Reduce Sedentary Behavior at Work

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.

Inclusion criteria

• Sedentary office workers the Medical College of Wisconsin who spend greater than 75% of their (8 hours or longer) work-day sitting at a desk. This includes at least 1 period of 2 hours or longer of uninterrupted sitting time per work day.
• Body mass index of 26.0-44.9
• Willing and able to sign Informed consent
• Permission from the subject's supervisor to participate in the intervention

Exclusion criteria

• Known history of atherosclerotic cardiovascular disease, including myocardial infarction, stroke, coronary stent, coronary artery bypass grafting, angina and peripheral vascular disease
• Diabetics on insulin or other diabetic medications (pre-diabetes would be acceptable, defined as a HbgA1c of 5.7 to 6.4%, and not on medications)
• Elevated blood pressure (SBP≥150 mm Hg or DBP ≥90 mm Hg) or on medication for hypertension; or SBP < 100 mm Hg.
• On cholesterol-lowering medication or LDL-C cholesterol ≥190 mg/dL
• Pregnancy, lactating or planning to get pregnant within the next 6 months
• Current tobacco use within previous 12 months. Tobacco use included cigarettes, cigars, and all forms of smokeless tobacco.
• Current excessive alcohol use (defined as more than 14 drinks/week for women, more than 28 drinks/week for men)
• Current illicit drug use, defined as overuse of prescription medications, or of any illegal mind altering substances.
• Known thyroid disease
• Taking diet pills, or supplements other than those contained in a multi-vitamin
• History of musculoskeletal surgery/injury that would interfere with prolonged periods of standing
• History of use of PDE-5 inhibitors for any reason within the last 5 days of screening visit, and the inability to hold use of PDE-5 inhibitors for 5 days prior to each of the FMD evaluations.