title: Effect of restorative yoga vs. stretching on diurnal cortisol dynamics and psychosocial outcomes in individuals with the metabolic syndrome: the PRYSMS randomized controlled trial.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: University of California, San Francisco, CA 94115, USA. Electronic address: sarahmcorey@yahoo.com.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Corey
authors.affiliation: University of California, San Francisco, CA 94115, USA.
authors.forename: Elissa
authors.initials: E
authors.lastname: Epel
authors.affiliation: University of California, San Francisco, CA 94115, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Schembri
authors.affiliation: San Francisco State University, San Francisco, CA 94132, USA.
authors.forename: Sarah B
authors.initials: SB
authors.lastname: Pawlowsky
authors.affiliation: Synchrony Applied Health Sciences, Del Mar, CA 92014, USA.
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Cole
authors.affiliation: University of California, San Diego, CA 92093, USA.
authors.forename: Maria Rosario G
authors.initials: MR
authors.lastname: Araneta
authors.affiliation: University of California, San Diego, CA 92093, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Barrett-Connor
authors.affiliation: University of California, San Francisco, CA 94115, USA.
authors.forename: Alka M
authors.initials: AM
authors.lastname: Kanaya
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology; D000368:Aged; D002940:Circadian Rhythm / Q000502:physiology*; D003863:Depression / Q000150:complications / Q000378:metabolism; D003907:Dexamethasone; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D024821:Metabolic Syndrome / Q000378:metabolism* / Q000628:therapy*; D008875:Middle Aged; D052580:Muscle Stretching Exercises; D010912:Pituitary-Adrenal Function Tests; D012463:Saliva / Q000378:metabolism; D012944:Social Support; D013315:Stress, Psychological / Q000150:complications / Q000378:metabolism; D015013:Yoga / Q000523:psychology*; D055815:Young Adult
chemical_list: D003907:Dexamethasone; D006854:Hydrocortisone
keywords: Dexamethasone; Diurnal cortisol; Metabolic syndrome; Social support; Stress; Waking cortisol