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 (ClinicalTrials.gov 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
Statistics from Altmetric.com
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.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.