DESCRIPTION (provided by applicant): A major independent predictor of the ability of congestive heart failure [CHF] patients to maintain physical function is the amount of functional skeletal muscle they have been able to preserve (10). Older patients with CHF--who make up the vast majority of CHF patients--are least able to do this. The disease is marked by a loss of aerobic muscle fibers (3-5), while aging is marked by a loss of glycolyic muscle fibers (6-9). Indeed, because of the loss of both muscle types in older CHF patients, the disease may be physiologically different in them than in younger ones, needing different therapeutic approaches. Tests of strategies aimed at increasing muscle mass by resistance strength training in systolic failure patients have been rare, small, and --above all-- generally lacking older subjects. The studies done among younger CHF patients have shown that both aerobic and combination aerobic and strength training can increase work capacity, oxidative muscle activity, and glycolytic muscle strength (18-22) while combination training can improve cardiac measures including left ventricular ejection fraction (20). The primary purpose of the proposed study is to test the hypotheses that: A program of exercise combining endurance and resistance strength training will increase the physical capacity of patients 65 and older with New York Heart Association Class II and Class III chronic congestive failure [CHF] more effectively than a program of purely aerobic exercise. We will do this by recruiting 200 subjects age 65 and older with Class II and III CHF and LVEF 20%-40% and measuring their work capacity in watts on a cycle ergometer exercise stress test [Time 1]. We will randomize them by gender, race, and disease severity into two exercise groups: RA = resistance and aerobic training, and A = aerobic training. Both groups will exercise 3 times a week for 4 months. At the end of the 4 months training, we will repeat the cycle ergometer stress test [Time 2.]. By comparing changes in maximum watts achieved from Time 1 to Time 2 in each group, we can compare the effectiveness of each program of exercise at improving work capacity. Secondarily, we will perform and compare measures of myocardial remodeling, leg strength, and leg muscle oxidative capacity at Time 1 and Time 2. We believe the results of this study can have important theoretical as well as practical implications shedding new light on the mechanisms of the disability of CHF in older patients and aiding in their rehabilitation.