No uncompensated coronary artery disease on electrocardiogram or physical examination, or a history of myocardial infarction or severe/unstable angina in the past 6 months. No diabetes mellitus with severe peripheral vascular disease and no deep venous or arterial thrombosis (including pulmonary embolism) within 3 months of entry. No New York class II-IV congestive heart failure, chronic obstructive lung disease requiring oxygen therapy or medication, or uncontrolled seizure activity. Uncomplicated asthma will be allowed. No active therapy for angina.