LOW-INTENSITY EXERCISE TRAINING IN PATIENTS WITH CHRONIC HEART-FAILURE

Objectives. The present study was designed to evaluate whether a speci fic program of low intensity exercise training may be sufficient to im prove the exercise tolerance of patients with chronic heart failure. B ackground. Recent studies have shown that exercise training can improv e exercise tolerance in patients with stable chronic heart failure, ma inly through peripheral adaptations. These changes have been observed with exercise regimens at intensities of 70% to 80% of peak oxygen upt ake and >8 weeks. Methods. We studied 27 patients (23 men, 4 women; me an [+/-SD] age 57 +/- 6 years) with mild chronic heart failure, We cla ssified patients into two groups: trained group and untrained group, T he trained group underwent a low intensity (40% of peak oxygen uptake) training program three times/week for 8 weeks. The untrained group pe rformed no exercise. Results. An increase in peak oxygen uptake (17%, p < 0.0001), lactic acidosis threshold (20%, p < 0.0002) and peak work load (21%, p < 0.0002) were obtained in the trained group only, Cardi ac output and stroke volume mere unchanged. A high correlation was fou nd between the increases in peak oxygen uptake and volume density of m itochondria of vastus lateralis muscle (r = 0.77, p < 0.0002). Conclus ions. Patients with stable chronic heart failure can achieve significa nt improvement in functional capacity from a low intensity exercise tr aining regimen. The mechanism responsible for this favorable effect in volves an increase in mitochondrial density, which reflects an improve ment in oxidative capacity of trained skeletal muscles.