General Guidelines for Fluid Needs During Exercise

Sports drinks can be helpful to athletes who are exercising at a high intensity for 60 minutes or more. Fluids supplying 60 to 100 calories per 8 ounces helps to supply the needed calories required for continuous performance. It's really not necessary to replace losses of sodium, potassium and other electrolytes during exercise since you're unlikely to deplete your body's stores of these minerals during normal training. If, however, you find yourself exercising in extreme conditions over 3 or 5 hours (a marathon, Ironman or ultramarathon, for example) you may likely want to add a complex sports drink with electrolytes.

General Guidelines for Fluid Needs During Exercise

While specific fluid recommendations aren't possible due to individual variability, most athletes can use the following guidelines as a starting point, and modify their fluid needs accordingly.
Hydration Before Exercise

• Drink about 15-20 fl oz, 2-3 hours before exercise
• Drink 8-10 fl oz 10-15 min before exercise

Hydration During Exercise

• Drink 8-10 fl oz every 10-15 min during exercise
• If exercising longer than 90 minutes, drink 8-10 fl oz of a sports drink (with no more than 8 percent carbohydrate) every 15 - 30 minutes.

Hydration After Exercise

• Weigh yourself before and after exercise and replace fluid losses.
• Drink 20-24 fl oz water for every 1 lb lost.
• Consume a 4:1 ratio of carbohydrate to protein within the 2 hours after exercise to replenish glycogen stores.

Hyponatremia - Drinking Too Much Water

Although rare, athletes can drink too much water and suffer from hyponatremia (water intoxication). Drinking excessive amounts of water can cause a low concentration of sodium in the blood - a serious medical emergency.