The limit to exercise tolerance in humans: mind over muscle?
In exercise physiology, it has been traditionally assumed that high-intensity aerobic exercise stops at the point commonly called exhaustion because fatigued subjects are no longer able to generate the power output required by the task despite their maximal voluntary effort. We tested the validity of this assumption by measuring maximal voluntary cycling power before (mean ± SD, 1,075 ± 214 W) and immediately after (731 ± 206 W) (P < 0.001) exhaustive cycling exercise at 242 ± 24 W (80% of peak aerobic power measured during a preliminary incremental exercise test) in ten fit male human subjects. Perceived exertion during exhaustive cycling exercise was strongly correlated (r = −0.82, P = 0.003) with time to exhaustion (10.5 ± 2.1 min). These results challenge the long-standing assumption that muscle fatigue causes exhaustion during high-intensity aerobic exercise, and suggest that exercise tolerance in highly motivated subjects is ultimately limited by perception of effort.
KeywordsMuscle fatigue Exercise tolerance Performance Perceived exertion Muscle power Motivation Effort
The authors are grateful to all participants for their effort during testing, to Mr. Kevin Williams for technical assistance, and to Mr. Gethin Wyn Francis for assistance with subject recruitment and testing. Funding for this study was provided by the School of Sport, Health and Exercise Sciences, Bangor University.
Conflict of interest statement
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