Effect of Acute Aerobic Exercise Intensity and Dose on Post-Exercise Cerebral Pulsatility in Healthy Young Runners

Greater cerebral pulsatility results in increased hemodynamic forces transmitted to the cerebral microvasculature and increases the risk of cognitive decline and cerebral pathologies. While the effect of acute aerobic exercise on post-exercise cerebral pulsatility has previously been investigated, the intensity-dependent and dose-dependent effects of acute aerobic exercise on post-exercise cerebral pulsatility are unclear. Therefore, the purpose of this study was to evaluate the influence of acute aerobic exercise, of differing intensities and doses, on post-exercise cerebral pulsatility index (PI). We hypothesized that acute aerobic exercise of greater intensities or larger doses would result in lower post-exercise cerebral PI. We recruited 12 healthy young adults who were habitual runners (5 Male, 7 Female; Age: 27 ± 5 years; BMI: 23 ± 2 kg/m 2 ; VO 2 max: 53 ± 9 mL/kg/min). Participants completed three semi-randomized study visits in which they walked at 30% VO 2 max for 30 minutes (30% EX), ran at 70% VO 2 max for 30 minutes (70% EX), or ran at 70% VO 2 max for a duration that resulted in energy expenditure equal to the 30% EX visit (70% EX EE ). Supine middle cerebral artery velocity (MCAv) was measured, via transcranial Doppler ultrasound, prior to exercise (Pre) and at 30 (30) and 90 minutes (90) post-exercise. Cerebral PI was calculated as (MCAv systolic – MCAv diastolic ) / MCAv mean . Pre cerebral PI did not differ across study visits (p = 0.12). Similarly, there were no differences in cerebral PI within the 30% EX visit (Pre: 0.75 ± 0.07 a.u.; 30: 0.79 ± 0.10 a.u.; 90: 0.77 ± 0.07 a.u.; p = 0.09), the 70% EX visit (Pre: 0.80 ± 0.11 a.u.; 30: 0.75 ± 0.10 a.u.; 90: 0.77 ± 0.09 a.u.; p = 0.13), or the 70% EX EE visit (Pre: 0.79 ± 0.09 a.u.; 30: 0.78 ± 0.08 a.u.; 90: 0.80 ± 0.10 a.u.; p = 0.61). There was, however, a study visit by measurement time interaction when cerebral PI was compared across all study visits (p = 0.03). Despite this interaction, there were no significant post hoc comparisons (p ≥ 0.06 for all). Lastly, when the pre- to post-exercise changes in cerebral PI were compared across study visits, there was a significant difference in the Pre-to-30 change in cerebral PI between the 30% EX and the 70% EX study visits (30% EX: 0.04 ± 0.08 a.u.; 70% EX: -0.05 ± 0.09 a.u.; p = 0.01). There were, however, no differences between study visits when the Pre-to-90 change was compared (p = 0.23 overall). In partial agreement with our hypothesis, acute aerobic exercise affected post-exercise cerebral PI in a dose-dependent manner, as there was a significant difference in the pre- to post-exercise change in cerebral PI between the 30% EX and the 70% EX study visits. Additionally, there were no intensity-dependent effects of acute aerobic exercise on post-exercise cerebral PI when the overall dose of exercise was the same. Future studies should explore the relationship between acute aerobic exercise intensity and dose on post-exercise cerebral PI in other populations, such as older adults or sedentary individuals. Funded by the Wisconsin Alumni Research Foundation and NIH HL118154. This abstract was presented at the American Physiology Summit 2025 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.