Midlife Physical Activity Preserves Lower Extremity Function in Older Adults: Age Gene/Environment Susceptibility-Reykjavik Study..

Chang M, Saczynski JS, Snaedal J, Bjornsson S, Einarsson B, Garcia M, Aspelund T, Siggeirsdottir K, Gudnason V, Launer LJ, Harris TB, Jonsson PV.  J Am Geriatr Soc. 2013 Feb;61(2):237-42