Health Beat Week 9: Hydration

By Christine Luff, About.com Updated: July 03, 2009

Staying hydrated is critical to your running performance and, more importantly, for preventing heat-related illnesses. Dehydration in athletes may lead to fatigue, decreased coordination, and muscle cramping. Other heat-related illnesses, such as heat exhaustion and heatstroke, have even more serious consequences. Runners need to pay attention to what and how much they’re drinking before, during and after exercise.

Pre-Run Hydration
If you're doing a long run or race (more than 8 to 10 miles), it's important to make sure you're well-hydrated during the few days leading up to your long run. In the days leading up to your long run (or race), drink plenty of water.An hour before you start your run, try to drink 16 to 24 ounces of water or other non-caffeinated fluid.

Drinking on the Run
Here's a general rule of thumb for fluid consumption during your runs: You should take in 6 to 8 ounces of fluid every 20 minutes during your runs. During longer workouts (90 minutes or more), some of your fluid intake should include a sports drink (like Gatorade) to replace lost sodium and other minerals (electrolytes).If you don't have access to water on your running routes, you'll have to carry your own fluids with you.

Determining Your Sweat Rate
The above guidelines are the basic rules of thumb, but it's important to remember that everyone's fluid needs vary. Some people sweat more than others.To determine how much liquid to take during a run or race, you need to know your sweat rate, and that can vary between 1 to 4 quarts per hour. Weigh yourself nude before a timed training run, and then again after. One pound of weight loss equals 1 pint of water loss. Calculate your sweat rate and use this to determine your fluid needs during a run or race. For example, if you lose 2 pounds during an hour run, that's 2 pints or 32 ounces. Thus, you need 8 ounces of water or sports beverage every 15 minutes.

Post-Run Hydration
Don't forget to rehydrate with water or a sports drink after your run. You should drink 20 to 24 fl oz. of water for every pound lost.