Peak torque and rate of torque development influence on repeated maximal exercise performance: Contractile and neural contributions

Morel, B, Rouffet, David, Saboul, D, Rota, S, Clémençon, M and Hautier, CA (2015) Peak torque and rate of torque development influence on repeated maximal exercise performance: Contractile and neural contributions. PLoS ONE, 10 (4). ISSN 1932-6203

Abstract

Rapid force production is critical to improve performance and prevent injuries. However, changes in rate of force/torque development caused by the repetition of maximal contractions have received little attention. The aim of this study was to determine the relative influence of rate of torque development (RTD) and peak torque (Tpeak) on the overall performance (i.e. mean torque, Tmean) decrease during repeated maximal contractions and to investigate the contribution of contractile and neural mechanisms to the alteration of the various mechanical variables. Eleven well-trained men performed 20 sets of 6-s isokinetic maximal knee extensions at 240°·s-1, beginning every 30 seconds. RTD, Tpeak and Tmean as well as the Rate of EMG Rise (RER), peak EMG (EMGpeak) and mean EMG (EMGmean) of the vastus lateralis were monitored for each contraction. A wavelet transform was also performed on raw EMG signal for instant mean frequency (ifmean) calculation. A neuromuscular testing procedure was carried out before and immediately after the fatiguing protocol including evoked RTD (eRTD) and maximal evoked torque (eTpeak) induced by high frequency doublet (100 Hz). Tmean decrease was correlated to RTD and Tpeak decrease (R²=0.62; p<0.001; respectively β=0.62 and β=0.19). RER, eRTD and initial ifmean (0-225 ms) decreased after 20 sets (respectively -21.1±14.1, -25±13%, and ~20%). RTD decrease was correlated to RER decrease (R²=0.36; p<0.05). The eTpeak decreased significantly after 20 sets (24±5%; p<0.05) contrary to EMGpeak (-3.2±19.5 %; p=0.71). Our results show that reductions of RTD explained part of the alterations of the overall performance during repeated moderate velocity maximal exercise. The reductions of RTD were associated to an impairment of the ability of the central nervous system to maximally activate the muscle in the first milliseconds of the contraction.

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Item type Article
URI https://vuir.vu.edu.au/id/eprint/31563
DOI https://doi.org/10.1371/journal.pone.0119719
Official URL http://dx.doi.org/10.1371/journal.pone.0119719
Subjects Current > FOR Classification > 1106 Human Movement and Sports Science
Historical > Faculty/School/Research Centre/Department > Institute of Sport, Exercise and Active Living (ISEAL)
Keywords fatigue; injury risk; muscle contractions; exercise intensity; knee joint; neuromuscular system; athletic performance
Citations in Scopus 14 - View on Scopus
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