The Influence of Aortic Compliance on Pulsatile Cerebral Blood Flow in Young Healthy Men: Insight from Endurance Training Intervention.

Aortic compliance reflects the ability to buffer arterial pulsations generated by the left ventricle (LV) and attenuate pulsatile cerebral blood flow (CBF). Endurance training is associated with increased stroke volume (SV) and enhanced LV systolic function, potentially increasing arterial pulsations to the brain. This study investigated the contribution of aortic compliance to the heart-brain hemodynamic interaction, providing insights from endurance training intervention and lower body negative pressure (LBNP) stimulus. Ten male collegiate tennis players underwent an eight-month endurance training program to improve cardiac function. SV and LV systolic function were measured using echocardiography and applanation tonometry. Pulsatile cerebral blood velocity in the middle cerebral artery was assessed by transcranial Doppler. Aortic compliance was calculated as the ratio between estimated SV via Modelflow and aortic pulse pressure via transfer function from radial arterial pressure. The release of -30 mmHg LBNP was used to initiate a rapid recovery of limited venous return and consequent increases in SV and CBF to assess dynamic recovery slopes. Endurance training increased SV, LV systolic function, and aortic compliance at rest, whereas pulsatile CBF was unchanged. The recovery slopes of SV and aortic compliance were steeper after endurance training, while the slopes of pulsatile CBF remained similar. The change in the slope of aortic compliance was negatively correlated with the change in the slope of pulsatile CBF (r=-0.758, P=0.011). These results suggest that improved aortic compliance after endurance training may accommodate increased SV and LV systolic function and buffer potential increases in arterial pulsations to the brain.