Downey, N. R., Buddo, K., Palmer, M. S., & Spriet, L. L. (2008). The effect of fluid ingestion during soccer training on fluid balance and aerobic test performance. ACSM 55th Annual Meeting Indianapolis, Presentation Number 833.

This study examine the pre-training hydration status, sweat and sodium losses of female varsity soccer players (N = 12), and evaluated their aerobic performance following three, 90-minute training sessions. All Ss completed the following conditions, 1) no fluid, 2) sweetened water, and 3) carbohydrate-electrolyte solution. Players drank 1 liter of the assigned fluid during training in the sweetened water and carbohydrate-electrolyte solution trials in doses of 250 ml at -30 minutes and 0 minutes before practice, and 30 and 60 minutes during practice. Pre-practice hydration status was estimated by measuring urine specific gravity. Sweat rates were calculated from body mass changes and fluid intake. Sweat sodium concentration was analyzed in forehead sweat patch samples and used with sweat rate to estimate sodium loss. Aerobic performance was measured with a repeated, 20-minute running test to fatigue (beep test) following all practices.

There were no differences between conditions for urine specific gravity. Body mass loss was greatest in the no-fluid condition when compared to the fluid conditions. Sweat rate during practice was significantly higher in the no-fluid condition than in the two fluid conditions. Sweat sodium concentration was similar for the three conditions, but net sodium loss was greater in no-fluid condition. When compared to the no-fluid condition, performance was prolonged over 7 levels in the sweetened water condition, and further prolonged by 4 levels in the carbohydrate-electrolyte solution condition.

Implication. Female varsity soccer players incurred large sweat and sodium loses during a 90-minute practice. Consuming 1 liter of fluid throughout practice prevented body mass losses and prolonged the onset of fatigue during an aerobic performance test. Consuming a carbohydrate-electrolyte solution was able to improve performance appreciably over water alone.

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