Impact of Acute Exercise on Vascular Insulin Sensitivity in Metabolic Syndrome

Obesity is an independent risk factor for type 2 diabetes and cardiovascular disease. The increased prevalence of obesity worldwide is a major concern among the scientific and medical communities. Insulin resistance is a common factor associated with obesity, metabolic syndrome, hypertension, and type 2 diabetes. Individuals affected by these conditions often experience endothelial dysfunction as well. Insulin resistance provides a key link between metabolic syndrome risk factors and vascular disease. Development of strategies aimed at preventing vascular dysfunction and future disease caused by metabolic disturbances is needed. Although the relationship between obesity and various diseases is well known, the acute effects of insulin on vascular function in obese individuals have yet to be fully determined. Additionally, the effects of acute exercise on insulin-stimulated endothelial function are unknown. Exercise may be an effective and potent treatment that protects against endothelial dysfunction, insulin resistance, and future cardiometabolic disease commonly present with obesity. However, less attention has been placed on vascular insulin sensitivity. The purpose of this study is to test the hypothesis that a single bout of exercise increases insulin-stimulated blood flow at the macro- and micro-vasculature level in obese individuals with metabolic syndrome to similar levels as healthy obese control. Our laboratory has available non-invasive methods to quantify vascular function and the gold-standard technique for assessing insulin sensitivity (euglycemic-hyperinsulinemic clamp). The investigators will assess vascular function (flow-mediated dilation, post-ischemic flow velocity and contrast-enhanced ultrasound) as well as arterial stiffness (augmentation index and pulse wave velocity) before and at the end of the clamp protocol performed the morning following a bout of exercise and a control (no-exercise) condition in 1) metabolic syndrome and 2) obese adults. If our hypothesis is sustained, it will suggest that a key role of the vasculature exists in regulating insulin following exercise and will provide insight into the link between the vasculature, obesity, metabolic syndrome and cardiovascular disease and may confer decreased risk for cardiometabolic disease.