Even at a moderate pace in mild temperatures, you can lose 3 to 4 liters of water during 2 to 3 hours of exercise. That’s equal to between 3/4 and one gallon of water!


The key to assimilating water and staying properly hydrated is to drink water continually, a little bit at a time, the cooler the better. Your body can absorb only about a liter of water per hour, which is often less than you’re losing. So a 2-liter hydration system (the equivalent of 3 large water bottles) is an ideal capacity for a vigorous 2- to 3-hour activity.


The American College of Sports Medicine (ACSM) – the leading authority on sports medicine and physiology in the United States – has released “Exercise and Fluid Replacement”, a position stand that provides scientifically-based guidelines for effective hydration. They recommend the following actions to minimize the debilitating effects of hydration on health and performance:

1. Drink Early Drink about 17 ounces of liquid about 2 hours before exercise.
2. Drink Often The body absorbs liquids better when it is continually sipped rather than gulped infrequently. Drink 5-8 oz every 15-20 minutes.
3. Add Sports Mixes For exercise over 1 hour, add mixes with carbohydrates and electrolytes.
4. Keep Fluids Cool Liquids in the 59-72 degree range are more easily absorbed.
5. Keep Fluids Accessible Fluids should be readily available and served in containers that allow adequate amounts to be ingested with ease and minimal interruption of exercise.
6. Drink After Exercise Make sure you drink after finishing exercise, since it is nearly impossible during exercise to ingest as much fluid as you are losing.