Abstract

Three groups of men with different VO2max (60.1, 47.7, and 35.6 ml/kg/min) were administered two submaximal tests at 23 degree C, at 41 and 82 W, before and after 8 days of heat acclimation (3-h work at 41 W at 39,4 degree C dry bulb, 30.3 degree C wet bulb). A control group with VO2max of 45.3 ml/kg/min was tested at 23 degree C and in heat before and after 6 days of exercise at 23 degree C. Trained subjects with the highest VO2max showed the best responses, and the lowest VO2max group showed the worst responses at 23 degreeC and in heat (differences in heart rates and rectal temperatures but not in sweat rates and oxygen consumption responses). Heat acclimation resulted in substantial improvements in responses at 23 degree C and in heat of the acclimation groups, with very minor changes shown by the control group. Changes at 23 degree C were characterized by decreases in heart rate, rectal temperature (o,3-0,5 degree C), oxygen consumption and sweat rate (25-30), and increasesof 13 and 23 in VO2max in the groups with average and low VO2max, respectively. VO2max correlated r= -0.62 and -0.65 with rectal temperatures at 23 degree C and in heat, respectively. It was shown that exercise rectal temperature at 23 degree C was mainly a function of heat acclimatization, as well as well as VO2max and surface area/mass ratio, that heat acclimation presented aneffective method of physical training, and that VO2 max partially related to heat tolerance. Verf.-Referat