Randomised and non-randomised trials were eligible if they studied any type of yoga in patients with asthma. Trials of patients of any age, either gender, and with any duration or intensity of asthma, were eligible. Trials of breathing exercises that mimicked yogic breathing were excluded. All study designs were eligible for evaluating safety data.
In the included trials, the types, durations, and intensities of the yoga interventions varied or were not reported. The outcomes and control treatments varied, including sham, no intervention, usual care and relaxation exercises. The patients' asthma severity ranged from mild, to moderate-to-severe. Three trials were conducted in India, two in the USA, one in Australia, and one in Germany. Publication dates ranged from 1985 to 2009.
Two reviewers independently selected trials for inclusion.