It was one of the hottest days of the year and I was standing inside a room with the heating on full whack, trying as hard as I could to get my forehead to touch the floor.

This was my first attempt at yoga.

In the past I'd always thought I'd find the practice a bit boring and could never understand how the likes of Madonna managed to get so super-toned doing something so slow.

But when a friend mentioned Bikram yoga, 90 minutes of stretching done in heat of 105°F (40°C), it sounded extreme enough for my liking.

Arriving at the studio, near St Nicholas Market, it became clear that, in a T-shirt and leggings, I was overdressed.

The people coming out of the previous class were so drenched in sweat they looked like they had been swimming in the stuff, while some of those going in had even worn their Speedos for the occasion.

The studio is run by Carl, 40, and Georgina, 42, who quit the London rat race in order to set up Bikram Yoga Bristol and to give themselves a better quality of life.

Georgina trained for nine weeks with Bikram Choudhary, the founder of this type of yoga, after deciding to become an instructor.

She says: "I used to do Ashtanga yoga because I had problems with my back. I had a slipped disc at 30.

"Then a hairdresser told me about Bikram yoga. I remember going into the room with about 40 people but I had such personal attention.

"The instructor was tall and in her late 50s. Her voice made the walls shake. Her aura was inspiring and I just wanted to be her."

Like Bikram himself, who was told after a weightlifting injury that he would never walk again, the exercises in hot temperatures soon helped to heal her injuries and it became clear that this was destined to be more than just a hobby.

Convincing Carl, a triathlete, that hot yoga would be enough of a challenge wasn't easy but eventually he was also hooked. He is due to undergo instructor training in September.

Opening the studio in Bristol, while the pair continued to work – Georgina as a sales director and Carl as a designer – proved an even bigger challenge.

"We've been amazingly received in Bristol," says Carl. "It was hard work but it has paid off. We have people coming from as far away as Pembrokeshire and Cardiff coming along, and people of all ages – even in their 70s.

"I think people here are very open to trying new things and we've really been overwhelmed with support."

Back in the hot room, I found myself a mat and was advised that the goal for the session was simply to stay in the room.

Lying opposite a wall of mirrors in neat rows I was told that we had to only concentrate on ourselves for the duration of the class.

After a few breathing exercises, which seemed strange to start with, we began the sequence of 26 different exercises. None of them were impossible but how far you could progress depended on flexibility.

For me, someone who blames long legs on the fact I can't touch my toes, I was incredibly sceptical that I would ever be able to place my head on the floor, or even through my legs – in spite of the instructor's promises.

By now the room was fully heated. Sweat was dripping from every part of my body but wiping it away was against the rules.

Instead we had to remain focused in the mirror, remembering to breathe only through our nose.

Around me, a couple of people dropped to their mats and sat out a few exercises.

Just when I started to panic that I couldn't carry on for much longer, we started the sitting series of exercises which included a "dead body" posture – finally, a rest.

Each exercise was targeted to a different part of the body, be it the immune system, the heart or the thyroid.

While my limbs rebelled at being asked to form shapes they'd never seen before, the heat of the room meant my muscles were fully warmed up and there was no pain.

Looking like a drowned rat I finished the class. Just.

After a shower I felt the exercise buzz as well as the sense of being incredibly clean, as if I had flushed out the toxins through sweat.

It might not have been a marathon attempt, or as painful as a big weights session, but Bikram yoga is a challenge in its own league.

For more information visit www.bikramyogabristol.com.