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

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 (IMTAE), 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).