The association between morning blood pressure surge and cardiovagal baroreflex sensitivity in young healthy females

BACKGROUND: Morning blood pressure (BP) surge is shown to be an independent predictor of cardiovascular events. In healthy adults, decreased cardiovagal baroreflex sensitivity (cBRS) is demonstrated to be associated with higher morning BP. However, previous investigations have utilized male or mixed sex samples potentially limiting the generalizability of findings to females, as cBRS differs between sexes. Paucity remains regarding the association between morning BP surge and cBRS in healthy females. The purpose of this investigation was to examine the relationship between morning BP surge and cBRS in young healthy females. We hypothesize that females with decreased cBRS will demonstrate a higher morning BP surge. METHODS: 20 females (21±4 yrs; body mass index [BMI]: 23±3 kg/m 2 ) were recruited. Participants wore an ambulatory BP monitor (ABPM) and wrist activity monitor for 24hrs with BP measurements obtained in 30-min intervals. Awake and asleep periods were determined from wrist worn activity data. Morning BP surge was calculated using two methods: the sleep-through morning surge is the difference between the average systolic BP (SBP) during the first 2hrs after awakening and the average of three SBPs during sleep, centered on the lowest SBP. Pre-awakening morning surge is the difference between the average SBP during the 2hrs post-awakening and the average SBP during the 2hrs prior to awakening. Following 15mins of supine rest, participants performed three 15s Valsalva maneuvers by exhaling into a pressure transducer at ~40mmHg. Each maneuver was separated by a 5min break, and cBRS was quantified as the slope between SBP and corresponding R-R interval during phase IV of the maneuver. The average of three trials was used for analysis. Normality was assessed using a Shapiro-Wilk test. Associations between both morning BP surge calculations and cBRS were assessed using partial Pearson’s correlations controlling for age and BMI. RESULTS: For all participants, 24hr ambulatory SBP 114±7 mmHg, diastolic BP 66±5 mmHg, and mean arterial pressure was 82±6 mmHg. The sleep through morning BP was surge 20±7 mmHg, and pre-awakening morning BP surge 15±7 mmHg. Additionally, cBRS was 9±4 ms/mmHg. No association was observed between cBRS and either pre-awakening (r=-0.320, p=0.196) or sleep-through (r=-0.165, p=0.514) morning BP surge. CONCLUSION: Our findings suggest that morning BP surge in young healthy females is not related to cBRS. These results contrast with previous mixed sex investigations, highlighting potential sex differences in the association between cBRS and morning BP surge. Future studies should examine additional contributors to the rise in morning BP, including sympathetic BRS and arterial stiffness. 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.