Effectiveness of respiratory muscle training in adults with multiple sclerosis: a systematic review and meta-analysis

To systematically evaluate the effects of respiratory muscle training (RMT) on respiratory muscle strength, lung function, fatigue, and quality of life in patients with multiple sclerosis (MS).

Four electronic bibliographic databases (PubMed, Web of Science, Embase, and Cochrane) were searched from inception to August 26, 2024. The screened trials compared RMT with sham RMT as well as conventional care. Two authors independently extracted key information from the eligible studies. A risk of bias assessment was conducted for randomized controlled trials (RCTs) and quasi-experimental (QE) studies using the RoB 2.0 and JBI critical appraisal tools. We assessed the certainty of the evidence according to the GRADE approach applied to the primary outcomes of respiratory muscle strength. Where feasible, the data were pooled and subjected to meta-analysis using RevMan 5.4 software. The results are reported as mean differences (MDs) and 95% confidence intervals (CIs).

A total of 14 trials (eight RCTs and six QE studies) involving 376 patients were included in the analysis. For the primary outcomes, RMT demonstrated significant improvements in maximum inspiratory pressure (MIP) (MD 4.74 cmH₂O, 95%CI 0.48-9.01, p = 0.03), predicted MIP (MD 14.27, 95%CI 2.45-26.09, p = 0.02), and maximum expiratory pressure (MEP) (MD 8.50 cmH₂O, 95%CI 1.59-15.42, p = 0.02); however, no statistically significant effect was observed for predicted MEP (MD 2.25, 95%CI -2.36-6.86, p = 0.34). For secondary outcomes, RMT failed to show a significant summary effect size on lung function and exercise capacity; however, it showed significantly reduced fatigue (MD -15.15, 95%CI -21.14- -9.16, p < 0.00001), as assessed using a modified fatigue impact scale. Due to the limited number of studies, qualitative analysis was used to assess quality of life (QOL), adherence to treatment, and adverse events.

Respiratory muscle training improves respiratory muscle strength and fatigue in MS, but evidence quality is low and effects on lung function, exercise capacity and QOL remain uncertain. The evidence was limited by the small number of trials with small sample sizes and the risk of bias. This necessitates additional randomized controlled trials.

https://www.crd.york.ac.uk/prospero/, identifier CRD42023457664.