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

Area of Science:

• Exercise Physiology
• Sports Science
• Hydration Research

Background:

• Maintaining euhydration during exercise is crucial for performance and health.
• Traditional fluid replacement strategies like ad-libitum drinking may be insufficient.
• The Water-Del system offers a metered approach to fluid intake.

Purpose of the Study:

• To evaluate the effectiveness of the Water-Del system for fluid intake during cycling.
• To compare the Water-Del system against ad-libitum fluid replacement strategies.
• To assess the impact of different hydration methods on physiological markers.

Main Methods:

• Ten subjects completed three 60-minute cycling trials at 50% VO2max in a controlled environment.
• Fluid intake was administered via Water-Del (metered), ad libitum every 15 minutes, or ad libitum.
• Measurements included total water intake, plasma volume change, body weight change, thirst, skin temperature, and heart rate.

Main Results:

• The Water-Del system resulted in significantly higher total water intake (1200 ml) compared to ad-libitum methods (358-522 ml).
• Subjects using Water-Del experienced less body weight loss (0.28 kg) versus ad-libitum groups (-0.34 to -0.63 kg).
• No significant differences were observed in plasma volume changes, thirst, skin temperature, or heart rate.

Conclusions:

• The Water-Del system is effective in promoting greater fluid intake during exercise.
• This metered delivery system aids in maintaining body weight, suggesting improved hydration status.
• Water-Del represents a superior fluid replacement strategy compared to ad-libitum drinking during moderate-intensity cycling.