Background: Sex, age, body mass index (BMI), perceived health and health behavior are correlates known to affect physical activity and sedentary time. However, studies have often been cross-sectional, and less is known about long-term correlates. Thus, the aims were to investigate 1) the associations between a set of characteristics (demographic, biological, psychological and behavioral) and objectively measured physical activity and sedentary time at 13 year follow-up, and 2) the association between changes in these characteristics over time and physical activity and sedentary time. Methods: Baseline characteristics were collected in 40-year-olds in 1996, and follow-up data on objectively measured physical activity and sedentary time were obtained in 2009 (n=240). Data were analyzed by multiple linear regressions. Results: Self-reported physical activity (p<0.001) and improved perceived health (p=0.046) were positively associated with moderate-to-vigorous physical activity (MVPA) whereas BMI (p=0.034) and increased BMI (p=0.014) were negatively associated with MVPA at follow-up. Women spent less time being sedentary than men (p=0.019). Education (p<0.001) was positively associated and improved perceived health (p=0.010) was negatively associated with sedentary time at follow-up. Conclusions: MVPA and sedentary time at follow-up were associated with behavioral, biological and demographic correlates. However, the nature of our analyses prevents us from inferring causality
