Association of physical activity and sitting time trajectories with mortality risk in 9430 Australian adults with coronary heart disease

OBJECTIVES: To examine the dose-response relationship between moderate-to-vigorous physical activity (MVPA) and sitting time trajectories with cardiac and all-cause mortality in a cohort of middle-aged and older-adults after a diagnosis of coronary heart disease (CHD). DESIGN: This prospective cohort study comprised Australian participants aged ≥45-years with CHD (2006-2020) who had self-reported MVPA (min/wk) and sitting time (hr/day) data from at least two survey waves. METHODS: MVPA and sitting time trajectories were categorised as remaining high, decreasing, increasing, and remaining low. Cardiac and all-cause mortality were the main outcomes. Associations were explored using Cox regression models. RESULTS: The cohort included 9430 participants (mean (SD) age, 70 (10) years; 3557 females (38 %)). During a median follow-up of 4.4 (IQR, 6.1) years, 540 cardiac and 2843 all-cause deaths were recorded. Compared with individuals that remained inactive, remaining active was associated with a 36 % and 49 % lower risk of cardiac and all-cause death, respectively. Decreasing or increasing MVPA over time was associated with a 20-33 % lower risk of all-cause death. Compared with high sitting time, individuals that maintained low sitting time or decreased their sitting time over time reduced the associated risk of cardiac and all-cause death by 33-38 %. CONCLUSIONS: Regardless of pre-CHD diagnosis movement behaviours, individuals' post-CHD diagnosis can reduce their risk of cardiac and all-cause mortality by achieving the physical activity thresholds at any time and reducing their sitting time over-time. Further research is needed to confirm the physical activity and sitting time thresholds to receive these benefits.