Cluster Randomized Controlled Trial of a Standard Versus Postures-Only Yoga Session: Potential Self-Regulatory and Neurophysiological Mechanisms of an Ancient Practice.

Background: It is well-recognized that maintaining a regular yogic practice is associated with numerous physical and psychological health benefits. However, few studies have explored the possible psychological and neurophysiological mediators through which the component parts of yoga-ethics, breath regulation, postures, and meditation-work to produce salutary effects.

Purpose: To address this gap, we conducted a cluster randomized trial to test the following set of theory-based mechanisms: emotion regulation for ethics, self-control for breath regulation, discomfort and distress tolerance for postures, and mindfulness for meditation. We also explored yoga's effects on the autonomic nervous system by examining salivary acetylcholinesterase levels.

Methods: Participants (N = 260) were randomly assigned in clusters (n = 37) to a single, hour-long standard or postures-only yoga class.

Results: Findings suggest that a single yoga class may confer both psychological and neurophysiological benefits, yet there were few differences between the two types of yoga classes. Pre- to post-session main effects of time, all in the expected direction, emerged for five of eight theoretical mediators, as well as for salivary acetylcholinesterase levels. Time X condition interactions observed for three of the mediators-cognitive reappraisal, discomfort tolerance, and expressive suppression-along with findings from the exploratory mediation analysis suggest potential unique benefits of the two yoga sessions for certain outcomes.

Conclusions: Additional studies are needed to replicate these results and to test other potential mediators and/or primary outcomes through which yoga might work to promote health.