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

Endurance athletes exhibited higher aortic recoil compared to sedentary controls.

• Athletes had aortic recoil of 5.7 cm²·s [4.1, 7.3] versus 4.1 cm²·s [2.6, 5.6] in controls.
• Aortic recoil was quantified by temporally integrating ascending aortic cross-sectional area change from CINE phase-contrast MRI.
• Study compared 15 young male endurance athletes with 19 age-matched sedentary male controls in resting supine condition.

Endurance athletes had higher stroke volume and lower heart rate than sedentary controls.

• Stroke volume was 97 ± 18 mL in athletes versus 82 ± 11 mL in controls.
• Heart rate was 53 ± 6 bpm in athletes versus 67 ± 12 bpm in controls.
• These findings are consistent with known cardiovascular adaptations to endurance training.

Total cerebral arterial blood and CSF flow volumes and rates across the full cardiac cycle were similar between endurance athletes and sedentary controls.

• Despite cardiovascular differences, whole-cycle cerebral blood and CSF flow metrics did not differ significantly between groups.
• Flow was measured using CINE phase-contrast MRI at both extra- and intracranial locations.
• Flow volume (mL/beat) and rate (mL/min) were quantified for the full cardiac cycle.

Endurance athletes showed significantly greater diastolic arterial cerebral flow volume and lower systolic arterial flow rate compared to controls.

• Flow metrics were quantified separately for systolic and diastolic phases of the cardiac cycle.
• Athletes demonstrated greater diastolic arterial flow volume (mL/beat) despite similar total cycle flow.
• Athletes demonstrated lower systolic arterial flow rate (mL/min) compared to sedentary controls.
• These phasic differences indicate redistribution of cerebral blood flow timing across the cardiac cycle in athletes.

The association between lower heart rate and greater diastolic cerebral arterial flow volume was mediated by higher aortic recoil.

• Mediation analysis was conducted across all participants (n = 34).
• Higher aortic recoil was identified as the mediating variable between lower HR and greater diastolic arterial flow volume.
• This suggests the Windkessel function of the aorta mechanistically links heart rate with diastolic cerebral perfusion.
• The prolonged cardiac cycle in athletes (due to lower HR) combined with enhanced aortic recoil sustains diastolic cerebral flow.

Endurance training adaptations allow more efficient brain perfusion with fewer cardiac cycles than in sedentary individuals.

• Athletes achieve similar total cerebral blood flow volume and rate per minute despite approximately 14 fewer beats per minute.
• Enhanced aortic recoil sustains diastolic cerebral arterial flow volume across the prolonged cardiac cycle.
• The authors suggest this represents greater per-beat efficiency of brain perfusion in endurance athletes.