Effects of High-Intensity Inspiratory Muscle Training on Cardiovascular Function in Patients With Heart Disease: A Randomized Controlled Pilot Study

Purpose: The aim of this study was to investigate whether higher intensity inspiratory muscle training (HI-IMT), beyond usual clinical care, improves inspiratory muscle strength, endothelial function, arterial stiffness, functional exercise capacity, and perception of dyspnea in patients with heart disease. Methods: In this randomized controlled pilot study, 11 participants with heart disease were included. Participants were randomized to 4 weeks of either HI-IMT with a resistance set to 60% of baseline maximum inspiratory pressure (MIP) or sham-IMT without resistance (sham-control group). Endothelial function was assessed using flow-mediated dilation (FMD%), arterial stiffness using pulse wave velocity (PWV), functional exercise capacity using the 6-minute walk distance (6MWD), dyspnea perception using the modified Medical Research Council (mMRC) dyspnea scale, and inspiratory muscle strength using MIP. Results: There were no differences between groups for baseline demographic and clinical characteristics. Brachial FMD% (mean difference = 3.00%, P = .001), 6MWD (mean difference = 43.6 meters, P < .001), mMRC score (mean difference = −1.4 points, P < .001), and MIP (mean difference = 25.2 cmH 2 O, P < .001) values showed significant improvements in the HI-IMT group compared to the sham-controls. There was no significant difference between groups in PWV ( P = .107). Conclusions: HI-IMT produced improvements in inspiratory muscle strength, endothelial function, functional exercise capacity, and perception of dyspnea in patients with heart disease.