The amount of fluid you need during exercise depends on how much you sweat.

With an entire aisle dedicated to water and sports drinks at the grocery store, how do we know what to choose? The answer lies in the timing, says Baylor, Scott & White Health Physiatrist, Dr. Heather Fullerton

DURING EXERCISE: “Maintaining fluid intake during endurance exercise prevents dehydration and electrolyte loss, which can compromise performance. The amount of fluid you need during exercise depends on how much you sweat.

“The goal is to consume the same amount of fluid as you’re losing per hour, otherwise known as your sweat rate. Your sweat rate is influenced by genetics, conditioning, heat, and other factors.

“It’s possible (and not difficult – to calculate your sweat rate, but for most people this is not necessary. Instead, simply weigh yourself nude before exercise. Drink about 8 ounces of fluid per 20 minutes of activity. Then, weigh yourself again after exercise.

“Weighing the same or less than two pounds under your pre-exercise weight is okay. If you weigh less than this you’re not drinking enough. Alternatively, you should not gain weight with exercise! If you do, you’re drinking too much.

“The fluid you choose to drink during endurance activity should contain electrolytes. If you’ll be on the course for less than an hour, a sports drink with calories is not necessary. For exercise over an hour, however, a 6 percent carbohydrate solution is recommended, for a total of 30-–-60 grams of carbohydrate per hour. More carbohydrate than this (some sports drinks are 8 percent carbohydrate s) can result in nausea.”

Dr. Heather Fullerton
Baylor, Scott & White Health – Austin/Round Rock