Cardiovascular Diseases (CVDs) are the primary source of global mortality and morbidity. The initial steps of CVD development occur in the endothelium. MicroRNAs (miRNAs) have recently emerged as novel regulators of cardiovascular physiology and pathology. Interestingly, regular aerobic exercise acts to prevent CVDs and also regulates miRNAs in the circulation (ci-miRNAs). The purpose of this study was to determine the effects of serum from highly active and sedentary, young, healthy individuals on migration rate of endothelial cells in vitro. Secondarily, CVD-associated ci-miRNAs in serum were compared between groups. The results of this study represent a novel way by which sedentary behavior may act as an early risk for CVD development before the appearance of other classic risk factors. RT-qPCR array analysis identified nine ci-miRNAs as > 4-fold differentially expressed in serum of trained versus inactive subjects, though more subjects are needed before any conclusions about ci-miRNA differences can be made.