A comparison of three fluid replacement strategies for maintaining euhydration during prolonged exercise.

ABSTRACT

The effectiveness of a new water delivery system (the Water-Del) was examined for maintaining euhydration compared to other fluid replacement strategies. Subjects (N = 10) performed three 60-min cycling trials (/50% of VO2max) in an environmental chamber (27 degrees C; RH = 50%). Trials were randomly assigned from Water-Del (metered 200 ml water every 15 min), ad libitum every 15 min (ad-lib-15), and ad libitum (ad-lib). Total water intake (TWI), changes in plasma volume (delta PV), body weight (delta BW), thirst, skin temperature (Tsk), and heart rate (HR) were measured. A significant difference (p < or = .05) among trials was observed for TWI, with metered (1,200 +/- 0 ml) being greater than ad-lib-15 (358 +/- 48 ml) and ad-lib (522 +/- 106 ml). No significant difference was found for delta PV. A significant difference (p < or = .05) for delta BW was observed with metered (0.28 +/- 0.16 kg) being different than ad-lib-15 (-0.63 +/- 0.12 kg) and ad-lib (-0.34 +/- 0.14 kg). No significant differences (p > .05) were found for thirst, Tsk, or HR. The water-Del provides for greater fluid intake during exercise compared to other replacement strategies.