“I think there is a significant danger of exercising in such heat,” said Dr Anita Green, the director of the peak health body Sports Medicine Australia.
Bikram is the latest, and trendiest, yoga to hit Sydney and involves 90-minute classes being conducted in a room heated to 37 degrees.
Bikram teachers claim benefits include increased blood circulation, better cardiovascular conditioning, detoxification through sweating, improved muscle and tissue elasticity and reduced risk of injury.
But those who believe that are wasting their time and money, Dr Green said.
“All this talk about detoxing is quite cultish,” she said.
“I have to say I have not seen good scientific evidence of what toxins are.
“Toxins is one of those buzz words and I have never seen anyone adequately define what toxins are.”
If you looked to Bikram yoga for cardiovascular fitness you would be better doing an aerobic exercise like jogging or swimming, she said.
Dr Green said she was convinced of the health benefits of regular yoga but said she would not recommend hot yoga for asthmatics, people on diuretics or fluid tablets or certain other medications or people with heart conditions.
“I think it is often difficult when practitioners put themselves up to be experts,” she said.
“It makes it very difficult for the public to question their claims.”
But Darren Ma has taught Bikram yoga for five years at the Bikram Yoga College of India at Darlinghurst and Rozelle and said he swears by its health benefits.
“I do 18 classes a week and I am in fine health. I don’t remember the last time I had a cold,” he said.
Mr Ma said he had been taught about the medical benefits of Bikram yoga from doctors and scientists.
“I don’t really question it, and the working of it all.
“That would be like revisiting the invention of the wheel, it has been going on forever.”