'Suppose you are going to make a sword', explains Bikram Choudhury in his book Bikram's Beginning Yoga Class.

'You start with a piece of fine steel and the first thing you do is put the steel in the fire and heat it up. When the steel is hot it becomes soft. Then you can hammer it and slowly make it change shape to the sword you want.?

Whether it?s the reference to fire or the mention of soft steel getting a good hammering, there?s something about this introduction which lets you know you?re not in for an easy ride. Bikram yoga is a gruelling series of two breathing exercises (pranayamas) and 26 asanas (postures) repeated every session without diversion, editing or rearrangement.

The routine is punctuated by a posture appropriately called Dead Body Pose (savasana). By this stage the uninitiated should be suitably deterred. However, according to Jessika Munnel, a certified Bikram instructor of 10 years standing, ?Bikram yoga is great for beginners as the postures themselves are relatively simple. No-one?s expected to put their toes behind their head, though from a cardiovascular viewpoint the unfit may need to take a few breathers.?

Bikram Choudhury was born in Calcutta and developed a regime using heat and Hatha yoga. The philosophy stresses mastery of the physical as a means to attain spiritual perfection. It also promotes weight loss and limits the effects of ageing.

Classes are conducted in a room heated to approximately 38 degrees celsius. The heat allows the body?s muscles to loosen and relax, making the body more pliable. It also helps to prevent injury and facilitates the flushing of toxins. While working up a serious sweat, controlled breathing stills the mind and creates calm and concentration.

Word of warning: drink plenty of water before the class and small amounts during sessions. Do not eat for at least two hours prior to exercising. Wear comfortable, fitted clothes and take a towel with you.