Objectives: This study assessed how and why the social stratification of leisure-time physical activity changes as adults at different points in the life course, and from different birth cohorts, grow older.
Methods: A series of multilevel models were estimated using longitudinal data from a national sample of more than 3,000 adults from the Americans' Changing Lives study.
Results: On average, rates of leisure-time physical activity increased within younger adults and decreased within middle-aged and older adults, throughout the study period. Initial Black-White differences in activity converged over time, whereas initial men advantages over women widened, particularly among older adults. Gender-based differences did not remain after accounting for differences in health; however, significant age and race differences in the trajectories of physical activity persisted, even after accounting for the effects of health and social relationships on leisure-time physical activity.
Discussion: American adults appear to be reducing their levels of physical activity relatively early in the life course and at increasingly steep rates among older age groups. The changing patterns of stratification in physical activity, as well as the associations between several time-varying predictors and physical activity, provide insight into the forces that may be responsible for these declines.