Lifetime risk factors for leisure-time physical inactivity in mid-adulthood

We aimed to identify factors from different life-stages that were associated with inactivity at two adult ages and stability and change between these ages. Leisure-time inactivity (activity frequency <1/wk) was assessed at 33y and 50y in the 1958 British Birth cohort (N = 12,271). We created scores representing several domains, i.e. physical health, mental function, social, family and neighbourhood circumstances at different life-stages, and examined associations with adult inactivity. 31% were inactive at 33y and 50y with 17% deteriorating to, and 18% improving from, inactivity. Adjusting for all domains and life-stages, most concurrent factors were associated with inactivity: e.g. per 1-unit worsening physical status (score range:0-2) OR_adjusted for 50y inactivity was 1.56(1.44,1.70). Physical status at 33y was associated with inactivity patterns 33y-to-50y (Relative risk ratios (RRRs) of inactivity persistence and deterioration (vs never inactive) per 1-unit worsening status (score:0-1) were 1.73(1.51,1.99) and 1.28(1.10,1.49) respectively; RRR for improvement (vs persistently inactive) was 0.75(0.63,0.88). Some early-life domain scores were associated with inactivity independent of concurrent factors: e.g. per 1-unit worsening early-life social score (range:0-3) OR_adjusted for 50y inactivity was 1.12(1.05,1.19). Highly urbanised neighbourhood in early adulthood was associated with inactivity (e.g. RRRs for persistent inactivity and deterioration were 1.42(1.22,1.65) and 1.15(1.01,1.31) respectively; 0.82(0.68,0.98) for improvement). Concurrent physical and mental function were associated with adult inactivity at two ages; poorer physical status was associated with greater risk of inactivity persistence and deterioration and lower risk of improvement 33y-to-50y. Young adult neighbourhood and early-life social and family circumstances were independently associated with mid-life inactivity.