Abstract des Autors

After a few days' exposure to a hot environment, tolerance to a given heat stress increases. The major physiologic changes during heat acclimation include decrease of heart-rate and body temperature at a given exercise intensity, an increase in sweat rate, a reduction of salt concentration in sweat, and an increase sensitivity of the sweating apparatus to increments of core temperature. These changes are accompanied by an improvement of subjective well-being and by a reduced risk of heat-related pathology. In a series of studies, we investigated both gender and age related differences in acclimation to exercise in the heat. The findings of these studies point to the following tentative conclusions: 1. Children, women and men, could reach similar acclimation levels to work in the heat. 2. Rate of acclimation of children and women is slower and thus more gradual than in men. 3. While in men most of the acclimation process is related to a drop in resting core temperature (increased thermal reserve), in children and women it is achieved by an increase in the efficiency and sensitivity of their sweating apparatus. 4. In children, unlike adults, there seems to be a mismatch (uneven changes) between the physiologic and the subjective changes during the acclimation period. 5. Children, unlike adults, can be acclimated to exercise in the heat, by a selective loading on either the thermoregulatory (passive heat exposure), or on the cardiovascular system (training in temperate climate). Verf.-Referat