BACKGROUND: Many secondary abnormalities in chronic heart failure (CHF) may reflect physical deconditioning. There has been no prospective, controlled study of the effects of physical training on hemodynamics and autonomic function in CHF. METHODS AND RESULTS: In a controlled crossover trial of 8 weeks of exercise training, 17 men with stable moderate to severe CHF (age 61.8 +/- 1.5 years; left ventricular ejection fraction 19.6 +/- 2.3%), increased exercise tolerance (13.9 +/- 1.0 to 16.5 +/- 1.0 minutes, p < 0.001), and peak oxygen uptake (13.2 +/- 0.9 to 15.6 +/- 1.0 ml/kg/min, p < 0.01) significantly compared with controls. Training increased cardiac output at submaximal (5.9 to 6.7 l/min, p < 0.05) and peak exercise (6.3 to 7.1 l/min, p < 0.05), with a significant reduction in systemic vascular resistance. Training reduced minute ventilation and the slope relating minute ventilation to carbon dioxide production (-10.5%, p < 0.05). Sympathovagal balance was altered by physical training when assessed by three methods: (1) RR variability (+19.2%, p < 0.05); (2) autoregressive power spectral analysis of the resting ECG divided into low-frequency (-21.2%, p < 0.01) and high-frequency (+51.3%, p < 0.05) components; and (3) whole-body radiolabeled norepinephrine spillover (-16%, p < 0.05). These measurements all showed a significant shift away from sympathetic toward enhanced vagal activity after training. CONCLUSIONS: Carefully selected patients with moderate to severe CHF can achieve significant, worthwhile improvements with exercise training. Physical deconditioning may be partly responsible for some of the associated abnormalities and exercise limitation of CHF, including abnormalities in autonomic balance.
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