Body Fluid Balance During Exercise-Heat Stress

摘要

During exercise, sweat output often exceeds water intake; producing a body waterdeficit or hypohydration. The water deficit affects both intracellular and extracellular volume. It also results in plasma hypertonicity and hypovolemia. Muscular strength and endurance can be reduced by hypohydration, but the effects are not clear-cut. Aerobic exercise tasks are likely to be adversely affected by hypohydration; with the potential being greater in warm environments. Hypohydration increases heat storage and reduces one's ability to tolerate heat strain. The increased heat storage is mediated by reduced sweating rate and reduced skin blood flow for a given core temperature. Hyperhydration has been suggested to reduce thermal strain during exercise in the heat, however, data supporting that notion are not robust.