[Exercise training in heart failure].
BACKGROUND: In patients with chronic heart failure, exercise limitation cannot be exclusively attributed to cardiac dysfunction. During progression of the disease, peripheral factors have a growing impact on functional capacity. Chronic underperfusion of skeletal muscles, inactivity and a harmful effect of neuroendocrine stimulation lead to a myopathy syndrome characterized by atrophy, a shift in muscle fiber type and a loss of capillaries and mitochondria, which cause reduced muscle strength and aerobic capacity. Unlike left ventricular systolic function, which is a poor predictor of exercise tolerance in patients with chronic heart failure, parameters characterizing the myopathy syndrome correlate well with functional capacity. In the last 20 years, numerous studies have demonstrated that chronic heart failure patients in NYHA classes II and III benefit from physical training without deterioration of their cardiac function. EFFECTS OF EXERCISE TRAINING: Physical activity primarily improves muscle function and increases maximal as well as submaximal exercise capacity. Advantageous effects have also been observed with regard to neuroendocrine stimulation. The effect on central hemodynamics is much smaller and indirectly mediated by a trend towards decreased peripheral resistance. Left ventricular diameters, ejection fraction and filling pressures do not show significant changes. The gain in exercise capacity is usually accompanied by an improvement in symptom status and quality of life. Recent studies indicate that prognosis may also be improved by exercise training. CONVERSION INTO CLINICAL PRACTICE: Although continuous exercise training (mainly by use of cycle ergometry) has been investigated most thoroughly, there is an increasing number of studies reporting beneficial effects of interval and resistance training. Before starting a standardized training program, functional limitation and training intensity should be determined by an appropriate stress test. During the first training sessions, patients should always be supervised by a physician. In order to increase efficiency and feasibility of the exercise therapy, home-based training should be engaged as soon as a stable condition during repeated training sessions has been proven.