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

Abstract

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-min 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-min 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. Clinical trial registration number NCT06258681.