 - Potential participants with a history of the following conditions remain eligible for study enrollment: gestational diabetes; treated, controlled, uncomplicated hypertension; treated hypo- or hyperthyroidism; cured nonmetastatic cancer; disease-free for 5 years excluding hematologic malignancies; localized skin cancer, resected including squamous cell and basal cell carcinomas, participants with a history of melanoma must be disease-free for 5 years; exercise-induced bronchospasm; mild asthma: use of inhalers only for control of symptoms is acceptable Persons who have required hospitalization for asthma within the previous 2 years or those who require chronic or frequent oralparenteral steroids will not be eligible; use of low to medium doses of inhaled steroids; history of coronary artery disease, asymptomatic NYHA Function Class I, on a stable medical regimen. Persons meeting these criteria must be at least 2 years post-myocardial infarction, cardiac bypass surgery, andor percutaneous coronary intervention e.g., angioplasty, stent placement, etc in order to qualify. Persons with a history of cardiac disease must be under the care of a physician. 