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Randomised controlled trial of adjunctive inspiratory muscle training for patients with COPD
  1. Noppawan Charususin1,2,3,
  2. Rik Gosselink1,2,
  3. Marc Decramer1,
  4. Heleen Demeyer1,2,
  5. Alison McConnell4,
  6. Didier Saey5,
  7. François Maltais5,
  8. Eric Derom6,
  9. Stefanie Vermeersch6,
  10. Yvonne F Heijdra7,
  11. Hanneke van Helvoort7,
  12. Linda Garms7,
  13. Tessa Schneeberger8,
  14. Klaus Kenn8,9,
  15. Rainer Gloeckl8,10,
  16. Daniel Langer1,2
  1. 1 Respiratory Rehabilitation and Respiratory Division, University Hospital Leuven, Leuven, Belgium
  2. 2 KU Leuven - University of Leuven, Department of Rehabilitation Sciences, Faculty of Movement and Rehabilitation Sciences, Leuven, Belgium
  3. 3 Department of Physical Therapy, Faculty of Allied Health Sciences, Thammasat University, Pathumthani, Thailand
  4. 4 Department of Human Sciences and Public Health, Faculty of Health and Social Sciences, Bournemouth University, Bournemouth, UK
  5. 5 Centre de recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec, Canada
  6. 6 Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
  7. 7 Department of Pulmonary Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
  8. 8 Department of Respiratory Medicine and Pulmonary Rehabilitation, Schoen Klinik Berchtesgadener Land, Schoenau am Koenigssee, Germany
  9. 9 German Center for Lung Research (DZL), Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
  10. 10 Department of Prevention, Rehabilitation and Sports Medicine, Technical University of Munich (TUM), Munich, Germany
  1. Correspondence to Dr Daniel Langer, Department of Rehabilitation Sciences, KU Leuven, Leuven 3001, Belgium; daniel.langer{at}


Background This study aimed to investigate whether adjunctive inspiratory muscle training (IMT) can enhance the well-established benefits of pulmonary rehabilitation (PR) in patients with COPD.

Methods 219 patients with COPD (FEV1: 42%±16% predicted) with inspiratory muscle weakness (PImax: 51±15 cm H2O) were randomised into an intervention group (IMT+PR; n=110) or a control group (Sham-IMT+PR; n=109) in this double-blind, multicentre randomised controlled trial between February 2012 and October 2016 ( NCT01397396). Improvement in 6 min walking distance (6MWD) was a priori defined as the primary outcome. Prespecified secondary outcomes included respiratory muscle function and endurance cycling time.

Findings No significant differences between the intervention group (n=89) and the control group (n=85) in improvements in 6MWD were observed (0.3 m, 95% CI −13 to 14, p=0.967). Patients who completed assessments in the intervention group achieved larger gains in inspiratory muscle strength (effect size: 1.07, p<0.001) and endurance (effect size: 0.79, p<0.001) than patients in the control group. 75 s additional improvement in endurance cycling time (95% CI 1 to 149, p=0.048) and significant reductions in Borg dyspnoea score at isotime during the cycling test (95% CI −1.5 to −0.01, p=0.049) were observed in the intervention group.

Interpretation Improvements in respiratory muscle function after adjunctive IMT did not translate into additional improvements in 6MWD (primary outcome). Additional gains in endurance time and reductions in symptoms of dyspnoea were observed during an endurance cycling test (secondary outcome)

Trial registration number NCT01397396; Results.

  • pulmonary rehabilitation
  • respiratory muscles
  • exercise

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  • Contributors RG, DL and NC had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. DL, NC, RG, MD and AM contributed substantially to the study design. DL, NC, HD, FM, DS, SV, HvH, LG, TS and RG provided data collection. DL, RG, NC and HD contributed to the data analysis and interpretation. DL, RG and NC drafted the report, and all authors then critically reviewed it for important intellectual content.

  • Funding DL and HD are postdoctoral fellows of Research Foundation Flanders. HaB International (Southam, UK) and McRoberts (The Hague, The Netherlands) provided equipment for testing and training in this study on loan. This study was further supported by local funds throughout the participating centres. The following specific funding sources were reported: University Hospital Leuven, Belgium (FWO grant GOA4516N en KU Leuven grant C22/15/035); Ghent University Hospital, Belgium (UZ Gent grant FS/LGZ/994); Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec, Canada (Ordre professionnel de la physiothérapie du Québec).

  • Disclaimer None of the sponsors had any role in the preparation of the trial design, patient recruitment, data collection, data analysis, interpretation of the data, approval of the report or the decision to submit this manuscript for publication.

  • Competing interests AM acknowledges a previous (now expired) beneficial interest in the POWERbreathe inspiratory muscle trainers in the form of a share of royalty income to the University of Birmingham, and a potential share of royalty income to Brunel University. In the past, she has also provided consultancy services to POWERbreathe International, but no longer does so. She is named on two patents relating to POWERbreathe products, including the device used in the present study, as well as being the author of two books on inspiratory muscle training. FM reports research support from Boehringer Ingelheim, GlaxoSmithKline, AstraZeneca, Grifols and Novartis, advisory board participation for Boehringer Ingelheim and GlaxoSmithKline, and speaking engagements for Boehringer Ingelheim, GlaxoSmithKline, AstraZeneca, Grifols and Novartis.

  • Patient consent Obtained.

  • Ethics approval University Hospital Leuven Institutional Review Board (approval number ML7489).

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

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