Respiratory muscle training improves respiratory muscle strength and pulmonary function in multiple sclerosis patients

OBJECTIVE: This systematic review and meta-analysis aimed to evaluate the effects of respiratory muscle training (RMT) on respiratory function, exercise capacity, and health-related quality of life (HRQoL) in individuals with multiple sclerosis (MS). METHODS: A systematic search was conducted across eight electronic databases-Web of Science, PubMed (including MEDLINE and PubMed Central), SPORTDiscus, ScienceDirect, Scopus, Cochrane Library, Embase, and ProQuest-from their inception through September 22, 2025. Randomized controlled trials (RCTs) and quasi-RCTs that compared RMT with passive control, sham RMT, or usual care in individuals with MS were eligible for inclusion, with no restrictions on publication date. Eligible studies were required to report at least one of the following outcomes: respiratory muscle strength (e.g., maximal inspiratory pressure, MIP; maximal expiratory pressure, MEP), pulmonary function (e.g., forced expiratory volume in 1 s, FEV; forced vital capacity, FVC), functional exercise capacity (e.g., 6-minute walk distance, 6MWD), or HRQoL (e.g., SF-36, MSQOL-54). Two independent reviewers conducted the literature search and performed data extraction. The methodological quality and risk of bias of the included studies were assessed using the Cochrane Risk of Bias 2.0 tool (RoB2) and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework. RESULTS: A total of 16 studies involving 542 participants were included. The meta-analysis indicated that RMT significantly improved respiratory muscle strength (MIP: Hedges' g = 0.47; MEP: Hedges' g = 0.28) and pulmonary function (FEV: Hedges' g = 0.39; FVC: Hedges' g = 0.24). In contrast, RMT did not significantly improve functional exercise capacity (6MWD: Hedges' g = 0.03) or the overall physical component summary of HRQoL (Hedges' g = 0.05). A secondary analysis of a specific quality-of-life domain, however, showed a significant effect on the SF-36 Physical Functioning subscale (Hedges' g = 0.40, 95% CI: 0.01 to 0.80). CONCLUSION: RMT effectively improves respiratory muscle strength and pulmonary function in individuals with MS, and positively impacts specific Physical Functioning domains of HRQoL. However, current evidence does not support an improvement in functional exercise capacity. Despite the limited number of included studies, RMT shows promise as an adjunctive therapy for targeted respiratory rehabilitation. This study provides a foundational evidence base to guide clinical practice and inform the design of future high-quality trials.