Short-term inspiratory muscle training, aerobic exercise, and detraining in women with COPD: a randomized controlled trial

Abstract

Abstract Background Inspiratory muscle dysfunction, exercise intolerance, dyspnea, and reduced well-being contribute to the burden of chronic obstructive pulmonary disease (COPD). We compared the short-term effects of inspiratory muscle training (IMT), aerobic exercise (AE), combined IMT and AE (IMT AE ), placebo IMT, and usual care on respiratory, functional, and patient-reported outcomes in women with stable COPD and examined early changes during two weeks after training cessation. Methods In this single-center, five-arm, partially blinded randomized controlled trial, 68 women with stable GOLD stage I–II COPD were randomized; 59 completed all assessments and were included in the per-protocol analysis. The four-week intervention was followed by assessments 7 and 14 days after cessation. The prespecified primary outcome was baseline-to-post change in maximal inspiratory pressure (MIP). Secondary outcomes were maximal expiratory pressure (MEP), peak inspiratory flow rate (PIFR), inspiratory volume (IV), forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), FEV₁/FVC, 6-min walk test (6MWT) distance, post-exercise Borg dyspnea, and WHO-5 well-being. The primary analysis tested the baseline-to-post group × time interaction for MIP using a 5-group × 2-time mixed-design repeated-measures analysis of variance. Four-time analyses examined secondary and detraining trajectories; additional Welch change-score comparisons were exploratory and unadjusted for multiplicity. Results The primary MIP interaction was significant (F(4, 54) = 28.969, p < 0.001, ηp² = 0.682). Secondary four-time interactions were significant for MIP, MEP, PIFR, IV, 6MWT distance, FVC, FEV₁, Borg dyspnea, and WHO-5, but not FEV₁/FVC. Combined training produced the largest improvements in inspiratory performance, walking distance, dyspnea, and well-being. Its 6MWT gain, however, was modest relative to commonly reported minimal clinically important differences. Several outcomes declined during detraining. Conclusions Within this sample of women with stable GOLD stage I–II COPD, combined IMT and AE produced the broadest short-term response across respiratory, functional, and patient-reported outcomes. Larger, prospectively registered trials with longer intervention and follow-up periods are needed to confirm these findings. Trial registration ClinicalTrials.gov, NCT07604961; first submitted on 17 May 2026 and first posted on 22 May 2026 (retrospectively registered).