Influence of Rate of Rehydration on Exercise Performance in Dehydrated Males

Abstract

PURPOSE: The objective of the current research study was to observe the influence of the rate of rehydration on exercise performance on dehydrated males (N=10) in a thermoneutral environment. METHODS: Each subject performed three testing sessions, including a O2peak test and two 1 hr cycle rides (75% O2peak) while dehydrated. During each of the 1 hr cycle rides, the subjects were administered a randomly selected rehydration strategy (4 × 250 ml every 15 min or 2 × 500 ml at 30 and 45 min). Numerous variables were collected throughout the course of each trial. Body Temperature and physiological variables were collected every 5 min and 11 2 × 13 ANOVAs were run. For blood variables, eight 2 × 3 ANOVAs were utilized, followed by t-tests on the changes in weights (D weights) and thermoregulatory data. RESULTS: Significant (p <.05) and expected changes over time existed for temperature and physiological data. No significant differences (p >.05) for the D weights or thermoregulatory data were reported. A significant interaction (p <.05) in percent change in plasma volume as well as a significant difference (p <.05) in hematocrit and cell volume were reported, indicating the possible benefits of rehydration early in an exercise bout rather than later when dehydrated. CONCLUSION: Enahncements or maintenece of plasma volume and hematocrit concentrations may indicate a benefit to performance by limiting cardiovascular strain during exericse. Increases in hematocrit and cell volume would have negatively affected cardiovascular performance through increased blood viscosity. By maintaining hematocrit levels and plasma volume through rehydration, performance may be enhance through decreasing cardiovascular strain over the duration of exericse.