Introduction: Congestive heart failure (CHF) patients suffer from functional aerobic impairment. Their reduced cardiac output impairs O2 delivery to the periphery. This leads to increased anaerobic metabolism in the working muscle and accumulation of lactate, leading to muscle fatigue. The ability to clear the lactate improves exercise recovery and can lead to an improved exercise performance. We hypothesized that exercise training will affect lactate clearance, thus will explain the beneficiary effect of exercise training in CHF patients.
Methods: Eighteen rats underwent left anterior descending artery ligation. At baseline, pre-training and upon exercise training completion the rats underwent exercise capacity test (VO2 max) and parasternal short axis echocardiography. Eight rats have also been assessed for lactate clearance during those times. Following the establishment of CHF, the animals were assigned to an eight-week training program (EX) or sedentary (SED).
Results: Five weeks after surgery, rats` exercise capacity was impaired, their LV was dilated, ejection fraction and fractional shortening attenuated. Lactate clearance, measured as time to basal lactate level, was impaired (time to basal level 21±4 min vs. 9±1 min at baseline, P<0.01). Upon completion of the exercise program, no improvements in VO2 max, traditional structural or functional parameters were noted in the SED group (Pvs. baseline), while in the EX group (n=5) those parameters improved (Pvs. baseline). The time to basal lactate level after training continued to increase in the SED group (33±3 min, n=3, Pvs. baseline), while in the EX group time to basal level was shortened towards baseline reaching 17±4 min (Pvs. baseline).
Conclusions: Exercise training induces improvement in cardiac function as well as exercise capacity in an animal model of CHF. We suggest that the beneficial effect of exercise training to CHF patients should be attributed to its effect on lactate clearance kinetics
