Effect of muscle training on dyspnea in patients with chronic obstructive pulmonary disease: A meta-analysis of randomized controlled trials

BACKGROUND: Rehabilitation training is beneficial for patients with chronic obstructive pulmonary disease (COPD). This study was aimed at evaluating the efficacy of muscle training on dyspnea. METHODS: We used 5 common databases for conducting a meta-analysis included PubMed, the Cochrane Library, Science Direct, Web of Science and Clinical Trials.gov, and eligible randomized controlled trials (RCTs) were included. The main results of include studies were dyspnea of patients who had a clinical diagnosis of COPD measured using Borg score and Medical Research Council (MRC) or modified Medical Research Council (mMRC) scale as the criteria before and after intervention. The intervention measures included respiratory or expiratory muscles or upper limb (UL) or lower limb (LL) training. The mean differences (MD) with the 95% confidence interval (CI) were considered for summary statistics. We also assessed risk of bias using the Cochrane collaboration's tool, and the value of I(2) was applied to evaluate the heterogeneity of the trials. RESULTS: Fourteen RCTs with 18 interventions (n = 860 participants) were included. Muscle training significantly improved dyspnea during exercise and in the daily life of patients with COPD (MD, 95% CI: −0.58, −0.84 to −0.32, P < .0001 and −0.44, −0.65 to −0.24, P < .0001, respectively). In the subgroup analyses, the trials that used respiratory muscle and UL trainings significantly improved dyspnea during exercise (MD, 95% CI: −0.72, −1.13 to −0.31, P = .0005 and −0.53, −0.91 to −0.15, P = .007, respectively). The studies also showed that the participants in the rehabilitation group, who received respiratory muscle and UL trainings, had a significant improvement of dyspnea in daily life (MD, 95% CI: −0.38, −0.67 to −0.09, P = .01 and −0.51, −0.80 to −0.22, P = .0007, respectively). CONCLUSION: There were some limitations that most of the subjects in this study were patients with moderate to severe COPD and were male, and the training period and duration were different. The analyses revealed that respiratory muscle and UL trainings can improve dyspnea in patients with COPD during exercise and in daily life.