Effect of Regular Exercise on Vascular Function and Cardiovascular Risk in a Sedentary Work Force

Evidence suggests that Americans are becoming increasingly sedentary at work and at home due to technological advances. Physical inactivity coupled with excess caloric intake, especially of calorie-rich fast foods, are responsible for the epidemic of obesity in this country. Physical inactivity in obese and non-obese individuals increases the risk of cardiovascular disease and all-cause mortality. Premature cardiovascular disease leads to lost productivity in the work place, impaired quality of life, and escalating health care costs. In response to these concerns, the American Heart Association advocates 30 minutes of aerobic exercise most days; however, busy schedules coupled with a lack of convenient access to exercise equipment (or motivation to use it) limit adoption of regular exercise by many. One year ago, the National Heart, Lung, and Blood Institute (NHLBI) initiated the Keep the Beat program which encourages Institute employees to engage in fifteen minutes of exercise during the work day, and provides exercise equipment at specific work sites to accomplish this goal. Yet, fewer than 10% of NHLBI employees regularly participate in Keep the Beat and many who initially enrolled have failed to continue participation. The purpose of our prospective cohort study is to determine whether participation in the Keep the Beat program can improve an important measure of cardiovascular risk-arterial endothelial function-by stimulating bone marrow-derived endothelial progenitor cells to repair endothelium. We propose to characterize important components of vascular health by measuring endothelial nitric oxide bioactivity, as determined by brachial artery reactivity to shear stress and nitric oxide metabolites in blood, and vascular repair potential, as determined by endothelial progenitor cell number and function, at baseline and at 3 months in National Institutes of Health employees who agree to participate in Keep the Beat. Secondary analyses will include other biomarkers of risk, such as C-reactive protein, blood pressure, body mass index, lipid profile, fasting glucose/insulin, and homeostasis model assessment index, to be measured in our study and subgroup analyses of participants at particularly high cardiovascular risk (greater than 20% over 10 years), minorities, and women. Demonstration of improved vascular function, with implications of reduced cardiovascular risk, may serve as an incentive for greater employee participation in established employer-initiated programs, and for adoption of similar programs by other employers. If objective benefit cannot be demonstrated in vascular function and other biomarkers of risk, modification of the program may be required to reduce cardiovascular risk.