Yoga: Towards an Evidence-Based Practice

A search of yoga science returns over a hundred million results on Google. Yet, a 2014 scoping review of yoga intervention components and study quality by Elwy and colleagues concluded that yoga is less than scientific and highlighted the inadequate reporting and methodologic limitations of current yoga intervention research. What is getting in the way of yoga becoming an evidence-based practice?

To start with, yoga resists definition. Yoga can be postures, meditation, breathing techniques, paying attention, or all of the aforementioned, to name a few possibilities. Yoga is difficult to pinpoint because it is an ever-evolving practice that changes based on the times in which and by whom it is practiced and taught. Further, the most effective yoga interventions are individualized, which “makes it incompatible with gold standard double-blind research studies from the get-go,” says Carol Horton, Ph.D., author and co-editor of two books on contemporary North American yoga.

Formal yoga research needs to start "paying careful attention to the duration, frequency, dose, location of yoga, additional emphases of yoga, instructor training, home practice description, and the potential sources of bias that can result in low-quality yoga intervention studies," conclude Elwy and colleagues. Yet, moving yoga towards an evidence-based practice is not and should not be the same as medicalizing yoga, which largely misses the point of yoga, says Doug Keller, distinguished professor in the Master of Science in Yoga Therapy program at the Maryland University of Integrative Health. He adds that researchers will have to be clear and specific about what aspects and practices they choose to study, and remain cognizant that this is a selective choice, and cannot necessarily be generalized into conclusions about yoga itself.

That's why Laura Schmalzl, Ph.D., from the Division of Behavioral Medicine at the University of San Diego School of Medicine, prefers the term "yoga-based practices" (YBP) in her research rather than the all-encompassing “yoga.” "We need to be pragmatic and operationalize the different aspects of YBP in order to study, measure, and understand the physiological, neurological, and psychological mechanisms that underlie their effects. The aim of formal yoga research should not be to prove that YBP work but to investigate how they work, so that they can be more efficiently applied to different populations," says Schmalzl.

The yoga industry has seen a proliferation of styles, studios, and yoga lifestyle products and services that are relentlessly marketed to consumers in “a confusing mess of proprietary claims reflexively attributed and accepted as yogic wisdom and privileged insight”, says Keller. The sheer variety of yogic practices, styles, and approaches also complicates researchers’ task in how best to define a consistent intervention that is comparable across studies.

The Yoga Journal’s 2012 Yoga in America survey shows that modern practitioners mostly seem to consume yoga to improve flexibility (78.3%) as well as for general conditioning (62.2%), stress relief (59.6%), and overall health (58.5%). However, there is a significant minority that practices yoga to improve mental health (36.7%) and for spiritual development (31.7%). People seem to be turning to yoga in a quest for pain relief, self-improvement and self-care, and better functioning on both physical and metaphysical levels.

This begs the question: do academic researchers on yoga really know how to study yoga in ways that are directly relevant to practitioners? “We don't even understand the science of stretching thoroughly yet, let alone the precise nature of the brain-body connection,” notes Horton. By understanding what yoga is good for, the field can work to create the conditions in which more can share in its benefits. Schmalzl agrees that yoga research is in its infancy, and that current scientific studies do not yet have enough direct applications in practical terms for yoga practitioners. Equally, she says, researchers, teachers, and practitioners need to learn to talk to each other so that studies are more relevant to practitioners’ concerns, and to ensure that scientific findings make it into yoga teacher training curricula. 

Yoga and allopathic medicine should neither be in competition, nor try to co-opt each other. The answer lies in the middle where yoga and medicine complement and communicate with each other. To quote Carl Sagan, “Absence of evidence is not evidence of absence.” Yoga is experientially valuable to people who practice it. But to become truly modern and to remain a relevant modality, yoga needs to take evidence seriously. 

Sources:

Elwy, A. R., Groessl, E. J., Eisen, S. V., Riley, K. E., Maiya, M., Lee, J. P., Sarkin, A., & Park, C. L. (2014). A Systematic Scoping Review of Yoga Intervention Components and Study Quality. American Journal of Preventive Magazine, 47(2), 220–232. Cited from http://www.ajpmonline.org/article/S0749-3797%2814%2900151-2/fulltext

Yoga Journal (2012). Yoga in America. Yoga Journal Magazine. Cited from personal copy.