The impact of respiratory muscle training on respiratory function in patients with neuromuscular disease: a systematic review and meta-analysis of randomized controlled trials

Abstract Background Neuromuscular diseases (NMDs) can impair respiratory muscle function, leading to increased morbidity and mortality. Respiratory muscle training (RMT) is widely used to manage these respiratory complications, but its efficacy across different NMDs remains unclear. This systematic review and meta-analysis evaluated the impact of physiotherapy interventions, specifically RMT, on respiratory muscle function in NMD patients. Methods A systematic search of multiple databases, including MEDLINE, EMBASE, Web of Science, Cochrane, CRS-Web, PEDro, LILACS, ICTPR, the China National Knowledge Infrastructure database, and ClinicalTrials.gov, was conducted up to February 2025. Randomized controlled trials (RCTs) and cohort studies evaluating RMT’s effect on lung volumes and respiratory muscle strength in NMD patients were included. Risk of bias assessment was performed using Cochrane Risk of bias tool for RCTs and Newcastle-Ottawa Scale for cohorts. Meta-analyses were performed using a random-effects model, and heterogeneity was assessed with I² statistics. Results Sixteen studies were analyzed from 9,626 screened articles. The meta-analysis demonstrated significant improvements in respiratory muscle strength, particularly in maximal inspiratory pressure (MD: 6.83 cmH₂O, 95% CI: 2.08 to 11.58, p < 0.01, I² = 3.8%) and maximal expiratory pressure (MD: 13.05 cmH₂O, 95% CI: 3.65to 22.42, p < 0.01, I² = 43%). No significant improvements were observed in forced vital capacity (MD: 3.13%, 95% CI: -8.06 to 14.34, p = 0.58), sniff nasal inspiratory pressure (MD: 1.47 cmH₂O, 95% CI: -15.45 to 18.39, p = 0.86), forced expiratory volume in one second (MD: -0.02 L, 95% CI: -0.17 to 0.13, p = 0.78), and vital capacity (MD: -0.10 L, 95% CI: -0.31 to 0.11, p = 0.33). Conclusion This review supports the role of respiratory muscle training in improving inspiratory and expiratory muscle strength in patients with neuromuscular diseases. However, variability in study methodologies and patient populations limits the statistical significance of some respiratory parameters. Future studies should aim to standardize interventions and outcome measures to provide more conclusive evidence on the efficacy of RMT.