Physical activity is associated with incident disability in community-based older persons

OBJECTIVES: To examine the association between physical activity and the risk of incident disability, including impairment in activities of daily living (ADLs) and instrumental activities of daily living (IADLs), in community-based older persons free of dementia. DESIGN: Prospective, observational cohort study. SETTING: Approximately 40 retirement communities across the Chicago metropolitan area. PARTICIPANTS: More than 1,000 older persons from the Rush Memory and Aging Project, an ongoing longitudinal clinical-pathological study of common chronic conditions of old age. MEASUREMENTS: All participants underwent detailed annual clinical evaluations that included assessments of physical activity, ADLs, IADLs, and gait performance. The associations between physical activity, mortality, and incident disability were examined using a series of Cox proportional hazards models controlled for age, sex, education, and baseline gait. RESULTS: At baseline, participants spent a mean +/- standard deviation of 3.0 +/- 3.5 hours per week engaging in physical activity (range 0-35). In a proportional hazards model, the risk of death decreased 11% (hazard ratio (HR)=0.89, 95% confidence interval (CI)=0.83-0.95) for each additional hour of physical activity per week. For those who were not disabled at baseline, the risk of developing disability in ADLs decreased 7% (HR=0.93, 95% CI=0.88-0.98) for each additional hour of physical activity per week. Similarly, the risk of disability in IADLs decreased 7% (HR=0.93, 95% CI=0.89-0.99) for each additional hour of physical activity. CONCLUSION: For community-based older persons without dementia, physical activity is associated with maintenance of functional status, including a reduced risk of developing impairment in ADLs and IADLs.