Effect of restorative yoga vs. stretching on diurnal cortisol dynamics and psychosocial outcomes in individuals with the metabolic syndrome: The PRYSMS randomized controlled trial.

Author: Corey SM1, Epel E2, Schembri M2, Pawlowsky SB3, Cole RJ4, Araneta MR5, Barrett-Connor E5, Kanaya AM2.
1University of California, San Francisco, CA 94115, USA. Electronic address: sarahmcorey@yahoo.com. 2University of California, San Francisco, CA 94115, USA. 3San Francisco State University, San Francisco, CA 94132, USA. 4Synchrony Applied Health Sciences, Del Mar, CA 92014, USA. 5University of California, San Diego, CA 92093, USA.
Conference/Journal: Psychoneuroendocrinology.
Date published: 2014 Jul 21
Other: Volume ID: 49C , Pages: 260-271 , Special Notes: doi: 10.1016/j.psyneuen.2014.07.012 , Word Count: 319

Chronic stimulation and dysregulation of the neuroendocrine system by stress may cause metabolic abnormalities. We estimated how much cortisol and psychosocial outcomes improved with a restorative yoga (relaxation) versus a low impact stretching intervention for individuals with the metabolic syndrome.
We conducted a 1-year multi-center randomized controlled trial (6-month intervention and 6-month maintenance phase) of restorative yoga vs. stretching. Participants completed surveys to assess depression, social support, positive affect, and stress at baseline, 6 months and 12 months. For each assessment, we collected saliva at four points daily for three days and collected response to dexamethasone on the fourth day for analysis of diurnal cortisol dynamics. We analyzed our data using multivariate regression models, controlling for study site, medications (antidepressants, hormone therapy), body mass index, and baseline cortisol values.
Psychosocial outcome measures were available for 171 study participants at baseline, 140 at 6 months, and 132 at 1 year. Complete cortisol data were available for 136 of 171 study participants (72 in restorative yoga and 64 in stretching) and were only available at baseline and 6 months. At 6 months, the stretching group had decreased cortisol at waking and bedtime compared to the restorative yoga group. The pattern of changes in stress mirrored this improvement, with the stretching group showing reductions in chronic stress severity and perseverative thoughts about their stress. Perceived stress decreased by 1.5 points (-0.4; 3.3, p=0.11) at 6 months, and by 2.0 points (0.1; 3.9, p=0.04) at 1 year in the stretching compared to restorative yoga groups. Post hoc analyses suggest that in the stretching group only, perceived increases in social support (particularly feelings of belonging), but not changes in stress were related to improved cortisol dynamics.
We found significant decreases in salivary cortisol, chronic stress severity, and stress perception in the stretching group compared to the restorative yoga group. Group support during the interactive stretch classes may have contributed to these changes.
Copyright © 2014 Elsevier Ltd. All rights reserved.
Dexamethasone; Diurnal cortisol; Metabolic syndrome; Social support; Stress; Waking cortisol

PMID: 25127084