Comparison of left ventricular function during interval versus steady-state exercise training in patients with chronic congestive heart failure

This study sought to assess the safety of interval exercise training in pat ients with chronic congestive heart failure (CHF) with respect to left vent ricular (LV) function. For effective rehabilitation in CHF, both aerobic ca pacity and muscle strength need to be improved. We have previously demonstr ated in both coronary artery bypass surgery and patients with CHF that inte rval exercise training (IET) offers advantages over steady-state exercise t raining (SSET). However, because LV function during IET has not yet been st udied, the safety of this method in CHF remains unclear. To assess LV funct ion during IET and SSET, at the same average power output, 11 patients with stable CHF were compared with 9 stable coronary patients with minimal LV d ysfunction (control group). Using first-pass radionuclide ventriculography, changes in LV function were assessed during work versus recovery phases, a t temporally matched times between the fifth and sixteenth minute of IET an d SSET. In CHF during IET, there were no significant variations in the para meters measured during work and/or recovery phases. During the course of bo th IET and SSET, there was a significant increase in LV ejection fraction ( 5 vs 4 U; p <0.05 each), accompanied by increased heart rate (6 vs 8 beats/ min; p <0.05 each) and cardiac output (2.4 vs 1.8 L/min; p <0.01 and p <0.0 5). In CHF, the magnitude of change in LV ejection fraction during IET was similar to that seen in controls. Both LV election fraction and the clinica l status in patients with CHF remained stable during IET. Because IET appea rs to be as safe as SSET with respect to LV function, IET can be recommende d for exercise training in CHF to apply higher peripheral exercise stimuli and with no greater LV stress than during SSET. (C) 1998 by Excerpta Medica , Inc.