Maximum Aerobic Exercise Induces Common Carotid Vasoconstriction And Increased Vascular Resistance

Abstract

Michael Diaz, Zaria Opara, Heysel Morales, Steven Hawkins, Louise Kelly, Allan Knox PURPOSE: Low-to-moderate intensity aerobic exercise has been reported to elicit changes in systemic hemodynamics. Recent evidence suggests that the cerebral circulation reacts independently to systemic circulations to the same physiological stimuli. The aim of this is to determine the influence of high-intensity aerobic exercise on common carotid artery (CCA) hemodynamics. METHODS: Hemodynamic measurements were recorded before and following the cessation of a maximum oxygen uptake test (VO2max). One minute video of the CCA by Doppler ultrasound were recorded and used to determine peak systolic velocity (PSV), end diastolic velocity (EDV), time averaged mean blood velocity (TAMEAN), timed average maximum velocity (TAMAX), pulsatility index (PI), and resistance index (RI). CCA diameters were calculated by commercially available vessel tracking software. Carotid stiffness index (β), Peterson’s pressure modulus (Ep), arterial compliance (AC) was also calculated. RESULTS: A total of 29 individuals, 14 male and 15 females, participated in this study (21.9 ± 3.9 years). Following the cessation of exercise, PSV (p < 0.001), TAMAX (p = 0.0085), RI (p < 0.001), and PI (p = 0.0032) significantly increased whilst the minimum diameter (p = 0.005), and maximum diameter (p = 0.020) decreased. No changes were observed for β (p = 0.491), Ep (p = 0.834) or AC (p = 0.535). CONCLUSION: The results show hemodynamic changes in the CCA following VO2max exercise. Specifically, increases in vascular resistance are likely due to the reductions in arterial diameter, which may be evident downstream of the CCA. Acute maximal aerobic exercise does not change CCA stiffness parameters.