Abstract
We investigated the body fluid balance with heat acclimatization and exercise in a hot environment. well-trained male subjects (aged; 18-22 yrs) completed training with twice a day for 4 consecutive days in summer at the ambient temperature (Ta) of 23.6°C-30.2°C(WBGT) The subjects were allowed access to a sports beverage after a measurement of weight loss (sweat loss). Mass of fluid intake and sweat loss, heart rate (HR), body temperature (Tb) and urine volume were determined at the time of get up and asleep and exercise periods. Blood sample were also taken at the same time. Sweat rate during exercise significantly increased and HR and Ta of pre- and post exercise decreased. Each parameters demonstrated plateau at 3rd day. Body fluid balance induced negative water balance by exercise while during recovery phase, became positive water balance resulting from excess of fluid consumption over base level of fluid replacement. Sweat rate during exercise significantly increased. HR and Ta responses significantly decreased and were plateau at 3rd day. Total body fluid balance indicated positive balance for 4 days. These results indicated that heat acclimation had occurred at about 3rd day and the increased sweat rate, the lower rate of rise in HR and Ta responses. [Jpn J Physiol 55 Suppl:S229 (2005)]
