Hydration Guide for Athletes: Before, During, After

By Rachel Williams · September 29, 2026

Why Hydration Matters for Performance

Even 2 percent dehydration reduces athletic performance by up to 25 percent. You lose focus, your muscles fatigue faster, and your body cannot regulate temperature effectively. Proper hydration is the single easiest way to improve your performance.

Before Exercise

Drink 16-20 ounces of water 2-3 hours before exercise. Then drink 8-10 ounces 15-30 minutes before starting. This ensures your body is fully hydrated without causing sloshing or discomfort during activity.

During Exercise

Under 60 Minutes

Water is sufficient. Drink 4-6 ounces every 15-20 minutes. Do not wait until you feel thirsty — thirst is a lagging indicator of dehydration.

Over 60 Minutes

Switch to a sports drink containing electrolytes and carbohydrates. You are losing sodium and potassium through sweat, and water alone cannot replace them. Aim for 14-20 grams of carbs and 100-200mg of sodium per 8 ounces.

After Exercise

Weigh yourself before and after exercise. For every pound lost, drink 16-24 ounces of fluid to rehydrate. Include sodium (through food or electrolyte tablets) to help your body retain the water you drink.

Signs of Dehydration

Dark yellow urine (aim for pale straw color)
Headache during or after exercise
Muscle cramps, especially in calves and feet
Dizziness or lightheadedness when standing
Reduced sweat production despite heat

Common Mistakes

Drinking too much water without electrolytes can cause hyponatremia (dangerously low sodium). This is rare but serious. If you exercise for more than 2 hours, always include electrolytes in your hydration plan.