ECHOGRAPHIC SIZE AND DOPPLER BLOOD FLOW PROFILE OF ASCENDING AORTA IN ENDURANCE-TRAINED ATHLETES

Abstract

In a recent study, endurance athletes, i.e. cyclists and long-distance runners, were found to have larger arterial conductance vessels than untrained controls. The aim of the present study was to determine the blood flow profiles of dilated vessels in these endurance-trained athletes. Twelve endurance-trained athletes (ET group) and twelve untrained control subjects (UC group) volunteered for the study. The cross-sectional area (CSA), peak and mean blood velocity in the ascending aorta (pV and mV), blood pressure (BP), and heart rate (HR) were measured in the semi-supine position on a cycle ergometer fitted with a backrest, at rest and during exercise at 40%, 60%, and 80%Vo₂max. Furthermore, stroke volume (SV), cardiac output (CO), total peripheral resistance, and double product were calculated. The SV and CO of the ET group were significantly larger than those of the UC group during exercise. The CSA of the ascending aorta in the ET group was significantly larger than that in the UC group at rest and during exercise. There were no differences in the mV and mean BP between the two groups. Upon comparison at the same SV, pV, mV, the total peripheral resistance, and double product of the ET group were lower than those of the UC group. These results suggest that the dilation of the arterial conductance vessels with endurance training contri-butes to an increase in blood flow to the exercising muscles without a rise in mechanical stress (shear stress and pressure) to the aortic wall. In other words, the arterial conductance vessels adapt morphologically to maintain an adequate degree of the mechanical stress on the aortic wall.