The Cochrane Review identified moderate-quality evidence that yoga improves symptoms and life quality for people with asthma.
Yoga is a popular mind and body practice that typically involves a combination of physical postures, breathing exercises and meditation or relaxation.
According to the National Center for Complementary and Integrative Health (NCCIH) - a part of the National Institutes of Health (NIH) - around 21 million adults in the United States practice yoga, making it one of the most commonly used complementary health practices in the country.
The popularity of yoga is perhaps unsurprising, given the wealth of health benefits the practice has been associated with. These include reduced stress, anxiety, depression, and blood pressure, as well as improvements in back pain and overall physical fitness.
While previous research has suggested that yoga may also benefit people with asthma, the researchers of this latest review note that other studies have found limited or no benefits.
"Such information may confuse people with asthma when they are deciding whether or not to devote time and resources to the practice of yoga," say the researchers, including lead author Dr. Zuyao Yang, of the Jockey Club School of Public Health and Primary Care at the Chinese University of Hong Kong.
More high-quality evidence of yoga's asthma benefits required
In an attempt to gain a better understanding of whether yoga benefits people with asthma, Dr. Yang and colleagues conducted a systematic review of 15 randomized, controlled trials involving 1,048 adults, most of whom had mild to moderate asthma.
- Around 25 million people in the U.S. have asthma
- Asthma cost the U.S. around $56 billion in 2007
- In 2008, more than half of Americans with asthma had an asthma attack.
Ten of the studies assessed the impact of yoga interventions that incorporated posture, breathing, and meditation, while five of the studies included yoga that solely focused on breathing.
The majority of participants continued to use their usual asthma medication during the study periods, which ranged from 2 weeks to over 4 years.
The researchers identified some moderate-quality evidence that yoga reduced some symptoms for people with asthma and improved overall quality of life.
However, the team was unable to identify sufficient evidence to suggest that yoga improves lung function, as studies investigating that factor produced varied results.
Additionally, the researchers were unable to determine whether yoga can reduce the need for asthma medication and whether the practice leads to any side effects, noting that few of the studies assessed these outcomes.
The researchers say more high-quality evidence of the impact of yoga on people with asthma is needed before the practice can be recommended as an additional treatment option.
"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."
Rebecca Normansell, deputy coordinating editor of the Cochrane Airways Group