Abstract
Sedentary behavior is associated with cardiovascular disease (CVD) and mortality, independent of physical activity. The biological mechanisms underlying these associations are largely unknown. We hypothesized that obese subjects with sedentary desk jobs, when assigned a sit-stand desk, will reduce daily sedentary time, and show improvement in arterial flow-mediated dilation (FMD), an early indicator of CVD. Overweight and obese subjects without known CVD were recruited at our institution and given an adjustable sit-stand desk at work. Activities were quantified with an accelerometer for 7 days at baseline and during the intervention. FMD of the brachial and superficial femoral arteries, fasting lipids, insulin and glucose labs, and anthropometrics were measured at baseline, and 12 and 24 weeks. Repeated one-way ANOVA tests were used to compare measurements over time. Fifteen participants were enrolled (93% female, mean age 40 ± 5 years, mean body mass index [BMI] 33 ± 5). Mean daily sedentary time at work decreased by 90 minutes from baseline (385 ± 49 minutes) to 12 weeks (297 ± 80 minutes, p = 0.002) and 24 weeks (295 ± 127 minutes, p = 0.015). Femoral FMD increased from baseline (4.9 ± 1.7%) to 12 weeks (6.4 ± 2.3%, p = 0.043) and further to 24 weeks (8.1 ± 3.2%, p = 0.009). Significant improvement in fasting triglycerides and insulin resistance occurred. There was no change in brachial FMD, exercise activity, step counts, weight, or BMI. A significant reduction in sedentary time during working hours was identified with utilization of a sit-stand desk and sustained over 24 weeks. Improvements in FMD, triglycerides, and insulin resistance provide insight into mechanisms of adverse health risks associated with sedentary behavior.