In a controlled laboratory study of prolonged sitting, 3 different interruption break types will be utilized. Ten sedentary, postmenopausal participants 55+ years of age and body mass index (BMI) of 27-45 will be enrolled. After screening and enrollment, participants will visit the clinic on 4 occasions for a 6-hour monitoring period and, following a 1-hour sitting run-in period, complete each of 4 5-hour sitting protocols. The 3 sitting interruption protocols will each include sitting interruptions of different break frequency and type and will allow evaluation of the effect of sit-to-stand transitions and interruption type on acute metabolism and health outcomes. All study protocols include baseline, mid-point, and end-of-study bathroom breaks for urine sample collection with additional bathroom breaks allowed as needed. During each protocol at multiple time points, blood samples will be collected to assess changes in biomarkers of glycemic regulation (glucose and insulin areas under the curve) and mitochondrial function over the course of the sitting protocols. During each protocol at multiple time points, changes in endothelial function, specifically, blood pressure (indirect measure) and femoral flow-mediated dilation (direct measure), will be assessed. Changes in these measures will be compared between protocols. A small aliquot (0.5mL) of plasma samples and urine samples collected during the protocol will be banked for possible ancillary, exploratory studies. This study is a crossover design and each participant will be her own control. The investigators hypothesize that frequent sit-to-stands during a 5-hour sitting period will result in health benefits that can be observed with a simple 2-minute standing interruption, and that this will be associated with improvements in metabolism and endothelial function. The investigators will test this hypothesis in the following aim: