Effect of yoga breathing exercises (pranayama) on airway reactivity in subjects with asthma.

The effects of two pranayama yoga breathing exercises on airway reactivity, airway calibre, symptom scores, and medication use in patients with mild asthma were assessed in a randomised, double-blind, placebo-controlled, crossover trial. After baseline assessment over 1 week, 18 patients with mild asthma practised slow deep breathing for 15 min twice a day for two consecutive 2-week periods. During the active period, subjects were asked to breathe through a Pink City lung (PCL) exerciser--a device which imposes slowing of breathing and a 1:2 inspiration:expiration duration ratio equivalent to pranayama breathing methods; during the control period, subjects breathed through a matched placebo device. Mean forced expiratory volume in 1 s (FEV1), peak expiratory flow rate, symptom score, and inhaler use over the last 3 days of each treatment period were assessed in comparison with the baseline assessment period; all improved more with the PCL exerciser than with the placebo device, but the differences were not significant. There was a statistically significant increase in the dose of histamine needed to provoke a 20% reduction in FEV1 (PD20) during pranayama breathing but not with the placebo device. The usefulness of controlled ventilation exercises in the control of asthma should be further investigated.