David M. Buchner, M.D., M.P.H., is a Shahid and Ann Carlson Khan Professor in Applied Health Sciences, in the Department of Kinesiology and Community Health, at the University of Illinois at Urbana-Champaign. He has published extensively in the area of physical activity and public health, with an emphasis on promotion of physical activity and prevention of fall injuries in older adults. Prior to joining the faculty at the University of Illinois, Dr. Buchner was a Professor in the School of Public Health at the University of Washington from 1984-1999. From 1999 to 2008, Dr. Buchner was Chief of the Physical Activity and Health Branch at the U.S. Centers for Disease Control and Prevention. In this role, he was chairman of the writing group for the 2008 Physical Activity Guidelines for Americans and he participated in numerous national initiatives involving physical activity and public health.