Endothelium serves as the permeability barrier between the blood and interstitial space. Endothelial function includes the production, secretion and metabolisation of bio-active molecules. Endothelium also plays significant roles in cell migration, remodeling of the vasculature (including proliferation and apoptosis). Finally, endothelial function is an important effector in the regulatory processes of vascular tonus which in turn determines the flow resistance. The role of hemodynamic shear forces in modulating the endothelial function is now well established. Cardiac output and flow rate in the vasculature significantly increases during exercise, resulting in enhanced wall shear stress affecting on the endothelium. Alterations in endothelial function were demonstrated in response to various exercise protocols in human beings and also in various experimental animals. Blood rheology may also be affected by acute exercise episodes and training, with the potential of modulating endothelial function.

This chapter will focus on the description of endothelial functions, role of wall shear stress in modulating these functions, hemodynamic and hemorheological determinants of wall shear stress in relation of endothelial function and finally review the literature on the modifications of endothelial functions in relation to exercise.