Cerebral Blood and Cerebrospinal Fluid Flow Dynamics in Endurance Athletes: Associations With Aortic Recoil and Heart Rate.

Endurance training elicits profound cardiovascular adaptations, including lower heart rate (HR), greater stroke volume (SV), and enhanced aortic Windkessel function. This study aimed to investigate cerebral blood and cerebrospinal fluid (CSF) flow dynamics in endurance athletes and their relations with cardiovascular parameters. Fifteen young male endurance athletes were compared with 19 age-matched sedentary male controls. In the resting supine condition, CINE phase-contrast MRI acquired the extra- and intracranial cerebral blood and CSF flow waveforms, as well as HR, SV, and ascending aortic cross-sectional area waveform. Cerebral blood and CSF flow volume (mL/beat) and rate (mL/min) were quantified for the full cardiac cycle and separately for systolic and diastolic phases. Aortic cross-sectional area change was temporally integrated to quantify aortic expansion and recoil. Athletes exhibited higher aortic recoil (5.7 cm2·s [4.1, 7.3] vs. 4.1 cm2·s [2.6, 5.6]) and SV (97 ± 18 mL vs. 82 ± 11 mL) and lower HR (53 ± 6 bpm vs. 67 ± 12 bpm) than controls. Total cerebral arterial blood and CSF flow volumes and rates across the full cardiac cycle were similar between groups; however, athletes showed significantly greater diastolic arterial flow volume and lower systolic arterial flow rate. The association between lower HR and greater diastolic arterial flow volume was mediated by higher aortic recoil across all participants. These results suggest that enhanced aortic recoil in endurance athletes sustains diastolic cerebral arterial flow volume across a prolonged cardiac cycle, enabling more efficient brain perfusion with fewer cardiac cycles than sedentary controls.