The acute effects of stretching on presynaptic inhibition and peak power

Stretching before and after physical activity is a controversial aspect of exercise preparation and recovery. Minimal research has been conducted regarding the neuromuscular effects of stretching including changes in the H-reflex, motor neuron excitability and presynaptic inhibition of muscle. The aim of this study was to examine the effects of static and dynamic stretching on the neuromuscular aspects and power output of the M. Soleus.

Twenty-one healthy college students (13 F, 8 M; 19.81±0.75 y; 171±8.40 cm; 70.71±11.32 kg) participated. On separate days, participants completed either static and dynamic stretching protocols. A double electrical stimulus, assessed via electromyography, was used to elicit the H-reflex and M-wave before and after each stretching protocol. Participants performed pre- and post-stretching countermovement jumps to produce power measurements.

After a single bout of dynamic stretching, presynaptic inhibition significantly decreased (P<0.001), whereas the static stretching produced no change (P=0.296). There was a slightly significant increase in power post-static stretching (369.03±808.3 W, P=0.049).

While dynamic stretching is beneficial in decreasing presynaptic inhibition, it did not lead to the hypothesized increase in power output. This study is the first to compare neurological mechanisms and power output, giving a comprehensive view of how stretching affects muscle.