Reduce Sedentary Behavior at Work

Overview

Prior research suggests that sedentary behavior is detrimental to health, independent of exercise activity. Sedentary behavior is defined as behaviors that involve low levels of energy expenditure ≤1.5 metabolic equivalents (including sitting, watching TV, reading, and driving). Due to the high burden of sedentary behaviors in modern-day societies, this has potential implications for novel intervention strategies to reduce sitting (outside of regular exercise activity) and improve health. In addition, the modern workplace fosters sedentary behavior, and sedentary jobs now make up more than 80% of the workforce. The goal of this project is to implement interventions to reduce sedentary behavior at work and evaluate their impact on physiologic parameters and markers of disease. Specifically, the investigators/study team will use direct measurement of vascular endothelial function as one of our outcomes. This is important since conduit artery endothelial function, assessed by arterial flow-mediated dilation (FMD), is a powerful indicator of vascular inflammation and predictor of future cardiovascular events.

The hypothesis is that obese subjects with sedentary jobs at the Medical College of Wisconsin, when assigned use of a standing desk to encourage movement, will reduce their daily sedentary time and demonstrate improvement in physiologic parameters and disease markers from baseline through the end of the intervention. Prior intervention studies are limited and not randomized, but have shown a reduction in waist circumference and improvements in cholesterol when overall sitting time is reduced over a 3-6 month interval (with a standing or treadmill desk). None of these intervention studies have directly measured vascular endothelial function, as assessed by arterial flow-mediated dilation (FMD), an early indicator of cardiovascular disease, and a powerful predictor of future cardiovascular events and vascular inflammation. Improvements in arterial FMD (or endothelial function) are known to reduce the future risk of cardiovascular events. Due to differences in the energy requirement of lying down, sitting, and standing, there has been increased research interest in activity type classification based on posture. In the science of sedentary behaviors, this is an important distinction to consider when evaluating health outcomes, such as in the present study. Accelerometers (physical activity monitors) utilize piezoelectric crystal sensor technology to provide a measure of accelerations of the body during movement and have the advantage of capturing frequency, duration, and intensity of physical movement minute by minute. Accelerometer technology will be used to analyze the primary outcome of interest (sedentary time). The study team will collect information on standing time, sedentary bouts, daily steps, cadence (walking speed in steps/minute), and exercise activity. The study team will employ a compact and re-usable physical activity monitor that adheres to the subject's thigh. This will provide objective assessments of activity levels at baseline and during the intervention. This data can be translated into energy expenditure or activity intensity categories (METs) and even position (sitting verses standing). The monitor output is Excel-compatible and is ideal for comparing each subject's activity and physiological parameters from baseline to intervention.