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Neuromuscular failure is unlikely to explain the early exercise cessation in hot ambient conditions
Author(s) -
Racinais Sébastien,
Girard Olivier
Publication year - 2012
Publication title -
psychophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.661
H-Index - 156
eISSN - 1469-8986
pISSN - 0048-5772
DOI - 10.1111/j.1469-8986.2012.01360.x
Subject(s) - transcranial magnetic stimulation , heart rate , perceived exertion , stimulation , cycling , cardiology , psychology , h reflex , medicine , reflex , exertion , physical medicine and rehabilitation , physical therapy , anesthesia , blood pressure , archaeology , history
Baseline, postexercise (20 min cycling) and postexhaustion (incremental test) neuromuscular function was assessed in control (24°C) and hot (40°C) conditions. Heat affects the plantar flexors and knee extensors differently, but most of the effects of heat (e.g., M ‐wave decrement) and fatigue (e.g., voluntary activation and H ‐reflex decrement) were independent of each other. However, peripheral fatigue of the knee extensors was lower at exhaustion in hot than neutral environment (peak twitch decrement from baseline to exhaustion: −19% vs. −33%, p < .05). In addition, heat had no negative effect on transcranial magnetic stimulation responses during cycling, and neuromuscular failure is unlikely to explain the early exercise cessation in the heat (13 min 50 s vs. 17 min 9 s) that occurred when participants reached maximal perceived exertion (19.2 vs. 19.1, ns ) with higher core temperature (38.7° C vs. 38.2° C , p < .05) and heart rate (184 bpm vs. 179 bpm, p < .05).