Is Yoga Safe? A Comprehensive Meta-Analysis Says Yes

In 2012, William Broad’s sensationalist article, “How Yoga Can Wreck Your Body” and subsequent book, The Science of Yoga: The Risks and the Rewards, triggered a firestorm of debate about the danger of yoga postures. His exaggerated claims about the perils of the practice set off alarm bells for yoga students and instructors alike. Now, a new meta-analysis of randomized yoga studies suggests that yoga is as safe as “usual care or exercise.”

A team of European researchers identified 94 published articles in which adverse events were reported. Studies were restricted to randomized controlled trials (RCTs) published in any language in which participants receiving a yoga intervention were compared to those in a control group receiving either no-treatment, usual care, exercise, or psychological or educational interventions. Healthy adults as well as those diagnosed with a medical condition were included. Yoga interventions could be of any length and from any yoga tradition.

The researchers assigned adverse events into one of three categories: (1) intervention-related adverse events, (2) non-serious adverse events, and (3) serious adverse events. Serious events included situations that resulted in death, life-threatening circumstances, hospitalization, permanent damage or disability, the need for medical or surgical intervention, or birth defects. The remaining events were categorized as non-serious.

Only 111 of the 355 full-text articles, less than one-third of published RCTs (31%), included data on adverse events. It is not clear whether these data were collected but not reported, or not collected whatsoever.

These 111 articles represented 94 independent studies. These studies included a total of 8,430 participants with a mean age ranging from 10.1-84.5 years of age across all studies (median = 48.8 years). Participants were predominantly female (median = 75%) and Caucasian (median = 83.0%).  The majority of research was conducted in the United States (42) followed by India (26), Australia (8) and the United Kingdom (5).

Approximately two thirds of the articles (61%) specified the style of yoga on which the interventions were based. Of those, Iyengar yoga was the most frequently endorsed. Yoga asana (postures) was the predominant mode of treatment, with only 4 studies mentioning pranayama (breathing exercises). Yoga programs ranged in length from 1 day to 18 months, with a median duration of 10 weeks. Control groups ranged from no treatment or usual care (53) to exercise (26) to psychological or educational interventions (22) to other alternative forms of treatment including Reiki and herbal remedies.

Yoga Is As Safe As Usual Care

After comparing adverse event rates for all 94 studies, the researchers discovered that the frequency of intervention-related, non-serious and serious adverse events or dropouts related to adverse events were no different when comparing yoga to no care or usual care. There were differences between yoga and psychological and educational interventions, however. Specifically, more non-serious intervention-related events occurred in yoga groups when compared to psychological and educational interventions.

For participants assigned to a yoga group across all studies, 19 of 856 (2.2%) reported some form of intervention-related adverse events.  Non-serious events were indicated for 87 of 800 (10.9%) of yoga participants, and serious events were reported for only 6 of 1,019 (0.6%) individuals. This includes both healthy and medically diagnosed participants.

The authors conclude that, “the frequency and severity of adverse events associated with yoga in randomized controlled trials are comparable to levels associated with physical activity or regular care.” In addition, yoga interventions may have higher rates of non-serious adverse events than psychological or educational treatments that do not involve physical activity.  

Several key issues limit our ability to interpret these results. First, adverse events were only reported for approximately one-third of all published research trials. While we cannot assume that there was a greater frequency of injury in the nearly 70% of studies that did not include adverse event data, the possibility of bias cannot be ruled out. As such “the findings can only be regarded as approximate,” according to the authors.

Second, while the overall findings of this meta-analysis suggest that well constructed yoga interventions are generally safe, the lack of conclusive evidence is disappointing. In order to counter the claims of Broad and others who paint a grim picture of the danger of yoga asana (postures), it is essential that future yoga research provide detailed descriptions of the types of yoga interventions used, as well as a comprehensive accounting of all adverse events. Although this may seem to be a risky proposition for those involved in yoga research, it is critical that we develop detailed knowledge of any and all potential risks and benefits of offering yoga as therapy.
 

B Grace Bullock, PhD, E-RYT 500, is the Founding Director of the International Science & Education Alliance, a firm that provides strategic planning, research consultation and assessment design to support the empirically rigorous evaluation and sustainable implementation of programs in education, leadership, health and human services. Grace is an intervention scientist, psychologist, yoga educator and author who has worked extensively in integrated behavioral health settings. Her research, clinical practice, teaching and writing emphasize the incorporation of empirically supported psychotherapy with yoga therapy and mindfulness practices to relieve the symptoms of stress, trauma, anxiety, depression and other psychological illnesses, and to promote healthy relationships. She is Faculty at the Integrated Health Yoga Therapy therapist training program, and Professor of Yoga & Neuroscience at the Taksha University School of Integrative Medicine. Grace is the former Editor in Chief of the International Journal of Yoga Therapy and recipient of a Francisco J. Varela Research Award from the Mind & Life Institute. For more information contact Grace at bgracebullock@me.com.

Sources
Cramer, H., Ward, L., Sapter, R., Fishbein, D., Dobos, G. & Lauche, R. (2015). The safety of yoga: A systematic review and meta-analysis of randomized controlled trials. American Journal of Epidemiology: Advance Access Published June 26, 2015. DOI: 10.1093/aje/kwv071

Broad WJ. How yoga can wreck your body. http://www.nytimes.com/2012/01/08/magazine/how-yoga-can-wreckyour-body.html?pagewanted=all&_r=0. Published January 5, 2012.