Pre-exercise glycerol hydration improves cycling endurance time

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Hydration Science

Background:

• Optimizing hydration is crucial for endurance performance.
• Glycerol ingestion is a potential hyperhydration strategy.
• Its effects on physiological strain and endurance require further investigation.

Purpose of the Study:

• To examine the effects of glycerol-enhanced hydration (GEH) on physiological strain and endurance during submaximal cycle ergometry.
• To compare GEH with placebo hydration (PH).
• To assess the impact of GEH combined with oral rehydration solution (ORS) during exercise.

Main Methods:

• Two double-blind, randomized, crossover trials were conducted on well-conditioned subjects.
• Study I compared pre-exercise GEH (1.2 gm/kg glycerol) to PH.
• Study II evaluated pre-exercise GEH followed by ORS during exercise.

Main Results:

• Glycerol-enhanced hydration significantly lowered mean heart rate in both studies (p ≤ 0.05).
• Endurance time was significantly prolonged following GEH in both Study I and Study II (p ≤ 0.049).
• No significant differences in rectal temperature were observed between hydration regimens.

Conclusions:

• Pre-exercise glycerol-enhanced hyperhydration effectively lowers heart rate and prolongs endurance time during submaximal exercise.
• This strategy remains beneficial even when combined with oral rehydration during exercise.
• The tested regimens show potential for adaptation in endurance activities.