No effect of moderate hypohydration or hyperthermia on anaerobic exercise performance.
OBJECTIVE
This study examined the effects of hypohydration and moderate hyperthermia (core temperature elevation) on anaerobic exercise performance in a temperate environment.


METHODS
Eight active males completed two passive heat exposure trials (180 min, 45 degrees C, 50% rh) with (EUH) and without (HYP) fluid replacement. A single 15-s Wingate anaerobic test (WAnT) was used to assess anaerobic performance (peak power, mean power, and fatigue index) before (-180 min) and again at three time points after passive heat exposure to include immediately (0 min), 30 min, and 60 min after in a temperate environment (22 degrees C). Rectal temperature (Tc) was measured throughout the experiment.


RESULTS
HYP reduced body mass (2.7+/-0.7%) (P<0.05) but had no effect on any WAnT performance measure. Passive heat exposure elicited moderate hyperthermia in both trials (EUH: 0.6 degrees C; HYP: 1.0 degrees C) and returned to baseline within 30-60 min following similar decay curves. HYP Tc remained higher (0.4 degrees C) than EUH throughout testing (P<0.05), but moderate hyperthermia itself produced no independent effect on anaerobic exercise performance in either trial.


CONCLUSIONS
This study demonstrates that neither moderate HYP nor the moderate hyperthermia accompanying HYP by passive heat exposure affect anaerobic exercise performance in a temperate environment.
Cheuvront
Samuel N
SN
U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA. Samuel.cheuvront@na.amedd.army.mil
Carter
Robert
R
Haymes
Emily M
EM
Sawka
Michael N
MN
D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology*; D001831:Body Temperature / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002980:Climate; D018592:Cross-Over Studies; D003681:Dehydration / Q000503:physiopathology*; D004781:Environmental Exposure; D005080:Exercise Test; D005221:Fatigue / Q000503:physiopathology; D005500:Follow-Up Studies; D018882:Heat Stress Disorders / Q000503:physiopathology*; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D008297:Male; D015532:Rehydration Solutions / Q000008:administration & dosage; D016037:Single-Blind Method; D013997:Time Factors
D015532:Rehydration Solutions