Respiratory muscle training in neuromuscular disease: a systematic review and meta-analysis

What is it about?

Neuromuscular diseases, such as spinal cord injury, amyotrophic lateral sclerosis and Parkinson's disease, cause the respiratory muscles of people with these disorders to become weaker over time. These muscles can be trained and made stronger, but it is unclear whether this training works across all of the diverse range of neuromuscular diseases. Previous systematic reviews have focussed on single diseases, whereas this study systematically reviewed the collective evidence for respiratory muscle training in children and adults with any neuromuscular disease. Methods: Seven databases were searched for randomised controlled trials. Three reviewers independently reviewed eligibility, extracted characteristics, results, determined risk of bias, and combined results using narrative synthesis and meta-analysis. Results: Thirty-six studies (39 publications, n=921 participants) were included. Respiratory muscle training improved forced vital capacity: standardised mean difference (SMD) 0.40 (95%CI 0.12, 0.69); maximal inspiratory SMD 0.53 (0.21, 0.85) and maximal expiratory pressure SMD 0.70 (0.35, 1.04) compared to control (usual care, sham training or alternative treatment). No impact on cough, dyspnoea, voice, physical capacity or quality of life was detected. There was high degree of variability between studies. Discussion: Study heterogeneity (children and adults, different diseases, interventions, dosage, and comparators) suggest the results should be interpreted with caution, however including all neuromuscular diseases increased the evidence pool and tested the intervention overall. Conclusions: Respiratory muscle training improves lung volumes and respiratory muscle strength in neuromuscular disease, but confidence is tempered by limitations in the underlying trials.

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