Deconditioning-induced exercise responses as influenced by heat acclimation.
Five young men were tested on a bicycle ergometer before (Test 1) and after (Test 2) 8 d of heat acclimation (exercise at 50% of Vo2max at 39.8 degrees C DB, 30.0 degrees C WB) and after 8 h of water immersion (Test 3). A control group of five subjects underwent a similar procedure in a temperate environment of 23.8 degrees C. Heat acclimation resulted in the usual decreases in exercise heart rate (30 beats/min) and rectal temperature (0.6 degrees C) and an increase in sweat rate (19%). The control group showed effects of moderate training by decreases in exercise heart rate (11 beats/min), rectal temperature (0.3 degrees C), and sweat rate (24%). Water immersion resulted in substantial diuresis in both groups, despite 1800 ml of water consumed by each subject. In the acclimation group, exercise responses in Test 2 were better than in Test 1, with little improvement shown by the control group. The acclimation group maintained exercise responses in Test 3 as in Test 1, with more adverse responses shown by the control group. The results show that heat acclimation provides an effective method to prevent the adverse effects of water-immersion deconditioning on exercise tolerance.
D000064:Acclimatization; D000328:Adult; D001831:Body Temperature; D006339:Heart Rate; D006358:Hot Temperature; D006801:Humans; D007101:Immersion; D008297:Male; D008451:Maximal Voluntary Ventilation; D010100:Oxygen / Q000502:physiology; D005082:Physical Exertion; D010809:Physical Fitness; D013542:Sweat; D014882:Water-Electrolyte Balance
D010100:Oxygen