What hydration strategies are recommended for athletes during and after prolonged exercise?

• A. Pre-hydration with water only; no during or post guidance
• B. Pre-hydration 5-7 mL/kg 4 hours before; during, 150-300 mL every 15-20 minutes with electrolytes as needed; post-exercise replacement of 1.25-1.5 L per kg body weight lost within 6 hours; monitor urine color and body weight
• C. Hydration is unnecessary during long events
• D. Drink only when thirsty

Answer: (B)

Prolonged exercise disrupts fluid balance as you sweat, which lowers plasma volume, impairs temperature regulation, and can hurt both performance and recovery. The best approach is a planned hydration strategy that covers before, during, and after activity to maintain fluid status and support electrolyte balance.

Starting hydrated before you begin is important. Aiming to ingest about 5-7 mL of fluid per kilogram of body weight about 4 hours before exercise helps ensure you start in a well-hydrated state and gives the kidneys time to adjust, reducing the chance of early dehydration.

During the activity, a steady intake of roughly 150-300 mL every 15-20 minutes helps replace sweat losses and maintain plasma volume. Including electrolytes as needed is especially important for longer efforts or hotter conditions, because sodium helps retain fluid in the bloodstream and supports nerve and muscle function. This schedule also minimizes gastrointestinal distress and keeps thirst from being the sole guide, which can lag behind actual needs during intense or long bouts of exercise.

After exercise, rehydration should focus on restoring fluid lost during the session. A guideline of about 1.25-1.5 liters of fluid per kilogram of body weight lost within six hours provides a practical target to fully replenish extracellular fluid and support recovery. Using urine color and body weight changes as simple feedback helps tailor the plan to the individual and ensure you're on track.

This approach contrasts with relying on drinking only when thirsty or ignoring hydration during long events, both of which can leave you under-fueled and performance or recovery-impaired.