Inclusion Criteria:

Exclusion Criteria:

• * The study group will include subjects with a history of stable cardiomyopathy (ischemic and non-ischemic, \>3 months duration, ages 45-75 yrs) despite a minimum of 6 weeks of optimal treatment.
• * Optimal therapy will be according to American Heart Association (AHA) /American College of Cardiology (ACC) and Heart Failure Society of America (HFSA) HF guidelines, including treatment with angiotensin-converting enzyme (ACE) and -blocker therapy (for at least 6 weeks), or have documented reason for variation, including medication intolerance, contraindication, patient preference, or personal physician's judgment.
• * Patient enrollment will be limited to those individuals with New York Heart Association (NYHA) class II and III symptoms, left ventricular ejection fraction \<35% (LVEF), with no or minimal smoking history (\<15 pk yrs), and without pacemakers.
• * Patients with atrial fibrillation or HF believed to be secondary to atrial fibrillation will be excluded.
• * Patients with HF secondary to significant uncorrected primary valvular disease (except mitral regurgitation secondary to left ventricular dysfunction) will also be excluded.
• * Patients will be sedentary, defined here as no regular physical activity for at least the prior 6 months and current activity level will be documented by an activity questionnaire.
• * Patients must have no orthopedic limitations that would prohibit them from performing knee-extensor exercise.
• * Due to the typical age of patients with HF, all women will be postmenopausal (either natural or surgical) defined as a cessation of menses for at least 2 years, and in women without a uterus, follicle stimulating hormone (FSH) \>40 IU/L.
• * These include a diagnosis of Dementia
• * Severe chronic obstructive pulmonary disease (COPD)
• * Peripheral Vascular Disease
• * Anemia
• * Sleep-related Breathing Disorder
• * Severe Valvular Heart Disease
• * Diabetes (if on insulin therapy)
• * or End-stage Malignancy
• * The investigators will also exclude morbidly obese patients (BMI \>40), patients with uncontrolled Hypertension (\>160/100), Anemia (Hgb\<9) and Severe Renal Insufficiency (individuals with creatinine clearance \<30 by the Cockcroft-Gault formula).