Heavy‐resistance exercise‐induced increases in jump performance are not explained by changes in neuromuscular function

Post‐activation potentiation ( PAP ) is the increased involuntary muscle twitch response to stimulation following strong contraction. The enhancement to whole‐body explosive muscular performance ( PE ) after heavy‐resistance exercise is often attributed to modulations in neuromuscular function that are proposed to reflect PAP , but the evidence to support this is equivocal. We assessed the neuromuscular basis of PE using transcranial magnetic stimulation ( TMS ) of the primary motor cortex, and electrical stimulation of the femoral nerve. Eleven male athletes performed heavy‐resistance exercise with measures of countermovement jump ( CMJ ) pre‐ and 8 min post‐exercise. Pre‐exercise and after the final CMJ , single‐ and paired‐pulse TMS were delivered during submaximal isometric knee‐extensor contractions to measure corticospinal excitability, short‐interval intracortical inhibition ( SICI ), and intracortical facilitation ( ICF ), with motor evoked potentials recorded from rectus femoris. Twitch responses to motor nerve stimulation during and post maximum‐knee‐extensor contractions were studied to quantify voluntary activation ( VA ) and potentiated twitch ( Q tw,pot ). The experimental protocol successfully induced PE (+4 ± 1% change in CMJ , P  = 0.01), but no changes were observed for maximum voluntary force, VA , corticospinal excitability, SICI or ICF (all P  > 0.05), and Q tw,pot declined ( P  < 0.001). An enhancement of muscular performance after heavy‐resistance exercise was not accompanied by PAP , or changes in measures of neuromuscular function.