Associations among dynamic cerebral autoregulation, baroreflex sensitivity, and carotid distensibility in young healthy adults: insight from endurance training

PURPOSE: Endurance training may influence cerebrovascular and cardiovascular regulation, as well as its interrelationship. This study tested the hypothesis that if an endurance training intervention altered dynamic cerebral autoregulation (dCA) in young healthy adults, improvements in carotid artery distensibility and baroreflex function would represent potential mechanistic factors contributing to alterations in dCA. METHODS: Sixteen collegiate tennis players underwent an eight-month progressive moderate-to-vigorous endurance training program to improve cardiorespiratory fitness and cardiovascular function. Beat-to-beat cerebral blood velocity (CBV) with transcranial Doppler, blood pressure (BP) with photoplethysmography, and heart rate (HR) with electrocardiography were measured at rest and during BP oscillations induced by repeated sit-stand maneuvers at 0.05 Hz. Transfer function analysis was used to assess dCA and cardiovagal BRS. Carotid arterial distensibility was measured using ultrasonography and applanation tonometry. RESULTS: Following the endurance training intervention, significant increases were observed in maximal oxygen uptake, low-frequency (~ 0.1 Hz) cardiovagal BRS gain at rest and during BP oscillations, and carotid arterial distensibility. However, CBV at rest and dCA gain at rest and during BP oscillations remained similar. Repeated measures correlation analysis showed that dCA gain at rest and during BP oscillations and carotid arterial distensibility were positively correlated with cardiovagal BRS gain in both conditions (r = 0.500 ~ 0.704, P = 0.002 ~ 0.041). CONCLUSION: These findings suggest that endurance training enhances cardiovagal baroreflex function, potentially through improved carotid arterial distensibility, which may contribute to the regulation of cerebral blood flow via dynamic cerebral autoregulatory mechanisms.