Breathing Exercises as Adjunct Therapy in Adult Asthma: A Systematic Review

Background Persistent symptoms and impaired quality of life can remain despite pharmacological treatment of asthma. Breathing retraining may address an additional component of this burden. We examined whether reported benefits are consistent across outcomes, interventions and settings, while distinguishing comparative evidence from uncontrolled observations. Methods The original review reported searches of Cochrane Library, PubMed/MEDLINE, Scopus, Web of Science and PEDro for studies published from January 2013 to March 2025. Randomised trials and uncontrolled pre-post studies were included. A supplementary targeted search and full-text review identified four additional eligible trials (three randomised and one quasi-randomised) that had not been incorporated in the original selection; these were checked against the review’s eligibility criteria and added. A further updated bibliographic search conducted in October 2026, restricted to the original January 2013–March 2025 window, identified five more eligible randomised trials that had likewise not been incorporated; these were also checked against the same eligibility criteria and added. In this revision, reported results were checked against source publications and synthesised by outcome and design. PEDro ratings were corrected; limitations of the original RoB 2 assessments and selection records are disclosed. Meta-analysis and formal GRADE assessment were not performed. Results Fifteen studies enrolled 1,786 participants with asthma: twelve randomised trials, one quasi-randomised trial, and two uncontrolled studies. Quality-of-life benefits relative to usual care or a non-active control were supported by Bruton, Andreasson, Prem, Rondinel, Sodhi and von Bonin; against active comparators, one additional trial favoured breathing exercises over progressive relaxation, three found no significant difference against aerobic training, a sham control or combined aerobic exercise, and two found no statistically significant between-group difference between two active breathing-based techniques. The uncontrolled Karam study did not show significant Mini-AQLQ improvement. Asthma-control findings were mixed, with no significant between-group ACQ benefit in Bruton or Andreasson, a significant benefit of incentive spirometry with expiratory positive-airway pressure over usual care in Rondinel, while one additional trial favoured a breathing technique over relaxation on the Asthma Control Test and two further trials against active comparators found no significant between-group difference in asthma-control scores. One trial demonstrated equivalence of DVD-and-booklet and face-to-face delivery of the same programme. Lung-function and FeNO benefits were not established, and one trial found a greater reduction in rescue-medication use with aerobic training than with breathing exercises. Safety evidence remained limited. The completeness of the original study selection could not be fully verified, although the eligibility of nine previously unresolved or newly identified candidate reports has now been checked and resolved across two targeted audits, including an updated database search. Conclusions Structured breathing retraining may improve health-related quality of life as an adjunct to asthma pharmacotherapy relative to usual care, although comparative evidence against active comparators is more mixed. Evidence for improved patient-reported asthma control is similarly inconsistent. Heterogeneity, uncontrolled designs, and incomplete original search documentation limit confidence and generalisability; RoB 2 classified nine of the twelve randomised trials at high overall risk of bias and three as having some concerns, limiting confidence in the apparent benefits. The evidence does not establish superiority of one technique, a medication step-down strategy, or prevention of exacerbations.