Abstract 042: Accelerometer-measured Light Physical Activity is Heart Healthy in Older Women: The OPACH Study

Abstract

Background: The longstanding, prevailing paradigm in physical activity (PA) research and US PA guidelines is that moderate to vigorous physical activity (MVPA) for at least 150 minutes/week, preferably in increments of at least 10 minutes, is needed to prevent cardiovascular disease (CVD) in adults. Because light physical activity (LPA; 1.1-<3 metabolic equivalents (METs)) is poorly measured by self-report, we know little about its association with CVD. Methods: Women’s Health Initiative participants in the OPACH Study (n=5861, mean age=78.5±6.7, 33.5% Black, 17.6% Hispanic) without a history of myocardial infarction or stroke wore accelerometers for up to 7 days and were followed for incident CVD for up to 4 years. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CIs) for CVD and coronary heart disease (CHD) across awake wear time adjusted quartiles of MVPA and LPA. Fully adjusted models accounted for age, race-ethnicity, smoking, education, body mass index, systolic blood pressure, co-morbidity score, physical function, and self-rated health. We then examined the LPA association with CVD/CHD after adjustment for MVPA. Results: Higher levels of both LPA and MVPA were associated with reduced risks of CVD and CHD after adjusting for covariates (Table; p-trend <0.05, all). Women with the highest vs. lowest levels of MVPA had markedly reduced risks of CVD (31%) and CHD (50%). Women in the highest vs. lowest quartiles of LPA had 22% reduced risks of CVD and 39% reduced risks of CHD even after adjustment for many indicators of health status and CVD risk factors. The LPA association with CVD persisted after adjustment for MVPA (highest vs. lowest LPA quartile HR: 0.81 for CVD, p-trend=0.01; 0.74 for CHD, p-trend=0.04). Conclusions: LPA is associated with reduced risks of incident CVD and CHD in older women independent of health status indicators, CVD risk factors, and MVPA. Increasing levels of LPA is an achievable behavioral intervention for improving heart health in older women.