No Effect of Moderate Hypohydration or Hyperthermia on Anaerobic Exercise Performance

CHEUVRONT, SAMUEL N.1; CARTER, ROBERT III1; HAYMES, EMILY M.2; SAWKA, MICHAEL N.1

Medicine & Science in Sports & Exercise: June 2006 - Volume 38 - Issue 6 - pp 1093-1097
doi: 10.1249/01.mss.0000222838.74015.15
BASIC SCIENCES: Original Investigations

Purpose: 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°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°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°C; HYP: 1.0°C) and returned to baseline within 30-60 min following similar decay curves. HYP Tc remained higher (0.4°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.

1U.S. Army Research Institute of Environmental Medicine, Natick, MA; and 2Florida State University, Tallahassee, FL

Address for correspondence: Samuel N. Cheuvront, PhD, U.S. Army Research Institute of Environmental Medicine, Kansas Street, Building 42, Natick, MA 01760; E-mail: Samuel.cheuvront@na.amedd.army.mil.

Submitted for publication November 2005.

Accepted for publication January 2006.

©2006The American College of Sports Medicine