Post-activation Potentiation is induced by a voluntary conditioning contraction, this contraction is typically performed at a maximal or near maximal intensity. The reason for performing this type of contraction in a workout is because it has consistently been shown to increase both peak force and rate of force development during subsequent twitch contractions.
In sporting activities the performance of explosive is largely determined by mechanical power. Mechanical power can be defined as the rate at which force (F) is developed over a range of motion (d), in a specific period of time (v). In other words Power = D x d/t [P = F x v]. Therefore to increase mechanical power one would have to increase force at a given velocity and/or decrease time over which a specific force is applied, without changing the velocity. There is where PAP could increase force and/or velocity of the muscle contraction, thus, increase the mechanical power associated with a sporting movement or performance.
The science behind PAP comes down to three mechanisms. 1. Phosphorylation of myosin regulatory light chains, max contraction alters structure of myosin head and leads to increased sensitivity of myosin head to calcium ions released by the sarcoplasmic reticulum. 2. Increased recruitment of higher order motor units, max contraction activates adjacent motoneurons via afferent neural volley and H-Reflex enhancement which increases neurotransmission. 3. Change in pennation angle, max contraction decreases pennation angle which increases force transmission to the tendon. If that just seems like a lot of words and not much meaning Yuri Vershansky explained PAP as, “When you perform a 3-5 RM followed by a light explosive set (eg body weight box jumps), to your nervous system it’s like lifting a ½ can of water when you think its full.” That is what PAP is!!
What does all this mean? PAP in nutshell will increase your explosive/power movements of sub maximal loads. Although there is more need for research on this topic we are still able to build a picture of what factors affect PAP. From my understanding there are 4 main areas that factor into PAP they are; Intensity, Rest Periods, Multiple Sets and Trained vs Untrained.
INTENSITY: When talking about intensity in this area we are talking about the load that is our conditioning. It is said that a sub maximal (60-85% 1RM) is more likely to active PAP than a heavy load (>85% 1RM).
REST PERIOD: This is where most of the conflicting data occurs as the PAP can occur at different times for different people, trained and untrained have a greater time frame. As PAP comes into effect after a submaximal effort one most recover before performing an exercise to gain the benefit of PAP.
Figure 1. Hypothetical model showing the relationship between PAP and fatigue following work effort.
As you can see in the graph above we want to concentrate on the solid line. We look to complete an exercise in “window 2” as this is when the line is more in favour of PAP. That is the conflicting data. When does someone hit “window 2”. In my setting I use a very small recovery time period due to time constraints but usually aim for the 3 minute mark. Some journals suggest as much as 7-10 minutes rest for the best results.
MULTIPLE SETS: More is better than minimal.
TRAINED VS UNTRAINED: Explained above but PAP will last longer in a trained individual or athlete. I believe this is because the fatigue factor will be greater in an untrained athlete and your “window 2” will be smaller.
Research has shown that PAP can usually increase a vertical jump by 3-5%. This may not mean a lot but with continued bouts of effort of this magnitude the central nervous system leading to increases in explosive power, the greatest need for any athlete.
Don’t over think when programming, as said before it is pretty much a guessing game. If you want to spend a couple of sessions completing squats and recording the time and vertical jump, this may help you get the “window 2”. We all don’t have time for this though, so ask your athlete how they feel. As soon as you feel recovered do your explosive exercise, like I mentioned before 3 minutes is usually the time I use due to time constraints if not a little shorter.
Squat – 60-85% 1RM x 2–6 reps x 3–6 sets
Box Jump – Body weight x 3-5 reps x 3-6 sets
PAP can also be used for upper exercises as well.
BB Bench Press – 60-85% 1RM x 2–6 reps x 3–6 sets
Clap Push Up – Body weight x 3-5 reps x 3-6 sets
Sport and Exercise Scientist
BSpExSc, ESSAM, ASpS1, AES, ASCA Coach