Effect of Inspiratory Muscle Training on Diaphragm Function and Activity Performance in Subacute Ischemic Stroke Patients: A Single-Blind Randomized-Controlled Trial

Abstract

Background: Respiratory dysfunction is common after stroke and may negatively affect functional recovery. Inspiratory muscle training (IMT) has been proposed to enhance diaphragmatic function and activity performance in this population. Objective: To investigate the effects of IMT on diaphragm function and activity performance in patients with subacute ischemic stroke. Methods: In this randomized controlled, single-blind trial, 26 patients with subacute ischemic stroke (>1 month post-onset) were randomly allocated to an intervention group (IG, n = 13) or control group (CG, n = 13). Both groups received standard neurorehabilitation, aerobic training, and the Active Cycle of Breathing Technique (ACBT). The IG additionally underwent IMT, 5 days per week for 6 weeks (30 sessions). Assessments included maximal inspiratory and expiratory pressures (MIP, MEP), diaphragmatic thickness (Ti, Te) and excursion via ultrasonography, 6-minute walk test (6MWT), and Canadian Occupational Performance Measure (COPM). Results: Twenty-two participants completed the study (IG = 11; CG = 11). Significant within-group improvements were observed in both groups for MIP, MEP, Ti, TF, excursion, 6MWT, and COPM scores (P < .05). Between-group analyses showed significantly greater improvements in the IG for ΔMIP (P < .001), ΔMEP (P = .003), affected-side ΔTi (P = .007), ΔTF (P = .008), and Δexcursion (P = .005). No significant differences were found for 6MWT and COPM (P > .05). Conclusions: IMT effectively improves respiratory muscle strength, diaphragmatic thickness, and excursion in subacute ischemic stroke and may be a valuable addition to post-stroke rehabilitation programs. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT06210516. © The Author(s) 2026