[1] Univ Pittsburgh, Dept Phys Therapy, Sch Hlth & Rehabil Sci, Pittsburgh, PA 15260 USA
[2] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Epidemiol, Pittsburgh, PA 15260 USA
[3] Univ Pittsburgh, Sch Med, Dept Geriatr Med, Pittsburgh, PA 15260 USA
[4] Cooper Inst, Div Res, Dallas, TX USA
[5] Univ N Texas, Coll Educ, Dept Kinesiol Hlth Promot & Recreat, Denton, TX 76203 USA