Health enhancing strength training in nonagenarians (STRONG): rationale, design and methods. - Rexach,JA.; Ruiz,JR.; Bustamante-Ara,N.; Villaran,MH.; Gil,PG.; Sanz Ibanez,MJ.; Sanz,NB.; Santamaria,VO.; Sanz,NG.; Prada,AB.; Gallardo,C.; Romo,GR.; et al. (BMC Public Health, 2009)