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Original research
Impact of respiratory muscle training on respiratory muscle strength, respiratory function and quality of life in individuals with tetraplegia: a randomised clinical trial
  1. Claire L Boswell-Ruys1,2,3,
  2. Chaminda R H Lewis1,2,3,
  3. Nirupama S Wijeysuriya1,
  4. Rachel A McBain1,
  5. Bonsan Bonne Lee1,2,3,
  6. David K McKenzie2,3,
  7. Simon C Gandevia1,2,3,
  8. Jane E Butler1,3
  1. 1 Neuroscience Research Australia, Sydney, New South Wales, Australia
  2. 2 Prince of Wales Hospital and Community Health Services, Sydney, New South Wales, Australia
  3. 3 University of New South Wales, Sydney, New South Wales, Australia
  1. Correspondence to Dr Claire L Boswell-Ruys, Neuroscience Research Australia, Randwick, Sydney, New South Wales, Australia; c.boswell-ruys{at}


Background Respiratory complications remain a leading cause of morbidity and mortality in people with acute and chronic tetraplegia. Respiratory muscle weakness following spinal cord injury-induced tetraplegia impairs lung function and the ability to cough. In particular, inspiratory muscle strength has been identified as the best predictor of the likelihood of developing pneumonia in individuals with tetraplegia. We hypothesised that 6 weeks of progressive respiratory muscle training (RMT) increases respiratory muscle strength with improvements in lung function, quality of life and respiratory health.

Methods Sixty-two adults with tetraplegia participated in a double-blind randomised controlled trial. Active or sham RMT was performed twice daily for 6 weeks. Inspiratory muscle strength, measured as maximal inspiratory pressure (PImax) was the primary outcome. Secondary outcomes included lung function, quality of life and respiratory health. Between-group comparisons were obtained with linear models adjusting for baseline values of the outcomes.

Results After 6 weeks, there was a greater improvement in PImax in the active group than in the sham group (mean difference 11.5 cmH2O (95% CI 5.6 to 17.4), p<0.001) and respiratory symptoms were reduced (St George Respiratory Questionnaire mean difference 10.3 points (0.01–20.65), p=0.046). Significant improvements were observed in quality of life (EuroQol-Five Dimensional Visual Analogue Scale 14.9 points (1.9–27.9), p=0.023) and perceived breathlessness (Borg score 0.64 (0.11–1.17), p=0.021). There were no significant improvements in other measures of respiratory function (p=0.126–0.979).

Conclusions Progressive RMT increases inspiratory muscle strength in people with tetraplegia, by a magnitude which is likely to be clinically significant. Measurement of baseline PImax and provision of RMT to at-risk individuals may reduce respiratory complications after tetraplegia.

Trial registration number Australian New Zealand Clinical Trials Registry (ACTRN 12612000929808).

  • exercise
  • pulmonary rehabilitation
  • respiratory muscles
  • respiratory measurement
  • respiratory infection
  • perception of asthma/breathlessness

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  • CLB-R and CRHL are joint first authors.

  • Contributors All authors contributed equally.

  • Funding This trial was supported by grants from the National Health and Medical Research Council (NHMRC) and The Prince of Wales Hospital Foundation (POWHF). The NHMRC and POWHF had no role in the design of the study nor the collection, analysis and interpretation of data or in writing the manuscript.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval New South Wales Government Health, South Eastern Sydney Local Health District, Human Research Ethics Committee, HREC Ref No: 12/192 (LNR/12/POWH/409). University of New South Wales, Human Research Ethics Committee, HREC Ref No: HC13388.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request from the corresponding author.