Influence of inspiratory muscle strength on exercise capacity before and after cardiac rehabilitation

Background/Aims Coronary artery bypass grafting is a complex procedure that triggers a series of clinical and functional complications. The reduction of inspiratory muscle strength that persists during the late postoperative period has been suggested as an important determinant of functional capacity after coronary artery bypass grafting. The aim of this study was to investigate whether inspiratory muscle strength, functional capacity and quality of life are determinants of exercise capacity before and after a short-term phase II cardiac rehabilitation programme in patients who have had coronary artery bypass graft surgery. Methods A prospective quasi-experimental study was undertaken with 20 patients who had recevied coronary artery bypass surgery. All patients completed a short-term, moderate-to-high intensity inspiratory muscle training programme, followed by aerobic and resistance exercise, two times a week for 12 weeks, totalling 24 sessions, under the direct supervision of a physical therapist. Results Pre-intervention, peak oxygen consumption (peak VO2) was associated with maximum inspiratory pressure (beta=0.037; 95% confidence interval 0.01-0.06; P=0.002). Post-intervention, peak VO2 was associated with maximum inspiratory pressure (beta=0.03; 95% confidence interval 0.007-0.053; P=0.014) and the 6-Minute Walk Test (beta=0.007; 95% confidence interval, 0.001-0.013; P=0.024). Conclusions Inspiratory muscle strength influences exercise capacity before and after a short-term cardiac rehabilitation programme in patients who have had coronary artery bypass graft surgery.