A new Cochrane Review, published in the Cochrane Library today, suggests that yoga may have a beneficial effect on symptoms and quality of life in people with asthma, but effects on lung function and medication use are uncertain.

Asthma is a common chronic disease affecting about 300 million people worldwide. The many typical symptoms of asthma include wheezing, coughing, chest tightness and shortness of breath.

Yoga has gained global popularity as a form of exercise with general life-style benefits, and recent studies have investigated the potential of yoga to relieve asthma-related problems.

A new Cochrane Review summarizes the results of randomised trials and has found evidence that practicing yoga might be able to improve asthma quality of life and symptoms to some extent. However, researchers also warned that higher-quality studies with more participants would be needed to draw any firm conclusions about the effects of yoga.

The team of Cochrane researchers wanted to find out the effects of yoga in people with asthma.

They found 15 randomised controlled trials which involved 1,048 men and women. Most of the trials were conducted in India, followed by Europe and the United States. The majority of participants had mild to moderate asthma for six months to more than 23 years. Six studies looked into the effects of breathing alone during yoga exercise, whilst the other studies assessed the effects of yoga that included breathing, posture and meditation.

Most people continued to take their usual asthma medication while participating in the studies. The studies were conducted over a time period of two weeks to over four years.

The researchers found some moderate quality evidence from five studies that yoga exercise reduces the impact of asthma on people's quality of life. However, evidence about yoga's impact on the participants' lung function is more uncertain because the results varied. The effects of yoga on medication use and any side-effects of yoga are also uncertain, because only a few very small studies reported these outcomes.

Lead author, Dr Zuyao Yang from the Jockey Club School of Public Health and Primary Care, at the Chinese University of Hong Kong commented, "Our findings suggest that yoga exercise may lead to small improvements in asthma quality of life and symptoms. However, it is unclear whether yoga has a consistent impact on lung function and we don't yet know if yoga can reduce people's medication usage, or if there are any side-effects of yoga for people with asthma."

Deputy Co-ordinating Editor of the Cochrane Airways Group, Rebecca Normansell, added, "At present, we just don't have enough high quality evidence to determine the effects of yoga as a type of exercise for helping people manage their asthma. Because there is uncertainty about the effects of yoga on lung function and use of asthma medication, it's important that people with asthma continue to take their medication, as prescribed. The findings of this Cochrane Review will help people make more informed choices about their future treatment options."