation (PAP) is the principle of acute improvement of explosively generated forces by muscles following heavy resistance training and should not be confused with a warm-up. Postactivation Potentiation has been successfully demonstrated by examining its effect on muscle fibers, but has shown contradictory results in practice. This can depend on the protocol followed aimed at achieving the highest possible “net potentiation,” which is the result of the added value of potentiation minus the negative influence of fatigue.

There also appear to be significant individual differences in the added value of Postactivation Potentiation. Some respond very well to it, while others see no difference or even a decline in performance under the same conditions. Therefore, no general standard seems to be found that yields the best results for everyone. It is necessary to individually determine if a protocol for Postactivation Potentiation works for someone and, if so, which protocol. This in combination with the necessary means to then apply it in practice suggests that Postactivation Potentiation may only be of value to professionals.

Update 05-03-2014 (k.nwosu): New research on PAP: Cyclists improve time on 20 kilometers after activation by leg presses.

Shortly after posting this article, the outcomes of a study to be published soon (21) appeared.

Researchers had their subjects cycle 20 kilometers twice. The first time as a baseline measurement. The second time, the leg press was done 10 minutes before cycling. They did 4 sets of 5RM (the maximum weight with which they can do 5 repetitions). The researchers then observed that they needed 6.1% less time to cycle the 20 kilometers:

Results were a 6.1% reduction (p < 0.05) in the time to complete the TT20km, a greater cycling economy (p < 0.01) and power output in the first 10% of the TT20km (i.e. trend; p= 0.06) in the potentiation condition. However, no differences were observed in pacing strategy, physiological parameters and RPE between the conditions. These results suggest that 5RM strength exercise bouts improve the performance in a subsequent TT20km.

R.A.S. Silva, Catholic University of Brasilia

References

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