Background
Asthma is a lung disease. Asthma works in two ways. It that causes the airways to become inflamed (the body's response to injury and infection) and it causes the small tubes of the airways to tighten (called airway obstruction). The tightening of the tubes can happen in response to asthma triggers, such as animal fur or feathers, dust or pollen.
Asthma is very common worldwide and is a major public health problem due to the high healthcare costs associated with hospitalisation and medication. Breathing exercises have been used to treat people with asthma as a way of controlling the symptoms of asthma without medication. People use various breathing techniques to change their breathing pattern.
Review question
We wanted to find out how effective breathing exercises are for adults with asthma. We were most interested to know if breathing exercises improved people's quality of life (our primary outcome), and also if they helped improve asthma symptoms, hyperventilation (over-breathing), and lung function (our secondary outcomes).
Key results
We searched for randomised controlled trials. This means people were selected at random to try either breathing exercises or a control. We included education about asthma or usual asthma care as the controls.
We found 22 studies involving 2880 adults with mild to moderate asthma. The studies used different breathing exercises. Fourteen studies used yoga, four studies used breathing retraining, one study used Buteyko method, one study used Buteyko method and pranayama, one study used Papworth method and one study used deep diaphragmatic breathing. Twenty studies compared breathing exercises with normal asthma care and two compared breathing exercises with asthma education. Studies assessed quality of life, asthma symptoms and hyperventilation symptoms, number of acute exacerbations (flare-ups), lung function (breathing tests), and general practitioner (GP) appointments.
Several studies looked at our primary outcome, quality of life. The results showed an improvement in quality of life after three months in the breathing-exercises group. We found that breathing exercises probably did not help to improve asthma symptoms. However, breathing exercises did improve hyperventilation symptoms, when measured from four months after starting the exercises to six months. One lung function test, percentage of predicted FEV1 (the amount of air you can force from your lungs in one second) showed some improvement in the people who did breathing exercises.
Certainty of the evidence
We are moderately certain about the benefits of breathing exercises. However, we found some differences between the studies in terms of type of breathing exercises performed, number of participants enrolled, number and duration of sessions completed, outcomes reported and statistical presentation of data.
Conclusion
Breathing exercises may have positive effects on quality of life, hyperventilation symptoms, and lung function in adults with mild to moderate asthma.
The evidence is current to April 2019.
Breathing exercises may have some positive effects on quality of life, hyperventilation symptoms, and lung function. Due to some methodological differences among included studies and studies with poor methodology, the quality of evidence for the measured outcomes ranged from moderate to very low certainty according to GRADE criteria. In addition, further studies including full descriptions of treatment methods and outcome measurements are required.
Breathing exercises have been widely used worldwide as a non-pharmacological therapy to treat people with asthma. Breathing exercises aim to control the symptoms of asthma and can be performed as the Papworth Method, the Buteyko breathing technique, yogic breathing, deep diaphragmatic breathing or any other similar intervention that manipulates the breathing pattern. The training of breathing usually focuses on tidal and minute volume and encourages relaxation, exercise at home, the modification of breathing pattern, nasal breathing, holding of breath, lower rib cage and abdominal breathing.
To evaluate the evidence for the efficacy of breathing exercises in the management of people with asthma.
To identify relevant studies we searched The Cochrane Library, MEDLINE, Embase, PsycINFO, CINAHL and AMED and performed handsearching of respiratory journals and meeting abstracts. We also consulted trials registers and reference lists of included articles.
The most recent literature search was on 4 April 2019.
We included randomised controlled trials of breathing exercises in adults with asthma compared with a control group receiving asthma education or, alternatively, with no active control group.
Two review authors independently assessed study quality and extracted data. We used Review Manager 5 software for data analysis based on the random-effects model. We expressed continuous outcomes as mean differences (MDs) with confidence intervals (CIs) of 95%. We assessed heterogeneity by inspecting the forest plots. We applied the Chi2 test, with a P value of 0.10 indicating statistical significance, and the I2 statistic, with a value greater than 50% representing a substantial level of heterogeneity. The primary outcome was quality of life.
We included nine new studies (1910 participants) in this update, resulting in a total of 22 studies involving 2880 participants in the review. Fourteen studies used Yoga as the intervention, four studies involved breathing retraining, one the Buteyko method, one the Buteyko method and pranayama, one the Papworth method and one deep diaphragmatic breathing. The studies were different from one another in terms of type of breathing exercise performed, number of participants enrolled, number of sessions completed, period of follow-up, outcomes reported and statistical presentation of data. Asthma severity in participants from the included studies ranged from mild to moderate, and the samples consisted solely of outpatients. Twenty studies compared breathing exercise with inactive control, and two with asthma education control groups. Meta-analysis was possible for the primary outcome quality of life and the secondary outcomes asthma symptoms, hyperventilation symptoms, and some lung function variables. Assessment of risk of bias was impaired by incomplete reporting of methodological aspects of most of the included studies. We did not include adverse effects as an outcome in the review.
Breathing exercises versus inactive control
For quality of life, measured by the Asthma Quality of Life Questionnaire (AQLQ), meta-analysis showed improvement favouring the breathing exercises group at three months (MD 0.42, 95% CI 0.17 to 0.68; 4 studies, 974 participants; moderate-certainty evidence), and at six months the OR was 1.34 for the proportion of people with at least 0.5 unit improvement in AQLQ, (95% CI 0.97 to 1.86; 1 study, 655 participants). For asthma symptoms, measured by the Asthma Control Questionnaire (ACQ), meta-analysis at up to three months was inconclusive, MD of -0.15 units (95% CI −2.32 to 2.02; 1 study, 115 participants; low-certainty evidence), and was similar over six months (MD −0.08 units, 95% CI −0.22 to 0.07; 1 study, 449 participants). For hyperventilation symptoms, measured by the Nijmegen Questionnaire (from four to six months), meta-analysis showed less symptoms with breathing exercises (MD −3.22, 95% CI −6.31 to −0.13; 2 studies, 118 participants; moderate-certainty evidence), but this was not shown at six months (MD 0.63, 95% CI −0.90 to 2.17; 2 studies, 521 participants). Meta-analyses for forced expiratory volume in 1 second (FEV1) measured at up to three months was inconclusive, MD −0.10 L, (95% CI −0.32 to 0.12; 4 studies, 252 participants; very low-certainty evidence). However, for FEV1 % of predicted, an improvement was observed in favour of the breathing exercise group (MD 6.88%, 95% CI 5.03 to 8.73; five studies, 618 participants).
Breathing exercises versus asthma education
For quality of life, one study measuring AQLQ was inconclusive up to three months (MD 0.04, 95% CI -0.26 to 0.34; 1 study, 183 participants). When assessed from four to six months, the results favoured breathing exercises (MD 0.38, 95% CI 0.08 to 0.68; 1 study, 183 participants). Hyperventilation symptoms measured by the Nijmegen Questionnaire were inconclusive up to three months (MD −1.24, 95% CI −3.23 to 0.75; 1 study, 183 participants), but favoured breathing exercises from four to six months (MD −3.16, 95% CI −5.35 to −0.97; 1 study, 183 participants).