Is one yoga style better than another? A systematic review of associations of yoga style and conclusions in randomized yoga trials
Introduction
Yoga is gaining increased popularity as a therapeutic practice. More than 20 million Americans (9% of the population of the United States of America) reported they practiced yoga in 2012. More than two thirds of practitioners utilized yoga explicitly to improve their health status.1 In the United States of America and Europe, yoga is most often associated with physical postures (asanas), breathing techniques (pranayama) and meditation (dhyana).2 A large variety of different yoga styles have emerged that put varying focus on physical and mental practices.2, 3 It is often claimed that the diverse yoga styles differ in terms of efficacy and safety in improving the practitioners’ health.4 However, these claims are rarely based on sound scientific evidence. Thus, the aim of this analysis was to estimate how far results and conclusions of randomized controlled trials (RCTs) on yoga differ between different yoga styles.
Section snippets
Methods
This was a secondary analysis of a previously published bibliometric analysis of yoga RCTs.5 Reporting is in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines,6 where applicable. But because PRISMA is designed as a guideline for efficacy reviews assessing differences between interventions,6 and this review has used a slightly different approach (identifying associations of study characteristics with study conclusions), not all PRISMA
Study characteristics
The complete results of the literature search have been published elsewhere.8 This review included a total of 306 RCTs9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103
Discussion
As previously reported, more than 90% of all 306 published RCTs on yoga reached positive conclusions.8 This secondary analysis found that the proportion of positive, neutral or negative conclusions was independent of the applied yoga style. This might be interpreted as demonstrating that the efficacy of yoga does not depend on the specific yoga style that was used but that all (or most) yoga styles can be regarded as equally effective. However, it should be noted that most yoga styles were
Acknowledgments
This review was supported by a grant from the Rut- and Klaus-Bahlsen-Foundation. The funding source had no influence on the design or conduct of the review; the collection, management, analysis, or interpretation of the data; or often in the preparation, review, or approval of the manuscript. The authors would like to thank Jana Hochstein, Essen, Germany, for her assistance in data extraction; Dr. Petra Klose, Essen, Germany, and Dr. Hoda Azizi, Mashhad, Iran, for their assistance in assessing
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