2005, Volume 11 No. 2

REVIEW ARTICLE

Nutritional Requirements of Athletes Exercising in a Hot Environment

Rabindarjeet Singh
Sports Science Unit, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia

ABSTRACT
Competition in a hot environment is not conducive for optimal sports performance as both dehydration and hyperthermia adversely affect mental and physical performance. In addition, the ability to train in heat is also impaired if the nutritional needs are inadequate. During prolonged bouts of exercise in a hot environment, an excess of 1 liter of body fluid per hour can be lost. Fluid intake strategies should be undertaken and should be of paramount concern to the athlete if the athlete has to perform more than one training or competition sessions in a single day. Fluid strategies, including hydration well prior to the exercise bout, drinking as much as is comfortable and practical during the exercise session, and rehydrating aggressively afterwards in preparation for the subsequent exercise bouts, are needed to ensure an adequate water intake to prevent chronic dehydration during competition in hot conditions as the body does not adapt to dehydration. Rapid recovery of fluid losses after an exercise bout is assisted by the replacement of some of the electrolytes losses. Carbohydrate is the main fuel used by the muscle during hard training and competition and its requirement for exercise in hot conditions is further increased due to the shift in substrate utilisation towards carbohydrate oxidation. Daily food intake should focus on replacing glycogen stores after exercise. Competition diet strategies such as enhancing carbohydrate availability (carbohydrate loading) prior to endurance competition, pre-event carbohydrate intake, intake of sports drinks in events lasting longer than 45 minutes should be undertaken in hot conditions and practised during training. Carbohydrate ingestion may not enhance performance for all events undertaken in hot environment, however, there is no disadvantage of consuming sports beverages containing the appropriate carbohydrates and electrolytes during competition and training. There is also no good evidence to suggest that specific supplementation is necessary or will improve performance in sports activities undertaken in a hot environment. In conclusion, the primary aim of athletes training in a hot environment must be to ingest a source of energy, usually carbohydrate and fluid for replacement of water lost as sweat.

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