Abstract des Autors

This paper compares our results obtained under various hydration conditions during effort in the heat. Two experimental series were carried out on healthy human subjects exercising intermittently on a cycloergometer for 3 hours of a 4 hour dry-heat exposure (Ta > 34 Grad C). The aim of the research was to examine the effects of dehydration and rehydration during prolonged muscular effort and to study the influences of initial hydration level on physiological adjustments associated with either further dehydration or rehydration. Therefore, during some experiments, on normal or hypohydrated or hyperhydrated subjects, no fluids were given while during others, rehydration was attempted by giving water or hypotonic or hypertonic glucidic solutions or isotonic-electrolyte-sucrose solution. In any initial hydration state, dehydration during exercise always induces larger rises in core temperature, heart rates and plasma volume reductions, while sweating response is only affected in case of high dehydration. Oral rehydration during exercise certainly facilitates thermal and cardiovascular adjustments. The effects of the ingested fluid may vary depending on initial hydration state, and depend on the schedule of rehydration and on the temperature of the fluids ingested. Verf.-Referat