The Role of Age in Moderating the Association Between Disability and Light-Intensity Physical Activity.

PURPOSE: There's a lack of evidence on the association between light-intensity physical activity and disability. This study examines the relationships in activity by self-reported physical function in five domains (i.e., activities of daily living [ADL], instrumental ADL, leisure activities, lower extremity, and general activities), and whether this association varies by age. DESIGN: Cross-sectional. SETTING: Data from National Health and Nutrition Examination Survey 2003-2004 and 2005-2006 waves. SUBJECTS: Participants included 5700 men and women ages 20 to 85 years. MEASURES: Difficulty with various activities was measured with the Physical Functioning Questionnaire, accelerometer-measured physical activity, demographics, and self-rated health. ANALYSIS: Ordinary least squares regression models were run to examine the relationship between physical function in each domain, light-intensity activity, and the moderating effect of age. Analyses controlled for body mass index, moderate-to-vigorous-intensity activity, self-reported health, accelerometer wear time, and gender. RESULTS: Little variation was seen in light-intensity physical activity among younger adults regardless of disability status. Older adults reporting difficulty with activities engaged in significantly less light-intensity physical activity compared to those with no disability (271.8 vs. 316.5 minutes). Age significantly moderated the association between light-intensity physical activity and leisure activities (p = .048), and lower extremity mobility (p = .039). Age did not moderate other domains of disability. CONCLUSION: Younger age may be protective regarding the influence of disability on light-intensity activity. In addition, disability may be more debilitating for some older individuals. Interventions to increase light-intensity activity should aim to address disability at all ages, with increased attention for older adults.