HYDRATION EFFECTS ON TEMPERATURE REGULATION

During exercise in the heat, sweat output often exceeds water intake w hich results in a body water deficit (hypohydration) and electrolyte l osses. Daily water losses can be substantial and persons need to empha size drinking during exercise as well as at mealtime. Aerobic exercise tasks are likely to be adversely affected by heat stress and hypohydr ation; and the warmer the climate the greater the potential for perfor mance decrements. Hypohydration increases heat storage and reduces one 's ability to tolerate heat strain. The increased heat storage is medi ated by reduced sweating rate (evaporative heat loss) and reduced skin blood flow (dry heat loss) for a given core temperature. Hyperhydrati on (increased total body water) has been suggested to reduce physiolog ic strain during exercise heat stress, however, data supporting that n otion are not robust.