Exercise training increases functional capacity and improves symptoms in selected patients with chronic heart failure and moderate-to-severe left ventricular systolic dysfunction. Patients should be assessed before they start an exercise program. Initial programs should be supervised, and the duration increased as tolerated. The most consistent benefits occur with exercise done at least three times per week for 12 or more weeks. Aerobic sessions can vary from 20 to 40 minutes, at 50% to 85% of peak heart rate on graded exercise tests or 40% to 70% of peak oxygen consumption. Low-risk patients who have completed at least 6 to 12 weeks of exercise without adverse effects may incorporate light-to-moderate resistance training.