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I’m generally a pretty skeptical guy. If someone tells me that X really works, but it can’t be verified by science because science is just one way of understanding things, I roll my eyes. But bear with me here. A couple of years ago, I interviewed a guy named Timothy McCall, the author of Yoga as Medicine, for an article about yoga research. He was a smart guy with some very interesting things to say, and I still get occasional e-mail updates from his website. The latest includes a link to this article, from the Spring 2011 issue of Yoga Therapy Today, by Nina Moliver, called “Yoga Research: Yes, No, or How?”
The article is a pretty wide-ranging look at the current debate (in yoga circles) about how yoga and science fit together. A couple of points caught my attention. First, McCall and Moliver argue, yoga is a very slow healing technique:
[E]ven six months is a drop in the bucket for a Yoga practice. By privileging short-term studies and standardized protocols, we are forever studying beginners, [and] we are systematically underestimating the healing potential of Yoga in our research…
The bigger argument is that randomized, controlled trials — of any length — to study yoga don’t work, for various complex, holistic reasons that don’t sound very convincing to me. The alternative is observational studies. And as it happens, Moliver completed an award-winning PhD thesis at Northcentral University last year that used an observational design — an online survey — to study yoga in 211 female yoga practitioners plus 182 controls. Observational studies have a lot of problems, in particular the inability to distinguish between cause and effect, as Moliver acknowledges:
For example, if a researcher didn’t randomly assign the participants, it is not possible to know if Yoga practitioners are happier because they practiced Yoga, or if people who were happier were naturally attracted to starting a Yoga practice.
But there are still ways of extracting useful data. For example, if you see a dose-response effect — the longer people have been yoga-ing, the happier they are — that’s pretty suggestive. And as for those confounding variables:
For the Yoga practitioner, these so-called confounders — a healthier diet, a simpler lifestyle, more time outdoors, more kindness and compassion, more loving relationships, more bike-riding, a better path to right livelihood — are not confusing. They are mutually enhancing and reinforcing.
In other words, who cares if you end up happier and healthier because you’ve aligned energy flows in your body or simply because you’ve spent more time being physically active and mindful — the result is what matters. And indeed, Moliver’s study did see evidence of a dose-response relationship in her subjects, some of whom had been practicing yoga for as a long as 50 years. (I’m hoping the study will be published, as the abstract isn’t very revealing about the “range of intercorrelated wellness measures” that demonstrated the dose-response effect.)
This all sounds very reasonable to me — and in fact, it’s very reminiscent of Paul Williams’ National Runners’ Health Study, which takes a similar observational approach (albeit with more than 100,000 subjects) to tease out dose-response relationships that would be nearly impossible to detect with conventional short-term intervention studies.
One caveat: this approach tells us what works, but it doesn’t tell us how it works. You can’t take an observational study that finds health benefits from yoga and conclude that this proves that we can indeed control the circulation of energy flow in our bodies. To make claims about cause and effect, you really do need proper randomized trials. Notably, Moliver’s study didn’t see any difference between different types of yoga: just doing it, and keeping at it for long periods of time, correlated to better levels of psychological and physical well-being.