Impact of Acute Exercise on Vascular Insulin Sensitivity in Metabolic Syndrome

Summary

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.

Conditions

• Metabolic Syndrome
• Obesity

Interventions

BEHAVIORAL

Single Bout of Exercise

An exercise condition, which will be walking at a moderate intensity (\~70% VO2peak). Time will vary based upon individual fitness levels to burn \~400kcals (estimated 0.5 - 1hr). Oxygen consumption will be measured during exercise via a metabolic cart to confirm energy expenditure. Participants will then rest following the exercise procedure for 20 minutes. Between 20 and 45 minutes following exercise, oxygen consumption will be measured to understand and capture excess post-exercise oxygen consumption (EPOC). Following this, participants will be provided with a standardize dinner and snack to consume in the AMP lab.

BEHAVIORAL

Control Condition

A control (no-exercise) condition. Participants will report to the AMP lab to rest for the same duration as the exercise bout and consume the standardized dinner and snack.

Sponsors & Collaborators

• American College of Sports Medicine

  collaborator OTHER

• University of Virginia

  lead OTHER

Principal Investigators

• Steve Malin, PhD · University of Virginia

Study Design

Allocation

NON_RANDOMIZED

Purpose

PREVENTION

Masking

NONE

Model

CROSSOVER

Eligibility

Min Age

40 Years

Max Age

70 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2019-02-18

Primary Completion

2019-09-30

Completion

2020-01-31

Countries

• United States

Study Locations