Evaluation of an estimation equation for water turnover in male collegiate sprinters based on the doubly labeled...

Appropriate hydration is essential for track-and-field sprinters to optimize training and competition performance. A recently developed estimation equation evaluates water turnover (WT) based on body size, environmental, and lifestyle factors. However, the assumption in the estimation equation-which may imply that athletes feel thirstier and have greater voluntary water intake than non-athletes because of an attenuated thirst-suppressing response-may not be applicable to sprinters engaged in high-intensity training. This study aimed to validate the estimation equation for WT in sprinters.

Twenty-four male collegiate sprinters participated in this study. The WT in participants was estimated and measured using the estimation equation (WT_Estimated) and the doubly labeled water (DLW) method (WT_Measured), respectively. Additionally, the total training time was evaluated using activity record. Preformed water volume was calculated by subtracting metabolic water, respiratory water uptake, and transcutaneous water uptake from WT_Measured.

WT_Estimated (4.95 ± 0.39 L/day) was significantly higher than WT_Measured (4.42 ± 0.74 L/day) (d = 0.57, P < 0.05). Total training time was significantly correlated with preformed water volume (r = 0.55, P < 0.05), and preformed water volume was significantly correlated with the difference between WT_Estimated and WT_Measured (P < 0.05).

Our findings indicate that the estimation equation overestimated WT by approximately 500 mL/day in male collegiate sprinters. These results suggest that sprinters should carefully consider the discrepancy difference between estimated WT and WT measurand using DLW method when using the estimation equation for hydration management.