Post Activation Potentiation Training - PAP


PAP training - what is it, what does it do and who is it for?

Post Activation Potentiation (or PAP for short) is a muscle phenomena by which the force exerted by a muscle is increased due to its previous contraction. For example, if you were to perform a set of heavy back squats, then after perform some vertical jumps, you'll see a greater performance in the vertical jump.

There are a few things that cause PAP.

Phosphorylation of the regulatory light chains - an increase in the phosphorylation of the myosin regulatory light chains (RLC). This increases the sensitivity of the myosin-actin interactions, which may lead to an increase in the cross-bridge cycling rate. Basically increasing the rate of the muscular contraction.

Potentiated H-reflex response - The H-reflex is measured by an electromyographic (EMG) and it shows the level of excitability in a muscle. Put simply, higher H-reflexes are associated with higher excitability - and therefore higher force outputs. There are other neural responses suggested to experience a state of excitation following a conditioning exercise, an increase in motor unit synchronisation, desensitisation of alpha motor neuron input and a decrease in the reciprocal inhibition of the antagonistic muscles. Studies have suggested however that the H-reflex potentiation is the dominant neural mechanism.

Pennation angle of the muscle fibres - although not highly researched, some studies have suggested that the conditioning exercise (such as Back Squats and Deadlifts) lowered the pennation angle of the muscle fibres. This results in a higher level of force being produced.


PAP training can be used with any athlete looking to improve their Force, Power and rate of force development. Studies have shown that acutely, sprint and CMJ performances improved due to PAP training. It is crucial however to pair two exercises that are bio-mechanically similar. For example, you should pair a Back Squat with a counter movement jump (CMJ), or a Deadlift with a Broad Jump.

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