Abstract: We included in the meta-analysis 10 studies with 762 participants across one or more comparisons. The sample size of included studies ranged from 11 to 206 participants. Nine out of 10 studies involving all levels of COPD severity were conducted in China with adults from 55 to 88 years of age, a higher proportion of whom were male (78%). Nine out of 10 studies provided tai chi and/or qigong programmes as AMBMT, and one study provided yoga. Overall, the term 'PR' has been uncritically applied in the vast majority of studies, which limits comparison of AMBMT and PR. For example, eight out of 10 studies considered walking training as equal to PR and used this as conventional exercise training within PR. Overall study quality for main comparisons was moderate to very low mainly owing to imprecision, indirectness (exercise component inconsistent with recommendations), and risk of bias issues. The primary outcomes for our review were quality of life, dyspnoea, and serious adverse events. When researchers compared AMBMT versus PR alone (mainly unstructured walking training), statistically significant improvements in disease-specific quality of life (QoL) (St. George's Respiratory Questionnaire (SGRQ) total score) favoured AMBMT: mean difference (MD) -5.83, 95% confidence interval (CI) -8.75 to -2.92; three trials; 249 participants; low-quality evidence. The common effect size, but not the 95% CI around the pooled treatment effect, exceeded the minimal clinically important difference (MCID) of minus four. The COPD Assessment Test (CAT) also revealed statistically significant improvements favouring AMBMT over PR, with scores exceeding the MCID of three, with an MD of 6.58 units (95% CI -9.16 to – 4.00 units; one trial; 74 participants; low-quality evidence). Results show no between-group differences with regard to dyspnoea measured by the modified Medical Research Council Scale (MD 0.00 units, 95% CI -0.37 to 0.37; two trials; 127 participants; low-quality evidence), the Borg Scale (MD 0.44 units, 95% CI -0.88 to 0.00; one trial; 139 participants; low-quality evidence), or the Chronic Respiratory Questionnaire (CRQ) Dyspnoea Scale (MD -0.21, 95% CI -2.81 to 2.38; one trial; 11 participants; low-quality evidence). Comparisons of AMBMT versus PR alone did not include assessments of generic quality of life, adverse events, limb muscle function, exacerbations, or adherence. Comparisons of AMBMT added to PR versus PR alone (mainly unstructured walking training) revealed significant improvements in generic QoL as measured by Short Form (SF)-36 for both the SF-36 general health summary score (MD 5.42, 95% CI 3.82 to 7.02; one trial; 80 participants; very low-quality evidence) and the SF-36 mental health summary score (MD 3.29, 95% CI 1.45 to 4.95; one trial; 80 participants; very low-quality evidence). With regard to disease-specific QoL, investigators noted no significant improvement with addition of AMBMT to PR versus PR alone (SGRQ total score: MD -2.57, 95% CI -7.76 to 2.62 units; one trial; 192 participants; moderate-quality evidence; CRQ Dyspnoea Scale score: MD 0.04, 95% CI -2.18 to 2.26 units; one trial; 80 participants; very low-quality evidence). Comparisons of AMBMT + PR versus PR alone did not include assessments of dyspnoea, adverse events, limb muscle function, exacerbations, or adherence. Given the quality of available evidence, the effects of AMBMT versus PR or of AMBMT added to PR versus PR alone in people with stable COPD remain inconclusive. Evidence of low quality suggests better disease-specific QoL with AMBMT versus PR in people with stable COPD, and evidence of very low quality suggests no differences in dyspnoea between AMBMT and PR. Evidence of moderate quality shows that AMBMT added to PR does not result in improved disease-specific QoL, and evidence of very low quality suggests that AMBMT added to PR may lead to better generic QoL versus PR alone. Future studies with adequate descriptions of conventional exercise training (i.e. information on duration, intensity, and progression) delivered by trained professionals with a comprehensive understanding of respiratory physiology, exercise science, and the pathology of COPD are needed before definitive conclusions can be drawn regarding treatment outcomes with AMBMT versus PR or AMBMT added to PR versus PR alone for patients with COPD.

Plain-language summary: We included 10 studies involving 762 participants who were randomly assigned to receive AMBMT alone or in combination with PR or PR alone (mainly unstructured walking training). The quality of included studies was generally poor. Given the quality of available evidence, effects of AMBMT in comparison with PR or of AMBMT added to PR in comparison with PR alone remain inconclusive. One key reason for this is that PR programmes used as comparators had major design flaws, for example, the term 'PR' was uncritically used in the vast majority of studies, and PR was often considered equal to unstructured walking training. This, together with the poor quality of evidence, limits our confidence in the observed effects. Available evidence suggests that when AMBMT was compared to PR alone, larger improvements in disease-specific quality of life were observed with AMBMT, although AMBMT was not superior to PR with regard to dyspnoea (breathlessness). AMBMT added to PR resulted in large improvement in generic quality of life when compared with PR alone, although the addition of AMBMT to PR did not lead to further improvements in disease-specific quality of life. However, before definitive conclusions can be drawn, future research studies comparing AMBMT to PR are needed, and these should follow current PR guidelines for designing comparator interventions, preferably delivered by properly trained professionals with a comprehensive understanding of respiratory physiology, exercise science, and the pathology of COPD.