An Introduction to Post-activation Potentiation

You’re driving on the motorway at 70mph (no quicker, that’d be illegal of course). Everything is fine- you come off the slip road into a 30mph zone and things start all of a sudden start to feel sloooowwwwww.

Why is that?

In this article you’ll learn about:

  • Why post-activation potentiation  primes the nervous system to react to a stimulus more effectively
  • The science
  • How to programme post-activation potentiation effectively

An Introduction to post-activation potentiation

Essentially you’ve conditioned the nervous system to speed up in order to match the needs of the activity- on that motorway- you’re travelling at high speed so the body realises that it needs to focus its attention and switch everything on- you’ve stimulated the nervous system. When you slow there’s a period in time when you’re body still thinks you’re travelling at 70mph. The nervous system is ‘over primed’ and things appear to have slowed down.

But after a short period of time travelling at 30mph the nervous system realises that its over primed and things start to normalise- but droning that short ‘window of opportunity’ you’ll be feeling like a superhero with special time control powers.

…and that is essentially what potentiation is-tricking the body into speeding up nerve signals and switching on more impulses than wheat are needed for an activity.

From a training perspective, post-activation potentiation is the black magic voodoo of the gym environment.



The science- what is it?

A definition of potentiation would probably relate to something like “enhanced neuronal effect results from increased motor unit recruitment” or something like that. In fact Bret Contreras sums it up eloquently with this definition- a phenomena by which muscular performance characteristics are acutely enhanced as a result of their contractile history.

It is essentially a method of maximising acute power development in athletes.

How it occurs is up for debate but current theories suggest that it could be to do with the phosphorylation of myosin regulatory light chains, which renders actin-myosin more sensitive to calcium released from the sarcoplasmic reticulum during subsequent muscle contractions [1].

It has also been described as an increase in rate coding and consequent motor unit pool innervation, and also changes in pennation angle. It has also been suggested that potentiation could be caused by synaptic excitation within the CNS.

Either way it’s like hitting the nervous system with a bolt of lightning- everything is switched on and the body is primed. There’s a subsequent increase in rate of force development (RFD) of the each successive twitch contractions. This allows a period of time where the athlete is stronger and can potentially develop more power.

According to Robbins et al [2] the peak torque of an isometric twitch in skeletal muscle is transiently increased after a brief maximum voluntary contraction. As you can see from the diagram below,fatiguing muscle contractions impair muscle performance, but non-fatiguing muscle contractions at high loads with a brief duration. Finding that small window of time where fatigue has reduced enough to not hider activation, but motor unit activation remains high is key and may therefore may enhance muscle performance.


So how do you do post-activation potentiation work?

There’s no one way of doing it really, as long as you follow a couple of general rules-

Typically the use of heavy resistance exercise provides an effective pre-load stimulus for inducing post-activation potentiation and increasing peak power output [3].

The main principle of PAP is that heavy loading occurs prior to explosives activities- for that reason many coaches think it the same as ‘contrast training’ (although many purists insist that there are differences). Think about two similar exercises but at opposition ends of the F-V curve.

PAP is used commonly to increase lower body force development, so a common set may comprise-

  • Back squat to sprint
  • Deadlift to hex bar jumps
  • Squat to box jump
  • Bench press to plyo pushup

It’s not just heavy loads that can elicit PAP effects-

High velocity exercises have also been used to create a PAP effect. Plyometrics have also previously been used to create a PAP effect due to their high CNS-stimulating effects. For example West [3] found that a ballistic bench press exercise provided an effective method of inducing PAP and increasing upper-body power.

Is there a set window of time between the two exercises to maximise effects?

Unfortunately it seems to differ from research to research but largely falls within the 8-12 minute time frame. The data has seen positive effects ranging from 5-30 minutes dependant on client profile and modality, but a meta analysis conducted by Wilson et al [4] reported that a rest period of 7-10 minutes elicits the best response. 

On a note regarding volume, multiple sets of strength work seems to elicit better velocity responses in comparison to single sets (in trained individuals) [4].


What-is-postactivation-potentiation


Practical applications to hypertrophy

There seems to be some merit in doing PAP via strength work- this could include cluster training, eccentrics etc. followed by more volume-led resistance training work with an emphasis on hypertrophy. The activation of additional motor units allows the recruitment, and subsequent fatigue of more total muscle fibres- this leads to more structural damage, and ultimately more growth.


Is PAP for everyone?

The short answer is no. It’s really based around athlete population where base foundation (both neural and structural) ability is high. There’s a decent amount of evidence to suggest that beginners and recreational exercisers just can’t tap into the motor pool like a more advanced athlete can [4]. In essence you’re wasting your time.

The advice there obviously is to focus on getting the individual to a more advanced level- by training hard and clever- before you incorporate techniques like PAP.


References

  1. Lorenz, D. Postactivation potentiation: an introduction. Int J Sports Phys Ther. 2011 Sep; 6(3): 234–240.
  2. Robbins, D et al. Post-activation potentiation: underlying physiology and implications for motor performance. Sports Med. 2005; 35(7):585-95
  3. West, DJ et al. Influence of ballistic bench press on upper body power output in professional rugby players.J Strength Cond Res. 2013; 27(8): 2282-7
  4. Wilson, JM et al. Meta analysis of postactivation potentiation and power effects of conditioning activity, volume, gender, rest periods, and training status. J Strength Cond Res. 2013; 27(3): 854-9

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