"Bikram" and other forms of hot yoga are popular among celebrities — Gwenyth Paltrow, Madonna, and Andy Murray to name a few — but new research from the American Council on Exercise (ACE) suggests that those sweaty stretches burn just as many calories as regular ones do.

The study measured the core temperatures and heart rates of 20 people before, during, and after a 60-minute yoga class performed in a 70 ºF room. The next day, the same group went through the exact same routine, but this time in 92 ºF. Humidity was held at about 34 percent for both sessions.

The researchers argue that people think hot yoga is better for them because there is more sweat involved and the stretches feel easier.

"I think some people are attracted to hot yoga because it's easier to go through a greater range of motion when your muscles are warmer," said co-author Dr. John Porcari, head of the Department of Exercise and Sport Science at the University of Wisconsin-La Crosse. "And I think some people like the challenge of exercising in a hotter environment because it allows them to work up a good sweat and feels like they are getting a better workout."

Core temperature and heart rate were almost identical between the two sessions, suggesting that hot yoga is just as strenuous as regular yoga.

"Looking at heart rate, they weren't working any harder in the hot yoga class than in the regular yoga class," said Porcari. "Normally if you go out and walk 3 miles per hour and then you do it again on a day that's really hot, your heart rate is going to be higher. So, because the heart rate was identical, this tells me that somehow people must have down-regulated how hard they were pushing themselves in the heated environment."

However, questions remain over more extreme versions of hot yoga, like Bikram where temperatures and humidity can reach as high as 105 ºF and 40 percent. Bikram may provide a better workout, but it is also suspected to have potential negative health consequences.

"Anytime exercise is conducted in extreme temperatures, it's important to remain hydrated and to watch signs for overheating," Dr. Cedric Bryant, ACE Chief Science Officer, said in a statement.