The longitudinal relation between purpose in life and accelerometer-measured physical activity

BACKGROUND AND AIMS: Purpose in life is associated consistently with accelerometer-measured physical activity assessed concurrently. This research addresses the longitudinal relation between purpose and accelerometry-measured physical activity among older adults. METHODS: Participants from the National Health and Aging Trends Study (N=747; Meanage=79.20) reported on their purpose and wore an accelerometer at four annual assessments. Physical activity was quantified with four metrics: total activity counts, number of active bouts, activity fragmentation, and sedentary fragmentation. RESULTS: Consistent with cross-sectional associations, purpose at baseline was associated prospectively with the four metrics measured one and two years later (median β=.08) but attenuated for two of the metrics at year three. Baseline purpose was associated with the intercept of physical activity but not change across the assessments. Within-person, participants were more physically active at assessments when their purpose was higher than their average. CONCLUSIONS: Purpose in life is a short-term prospective and within-person predictor of physical activity but is unrelated to the rate of change in accelerometer-measured physical activity over three years in older adulthood.