Abstract

Seven highly trained subjects underwent exercise dehydration without fluid replacement (X), resulting in approximately 1.9% and approximately 3.5% body weight (fluid) losses at one and two hours, respectively. Subsequently, subjects underwent two identical exercise trials with isovolumetric fluid replacement of water (W) and an experimental formulation (Q). An anti-dehydration schedule was initiated prior to, and continued throughout the exercise, with W and Q supplied every 15 minutes at 16 degrees C in volumes related to each subject's fluid loss estimate derived from trial X. A rehydration schedule was maintained for two hours of recovery, with total fluid replacement equivalent to the body weight decrement due to fluid losses. In both W and Q trials, selected physiological indices of work performance were maintained closer to homeostatic levels during exercise, with a more rapid return to pre-exercise resting levels during recovery than during that trial X. Furthermore, W and Q were equally effective in preventing plasma volume changes during exercise and restoration to pre-exercise levels during recovery, as well as in preventing plasma osmolality disturbances during exercise and recovery, although minimal plasma electrolyte changes were associated with Q.