Neuromuscular Adjustments of the Quadriceps Muscle after Repeated Cycling Sprints

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Girard, Olivier, Bishop, David and Racinais, Sébastien (2013) Neuromuscular Adjustments of the Quadriceps Muscle after Repeated Cycling Sprints. PLoS ONE, 8 (5). ISSN 1932-6203

Abstract

Purpose This study investigated the supraspinal processes of fatigue of the quadriceps muscle in response to repeated cycling sprints. Methods Twelve active individuals performed 10 × 6-s “all-out” sprints on a cycle ergometer (recovery = 30 s), followed 6 min later by 5 × 6-s sprints (recovery = 30 s). Transcranial magnetic and electrical femoral nerve stimulations during brief (5-s) and sustained (30-s) isometric contractions of the knee extensors were performed before and 3 min post-exercise. Results Maximal strength of the knee extensors decreased during brief and sustained contractions (~11% and 9%, respectively; P<0.001). Peripheral and cortical voluntary activation, motor evoked potential amplitude and silent period duration responses measured during briefs contractions were unaltered (P>0.05). While cortical voluntary activation declined (P<0.01) during the sustained maximal contraction in both test sessions, larger reductions occurred (P<0.05) after exercise. Lastly, resting twitch amplitude in response to both femoral nerve and cortical stimulations was largely (> 40%) reduced (P<0.001) following exercise. Conclusion The capacity of the motor cortex to optimally drive the knee extensors following a repeated-sprint test was shown in sustained, but not brief, maximal isometric contractions. Additionally, peripheral factors were largely involved in the exercise-induced impairment in neuromuscular function, while corticospinal excitability was well-preserved.

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Item type Article
URI https://vuir.vu.edu.au/id/eprint/24234
DOI https://doi.org/10.1371/journal.pone.0061793
Official URL http://www.plosone.org/article/info%3Adoi%2F10.137...
Subjects Current > FOR Classification > 1106 Human Movement and Sports Science
Historical > Faculty/School/Research Centre/Department > Institute of Sport, Exercise and Active Living (ISEAL)
Current > Division/Research > College of Sports and Exercise Science
Keywords electromyography, exercise, fatigue, interpolation, knees, motor cortex, motor neurons, muscle analysis
Citations in Scopus 45 - View on Scopus
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