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Heavy‐resistance exercise‐induced increases in jump performance are not explained by changes in neuromuscular function
Author(s) -
Thomas K.,
Toward A.,
West D. J.,
Howatson G.,
Goodall S.
Publication year - 2017
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/sms.12626
Subject(s) - isometric exercise , transcranial magnetic stimulation , physical medicine and rehabilitation , medicine , stimulation , electromyography , motor cortex , femoral nerve , physical therapy , anesthesia
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.