1. Division of Cardiology, Duke University Medical Center, Durham, North Carolina,
2. Department of Exercise and Sports Science and Human Performance Laboratory, East Carolina University, Greenville, North Carolina
3. Division of Geriatric Medicine, Duke University Medical Center, Durham, North Carolina,
4. Geriatric Research, Education and Clinical Center, Durham Veterans Affairs Medical Center, Durham, North Carolina,
5. Duke Center for Living, Duke University Medical Center, Durham, North Carolina,