Moderate quality evidence that yoga reduces impact of asthma

Aarti Dhar, CNS Correspondent, India 
[First published in Theindiasaga.com
Researchers have found moderate-quality evidence that yoga probably leads to small improvements in quality of life and symptoms in people with asthma, but there is more uncertainty about potential adverse effects of yoga and its impact on lung function and medication usage. According to a new Cochrane Review, the results of randomised control trials (RCTs) 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. "RCTs with a large sample size and high methodological and reporting quality are needed to confirm the effects of yoga for asthma," researchers have said. They found15 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. Asthma is a common chronic disease that affects about 300 million people worldwide. A non-communicable disease (NCD) that causes periodic episodes of breathlessness and coughing, the WHO estimates 235 million people suffer from the disease, while the Global Burden of Diseases Study says the true number may be as high as 334 million.

The episodic onset of symptoms is called asthma attack. During an asthma attack, the bronchial tubes in the lungs become inflamed and narrow, making it difficult to breathe. Attacks can recur for asthmatics multiple times a day or week, with differing intensity, depending on the individual. Asthma is not curable, but through proper medication and appropriate management the disease’s burden can be reduced. In addition to access to medication that relieves both short-term and long-term symptoms, this means providing care to individuals with asthma in which patients are explicitly warned about avoiding inhaled substances and particles and other potential triggers of attacks. These triggers include irritants such as air pollution, tobacco smoke, indoor and outdoor allergens, and harmful chemicals in the workplace, as well as cold air, physical exercise, and emotional arousal.

Since 2015, United Nations has declared June 21 as International Yoga Day and first Tuesday of May is observed as Asthma Day. This year the day falls on May 3. Yoga, the popularity of which has expanded globally, has the potential to relieve some asthma-related problems. However, the effects of yoga for asthma need to be confirmed due to the inconsistent findings of existing studies.

Yoga originated from ancient India and remains an important aspect of India's diverse culture. Yoga includes such common components as breathing exercises (pranayama), postures (asanas), and meditation (dhyana). It is difficult to know exactly how many types of yoga are being practiced around the world, as different combinations of and variations in components could represent a 'new' type of yoga. To our knowledge, types of yoga include, but are not limited to, the following: aerial yoga, Ananda yoga, Anusara yoga, Ashtanga (or Astanga) yoga, Bhakti yoga, Bikram yoga (hot yoga), Chair yoga, Forrest yoga, Hatha yoga, ISHTA (Integral Science of Hatha and Tantric Arts), Iyengar yoga, Jivamukti yoga, Jnana yoga, Kali Ray TriYoga, Karma yoga, Kripalu, Kriya yoga, Kundalini yoga, Mantra yoga, Moksha, Power yoga, prenatal yoga, Purna yoga (integral yoga), Raja yoga, Restorative yoga, Sahaja yoga, Satyananda yoga, Sivananda yoga, stand-up paddle yoga, Svaroopa yoga, Swara yoga, Tibetan yoga, Viniyoga yoga, Vinyasa yoga, and White Lotus yoga.

As a holistic therapy, yoga contains no asthma-specific posture or breathing exercises. The exact mechanism by which yoga may affect asthma symptoms is not fully understood. However, several explanations have been proposed. The first explanation is related to the breathing pattern in yoga practice. One trigger of asthma attacks is frictional stress in airways, which could damage the airway wall, affect the dynamics of airway smooth muscle, and result in mast cell degranulation. Some studies have shown that the tidal volume and breathing rate decrease during yoga practice, which may interfere with the process that triggers asthma attacks.

Empirically, randomised controlled trials (RCTs) conducted in people with asthma have demonstrated that specific breathing exercises or techniques could help reduce acute exacerbations and rescue bronchodilator use as compared with no intervention, and could significantly improve quality of life as compared with asthma education. However, in a Cochrane review comparing breathing exercises with usual care or asthma education control, data were insufficient to be able to draw conclusions to this effect. Consequently, yoga practice involving breathing techniques may have some impact on asthma symptoms. Breathing exercises in yoga practice could help release suppressed emotion, reduce anxiety and self consciousness, and relax muscle tension. Secondly, certain yoga postures may help expand the chest and increase breath-holding time as well as vital capacity. This could logically have some effect on the lung function of people with asthma. Thirdly, by practicing yoga people with asthma may achieve a sense of relaxation and a positive mood, thus reducing the autonomic arousal factors. Meditation, a common component of yoga, may even help practitioners reach a state of complete mental silence ('Sahaja' in Sanskrit), which yoga advocates consider to be an innately therapeutic process beneficial to people with chronic diseases, including asthma. Meditation may also help the control and feedback of respiratory muscles which would be adversely affected by asthma attacks, researchers have said citing several earlier studies done on yoga.

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."

[First published in Theindiasaga.com

Aarti Dhar, Citizen News Service - CNS
3 May 2016

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