M-wave normalization of EMG signal to investigate heat stress and fatigue

Girard, O., Bishop, D.J. and Racinais, S. (2018) M-wave normalization of EMG signal to investigate heat stress and fatigue. Journal of Science and Medicine in Sport, 21 (5). pp. 518-524.

Abstract

Objectives
We examined the extent to which peripheral changes affect EMG signal adjustments during repeated sprinting in temperate and hot conditions.

Design
Randomised, crossover study.

Methods
Ten males performed 10 × 6-s ‘all-out’ cycling sprints (recovery = 30 s) in either a temperate (24 °C/30%rH) or a hot (35 °C/40%rH) environment with concomitant surface EMG recordings of the vastus lateralis (VL) and rectus femoris (RF). In addition, peak-to-peak M-wave amplitudes were obtained for each muscle after each sprint (i.e., 15 s into recovery).

Results
For both the VL and RF muscles RMS decreased across sprint repetitions (P < 0.01), while significantly lower values for the VL (P = 0.012), but not the RF (P = 0.096), occurred in hot vs. temperate conditions. M-wave-normalised RMS for VL muscle decreased across sprint repetitions (P = 0.030), with no condition or interaction effects (both P > 0.621). M-wave-normalised RMS for the RF muscle was lower in the heat (P < 0.034), with no significant sprint or interaction effects (both P > 0.240).

Conclusions
Controlling for changes in maximal M-wave amplitude of the quadriceps muscles after each bout of a repeated cycling exercise in hot and temperate conditions allows researchers to account for fatigue- and/or heat-induced neural and peripheral adjustments.

Item Type:	Journal Article
Publisher:	Elsevier BV
Copyright:	© 2017 Sports Medicine Australia
URI:	http://researchrepository.murdoch.edu.au/id/eprint/45524

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