But is yoga necessarily good for everyone? I myself have suffered two quite serious injuries from yoga, one of which landed me in hospital. Over-ambition and untrained teachers are partly to blame, but some Indian holy men have another theory: they are alarmed at the way women are now taking to yoga, arguing that it was originally conceived for men and, if practised to an advanced level, can be an unsuitable exercise for the female anatomy.
Nobody would guess the possible hazards of yoga from its popularity. It is promoted as the panacea to 20th-century ills: gentle exercise that invigorates and de-stresses. Not only is it available in gyms, health centres and parish halls around the country, but is increasingly recommended by doctors. Clinical trials are being conducted in several British hospitals, looking at the mental, physical and stress-
reducing benefits of yoga.
Dr Pijush Saha is one GP who runs weekly classes in yoga and meditation at his surgery in Tilbury, Essex. He says yoga has helped reduce medication for many of his patients suffering from high blood pressure. 'I have about 190 patients who have attended the yoga clinic,' he says, 'but there is so much demand that I cannot see everybody.'
Another GP, Dr David Spiro, who has been practising yoga for 15 years, recommends it to patients as a relaxation technique. 'Clinical trials in Delhi have shown that yoga can have a dramatic effect on hypertension,' he says. 'Ever more people are looking for non-drug solutions to chronic health problems.'
Dr Spiro has just begun a trial at the Institute of Psychiatry in London, with psychiatrist Dr Peter Fenwick, looking at the physiological effects of yoga relaxation techniques. 'We are hoping to discover just what happens to the mind, the body and the brain when practising yoga,' he explains.
Clinical trials already conducted suggest that apart from reducing hypertension, yoga can correct posture, improve mood, clear up asthma and soothe away back problems. As well as being calming and relaxing, it is said to realign the skeletal system bringing the body back into harmony and symmetry. It increases suppleness, and has the advantage that anybody can do it to a basic level.
This is certainly what I believed when I took up yoga myself. Then came two serious injuries: one was an inguinal hernia, the other an agonising back condition which was corrected by chiropractic. There seems little doubt that they were caused by contorting myself into advanced yoga postures.
The reasons for the injuries were, I believe, twofold: one was that several of the teachers at the centre I attended were barely qualified, and as they were all volunteers we had many different ones. But the other, more serious reason was my own attitude: I found yoga deeply boring. Because of this, and because I had been very supple and gymnastic when young, every week I had to push myself that little bit further, into postures that had been beyond me the week before - just to liven things up a bit. Also, although you are constantly told that yoga is non-competitive, it can be very galling to be in classes week after week where everybody apart from you, it seems, can twist themselves into advanced postures. People tend to show off a lot at yoga classes.
Perhaps the first thing people should consider, when thinking about taking up yoga, is that it has to suit their personality. It is a practice more suited to those who want to calm down, relax and be still than it is to people who crave excitement and an adrenalin rush in their lives. Also, although yoga is popularly supposed to be gentle, it does have its Olympic, elitist aspect. Although slow and sedate, the dramatic postures you see illustrated in yoga books demand a high level of fitness, suppleness and skill. Many take years to achieve.
There are two aspects to yoga, distinct but interrelated - the breathing techniques, or pranayama, and the postures, or asanas. All the medical trials so far have concentrated only on breathing techniques, where you sit still, either cross-legged or, preferably, in the lotus position, and slow your breathing until a meditative state is reached. But there has been little research into the possible advantages of twisting yourself into the postures.
Although bringing the blood to the head, through such asanas as the headstand and shoulder stand, is supposed to improve circulation, aid digestive problems and prevent heart attacks, there is no medical evidence for this. Another of the controversies surrounding yoga is that it may not be suitable for women. Although, in the West at least, it is practised more by women, it was originally developed thousands of years ago as an aid to spirituality for men. Women only started doing yoga about 30 years ago.
Some Indian swamis (Hindu holy men) have professed themselves alarmed at the way women are now taking to yoga, as they believe the postures, if practised long and hard enough, will turn them into men. Not literally - but yoga eventually makes the body shape more masculine, lean and hard. Most teachers advise women not to do headstands (far easier than you might imagine) or shoulder stands during menstruation. Theoretically, the blood could go back into the body, causing problems, although there is no evidence for this either.
Could yoga be dangerous, for women or men? I spoke to Dr Robin Munro, founder of the Yoga Biomedical Trust, which instigates and supervises clinical trials into the ancient art. Dr Munro has just set up the Yoga Therapy Centre at the Royal London Homeopathic Hospital, which specialises in treating serious back problems.
A fellow of Girton College, Cambridge, Dr Munro became interested in researching the medical aspects of yoga when he discovered it cured his asthma - something no prescription medication had been able to do. He believes yoga should be taken seriously, taught properly and understood correctly.
'Although our research has shown many exciting benefits from yoga,' he says, 'such as delaying ageing and correcting chronic back problems, it has to be used with care. Doing the wrong kind of yoga, or being taught it in the wrong way, can make conditions worse. Quite a few people have had their backs permanently damaged by yoga.'
Dr Munro and his team are working with an orthopaedic surgeon so they can offer the right type of yoga for particular back conditions. 'Forward bending is bad for people with low back pain,' Dr Munro says, 'and backward bending is very bad for osteoarthritis. Most teachers don't realise this, and you can do your back a lot of damage by stretching it out of its usual range.'
It is not widely appreciated that there are many different types and schools of yoga. 'Those which concentrate on gentle relaxation and meditation, such as sahaja yoga or transcendental meditation, are unlikely to do physical harm,' says Dr Munro. 'But certain kinds, such as Iyengar and Sivananda yoga - where you can get into dramatic postures - are extremely strenuous. These demand a high level of fitness before you begin.'
Back pain is extremely common, he adds, yet very few yoga teachers know anything about it as it doesn't form part of their training. The fact is that many yoga teachers aren't properly trained at all, unfortunately, so injuries arise more frequently than they should.
'We are now working to establish links with the NHS,' says Dr Munro, 'so that properly taught yoga can become available as a standard therapy for certain conditions. There is now no doubt that the relaxation and breathing aspects of yoga can do wonders for hypertension, asthma, diabetes and digestive problems.'
A pilot study conducted last year at the Queen's Medical Centre at Nottingham University found that yoga significantly reduced cases of pre-eclampsia during pregnancy. 'All the clinical trials conducted so far have shown dramatic benefits from learning yogic breathing,' says Dr Munro, 'and it is hard to imagine any adverse side-effects. But as more and more people take up yoga as exercise, we need to conduct proper research into the good and bad effects of yoga postures.'
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