Exercise and endothelial function

Regular exercise has many benefits for health and has been found to result in a lower incidence of cardiac events and mortality. The exact mechanism is not known; however, physical activity improves cardiac risk factor profiles and may also lead to an improvement in endothelial function. The endothelium acts to maintain normal vasomotor tone, enhance the fluidity of blood, and regulate vascular growth. Abnormalities in these functions contribute to many disease processes, including angina, myocardial infarction, coronary vasospasm, and hypertension. Exercise causes increases in blood flow leading to increased shear stress, which is the force acting parallel to blood vessels. Enhanced shear stress results in endothelium-dependent, flow-mediated dilation of vessels. Chronic increases in shear stress have been found to improve endothelial function in animal studies as well as in some limited human studies. In addition, chronic exercise has been found to enhance fibrinolysis and platelet activity. This review will focus on the benefits of exercise, the role of normal endothelium, the consequences of abnormal endothelial function, and potential improvements in endothelial function in response to chronic exercise.