One hundred and nine degrees Fahrenheit. That was the heat index—the combined measure of temperature and humidity—on the summer day in 2001 when Minnesota Vikings offensive tackle Korey Stringer died of heatstroke during a preseason practice.
One hundred and forty-nine degrees Fahrenheit. That's the approximate heat index of a typical Bikram Yoga studio (105 degrees, 60 percent humidity), where students spend 90 minutes working out.
Obviously, not everyone experiences adverse effects from exercising in the heat. Bikram Yoga has attracted a devoted following, and its Web site claims that practicing yoga in the heat improves joint mobility, enhances stretching, reduces the risk of injury, aids circulation, and allows the body to release toxins.
But along with the potential benefits, excessive sweating can result in dehydration, a condition that sets the stage for heat-related health problems, such as heat cramps, heat exhaustion, and even heatstroke.
If you enjoy hot yoga, pay attention to your body's reaction to the heat—your safety is ultimately what's at stake. You can protect yourself from potentially dangerous levels of dehydration by following these essential guidelines.
Acclimate and modify. If you're new to hot yoga or if you're returning after a break from it, give your body time to adjust. "Your initial exposure to heat should be without exercise," exercise physiologist and yoga instructor Leslie Funk says. You may want to just sit still during portions of your first few classes. Start by holding poses for a fraction of the time the teacher suggests, and build your endurance gradually with each session.
Water, water, and more water. Funk recommends drinking at least 16 ounces of water two hours before class, drinking frequently during the practice, and consuming 20 to 40 ounces afterward for every hour of exercise.
Show some skin. Sweating is the body's primary defense against overheating, and bare skin allows your body to release heat more easily.
Recognize the signs of heat exhaustion. The first symptom of heat exhaustion is a pulse rate that rockets and stays elevated. Dizziness, headache, nausea, confusion, vomiting, cramps, fatigue, weakness, and vision disturbances are cause for immediate concern. Also, beware decreased sweating—a sign of serious dehydration.
Follow your Instincts. If you experience any of the above symptoms, act immediately. Leave the heated studio (or find the coolest area) and lie down on your back. If you feel like you might pass out before getting out of the room, lie down on your mat. Elevate your legs on a cushion or chair. Apply a wet cloth to your skin and drink plenty of cold water. If the symptoms persist, seek medical attention.
Get your doctor's OK. Medical conditions such as diabetes, pregnancy, cardiovascular disease, respiratory disease, eating disorders, sleep deprivation, a history of heat-related illness, and being overweight may increase the risk of developing a heat-related illness, says Randell Wexler, M.D., assistant professor of clinical family medicine at Ohio State University. Also, some medications can interfere with the body's heat regulation system and shouldn't be used during any hot yoga practice.