Abstract des Autors

The effects of endurance training on maximum aerobic capacity (VO2max) and thermoregulatory responses to exercise were studied in 22 young men. A three months endurance training consisted of controlled physical activity involving running, jogging, callisthenics and basketball. Before and after every month of training the subjects performed 60 min bicycle ergometer exercises with an intensity of 50% VO2max in a thermoneutral environment. Temperature in the auditory canal (Tac), mean skin temperature, and mean body temperature, the delay and time constant of sweating reaction, as well as changes in body mass, were recorded during the exercise. VO2max increased in the course of training from 3.2 to 3.7 l/min. The increase in VO2max was most pronounced during the first month of training. Tac, in response to the same relative exercise, increased by 0.98ø C before and by 0.57ø C after the last month of training. The onset of sweating was delayed by 4.0 min before and by 0.9 min after the training, the time constant decreasing from 9.5 to 5.7 min, respectively. The improved dynamics of sweating was associated with an increased body water loss (524 vs 607 g, P<0.05). It is concluded that adaptive changes in the thermoregulatory system, related to the endurance training, can be regarded as an effect of exercise-induced heat acclimation. Verf.-Referat