Improvement in peripheral airway function after a 12-week exercise intervention in COPD

BACKGROUND: Exercise is a cornerstone of chronic obstructive pulmonary disease (COPD) management and improves quality of life, exercise capacity, exacerbation frequency and survival. However, the physiological mechanisms underlying these effects remain unclear. Small airway dysfunction and airway remodeling may not be adequately captured by spirometry, whereas impulse oscillometry (IOS) may be more sensitive to changes in respiratory mechanics. We hypothesized that an exercise intervention designed to engage the peripheral lung may promote adaptive, and potentially, reparative processes in COPD. The aim of the study was to evaluate changes in lung function after a 12-week exercise intervention, focusing on small airway-related measures assessed by IOS. Secondary aims were to assess changes in exercise capacity and patient-reported outcomes. METHODS: In this prospective multicenter single-arm non-randomized intervention study, participants with COPD (n = 62) completed a 12-week supervised, individually tailored moderate-intensity aerobic- and muscle-strengthening exercise program (3 sessions/week). Lung function (spirometry, body plethysmography, diffusing capacity and IOS), exercise capacity (6-minut walk test, 1-minute sit-to-stand) and symptom burden (CAT, CCQ, mMRC) were assessed before and after the intervention. RESULTS: Significant improvements were observed in IOS measures including R5 (median paired difference (Δ) = - 0.75 z-score, p = 0.001), R5-R20 (Δ=-0.18 z-score, p = 0.007), Fres (Δ=-0.33 Hz, p = 0.022) and AX (Δ=-0.05 kPa·s⁻¹, p = 0.042). No significant changes were observed in spirometry or lung volumes, except for a small increase in FVC (Δ = 0.12 z-score, p = 0.027). Exercise capacity improved (Δ6MWT = + 15 m, p = 0.002; Δ1STS = + 3 repetitions, p < 0.0001), while symptom burden decreased (ΔCAT = - 1.0, p = 0.014; ΔCCQ = - 0.1, p = 0.011). CONCLUSIONS: IOS measures improved after the exercise intervention, suggesting physiological adaptations beyond skeletal muscle conditioning that resulted in improved airway mechanics and ventilation distribution in the peripheral lung, while other lung function measures remained largely unchanged. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov ID NCT06335992 (Registration date 2024-03-28).