Improved ventilation and decreased sympathetic stress in chronic heart failure patients following local endurance training with leg muscles.

BACKGROUND

Two-legged knee extensor training activates only about half the muscle mass used in traditional cycle ergometer training. With such an exercise model it is possible to achieve a substantial local training effect in spite of a restricted circulatory capacity. The present study sought to investigate the systemic effects of such local training on ventilation and neurohumoral activity in patients with moderate heart failure.

METHODS AND RESULTS

Thirteen male patients with chronic heart failure (age 56 +/- 3 years, EF 28 +/- 3%) performed two-legged knee extensor exercises (about 4 kg of working muscle) for 15 minutes 3 times a week during 8 weeks at 65-75% of peak VO2 of a two-legged kick and were compared to a non-training control group (n = 7, age 62 +/- 3, EF 27 +/- 3%). Before and after the training period VO2, VCO2 and the minute ventilation (1/min) were determined at rest and at submaximal and maximal workloads. Also measured before and after training were two-legged knee extensor peak exercise capacity (W), strength (Nm), a 6-minute walking test (m), quadriceps femoris citrate synthase activity, plasma catecholamines, vasoactive amines and blood lactate during submaximal knee extension exercise, and perceived health-related quality of life. After training, VO2 and VCO2 were reduced at submaximal exercise by 20-30% (P < .01) but were unchanged at peak exercise. With training, the two-legged knee extensor peak exercise capacity increased by 38% (P < .01). The 6-minute walking gait velocity increased by 12% (P < .01) and skeletal muscle citrate synthase activity by 28% (P < .01). Training improved the quality of life (P < .01). After training, VO2 (P < .001), VCO2 (P < .001) and minute ventilation (P < .001) were reduced at the workload corresponding to the maximal workload before training. The ratio minute ventilation/VO2 was reduced (P < .05) after training at the before-training maximal workload. No change was observed in the control group with regard to two-legged peak exercise capacity or peak VO2. Plasma NPY was reduced both at rest and at submaximal exercise by 35% (P < .01), whereas noradrenaline was reduced only during exercise (P < .05).

CONCLUSIONS

Local muscle training is effective in stable chronic heart failure and can improve, in addition to exercise capacity and quality of life, the ventilatory response, and decrease the sympathetic stress.