Effects of integrated inspiratory–expiratory muscle training within hybrid cardiac rehabilitation following cardiac surgery: A randomized controlled study

Abstract

Background: Cardiac surgery may reduce pulmonary function, respiratory muscle strength, and functional capacity after surgery. Respiratory muscle training (RMT) is recommended in cardiac rehabilitation; however, evidence regarding RMT within HCR remains limited. Objective: To evaluate the effects of adding RMT to an HCR program following cardiac surgery in a randomized controlled trial. Methods: In this randomized controlled trial, 20 patients were randomized to HCR (n=10) or HCR+RMT (n=10). Rehabilitation started in postoperative week 1 and continued for 8 weeks. Both groups received HCR, while the HCR+RMT group performed combined inspiratory and expiratory muscle training. Primary outcomes were pulmonary function, respiratory muscle strength, and 6-minute walk distance. Secondary outcomes included quality of life, physical activity, usability, feasibility, and satisfaction. Results: Twenty participants completed the study, with 100% retention and attendance in both groups and no adverse events. At postoperative week 1, respiratory and functional parameters declined in both groups. By week 8, 6-minute walk distance increased by 49.5 m in the HCR group and 55.5 m in the HCR+RMT group. Duke Activity Status Index scores improved by 5.25 and 4.95 points, respectively, while Minnesota Living with Heart Failure Questionnaire scores decreased by 7–9 points. No significant between-group differences were found for any outcome (all p>0.05). Conclusions: Adding RMT to HCR is feasible, safe, and well accepted. Both interventions improved respiratory function, respiratory muscle strength, functional capacity, physical activity, and quality of life. Although no additional short-term benefit was observed with RMT, it may be considered complementary to HCR programs.