Establishing sex-specific baseline values for cerebrovascular critical closing pressure and resistance area product during supine rest in healthy, young adults

Calculating cerebrovascular critical closing pressure (CrCP) and resistance area product (RAP) have been argued to provide greater characterization of cerebral hemodynamics when compared with traditional metrics. However, CrCP and RAP are underutilized, limiting progress on their applications. Additionally, resting middle cerebral artery velocity (MCAv) is known to differ between the sexes, however, sex-based analysis of CrCP and RAP has yet to be established. PURPOSE: To establish sex-specific baseline values for CrCP and RAP in healthy, young adults during supine rest. METHODS: 35 subjects (18 females, tested days 1-5 of menstrual cycle) rested in the supine position while mean arterial pressure (MAP, mmHg, finger photoplethysmography) and middle cerebral artery velocity (MCAv, cm/s, transcranial doppler) were measured continuously for five minutes. CrCP and RAP were calculated using the 2-point mean method by a custom-made application created in R shiny studio (R-studio, v.2024.04.2). Mean normalized squared error (MNSE) was calculated to determine the goodness of fit between the observed and model-predicted CrCP and RAP values. Group differences were evaluated using independent t-tests or Mann-Whitney U tests depending on normality. RESULTS: Outcomes were referenced to each participant’s mean over the last 20 seconds of resting period, and values are reported as mean ± SD. All calculated and measured values were not different between sexes (CrCP Male 32.21± 12.84 vs. Female 27.72±10.25 mmHg, p=0.26, d=0.39) and (RAP Male 1.12±0.32 vs. Female 0.96±0.21 mmHg·cm/s, p=0.11, r=0.27, MAP Male 102.38±13.52 vs Female 102.20±13.97 mmHg, p=0.95, r=0.01). Not surprisingly, MCAv was higher in females compared to males (Male 65.34±12.10 vs. Female 78.94±8.62 cm/s, p=< 0.001, d=1.3). MNSE was small in both sexes (Male 5.0 × 10^-5 ± 9.0 × 10^-5 vs. Female 4.0 × 10^-5 ± 1.3 × 10^-4, p=0.41, r=0.14). CONCLUSION: These data indicates that CrCP and RAP are comparable between males and females despite females exhibiting a greater MCAv. With no detectable sex differences, these baseline CrCP and RAP values in healthy, young adults constitute practical references for future investigations of cerebral hemodynamics. 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.