Evaluating Standing as a Health Behavior to Promote Cardiovascular Risk Reduction in African Americans

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US adults are sedentary for ~11-12 h/day - which greatly increases cardiovascular disease (CVD) and mortality risk. The Physical Activity Guidelines for Americans have expanded beyond promoting moderate- vigorous physical activity and now also advocate for reductions in sedentary time. Accordingly, there is strong interest in elucidating simple, cost-effective methods to reduce sedentary time. The popular press and corporations seeking to capitalize on health trends have perpetuated the notion that simply standing in place is a healthful alternative to sitting. Consequently, standing and sit-to-stand desks are the fastest growing employee benefit in US workplaces. However, there is a paucity of evidence documenting the health benefits of standing. As such, despite public perception that standing is a healthful alternative, it remains absent from physical activity guidelines, with concerns raised that standing could be more harmful then sitting. The goal of the proposed study is to comprehensively evaluate purported benefits (cardiometabolic) and risks (vascular damage to lower limbs, musculoskeletal pain) that may be incurred with standing and its accrual pattern in the highest risk group in the US - African Americans living in the stroke belt. The prospective association between objectively-measured standing time and the 2-year change in a composite CVD risk score (comprising glucose, triglycerides, cholesterol, blood pressure, waist circumference) will be evaluated (Aim 1). Multiple novel standing pattern variables (e.g. distribution, length, and regularity of standing bouts) will be investigated to identify which aspects of standing are most associated with the 2-year change in CVD risk score (Aim 2). State of the art analytic techniques will be used to evaluate if reallocating time from sedentary to standing would yield CVD risk score reductions (Secondary Aim). Prospective associations between standing time/patterns and the 2-year change in the ankle-brachial index (ABI, an index of peripheral vascular disease) and musculoskeletal pain symptoms, and the cross-sectional/prospective predictors of standing will also be examined (Exploratory Aims). To address our study aims, we will leverage the infrastructure of the Jackson Heart Study (JHS), an exclusively African American cohort study. A fourth JHS exam is scheduled to be conducted in 2020-2022 and will include assessment of CVD risk factors. For this ancillary study, we propose to add a 7-day accelerometer protocol (with posture detection), ABI assessment, and questionnaires to this exam for 1,250 participants. We furthermore propose a follow-up visit 2 years later to re-assess these measures and CVD risk factors. Findings will (1) inform probable cause and effect associations with respect to standing and health outcomes, (2) identify optimal patterns of standing that should be promoted, (3) establish endpoints for future trials promoting standing, and (4) identify predictors of standing that can serve as intervention targets. We view this project as a critical next step that will provide foundational evidence important for success of future trials and ultimately public health efforts targeting sedentary behavior in African Americans and other population groups.