Abstract MP26: Replacing Sedentary Behavior Time With Various Daily-life Physical Activities And Structured Exercises, Recommended Physical Activity, And Incident Coronary Heart Disease

Introduction: While excessive sedentary behavior time has been associated with cardiovascular diseases, it is largely unknown to what extend substituting sedentary behaviors with various physical activities may offset the risk of coronary heart disease (CHD). Hypothesis: We hypothesize that reallocating time from sedentary behavior to various daily-life physical activities and structured exercises might be associated with lower risk of CHD. We particularly examined such reallocations according to whether or not the participants meet the recommended physical activity level. Method: A total of 468,960 UK Biobank participants free of CHD were included. Sedentary behavior time was quantified by summing up the time spent on television watching, computer use (not at work), and driving. Physical activities were categorized as daily-life activities (walking for pleasure, light DIY, and heavy DIY) and structured exercise (strenuous sports and other exercises). We used iso-temporal substitution model to estimate the effect of replacing sedentary behavior with each type of physical activity for the same amount of time. Results: During a median follow-up of 11 years, 7,982 incident CHD cases were documented. Sedentary behavior time was significantly associated with a higher risk of CHD, independent of physical activity. In comparison of the extreme categories (≥6 vs. <2 h/d), the HR for CHD was 1.31 (95% CI: 1.18-1.46). Replacing 30 minutes of sedentary behavior per day with an equal time of various physical activities was significantly associated with a 3%-12% risk reduction of CHD. Replacing 1 hour of sedentary behaviors with different types of physical activities was associated with a 6%-23% risk reduction of CHD. Sedentary behavior-to-strenuous sports reallocations showed the largest reduction in CHD risk when replacing sedentary behavior. Moreover, reallocations of sedentary behavior to various physical activities showed particularly greater benefits among those who did not meet the physical activity recommendations. Conclusion: Our study indicates that replacing sedentary behavior time with various daily-life activities or structured exercise was associated with significant reductions in CHD risk.