Fluid balance in exercise dehydration and rehydration with different glucose-electrolyte drinks

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Fluid Balance

Background:

• Exercise-induced dehydration significantly impacts physiological parameters.
• Restoring fluid and electrolyte balance is crucial for recovery and performance.
• Different beverage compositions may influence rehydration effectiveness.

Purpose of the Study:

• To investigate the effects of various rehydration solutions on fluid balance after exercise dehydration.
• To assess the impact of different drinks on plasma volume restoration and body fluid compartments.
• To evaluate the influence of rehydration strategies on subsequent exercise performance.

Main Methods:

• Six male subjects underwent exercise dehydration (3% body weight loss).
• Rehydration involved consuming one of four solutions (control, high potassium, high sodium, high sugar) over 2 hours.
• Exercise tests (submaximal and supramaximal) were conducted before dehydration and after rehydration.

Main Results:

• Plasma volume decreased by 16% post-dehydration, with partial recovery during rest before fluid intake.
• All drinks increased plasma volume above baseline after 2 hours; sodium and control drinks yielded significantly higher volumes.
• Sodium drinks favored extracellular rehydration, while potassium and sugar drinks favored intracellular rehydration.
• Despite elevated plasma volume, heart rate during submaximal exercise was higher post-rehydration.
• Supramaximal exercise capacity was reduced by 20% post-dehydration and rehydration, irrespective of drink type.

Conclusions:

• Sodium-containing beverages are effective for restoring extracellular fluid volume after exercise dehydration.
• Intracellular rehydration is favored by potassium and sugar-based drinks.
• Reduced muscle glycogen content appears to be the primary factor limiting exercise performance recovery, independent of rehydration strategy.