How does yoga reduce stress? A systematic review of mechanisms of change and guide to future inquiry

Abstract

Yoga is increasingly used in clinical settings for a variety of mental and physical health issues, particularly stress-related illnesses and concerns, and has demonstrated promising efficacy. Yet the ways in which yoga reduces stress remain poorly understood. To examine the empirical evidence regarding the mechanisms through which yoga reduces stress, we conducted a systematic review of the literature, including any yoga intervention that measured stress as a primary dependent variable and tested a mechanism of the relationship with mediation. Our electronic database search yielded 926 abstracts, of which 71 were chosen for further inspection and 5 were selected for the final systematic review. These five studies examined three psychological mechanisms (positive affect, mindfulness and self-compassion) and four biological mechanisms (posterior hypothalamus, interleukin-6, C-reactive protein and cortisol). Positive affect, self-compassion, inhibition of the posterior hypothalamus and salivary cortisol were all shown to mediate the relationship between yoga and stress. It is striking that the literature describing potential mechanisms is growing rapidly, yet only seven mechanisms have been empirically examined; more research is necessary. Also, future research ought to include more rigorous methodology, including sufficient power, study randomisation and appropriate control groups.

Yoga research review

“…In this study practitioners of two years or more were noted to have higher levels of antioxidants than a control group. In a systematic review of mechanisms underlying stress reduction by yoga, the four biological mechanisms identified were the posterior hypothalamus (the initial point in the cortisol release pathway), elevated cortisol, increased interleukin-6 (as a pro-inflammatory cytokine), and Creactive protein (another pro-inflammatory cytokine) [54]. In anther systematic review on yoga for stress management, 17 studies met inclusion criteria and of those 17, 12 showed positive psychological and physiological outcomes following a yoga intervention [55].…”

Evaluation of a Specialized Yoga Program for Persons Admitted to a Complex Continuing Care Hospital: A Pilot Study

“…This construct has been identified in the yoga literature as one of seven possible mediators of yoga and stress; other mediators include psychological (positive self-affect and mindfulness) and biological (activity in the posterior hypothalamus and inflammatory and endocrine responses: C-reactive protein, Interleukin-6, and cortisol) pathways for therapeutic effects [104]. This is the first study to date that demonstrated the mediating role of self-compassion on psychological changes in a population experiencing medical concerns who participate in a yoga program.…”

“…Targeting self-compassion in the content and philosophy portions of the yoga interventions may enable researchers to further explore its mediating role of this construct on other psychological or physical experiences prevalent in this population. Trials that seek to further illuminate processes that underlie therapeutic gains may wish to use measures of self-regulation, self-compassion, stress, and positive affect alongside neuroendocrine-inflammatory markers of physiological status [104]. Evaluation of how these variables interact with pain-related constructs associated with the fear-avoidance model of chronic pain (e.g., chronic pain acceptance, pain-related disability, fear of pain, pain anxiety, and pain self-efficacy) may be warranted to better understand the converging impacts that result in distress and disability and with the end purpose to improve health and well-being.…”

Developing a Small Theory of Treatment of Yoga

“…Their schema attempts to reconcile both peripheral and central mechanisms by which yoga brings about its effect [7]. Riley and Park identify biological & psychological theories to explain the action of yoga [20]. Singh offers psycho neuro endocrine immunological basis for yoga action [21].…”