 - Framingham Risk Score for cardiovascular disease 10; no history of heart disease, e.g. previous treated arrhythmia or myocardial infarction; no horizontal positioning-induced or activities of normal living exercise-induced shortness of breath; no history of stroke or claudication; no current treatment with medication for high cholesterol or other lipid abnormality; a documented electrocardiogram ECG and cardiac troponin must be within normal institutional limits in the past 30 days; normal ECG with sinus tachycardia or normal ECG with sinus bradycardia is allowable based on a history of absent cardiacexercise related symptoms as determined by the P.I. in consultation with a senior staff cardiologist 