Moderate-to-high intensity inspiratory muscle training improves the effects of combined training on exercise capacity in patients after coronary artery bypass graft surgery: a randomized clinical trial

Background: The effects of adding moderate-to-high intensity inspiratory muscle training (IMT) to short-term aerobic and resistance exercise (combined training [CT]), after coronary artery bypass grafting (CABG) are not established. Objective: This study aimed to determine the effects of moderate-to-high intensity IMT+CT on exercise capacity, pulmonary function, respiratory muscle strength, quality of life (QoL), and antioxidant activity in patients after CABG who were participants of a phase II cardiac rehabilitation program. Methods: Twenty-four patients were randomly assigned to either the IMT+CT group (n=12), who performed moderate-to-high intensity IMT with CT or the sham-IMT+CT group (n=12). Patients completed two sessions per week for 12 weeks. Each patient underwent a cardiopulmonary exercise test, six-minute walk test (6MWT), respiratory muscle strength, QoL questionnaire, and ferric reducing antioxidant power (FRAP), before and after the 12-week intervention. Results: The IMT+CT group showed significantly greater improvements in peak VO2 (1.33 mL∙kg-1∙min-1; 95% confidence interval [95% CI], 0.51 to 2.16), distance covered during the 6MWT (78.80 m; 95% CI, 28.09 to 129.50), maximal inspiratory pressure (23.0 cmH2O; 95% CI, 9.32 to 36.67), QoL (-15.08 points; 95% CI, -26.91 to -3.26), and FRAP (83.67 µmol/L; 95% CI, 20.24 to 147.10) compared to the sham-IMT+CT group. Conclusions: Short-term moderate-to-high intensity IMT with CT provided additional benefits in exercise capacity, inspiratory muscle strength, QoL, and antioxidant activity in patients after CABG.