Key Takeaway
Complete rehydration after exercise requires sodium replacement; water alone is insufficient as it dilutes blood sodium and suppresses thirst before full rehydration.
Summary
This review examined the physiology of fluid and electrolyte balance during exercise and recovery.
Key findings on sodium:
- Drinking plain water after exercise suppresses thirst prematurely
- Water dilutes plasma sodium, reducing drive to drink
- Sodium maintains plasma osmolality and sustains thirst
- Complete rehydration requires sodium equivalent to sweat losses
Practical recommendations:
- Include sodium in post-exercise fluids
- Drink 150% of fluid lost (to account for ongoing urine losses)
- Salty foods with water work as well as sports drinks
- Individual sweat rates and sodium losses vary significantly
Significance:
Established the mechanistic basis for why electrolyte replacement is necessary for complete rehydration.