Beneficial effects of exercise training in heart failure patients with lowcardiac output response to exercise - a comparison of two training models

Background. Exercise capacity of patients with chronic heart failure (CHF) correlates poorly with estimates of cardiac function. Yet, it has been sugg ested that only patients without severely impaired cardiac output (CO) bene fit from exercise training. Comparisons of different training models have n ot been made in the same study. Aims. To evaluate whether the response to different training models diverge s according to the cardiac output response to exercise in patients with chr onic heart failure. Methods. Sixteen CHF patients (63 +/- 11 years) with an ejection fraction o f 30 +/- 11% underwent a baseline cardiopulmonary exercise test, right hear t catheterization and leg muscle biopsy. Cardiac output (CO) response to ex ercise was defined as the ratio between CO increase and the increase in oxy gen uptake (CO response index) during exercise. Patients were randomized in to two training regimens, differing with regard to active muscle mass, i.e. whole body and one-legged exercise. Results. Baseline exercise capacity expressed as W kg(-1) correlated with t he CO response index (r = 0.51, P < 0.05). Exercise capacity on the cycle e rgometer increased in both groups but more in the one-legged than in the tw o-legged training group (P < 0.05). The improvement in exercise capacity di d not correlate with base-line exercise capacity. It correlated with CO res ponse index in the one-legged (r = 0.75, P < 0.01) but not in the two-legge d training group. CO response index correlated negatively with the pulmonar y capillary wedge pressure at peak exercise (r = - 0.60, P < 0.05). The inc rease in leg muscle citrate synthase activity after training correlated neg atively with the baseline CO response index (r = - 0.50, P < 0.05). Conclusions. The improvement of exercise capacity after one-legged training correlates with the CO increase in relation to the O-2 uptake before train ing. In patients with low CO response, individualization of the exercise re gimen is needed and the benefits of training a limited muscle mass at a tim e deserve further study.