Inspiratory muscle training with balance challenge improves diaphragmatic thickness, respiratory function, balance, exercise capacity and quality of life in people after stroke: a randomised trial.

Abstract

QUESTION: What are the relative effects of inspiratory muscle training (IMT) performed on an unstable or a stable seated surface and sham training on respiratory function, diaphragmatic thickness, balance/functional mobility, exercise capacity and quality of life in people after stroke? DESIGN: A randomised trial with concealed allocation, blinded assessors and intention-to-treat analysis. PARTICIPANTS: Eighty-eight adults after stroke. INTERVENTION: Participants were randomly allocated to three groups: IMT at 50% maximal inspiratory pressure (MIP) while seated on an unstable surface (unstable IMT), the same training on a stable surface (stable IMT), and IMT at 10% MIP on a stable surface (sham). All participants received conventional rehabilitation and their allocated IMT protocol for 4 weeks. OUTCOME MEASURES: Diaphragmatic thickness, forced expiratory volume in 1 second, forced vital capacity, MIP, Trunk Impairment Scale (TIS), Timed Up and Go (TUG), 6-minute walk distance and Stroke Impact Scale were assessed at weeks 0, 4 and 16. Postural sway using centre of pressure analysis during seated balance tasks was used to evaluate trunk balance at weeks 0 and 4. RESULTS: Compared with sham at week 4, stable IMT improved diaphragmatic thickness, respiratory function, TIS and TUG, whereas unstable IMT improved these same outcomes - typically with about 50% greater magnitude of benefit - and also improved 6-minute walk distance, Stroke Impact Scale and centre of pressure measures. Many of the benefits of stable IMT and most of the benefits of unstable IMT were maintained at week 16. CONCLUSION: As an adjunct to conventional rehabilitation, IMT at 50% MIP improves diaphragmatic thickness, respiratory function, TIS and TUG. Adding a postural challenge to the IMT increased the magnitude of these benefits and yielded additional benefits in exercise capacity, quality of life and dynamic sitting balance. We recommend IMT on an unstable surface as a complementary, synergistic adjunct to conventional post-stroke rehabilitation. REGISTRATION: NCT06640101.