The distribution of blood flow in the carotid and vertebral arteries during dynamic exercise in humans

• Published in: The Journal of physiology Vol. 589; no. 11; pp. 2847 - 2856
• Main Authors: Sato, Kohei, Ogoh, Shigehiko, Hirasawa, Ai, Oue, Anna, Sadamoto, Tomoko
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-06-2011; Wiley Subscription Services, Inc; Blackwell Science Inc
• Subjects: Adult; Blood Pressure - physiology; Body Temperature Regulation - physiology; Carbon Dioxide - blood; Cardiac Output - physiology; Cardiovascular; Carotid Arteries - physiology; Cerebrovascular Circulation - physiology; Exercise - physiology; Female; Forehead; Heart Rate - physiology; Humans; Male; Middle Cerebral Artery - physiology; Oxygen Consumption - physiology; Partial Pressure; Regional Blood Flow - physiology; Skin - blood supply; Stroke Volume - physiology; Vascular Resistance - physiology; Vertebral Artery - physiology; Young Adult
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.2010.204461

Non‐technical summary  The mechanism underlying the plateau or relative decrease in cerebral blood flow during maximal incremental dynamic exercise remains unclear. We show that during graded dynamic exercise, the regulation of internal carotid artery blood flow was limited by a large increase in external carotid artery blood flow, one function of which is thermoregulation during heavy exercise. The mechanism of the plateau or decrease in internal carotid artery blood flow appears to be partly due to exercise‐induced redistribution of arterial blood flow to the head and brain.
  The mechanism underlying the plateau or relative decrease in cerebral blood flow (CBF) during maximal incremental dynamic exercise remains unclear. We hypothesized that cerebral perfusion is limited during high‐intensity dynamic exercise due to a redistribution of carotid artery blood flow. To identify the distribution of blood flow among the arteries supplying the head and brain, we evaluated common carotid artery (CCA), internal carotid artery (ICA), external carotid artery (ECA) and vertebral artery (VA) blood flow during dynamic exercise using Doppler ultrasound. Ten subjects performed graded cycling exercise in a semi‐supine position at 40, 60 and 80% of peak oxygen uptake () for 5 min at each workload. The ICA blood flow increased by 23.0 ± 4.6% (mean ± SE) from rest to exercise at 60%. However, at 80%, ICA blood flow returned towards near resting levels (9.6 ± 4.7%vs. rest). In contrast, ECA, CCA and VA blood flow increased proportionally with workload. The change in ICA blood flow during graded exercise was correlated with end‐tidal partial pressure of CO2 (r= 0.72). The change in ICA blood flow from 60% to 80% was negatively correlated with the change in ECA blood flow (r=−0.77). Moreover, there was a significant correlation between forehead cutaneous vascular conductance and ECA blood flow during exercise (r= 0.79). These results suggest that during high‐intensity dynamic exercise the plateau or decrease in ICA blood flow is partly due to a large increase in ECA blood flow, which is selectively increased to prioritize thermoregulation.