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Physiological responses to glycerol ingestion during exercise.
1Exercise Physiology Laboratory, John Stuart Research Laboratories, Quaker Oats Company, Barrington, Illinois 60010.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|July 1, 1991
Summary
Consuming glycerol solutions during exercise did not provide significant cardiovascular, thermoregulatory, or hormonal benefits. While glycerol affected hydration markers and thirst, it did not enhance exercise performance or physiological responses.
Area of Science:
- Exercise Physiology
- Sports Nutrition
- Endocrinology
Background:
- Glycerol is a hyperhydrating agent that may improve exercise performance.
- Its effects on cardiovascular, thermoregulatory, and hormonal responses during prolonged exercise are not fully understood.
Purpose of the Study:
- To investigate the physiological effects of consuming glycerol solutions during endurance exercise.
- To compare glycerol beverages with carbohydrate-electrolyte and placebo drinks.
Main Methods:
- Nine subjects performed 90-minute cycling trials in a hot environment.
- Four beverages were tested: 10% glycerol (G), 6% carbohydrate-electrolyte (CE), CE + 4% glycerol (CEG), and water placebo (WP).
- Cardiovascular, thermoregulatory, and hormonal markers were measured.
Main Results:
- Glycerol increased plasma osmolality and reduced plasma volume loss compared to placebo.
- Plasma renin activity was highest with placebo, while antidiuretic hormone increased with glycerol.
- Thirst was lowest with CEG and G, but gastrointestinal distress was highest with G.
- No significant differences were found in heart rate, core temperature, sweat rate, or perceived exertion.
Conclusions:
- Glycerol solutions did not offer substantial metabolic, hormonal, cardiovascular, or thermoregulatory advantages during exercise.
- While glycerol impacts hydration, it does not appear to enhance overall exercise performance in this context.