Bend it like Bikram

If the idea of practising yoga in a hot, humid room sounds like hard work, then you'd be right. Yet people all over the world are flocking to Bikram studios to sweat buckets and push themselves to new levels of strength and flexibility.

So what is Bikram yoga and why is it so popular? Bikram is a form of hot yoga devised by Indian guru Bikram Choudhury. The class is a sequence of 26 beginner postures and two breathing exercises performed in a room heated to about 40degC, with 40% to 60% humidity. And it's not easy - the guru himself calls it Bikram's Torture Chamber!

• The ever-expanding business of Bikram 

The Bikram sequence is designed so that each posture enables you to perform the next, building on the progress you've already made. Class begins with a breathing exercise, moves into the cardio then floor postures and ends with a second breathing exercise.

Donna Wikio, Bikram teacher and owner of Bikram Yoga Dunedin, calls it the hardest training in the world. "The humidity accelerates your heart rate and makes it denser for your breathing. It makes you feel like you're struggling a little with your breath."

The humidity also causes excessive sweating, which cools the body down and is said to rid the body of toxins.

"During the first class it's normal to get headaches and feel nauseous," she says. "A big part of that is detoxing. But it's also dehydration. Hydration before and after is the most important. Too much water during can make you feel sick."

"After class, it's very normal to feel elated. A lot of that could be toxin release or endorphins."

The heat makes Bikram better for beginners than other forms of yoga, she says. "It's simple, effective and the heat gets straight in. Even the stiffest of guys with terrible backs can get benefits."

The health benefits attributed to Bikram are many - increased strength and flexibility, weight loss, a sense of wellbeing - and practitioners claim it helps with practically everything, including injuries, insomnia, stress, even cancer.

Another advantage of Bikram over other yoga, says Donna, is that all the teachers have undergone the intensive Bikram training course, which includes first aid.

"The New Zealand yoga industry is unregulated. In other countries, instructors need certification. It's important if you're putting your body and its ailments in someone's hands."

The heat and the warm-up sequence help prevent any strains or injuries and everyone works to their own capabilities.

"One percent of the posture done the right way will bring 100% benefit," says Donna.

Dunedin firefighter Grant Swanson (52) has been doing Bikram yoga for the past year and "was hooked right away". A lifetime of playing sport and 35 years of binge drinking had taken their toll on his body.