Abstract Body: Introduction: Many studies report physical activity (PA) and sedentary behavior (SB) to be independently associated with lower and higher cardiovascular disease (CVD) risk, respectively. We evaluated a combined exposure of PA and SB in association with CVD risk.

Methods: Data were gathered from 35,844 participants from six NHLBI cohorts: Atherosclerosis Risk in Communities Study, Coronary Artery Risk Development in Young Adults Study, Cardiovascular Health Study, Framingham Heart Study, Jackson Heart Study, and the Multi-Ethnic Study of Atherosclerosis. We harmonized time-varying PA and SB into quintiles, considering the cumulative average over all timepoints prior to a first CVD event (fatal and non-fatal) or end of follow-up. We created a 6-level ‘PASB index’ based on combining the PA and SB quintiles. We performed Cox regression to examine the associations of PA and SB quintiles, and the PASB index with incident CVD risk. Covariates were age, sex, race/ethnicity, study center, education, smoking, alcohol use, and dietary quality. A random effects model was used for the pooled results.

Results: Across cohorts, there were 10,913 CVD events. In pooled analyses, PA had a graded inverse association with CVD risk (HR=0.92 per quintile increment; 95% CI: 0.89, 0.95), and SB had a non-linear threshold association with CVD with the highest SB quintile having a greater risk relative to the lowest quintile (HR=1.13; 95% CI: 1.01, 1.26). Results for the six-level PASB index are shown in Figure 1, with the lowest HRs for those with low to moderate SB and either moderate or high PA.

Conclusion: The combined behaviors of moderate to high PA and low SB were associated with the lowest risk for CVD. These findings support current public guidelines to engage in regular PA of at least moderate intensity and to avoid high levels of SB.