Metabolic abnormalities, including visceral adiposity, insulin resistance, hyperglycemia, hypertension, and dyslipidemia, occur together and are associated with excess caloric intake and inadequate physical activity. Approximately 66% of American adults are overweight, and almost half of all obese persons meet criteria for the 'metabolic syndrome', which substantially increases risk of developing diabetes and cardiovascular disease. Lifestyle and behavioral interventions reduce these risks, but many individuals with increased metabolic risk find it difficult to achieve and maintain weight loss and increased physical activity. Yoga is an ancient self-awareness system that combines the use of body postures, breathing, and mental focus. A recent review of the effect of yoga on cardiovascular risk factors found beneficial changes in metabolic risk factors. We have completed two pilot trials of Restorative yoga, a type of yoga that uses supported poses to induce a state of total relaxation without muscular strain. In a randomized controlled pilot trial of overweight and underactive individuals with the metabolic syndrome, we found that teaching Restorative yoga to persons with the metabolic syndrome is feasible, and adherence and retention were excellent. After 10 weeks of weekly yoga training, there were trends toward improvements in weight, waist circumference, and blood pressure in the yoga group compared to the wait-list control group. We propose a rigorous randomized controlled trial coordinated by the University of California, San Francisco (UCSF) with two clinical sites, UCSF and UC San Diego, to determine whether Restorative yoga vs. a stretching control group improves visceral adiposity, insulin sensitivity, glucose tolerance, dyslipidemia, and hypertension among 142 underactive adults with the metabolic syndrome. Participants will be randomized in two waves of 36 participants at each site for a 48-week trial. Participants in the yoga and control groups will participate in group classes twice per week for the first 6 weeks, once per week during weeks 7-12, and twice per month during weeks 13-24. After evaluation at 6 months, both groups will enter a 24-week maintenance phase and undergo a 12-month end-of-trial evaluation. We propose the following specific aims:
Aim 1 : To test the hypotheses that Restorative yoga decreases visceral adiposity (primary outcome) and improves features of the metabolic syndrome: insulin resistance, hypertension, glucose intolerance, and dyslipidemia (secondary outcomes) compared to a stretching control group after a 24-week intervention and after an additional 24-week maintenance period;
Aim 2 : To test the hypotheses that Restorative yoga reduces stress (the potential pathway resulting in improved visceral adiposity and the metabolic syndrome) compared to the stretching control group;
and Aim 3 : To test the hypotheses that reduced visceral adiposity improves inflammatory factors and an adipocytokine, a potential mechanism for the amelioration of the metabolic syndrome.
Persons with the metabolic syndrome are at high risk of developing type 2 diabetes and cardiovascular disease. We propose a randomized, controlled trial of Restorative yoga, a relaxing form of yoga to reduce metabolic risk factors in adults with the metabolic syndrome. If yoga is associated with improved metabolic risk factors, this would offer an inexpensive and safe alternative to diet and exercise to delay or prevent diabetes or cardiovascular disease.
