Journal of Applied Physiology, Vol 57, Issue 6 1731-1737, Copyright © 1984 by American Physiological Society

ARTICLES

Effect of slightly lowered body temperatures on endurance performance in humans

V. Hessemer, D. Langusch, L. K. Bruck, R. H. Bodeker and T. Breidenbach

Eight well-trained male rowers exercised as hard as possible on a bicycle ergometer for 60 min at an ambient temperature of 18 degrees C. On 1 day (precooling test, PRET) exercise was preceded by a double cold exposure that caused starting body temperatures to be approximately 4.5, 1.0, 0.8, and 0.4 degrees C (mean skin, mean body, tympanic, and esophageal temperatures, respectively) lower than in the control test (CONT). In PRET the mean 1-h work rate (172 W) was 6.8% larger than in CONT (161 W), O2 uptake (Vo2) was 9.6% higher (2.86 vs. 2.61 1 X min-1), and O2 pulse was increased by 5.6% (18.8 vs. 17.8 ml), whereas the sweat rate was 20.3% lower in PRET (1.06 vs. 1.33 mg X cm-2.min-1). No differences in heart rate, efficiency, postexercise blood values of lactate, or acid-base status were demonstrated. It appears that the improved performance in PRET was related to an increased O2 supply to the working muscles. Although plasma levels of total beta H-endorphin immunoreactivity were in the same range under both test conditions, different components of beta H-endorphin immunoreactivity were indicated to exist in PRET and CONT.

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