EFFECT OF HIGH-INTENSITY EXERCISE TRAINING ON CENTRAL HEMODYNAMIC-RESPONSES TO EXERCISE IN MEN WITH REDUCED LEFT-VENTRICULAR FUNCTION

Objectives. The aim of this study was to evaluate the effects of high intensity exercise training on left ventricular function and hemodynam ic responses to exercise in patients with reduced ventricular function . Background. Results of studies on central hemodynamic adaptations to exercise training in patients with chronic heart failure have been co ntradictory, and some research has suggested that training causes furt her myocardial damage in these patients after a myocardial infarction. Methods. Twenty five men with left ventricular dysfunction after a my ocardial infarction or coronary artery bypass graft surgery were rando mized to an exercise training group (mean age +/- SD 56 +/- 5 years, m ean ejection fraction [EF] 32 +/- 7%, n = 12) or a control group (mean age 55 +/- 7 years, mean EF 33 +/- 6%, n = 13). Patients in the exerc ise group performed 2 h of walking daily and four weekly sessions of h igh intensity monitored stationary cycling (40 min at 70% to 80% peak capacity) at a residential rehabilitation center for a period of 2 mon ths. Ventilatory gas exchange and upright hemodynamic measurements (re st and peak exercise cardiac output; pulmonary artery, wedge and mean arterial pressures; and systemic vascular resistance) were performed b efore and after the study period. Results. Maximal oxygen uptake (VO(2 )max) increased by 23% after 1 month of training, and by an additional 6% after month 2. The increase in VO(2)max in the trained group paral leled an increase in maximal cardiac output (12.0 +/- 1.8 liters/min b efore training vs. 13.7 +/- 2.5 liters/min after training, p < 0.05), but maximal cardiac output did not change in the control group. Neithe r stroke volume nor hemodynamic pressures at rest or during exercise d iffered within or between groups. Rest left ventricular mass, volumes and EF determined by magnetic resonance imaging were unchanged in both groups. Conclusions. High intensity exercise training in patients wit h reduced left ventricular function results in substantial increases i n VO(2)max by way of an increase in maximal cardiac output combined wi th a widening of maximal arteriovenous oxygen difference, but not chan ges in contractility. Training did not worsen hemodynamic status or ca use further myocardial damage, (C) 1997 by the American College of Car diology.