RT Journal Article SR Electronic T1 Walking lowers mortality risk in older US adults JF BMJ Evidence-Based Medicine JO BMJ EBM FD BMJ Publishing Group Ltd SP bmjebm-2018-110902 DO 10.1136/bmjebm-2018-110902 A1 Klaus Gebel A1 Ding Ding YR 2018 UL http://ebm.bmj.com/content/early/2018/05/04/bmjebm-2018-110902.abstract AB