The New York Times article How Yoga Can Wreck Your Body sent journalist Willam J. Broad’s new book, The Science of Yoga, racing up Amazon’s list of best-selling yoga books – even before it was published. My copy has arrived and I’ve been reading his assessment of the “risks and rewards” of yoga this weekend.
The NYT article was undoubtedly a great piece of marketing; would it have got any publicity at all if it had been headlined “How Yoga Makes You Feel Good”? But after all the hype, what does Broad actually tell us about a scientific assessment of yoga? He certainly did his homework; over five years trawling through nearly a thousand scientific papers that have studied yoga over more than 100 years.
On the risks, Broad has definitely done a service in highlighting those posed by some yoga asanas (postures) and pranayama (breathing techniques), if not taught carefully and individually to students by knowledgeable teachers.
He gives a biological explanation for what many careful yoga teachers already know; postures that strain or put weight on the neck, such as shoulderstands and headstands, should not be taught in group classes at a “general” or “beginners” level. He explains why: there is a risk of damaging arteries supplying blood to the brain, causing nerve damage or stroke.
For the same reason, avoid taking the head too far back in postures such as Cobra and the Wheel, or turning the head too far round in spinal twists.
That’s not to say these postures are bad for us; in the chapter on “Mood”, he explains how inversions such as headstand and shoulderstand can be deeply relaxing, reducing physical stress responses and lowering blood pressure. It’s just that in a group class, of perhaps over-enthusiastic and inexperienced students, it is hard for a yoga teacher to ensure everyone is practising the postures safely.
It is beyond the scope of the book, but it would be useful to make a comparison with the risks associated with other physical activities; is yoga more risky than football, tennis, skiing, basketball, jogging – especially if played too hard for someone’s physical ability or not coached by a knowledgeable and sensitive teacher?
Only one chapter of the book covers risks; a further six chapters assess the evidence for the effects of yoga on health; athletic fitness; healing of injuries; psychological wellbeing; sex; and creativity. Some are stronger than others; the best are those where there is a wealth of scientific study to draw from.
The chapter on health asserts there is good evidence that yoga:
- reduces stress, with physiological benefits for blood pressure and the immune system
- aids cardiovascular health by raising levels of anti-oxidants in the blood (preventing cell damage) and reducing blood pressure, blood sugar, cholesterol and atherosclerosis (thickening of artery walls)
- slows physical aging by improving spine health and balance, thus preventing back and limb pain and falls; and, through stress reduction, slowing the “biological clock” in the DNA of cells.
On fitness, he concludes that yoga has no more beneficial effects on athletic fitness than regular walking; and that because it slows the body’s metabolic rate, yoga is not a powerful tool for weight loss. Although he adds that its capacity to encourage mindfulness, and awareness of desires could explain why many people claim yoga helps keep them in shape.
His understanding of the health benefits of yoga emphasise the power of asanas and pranayama – and their ability to cultivate physical and mental relaxation – to enable us to take control of some of the biological functions of the body, in particular the balance between the sympathetic (fight-or-flight) and parasympathetic (rest-and-digest) responses of the autonomic nervous system.
There is a wealth of evidence that while the fight-or-flight response is really useful when we need to escape an immediate danger (it enabled our forbears to close down bodily systems such as digestion and reproduction in order to focus on the biological necessities of running away very fast from a wild animal), to be constantly in such a stressed state causes long-term damage, for example to the immune system.
And yet many of us today live in a semi-permanent state of stress or anxiety, perhaps explaining why yoga is currently so popular.
In the chapter on “Mood” Broad likens yoga practice to gaining control of the accelerator and brake pedals of the body’s nervous system. He outlines scientific studies that have confirmed yoga’s power to tackle anxiety and depression. It “succeeds brilliantly at smoothing the ups and downs of emotional life,” he concludes.
The book is less convincing on subjects where the scientific evidence is more scarce: on sex and creativity, for example. And it barely touches on the spiritual and ethical aspects of yoga, areas I describe in a separate post here, and which the scientific method has yet to explore. Along the way it gives a readable and useful explanation of the history of modern yoga and its journey from magical and religious practice in the East to exercise classes in gyms throughout the West.
Understandably for a book about science, Broad focuses on the physical aspects of yoga and that which can be measured. But that is only half of the story of yoga. He concedes that science is crude. “It ignores much about reality to zero in on those aspects of nature that it can quantify and comprehend… No equation is going to outdo Shakespeare.”
So impressed is Broad with the health and healing power of yoga he envisages a possible future where yoga will be prescribed by doctors instead of drugs to help an aging population enjoy greater wellbeing in our extended years. But he comes with an agenda; for this to happen he wants greater medicalisation of yoga training and teaching, and with it greater regulation. This is something strongly resisted by many in the yoga community, particularly by those such the UK’s Independent Yoga Network, who fear that the spiritually liberating aspects of yoga will be lost if it is taken over and regulated by the physical fitness industry.
The quietening the body and mind through yoga brings a serenity and awareness in which it is possible to experience spiritual insight. This experience is no less a part of reality because it has not yet been explained by science.
For me this debate is fascinating and exciting; it’s where science and spirituality come face to face; the 400-year-old scientific approach that has done much to free us from dogma, and self-serving authority meets the universal and timeless yearning of the human soul for meaning.
Broad’s book shows us that science has begun to explain why people for thousands of years have benefited physically and psychologically from yoga. It does nothing to explain the internal spiritual landscape that is revealed by the practice of yoga and meditation. For that you need other books, such as David Fontana’s The Meditator’s Handbook or Jack Kornfield’s After the Ecstasy, the Laundry.