The Analysis of Wall Shear Stress Modulated by Acute Exercise in the Human Common Carotid Artery with an Elastic Tube Model

Assessment of the magnitude and pattern of wall shear stress (WSS) in vivo is the prerequisite for studying the quantitative relationship between exercise-induced WSS and arterial endothelial function. In the previous studies, the calculation of the WSS modulated by exercise training was primarily based upon the rigid tube model, which did not take non-linear effects of vessel elastic deformation into consideration. In this study, with an elastic tube model, we estimated the effect of a bout of 30-minute acute cycling exercise on the WSS and the flow rate in the common carotid artery according to the measured inner diameter, center-line blood flow velocity, heart rates and the brachial blood pressures before and after exercise training. Furthermore, the roles of exercise induced arterial diameter and blood flow rate in the change of WSS were also determined. The numerical results demonstrate that acute exercise significantly increases the magnitudes of blood flow rate and WSS. Moreover, the vessel elastic deformation is a non-negligible factor in the calculation of the WSS induced by exercise, which generates greater effects on the minimum WSS than the maximum WSS. Additionally, the contributions of exercise-induced variations in blood flow rate and diameter are almost identical in the change of the mean WSS.