In 1967 I went to my first yoga class and loved it. Not only did I find the postures relaxing, but I was very flexible. I could stand on my head, do shoulder stands, bend and twist, and hold the full lotus position with ease.

I practised yoga diligently for the next 12 years. I spent several years in an Indian ashram, where we did hours of yoga daily.

In 1979 I took classes with the legendary B.K.S. Iyengar in Pune. He was a harsh taskmaster. When we sat on the floor and leant over towards our toes, he would sit or even jump on our backs to flatten them.

It wasn’t long after that I began to have back pain. A chiropractor in Pune told me to stop doing yoga. Even so, I didn’t give it up straight away. After I returned to Australia, I’d occasionally attend a yoga class or do the odd position when I felt like it. I especially liked to nestle into the child’s pose, as it would calm my mind.

Even though there is a widely held perception that yoga is harmless, some studies do not support these claims.

Yoga might popular, but that doesn’t make it perfect. Photo: Getty

In 2009 Columbia University’s College of Physicians and Surgeons conducted a worldwide survey of yoga teachers, therapists and doctors to determine the extent, nature and causes of yoga-related injuries they had seen. The largest number of injuries was to the lower back, associated with forward bends, twists, and backbends. Injuries included herniated discs.

Physiotherapist Tim Bagshaw, from Maleny in the Sunshine Coast hinterland, said he had seen clients with back problems caused by yoga. He warned people to be careful of poses where their spine was flexed and rotated (bent and twisted) at the same time.

Dr Stuart McGill, professor of biomechanics at Canada’s University of Waterloo, is a world authority on low back pain. He said some yoga poses might be beneficial or feel good at the time but can lead to cumulative trauma in the discs. Also, yoga can aggravate back conditions in some people.

Dr McGill said people with bad backs should be discouraged from doing common yoga poses such as forward bending, toe touching, sit-ups and the child’s pose. Stretching is also to be minimised.

“Although stretches feel good, the underlying tissues often become sensitised and eventually sustain damage,” he said.

Experts caution against yoga for those with back issues. Photo: Getty

Furthermore, Dr McGill said, the whole idea of “flexibility” was misguided. Flexible people had no trouble doing yoga, he said, but he has found they have a higher incidence of back symptoms than those who are less flexible.

His philosophy is to adapt yoga to the individual and their body type.

“Each individual is different. Every single exercise should be justified and then modified if necessary to suit each person,” Dr McGill said.

At the University of Sydney, Professor Chris Mayer, co-author of a recent Lancet paper on back pain and recommendations for treatment, said yoga was effective for chronic, non-specific low back pain.

However, he said, all kinds of exercises had the potential to make back pain worse if they were not used skilfully and individualised to the patient.

“I think if you go to one of these modified programs that recognise that participants have various health problems, you can greatly reduce the chances of making things worse,” Professor Mayer said.

As a cautionary tale, consider New York’s Glenn Black, a master of yoga. He has had surgery for spinal stenosis, which he said had its origins in four decades of extreme backbends and twists.

Yoga, like other forms of exercise, is said to reduce stress, lower anxiety and improve sleep. For many, the benefits will outweigh any risks.

But for doctors to simply prescribe yoga to a patient with back pain is irresponsible. Unless it is an individualised program, it might make their back worse.