The Science of Yoga: The Risks and the Rewards by William J. Broad

My rating: 3 of 5 stars

I brought a great deal of interest and enthusiasm towards this subject as I began reading this book. As I proceeded to read, my feelings about The Science of Yoga became much more mixed. At its best, the book shows the state of scientific research on yoga and crushes myths that are deeply ingrained, and it points out risks of which yogis and yoginis should take notice. At its worst, it is sensationalism run-amok–suggesting hugely expensive solutions to issues that are either relatively small problems or that the author fails to prove are really problems at all. Put more simply, at its best it’s outstanding, but at its worst it’s tripe. What I will say about this book is the same thing that its author says about yoga, which is that—on balance—it does more good than harm.

The book is arranged into seven chapters, each of which discusses the scientific research on a different dimension of controversial beliefs about yoga. These include the historic claims of supernatural yogic abilities, the issue of whether yoga increases cardiovascular health, the role of yoga in mental health and well-being, the safety of practicing yoga, the role of yoga in healing, the sexual claims of yogis, and whether yoga enhances creativity. It is written in a scholarly format, heavily end-noted and with bibliographic citations. There is front matter giving information about key people, time lines, and yoga styles in outline form.

In an afterword, Broad points out that this has been his most controversial book to date. I can see why, but, to be fair, I’m sure much of the criticism is unfairly based on a failure to read the book or a desire for the author to treat many of yoga’s mythical aspects as science (as many of its practitioners do.) The former problem was exacerbated by the fact that a single chapter excerpt was published in the New York Times as a teaser for the book. Designed to spark controversy (always good for readership), it was one of the most negative of chapters—the one dealing with yoga injuries. Some who took umbrage probably didn’t realize that Broad is a yoga practitioner, and that there are chapters that are overwhelmingly positive on yoga (e.g. the chapter on “mood” which deals with yoga’s influence on psychology has mostly great things to say about the discipline.) While all of the chapters combine a mix of good and bad news, one comes away from some of them seeing a positive picture of yoga and others with a negative one. In the first half of the book it seems as though chapters may have been arranged to alternate positive and negative dimensions.

Of course, there will also be people who are outraged because of the discussions of the debunking of the con games of their beloved yogis, or for a failure to discuss the critical importance of things like Chakra fluffing. It should be noted that Broad doesn’t deride or mock such spiritual beliefs, he more or less ignores them beyond the occasional off-hand mention—as one would expect in a book about science.

My primary criticism with The Science of Yoga is a common one consideration of problem-solving utilizing public policy (not just with respect to yoga), which is to become so impassioned about a problem that you lose all sight of cost-benefit considerations or the negative feedback effects incentivized by your “solutions.” The problems about which Broad gets so exercised as to suggest an overhaul of yoga as we know it, largely fall into two categories. First, there are problems that are exceedingly rare but catastrophic for in individual involved. This is exemplified by the apparent heightened incidence of strokes among individuals engaged in certain inversions (e.g. a shoulder stand in which the neck is under compression.)

In an interesting turn away from science, Broad makes assumptions in the face of lack of evidence about the incidence of stroke in yoga practitioners. He assumes that yogis have at least the same incidence of stroke due to vertebral artery injury as the general population because of inversions and other yogic activities that put pressure on blood vessels in the neck. He does make clear that it’s just a guess, but one could equally well speculate that those who practice yoga suffer a diminished rate of such strokes because of greater flexibility and strength in the neck. (For the most part the human body is an anti-fragile system, i.e. it grows stronger when subjected to stresses—up to a point—than when shielded from stresses.) While he does call for increased study of the issue, he’s also simultaneously calling for expensive reforms. In essence, he’s calling for a solution before awaiting the evidence that there’s actually a real problem. Stroke is the 800 pound gorilla of the risks the Broad writes about in terms of damage, and so it’s not surprising that he paints the risk in ominous terms. He criticizes the Yoga Journal for dismissing it as a “minuscule number of cases”, but even taking his estimate of 300 (and realizing it could be much lower and is compared to 800,000 cases of stroke per year in the US according to the CDC) “minuscule” does not sound that out of line in a country of 314 million people.

Second, there is the issue of bad information being spread by yoga teachers and authors either because they don’t know any better or because they have an incentive to deceive. This is exemplified by the widespread notion that yoga (and particularly pranayama— breathing exercises) increases one’s cardiovascular fitness. Is it wrong? Yes, but it’s not clear that this propagation of bad information has hurt anybody. That may sound harsh, but—think about it–many people lead long and fruitful lives believing things that aren’t true. Now you may say, “Yes, but people who believe the Earth is flat can’t get hurt believing that, but yoga practitioners can be hurt by wrong information.” I would agree that some wrong information could be damaging, but consider the example given, which–I might add–is one of the main thrusts of Broad’s book. If it were the case that many people got fat because they thought yoga would help their cardio when instead it decreased their metabolism (as the evidence suggests it does), then no one would believe the myth. The idea wouldn’t have the strong hold that it does. What happens more often is that people either lose weight because they stress and eat less or they stay the same—either way they haven’t been hurt any more by bad information. Even if someone came to yoga to lose weight and gained some, they will abandon yoga and go to Zumba or Taebo with greater flexibility and probably a diminished risk of injury for having done yoga.

By spreading information about the risks and the state of scientific understanding of them Broad is doing good work. However, he goes on to suggest that we need lots of bureaucrats to monitor and license yoga and that we need much more rigorous requirements for yoga teachers than the 200 or 500 hour Yoga Alliance certifications that currently exist (or the teaching certificates issued by the gurus or teacher trainers of various styles of yoga), and herein lies two problems. It’s not clear that a problem exists to merit such an expensive solution.

First of all, many of the worst cases that he points out were people engaged in questionable practices on their own. I’m sorry for my frankness, but you can’t regulate stupid out of existence. There was one kid who sat for hours in Vajrasana (sitting on haunches), one who fell asleep in a forward bend, and another who had a stroke after holding a shoulder stand on a hard surface for hours. Now, my experience may not be as extensive as others, but I’ve attended yoga classes in the US, India, and Thailand. I’ve had teachers tell me to hold a pose for 5 deep breaths. I’ve even had teachers tell me to hold a pose for 10 deep breaths. No teacher has ever said to me, “Hold that pose for four hours or until you have a stroke, whichever comes first.” Even teachers with a couple hundred hours of instruction and a couple hundred more of experience don’t—as a rule—give patently stupid advice. (To the degree that there are rare exceptions, thinking that no teacher would ever again give a piece of bad advice if they just all had PhDs is a little presumptuous.)

The major problem with Broad’s suggestion of a need to overhaul the system and install bureaucratic gatekeepers and overseers and to make teachers jump through vastly more educational hoops is that it increases the cost of doing yoga with a teacher. Now, I know that yoga is associated with relatively affluent people, but—believe it or not–there are yoga practitioners who aren’t SUV-driving, Abercrombie&Fitch-wearing, maid-hiring suburbanites. If the monthly cost of attending yoga class goes from tens of dollars to hundreds of dollars because every yoga teacher has to have a PhD in Kinesiology and every studio has to comply with the extensive regulations and licensing fees of the newly formed Department of Yoga Management, then many people who are happy with the level of instruction they are currently getting are going to be emulating books and videos and injury rates could actually go up.

Another example of a “problem” that is not definitively shown to be a problem is Broad’s extensive criticism of an author of a popular book on yoga (i.e. Larry Payne) for using a Ph.D. designation that was from a southern Californian diploma-mill. While there is something objectionable about putting a PhD behind one’s name that wasn’t justly earned, it’s not at all clear that this was a problem. One expects to hear how Larry Payne left a pile of wrecked souls in his wake. However, while Broad devotes pages to ridiculing Payne for putting PhD after his name, the few mentions of the Payne’s interactions with others suggest that he helped them get healthier (e.g. Dr. Ursatine) and that he furthered the state of his professional field. The implication being that the credential matters vastly more than the individual’s experience and diligence. Interestingly, Dr. Fishman (for whom Broad has nothing but kind words—presumably because he holds an MD) is quoted as speaking glowingly about Payne and his contributions to the field.

Another example of sensationalism can be seen in the chapter on sexuality. While we would expect this chapter to be entirely about the claims of yoga being able to enhance one’s sex life, a fair amount of it is devoted to pointing out instances of lecherousness among yogis. I’m not saying that it’s bad to point out bad behavior of gurus in terms of harassing or molesting their female students, but unless there’s some evidence that this inclination is tied the sexual practices of yoga, this would seem to be the wrong venue for the discussion. In other words, if yogis are no more lecherous on the whole than other teachers or coaches, then it would seem that mention of this issue is just to titillate. If yogis are uncontrollable horn-dogs because of yogic practices, then fine, but you’ve got to establish that there’s evidence for that somehow.

Overall, I’d recommend that individuals interested in the scientific literature on yoga read this book. It provides a good overview of the literature, and is well-cited. The books weakness comes from insisting that a large number of mole hills are really the Himalayas. These mole hills can be addressed with education, but can never be eliminated. Suggesting we upend the apple cart to produce “solutions” to marginal problems is ridiculous. We may think a world in which there was never another fatal traffic accident would be nice, but I assure you we would not want to live in the world in which all the actions were taken necessary to achieve said goal. If one compares the extrapolated estimates of hospital visits for yoga injuries, they are really quite few and we have no reason to believe that the vast majority aren’t life-threatening or permanently disabling.

For me it would have been a great book if it laid out the risks and rewards, and suggested caution. Of course, then it probably wouldn’t have gotten any more attention than the many books that already exist on the subject of yoga injuries, so maybe some good can come of Broad’s implication that going to the yoga studio is akin to storming the beaches at Normandy and that we need to stop the horrors or yoga practice.

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