Nutritional needs for exercise in the heat

Although hot conditions are not typically conducive to optimal sports perfo rmance, nutritional strategies play an important rule in assisting an athle te to perform as well as possible in a hot environment. A key issue is the prevention of hypohydration during an exercise session. Fluid intake strate gies should be undertaken in a cyclical sequence: hydrate well prior to the workout, drink as much as is comfortable and practical during the session, and rehydrate aggressively afterwards in preparation for future exercise b outs. There is some interest in hyperhydration strategies, such as hyperhyd ration with glycerol, to prepare the athlete fur a situation where there is little opportunity for fluid intake to match large sweat losses. Recovery of significant fluid losses after exercise is assisted by the simultaneous replacement of electrolyte losses. Carbohydrate (CHO) requirements for exer cise are increased in the heat, due to a shift in substrate utilization tow ards CHO oxidation. Daily food patterns should focus on replacing glycogen stores after exercise: and competition strategies should include activities to enhance CHO availability, such as CHO loading for Endurance events; pre -event CHO intake, and intake of sports drinks in events lasting longer tha n 60 min. Although CHO ingestion may not enhance the performance of all eve nts undertaken in hot weather, there are no disadvantages to the consumptio n of beverages containing 4-8% CHO and electrolytes. In fact, the palatabil ity of these drinks may enhance the voluntary intake of fluid. Although the re is some evidence of increased protein catabolism and cellular damage due to production of oxygen radicals during exercise in the heat, there is ins ufficient evidence to make specific dietary recommendations to account for these issues. (C) 2001 Elsevier Science Inc. All rights reserved.