3 hidden dangers of hot yoga and other exercise fads

For some, hot yoga is the ultimate chill breaker. One popular style, Bikram yoga, is done in a room heated to at least 105⁰ F. Fans say it helps you "sweat out toxins" and achieve deeper poses. Lady Gaga, Madonna, and Gwyneth Paltrow are among the celebrities recently spotted sweating it out. Its popularity has spawned several other sizzling exercise trends, including heated indoor cycling, hot Pilates, and (ballet) Barre "burn" classes. The problem is that these classes have safety risks.

Julianne Pepe, 28, of Tarrytown, N.Y., had a terrible experience at her first hot yoga class. She was in good shape but quickly became lightheaded and dizzy. She asked to go out for some water, a request that was clearly frowned upon. She finished the 90-minute session, but she felt exhausted and sick for the rest of the day.

"There is little research about yoga, much less hot yoga, and most of what's available has been poorly done," the exercise physiologist Carol Ewing Garber, Ph.D., of the American College of Sports Medicine, said. But she points to other research about physical activity in hot settings and says there is reason for concern. Here are three risks of hot workouts.

Problem: Heat stroke

Why it happens: Exercising in the heat (outdoors or indoors) can overwhelm your body's ability to control its core temperature. That can lead to heat stroke, a potentially fatal condition in which your heart, liver, kidney, and other organs shut down. In the last 20 years, 40 high school football players have died from heat stroke caused by workouts in hot weather, according to the National Center for Catastrophic Sport Injury Research at the University of North Carolina. Far less serious, but more common, is what happened to Pepe: heat exhaustion. That can cause muscle cramps and can make you light-headed, dizzy, and physically wiped out.  

What to do: Drink plenty of fluids and watch out for the early signs of heat stroke, including dizziness and exhaustion. Stop if you start to feel feverish, dizzy, lightheaded, confused, or nauseated. Be especially cautious you're at increased risk of heat illness because of your age (50 or older), your health (you are pregnant, or have heart disease, diabetes, or lung diseases), or the drugs you take (antidepressants, alpha-blockers and beta-blockers, antipsychotics, diuretics, antihistamines, and anticholinergic drugs).

Problem: Joint and muscle damage

Why it happens: Some people think they can stretch deeper in the heat. "Although it may feel good, overstretching your muscles actually backfires," Win Chang, M.D., clinical professor of orthopedic surgery at New York University's Hospital for Joint Diseases, said. That can lead to joint problems, inflammation, and arthritis. Orthopedic surgeons are seeing more and more yoga injuries, says Chang.

What to do: Avoid overstretching. You should feel tension, not pain. Hold the stretch; never bounce. That can cause small muscle tears.

Problem: Infection

Why it happens: Hot, humid gyms can be a breeding ground for germs.
What to do:  Don't share mats, towels, or clothing with others. If you use a gym mat, cover it with a clean towel, or clean with alcohol spray or wipes. Bandage any cuts or scrapes. And if the room is dirty or wet with sweat, leave.