Layne AS, Hsu FC, Blair SN, Chen SH, Dungan J, Fielding RA, Glynn NW, Hajduk AM, King AC, Manini TM, Marsh AP, Pahor M, Pellegrini CA, Buford TW. Predictors of Change in Physical Function in Older Adults in Response to Long-Term, Structured Physical Activity: The LIFE Study. Arch Phys Med Rehabil. 2017 01; 98(1):11-24.e3.