Chug some water. Down a Brisk. Sweat off those pounds.

These are all misconceptions concerning exercising and heat that help lead to dehydration, pain, and possibly death. “Hot weather can pose serious problems to a body that’s already heating up during summer exercise,” warns Susan Kalish, executive director of the American Running Association. “Without adequate fluid intake, you’re at risk for dehydration and heat-related illness such as heat cramps, heat exhaustion, heat stroke, and in extreme cases, death.”

Even though you may think drowning your body with water or exercising until you feel thirsty are typical practices, they are common mistakes that iron men and women like yourself make every summer. Here are the facts on your common misconceptions.

As long as I’m not thirsty, I’m fine. In reality, when you feel your mouth start to dry up, the rest of your body is a barren sand pit. Studies show that fluid levels change quickly during exercise, which means using thirst as a gauge for hydration is like relying on an “idiot” light on your car’s gas gauge. By the time you feel thirsty, your body is already dehydrated.

When I exercise, fat leaves my body in sweat form. Actually, it really doesn’t. Sweat is a way for your body to release heat and cool the body during activity. The weight lost during exercise is water weight, and represents a proportional amount of water that should be replaced. For every pound you lose during exercise, you should drink at least 24 ounces of fluid. As little as a 2 percent decrease in your body weight during exercise can impair your performance.

Caffeine gives me more energy, so it helps me exercise. Drinks with a large amount of caffeine are far worse for you than water and sports drinks. Caffeine’s diuretic effect causes you to lose fluids from your body, leading to further dehydration. Instead, properly formulated sports drinks can help sustain your performance during intense exercise lasting longer than 60 minutes. Sports drinks also are absorbed into your bloodstream more quickly than water.

If I store water before exercise I’ll have enough during. This idea is good if you like getting cramps and side stitches during exercise. Unlike food, you can’t stock up on fluids for exercise later in the day. You should drink at least six to eight glasses of water per day to keep hydrated for daily activities. During exercise, drink at least five to 10 ounces every 15 minutes. A good indicator of hydration is clear urine throughout the day.

Address: American Running Association, 4405 East West Highway, Suite 405, Bethesda, MD 20814-4535; run@americanrunning.org, www.americanrunning.org.

— Andrew Tufts —