Race Hydration Begins NOW!!
Staying hydrated is critical to your running performance and, more importantly, for preventing heat-related illnesses. Dehydration in athletes may lead to fatigue, headaches, 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.
An hour before you start your run, try to drink about 16 ounces of water or other non-caffeinated fluid. Stop drinking at that point, so that you can void extra fluids and prevent having to stop to go to the bathroom during your run. To make sure you're hydrated before you start running, you can drink another 4 to 8 ounces right before you start.
Drinking on the Run
If you're looking for a general rule of thumb for fluid consumption during your runs: You should take in 4 to 6 ounces of fluid every 20 minutes during your runs. Runners running faster than 8-minute miles should drink 6 to 8 ounces every 20 minutes.
If you don't have access to water on your running routes, you'll have to carry your own fluids with you. Here are some fluid carriers that you can use to hold your fluids while you run. However, if you're running in a race, you shouldn't have to carry your own fluids because they should have water stops on the course.
Determining Your Sweat Rate
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. Note the weather conditions on that day, and keep in mind that you may need to adjust your consumption if the conditions are different. You can do the sweat rate test on another day to see how different conditions affect your sweat rate.
Eric K. O'Neal, PhD, Jonathan E. Wingo, PhD, and Phil A. Bishop, EdD