Device-measured physical activity as a predictor of disability among mobility-limited older adults
HHS Public Access Author manuscript J Am Geriatr Soc. Author manuscript; available in PMC 2018 October 01.
Published in final edited form as: J Am Geriatr Soc. 2017 October ; 65(10): 2251–2256. doi:10.1111/jgs.15037.
Device-measured physical activity as a predictor of disability among mobility-limited older adults
Robert T. Mankowski, PhD1, Stephen D. Anton, PhD1, Robert Axtell, PhD2, Shyh-Huei Chen, PhD3, Roger A. Fielding, PhD5, Nancy W. Glynn, PhD6, Fang-Chi Hsu, PhD3, Abby C. King, PhD7, Andrew S. Layne, MSc1, Christiaan Leeuwenburgh, PhD1, Todd M. Manini, PhD1, Anthony P. Marsh, PhD4, Marco Pahor, MD1, Catrine Tudor-Locke, PhD8, David E. Conroy, PhD9, Thomas W. Buford, PhD10, and LIFE Research Group
1Department of Aging and Geriatric Research, University of Florida College of Medicine, Gainesville, FL, USA
2Department of Exercise Science, Southern Connecticut State University, New Haven, CT, USA
3Department of Biostatistics, Wake Forest School of Medicine, Winston-Salem, NC, USA
4Department of Health & Exercise Science, Wake Forest School of Medicine, Winston-Salem, NC, USA
5Tufts University, Jean Mayer USDA Human Nutrition Research Center on Aging, Boston, MA, USA
6University of Pittsburgh, Center for Aging and Population Health, Department of Epidemiology, Pittsburgh, PA, USA
7Department of Health Research & Policy, and Stanford Prevention Research Center, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
8Department of Kinesiology, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA, USA
9Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA
10Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
Abstract
Background—The utility of wearable devices for objectively monitoring physical activity (PA) and predicting mobility disability in older adults is unknown.
Objectives—The aim of this analysis was to examine associations between objectively-measured PA and the incidence of major mobility disability (MMD) and persistent MMD (PMMD) among older adults in the Lifestyle Interventions and Independence for Elders (LIFE) Study.
Design—Prospective cohort of individuals aged 65 and older undergoing structured physical activity intervention or health education. Setting—Eight sites. Participants—LIFE Study participants (n=1590) had a mean age (SD) of 78.9 (5.2) years, with low levels of PA and measured mobility-relevant functional impairment at baseline.
Measurements—Activity data were collected by hip-worn 7-day accelerometer at baseline and 6, 12, and 24 months post-randomization to test for associations with incident MMD and PMMD (≥ 2 consecutive instances of MMD).
Results—At baseline, every 30 minutes spent being sedentary (<100 accelerometry counts per minute) was associated with higher rate of subsequent MMD (10%) and PMMD (11%) events. Every 500 steps taken was associated with lower rate of MMD (15%) and PMMD (18%). Similar associations were observed when fitting accelerometry-based PA as a time-dependent variable.
Conclusion—Accelerometry-based PA levels were strongly associated with the MMD and PMMD events among older adults with limited mobility. These results support the importance of daily PA and lower sedentary time levels in this population and suggest that accelerometry may be a useful tool for assessing risk for mobility disability.
Keywords: Accelerometry; mobility disability; physical activity; sedentary time; older adults
