Physical activity (PA) has a critical role to play in addressing two of the most important public health challenges of modern times: the rising prevalence of obesity and population ageing.
Despite the publication of national and international recommendations which aim to promote the uptake and maintenance of PA across life, a significant proportion of the world’s population still do not regularly participate in PA. To address this challenge we need to better understand the determinants of PA. While many determinants of PA have been identified, it is often not possible, due to a lack of suitable data, to assess the impact of age-related changes and secular trends in PA on these associations. This is a significant limitation as the influence of different determinants may vary by age and birth cohort with important implications for the targeting of interventions. Essential insights are thus to be gained from investigating age and cohort differences in associations where comparable data are available; coordinated analyses of data from CLOSER studies provide a unique opportunity to do this across the life course in a UK setting.