Sex differences in internal carotid artery flow during sustained light intensity aerobic exercise

Approximately 70% of blood flow to the brain is delivered via the internal carotid arteries (ICAs), making regulation of blood flow through these vessels vital. Aerobic exercise challenges this regulation and has been shown to induce increases in ICA flow at light exercise intensities. There is evidence to suggest that regulation of blood flow to the brain may differ between males and females. However, little is known about sex differences in ICA flow responses to aerobic exercise. The purpose of this study was to investigate sex-based differences in ICA flow responses to light intensity aerobic exercise. We hypothesized that males would have greater magnitude of change in ICA flow during light exercise when compared to females. To address this, 33 recreationally active young adults (18 females, 15 males; age: 28 ± 6 yrs; BMI: 23.34 ± 2.35 kg/m 2 ) completed a maximal oxygen uptake (VO2max) cycling test and an experimental study visit on a separate day where they exercised at 30-35% of their VO2max for 10 minutes on a recumbent cycle ergometer. Mean arterial pressure (MAP) was measured via brachial sphygmomanometry during seated rest (BSL) and exercise (EXE). The left ICA was imaged using doppler ultrasound at BSL and EXE, once participants had achieved steady state. ICA diameter and blood velocity were captured, and ICA flow was calculated as velocity x cross sectional area x 60. Cerebrovascular conductance (CVC) was calculated as ICA flow/MAP. In the combined group, ICA flow was higher during EXE when compared to BSL (BSL: 422 ± 122 mL/min, EXE: 447 ± 121 mL/min, P < 0.05). ICA flow was not significantly different between males and females at BSL (males: 436 ± 115 mL/min, females: 411 ± 130 mL/min, P = 0.58) or EXE (males: 482 ± 121 mL/min, females: 418 ± 118 mL/min, P = 0.13). However, there was a trend for sex differences in the change in ICA flow (males: 46 ± 64 mL/min, females: 7 ± 56 mL/min, P = 0.07) with males showing a significant increase in ICA flow during exercise (P < 0.05), while females had no significant difference between conditions (BSL: 411 ± 130 mL/min, EXE: 418 ± 118 mL/min, P = 0.66). In the combined group, there were no significant differences in CVC between BSL and EXE (BSL: 4.8 ± 1.4 mL/min/mmHg, EXE: 4.9 ± 1.5 mL/min/mmHg, P = 0.52). There were also no significant differences in CVC between males and females at BSL (males: 4.9 ± 1.3 mL/min/mmHg, females: 4.8 ± 1.6 mL/min/mmHg, P = 0.77) or EXE (males: 5.2 ± 1.5 mL/min/mmHg, females: 4.7 ± 1.5 mL/min/mmHg P = 0.30), or in the change in CVC from BSL to EXE (males: 0.3 ± 0.7 mL/min/mmHg, females: -0.1 ± 0.8 mL/min/mmHg, P = 0.13). In summary, males, but not females, showed increases in ICA flow during light aerobic exercise. When comparing CVC to account for MAP changes with exercise, there were no sex differences. Taken together, this data suggests that regulation of ICA flow during light steady state aerobic exercise may differ between males and females. Funding Source: Wisconsin Alumni Research Foundation This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.