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Effect of beverage osmolality on intestinal fluid absorption during exercise
C V Gisolfi1, R W Summers, G P Lambert
1Departments of Exercise Science and Internal Medicine, University of Iowa, Iowa City, Iowa 52242-1111, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 6, 1998
Summary
Fluid absorption from the upper intestine during exercise is not affected by the osmolality of 6% carbohydrate-electrolyte beverages. Different beverage osmolalities did not alter total fluid absorption compared to a water placebo.
Area of Science:
- Exercise Physiology
- Gastroenterology
- Sports Nutrition
Background:
- Fluid replacement during exercise is crucial for performance and thermoregulation.
- The osmolality of ingested beverages can influence gastric emptying and intestinal fluid absorption.
- Understanding how different osmolalities affect fluid absorption during exercise is important for optimizing hydration strategies.
Purpose of the Study:
- To investigate the impact of varying osmolalities of 6% carbohydrate-electrolyte beverages on intestinal fluid absorption.
- To compare fluid absorption from duodenum and jejunum during cycling exercise.
- To determine if beverage osmolality affects total fluid absorption and hydration status during exercise.
Main Methods:
- Seven healthy subjects performed 85 minutes of cycle exercise.
- Subjects ingested a water placebo or 6% carbohydrate-electrolyte beverages with mean osmolalities of 197, 295, or 414 mosmol/kgH2O.
- Intestinal fluid absorption was measured using segmental perfusion techniques in the duodenum and jejunum, with gastric emptying rate used as intestinal perfusion rate.
Main Results:
- No significant differences were found in gastric emptying or total fluid absorption among the water placebo and the three carbohydrate-electrolyte beverages.
- While water placebo was absorbed faster in the duodenum than jejunum, overall absorption rates were similar across all tested beverages.
- Fluid absorption percentages ranged from 68% to 82% of ingested volume, with no significant differences between beverage types.
Conclusions:
- The osmolality of 6% carbohydrate-electrolyte beverages, within the tested range, does not significantly alter total fluid absorption from the duodenojejunum during moderate-intensity exercise.
- These findings suggest that athletes can choose from a range of osmolalities for carbohydrate-electrolyte beverages without compromising fluid absorption during exercise.
- Further research may explore the effects of higher carbohydrate concentrations or different electrolyte compositions on fluid absorption during exercise.