Marathoners or couch potatoes: what is the role of exercise in the management of heart failure?

Patients with chronic heart failure have diminished exercise capacity as a major aspect of their clinical syndrome, regardless of the cause of their left ventricular contractile dysfunction. The mechanisms for the reduction in exercise capacity are multifactorial and include central cardiac, peripheral vascular, respiratory, and skeletal muscle maladaptations that accompany the pathophysiology of heart failure. Increased sympathetic nervous system activity and elevations in circulating neurohormones and cytokines also influence the cardiovascular and metabolic responses to exercise in these patients. Despite the improvements in clinical outcomes with beta-blockers and resynchronization therapy in heart failure patients, their exercise capacity remains substantially reduced when compared with normal age-matched patients. Exercise training has the potential to reverse or improve most of the abnormal physiologic responses to exercise in these patients, and it may serve as adjunctive therapy to standard medical care of these patients. In addition, a body of evidence is being accumulated that suggests that exercise training itself has important secondary prevention benefit in these patients. This review identifies the potential mechanisms whereby exercise training may improve exercise capacity in patients with chronic heart failure and presents the current information regarding clinical outcomes of this therapy.