Gender Differences Of Sweat Rates In Endurance Trained Athletes

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Adequate fluid replacement around exercise is an important consideration for endurance athletes. While sex-based differences in maximal sweat rate have been identified, sex-based differences in sweat rate variability between training sessions is less understood. PURPOSE: The purpose of this study was to observe differences in sweat rate in endurance-trained males and females. METHODS: Endurance-trained males (n=4) and females (n=14) completed training sessions lasting a minimum of 30 minutes once per week. Body mass was collected before and immediately after exercise. Total sweat loss (TSL) was calculated from changes in body mass. TSL and duration of exercise were used to calculate absolute sweat rate (ASR), and subsequently relative sweat rate (RSR). Heat stress was recorded using a WBGT, with temperatures ranging from 9.21-23.65°C. Data were analyzed using two-sample T-tests to evaluate differences between the maximum ASR and RSR between male and female runners. Significance was set a priori at P<0.05. RESULTS: Males had a significantly higher ASR than females (1.46±0.36 vs. 0.89±0.21 L/h; p<0.001). Males and females did not differ for RSR (0.018±0.004 vs. 0.014±0.004 L/kg/h; p=0.116). CONCLUSION: This observational study indicates males had a significantly higher ASR compared to females but similar RSR. Despite lack of significance in RSR, these results correspond with previous studies demonstrating sex differences due to differences in total body surface area. These results suggest sex should be a consideration when implementing different hydration strategies.