Background: We investigated the population trajectory of leisure time physical activity (LTPA) in adults age 18 to 60 y (n = 881), who were recruited in 1981 for the Canada Fitness Survey and followed-up through the Campbell's Survey on Well-Being (1988) and the Physical Activity Longitudinal Study (2002/04).
Methods: Data on involvement in LTPA were collected by questionnaire and used to estimate average daily energy expenditure (EE) (kcal . kg-1 . d-1) during leisure time. Growth trajectory modeling was used to describe the overall population trajectory of LTPA and the extent to which average trajectories varied between sub-groups defined by age, sex, and education.
Results: The population trajectory of LTPA over time was modified by baseline age, but not by sex or by level of education. Disparities in LTPA related to sex and education persisted over two decades.
Conclusion: This longitudinal investigation improves our understanding of the processes underlying patterns of LTPA in adults.