Cheuvront, S. N., Carter III, R., Brownlee, K. K., Bronson, L. L., & Sawka, M. N. (2005). Hypohydration does not reduce aerobic exercise performance in a cold environment. Medicine and Science in Sports and Exercise, 37(5), Supplement abstract 1130.

"Hypohydration (>2% body mass) impairs aerobic exercise performance in hot and temperate environments" (p. S212). On two occasions, Ss (M = 4; F = 1) were exposed to ~three hours of passive heat stress (45C) in the morning with euhydration or with developing hypohydration. Later in the day, Ss sat in a cold environment (2C) with minimal clothing for one hour before performing a 30-minute cycle ergometer ride at 50% VO2peak, followed by a 30-minute performance time-trial.

Body mass was significantly reduced in the hypohydration condition. No differences were observed in temperatures during the cycling exercise. Heart rate was significantly higher in the hypohydration condition. Ratings of perceived exertion and performance did not differ between conditions.

Implication. Hypohydration does not reduce performance or increase thermoregulatory strain in the cold.

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