The Effect of Fluid Replacement on Endurance Performance

The purpose of this study was to examine the effects of fluid replacement on power output (PO), rating of per-ceived exertion (RPE), heart rate (HR), body weight (BW), urine osmolarity (Uosm), and urine electrolyte concentra-tions ( ) in physically active men (n 5 4)[U], [U], [U]1 1 2Na K Cl and women (n 5 7). The participants were asked to gen-erate their highest possible PO during 60 minutes of cycling under 3 randomized conditions: ingestion of (a) no fluid (trial 1); (b) 1200 ml of distilled water (trial 2); and (c) 1200 ml of Gatorade (trial 3). BW and urine volume (Vu) were measured before and after the ride to determine sweat rate [(SR 5 DBW 1 Vfluid intake 1 Vu)/time]. The results indicated that there were no significant differences between trials for PO (123–127 W), RPE (14), HR (140–142 b·min21), and SR (11.9–12.4 ml·min21). However, was significantly (p[U]1Na, 0.05) lower postexercise for all 3 trials, and was[U]2Cl significantly reduced following trials 2 and 3. There was a significant increase (p, 0.001) in BW postexercise for trials 2 and 3 when compared with the no-fluid trial; however, the effects of water and Gatorade were similar. These re-sults suggest that fluid replacement during 1 hour of mod-erately intense cycling does not enhance performance in physically active men and women who are normally hy-drated