M-wave normalization of EMG signal to investigate heat stress and fatigue. Issue 5 (May 2018)

• Record Type: Journal Article
• Authors: Girard, Olivier; Bishop, David J.; Racinais, Sébastien
• Is Part Of: Journal of science and medicine in sport. Volume 21:Issue 5(2018)
• Page Start: 518
• Page End: 524
• Publication Date: 2018-05
• Subjects: Environmental temperature -- Neuromuscular efficiency -- Repeated-sprint ability -- Root Mean Square -- Surface electromyography -- Thermoregulation; Sports sciences -- Periodicals; Sports medicine -- Periodicals; Exercise -- Physiological aspects -- Periodicals; Sports -- physiology -- Periodicals; Sports Medicine -- Periodicals; Sportgeneeskunde; 617.102705
• DOI: 10.1016/j.jsams.2017.07.020
• Languages: English
• ISSNs: 1440-2440

Abstract

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.