If your opinion of hot yoga involves hundreds of spandex-clad yogies pushing and twisting their bodiesto the point of heat exhaustion and dehydration in some sort of mystical sweat lodge somewhere, you arn't alone. Hot yoga, usually practiced in a room heated to between 90 and 105 degrees F, has been steadily growing in popularity, but the jury's been out on it's safety...until now. A recent study published by the American Council on Exercises finds that with proper hydration, hot yoga is just as safe as its less sweaty counterpart.

University of Wisconsin -La Crosse researchers recruited 20 healthy , relatively fit people between the ages of 19 and 44 and measured their core body temps after a 60-min Vinyasa yoga class in a 70-degree F room, and then again after another class where the temps was jacked up between 90 and 95 degrees F with 35% to 40% humidity.

Surprisingly, no difference between the core body temps after the two classes was found. After both, the student's core temps rose an average of 99 degrees, well below the unsafe 104 degree level when you start seeing trouble, says John Porcari, PhD, an exercise and sports science professor at UW-Lacrosse and on of the study authors.

"When you're exercising it's almost like your body shuts down if you get to that level," he says. "It's considered dangerous, and heat related illness is almost impending."

Porcari sys the results were likely similar because the participants were well hydrated. The yoga teachers encouraged students to drink plenty of water before and during class.

"If you go into the class dehydrated or don't drink during class there is a potential for problems," says Porcari. He suggests starting to hydrate at least 30 mins before a class, drinking 6-8 ounces of water immediately before class, and more as necessary during class.

He says another study would need to be done to test the safety of Bikram yoga a popular and very regimented, 90min practice where students hold poses in a 105-degree room.