1. a Department of Human Performance and Sport Sciences , Winston Salem State University , Winston Salem, North Carolina, USA
2. b Division of Gerontology , University of Maryland School of Medicine, and Baltimore Geriatric Research, Education and Clinical Center, Virginia Maryland Health Care System , Baltimore, Maryland, USA
3. c Department of Neurology , Baltimore Veterans Administration Maryland Health Care System , Baltimore, Maryland, USA
4. d Department of Neurology , University of Maryland School of Medicine , Baltimore, Maryland, USA