Twenty-three trials were included: 16 RCTs (about 1,049 participants) and seven non-randomised controlled trials (672 participants). The overall quality of the trials was medium to poor. Nine RCTs reported adequate randomisation methods, three reported blinding of outcome assessors or analysts, two reported an intention-to-treat analysis, and one reported adequate allocation concealment. Further quality assessment results were reported.
Self-reported measures: Five RCTs were of women with breast cancer; four showed a statistically significant benefit of yoga for state anxiety, compared with other forms of supportive therapy, education and counselling. Four RCTs were of healthy adults; two showed statistically significant benefits of yoga for state anxiety, compared with waiting-list controls, exercise, progressive muscle relaxation, or no treatment. One RCT was of patients with migraine headaches; a statistically significant benefit of yoga for state anxiety was reported, compared with self-care education.
No significant differences in state anxiety were found, in healthy people, between yoga and progressive muscle relaxation (one RCT) and no treatment (one RCT). No significant differences were found between yoga and waiting-list controls, in patients with lymphoma (one RCT) and patients with multiple sclerosis (one RCT). Effect sizes were reported to be small to medium.
Physiological parameters: One RCT of patients with breast cancer demonstrated a statistically significant decrease in cortisol with yoga, compared with individual support therapy sessions. One RCT of healthy people showed a statistically significant lower heart rate with yoga, compared with exercise. Another RCT of healthy people found no significant difference in blood pressure, when comparing yoga with progressive muscle relaxation.
The results for the non-randomised controlled trials were reported.