To examine the effects of water replacement on sweating and body cooling during exercise, We studied the sweat rate, changes in body weight and body temperature during exercise with or with-out drinking various amounts of water. The subjects had been dehydrated or normally hydrated prior to exercise.
1. Rectal temperature increased significantly with body weight loss.
2. Sweat rate during exercise was constant (968-996 g/h) regardless of whether the subjects were dehydrated or hydrated.
3. Body weight loss was negatively correlated with the amount of water intake, but was not correlated with the total amount of sweating.
4. Total heat loss increased with increased water intake, and corresponded to 1345% of heat storage during exercise without drinking.
These results suggest that although water replacement during exercise dose not affect the sweat rate, it has physiological significance in the maintenance of body fluid, and a physical effect in terms of body cooling.