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[Glucose polymer solutions and prolonged exertion in the heat]
R Burstein1, D S Seidman, J Alter
1Heller Institute of Medical Research, Chaim Sheba Medical Center, Tel Hashomer.
Harefuah
|June 1, 1992
Summary
Glucose polymer (GP) solutions did not significantly improve hydration or plasma volume compared to tap water (TW) during prolonged heat exercise. Standard fluid intake recommendations appear adequate for maintaining hydration during intense physical activity in hot conditions.
Area of Science:
- Exercise Physiology
- Sports Nutrition
- Environmental Physiology
Background:
- Glucose polymer (GP) solutions are often studied for athletic performance, but typically in controlled lab settings.
- Real-world conditions, like prolonged exercise in heat, require investigation into their effects on hydration and glycemic state.
- Understanding fluid balance during endurance events is crucial for athlete health and performance.
Purpose of the Study:
- To investigate the effects of glucose polymer (GP) electrolyte beverages versus tap water (TW) on fluid balance and glycemic state during prolonged, moderate-intensity exercise in the heat.
- To assess hydration status and plasma volume changes in endurance-trained men under field conditions.
- To evaluate current fluid intake recommendations during strenuous physical activity in hot environments.
Main Methods:
- 48 endurance-trained men participated in a 134 km march in 32-41°C heat.
- Participants were randomly assigned to consume either a 7.2% GP electrolyte beverage or tap water (TW).
- Fluid consumption was either ad libitum or a fixed 1000 ml/hr; plasma volume and blood glucose were measured.
Main Results:
- A greater change in plasma volume was observed in the TW group compared to the GP group (+7.9% vs. +4.8%, p<0.05).
- Dehydration did not exceed 2% of body weight in either group.
- Blood glucose significantly increased with GP intake but decreased with TW intake.
Conclusions:
- Current International Diabetes Federation (IDF) fluid intake recommendations are adequate for maintaining normal hydration during heat-exposed physical exertion.
- The observed differences between GP and TW groups do not support replacing water with glucose-polymer solutions for prolonged, moderate exercise in the heat.
- Further research may be needed to explore specific scenarios where GP solutions might offer benefits.