Physical Activity Influences the Relationship between Objectively Measured Hot Flashes and Endothelial Function in Perimenopausal Women
Authors: Witkowski Sarah , Tha Ra Wun Tint , Buszkiewicz Sara , Brunzelle JoSophia , Murphy Lorna , Garcia Randi , Leidy Sievert Lynnette 
Published: May 2024

Hot flashes (HF) are disruptive symptoms experienced by approximately 80% of women undergoing menopause. The transition to menopause is associated with increases in CVD risk factors. The frequency and severity of HF have been associated with poorer cardiovascular health but most of these studies have quantified HF by self-report and have not considered physical activity (PA), known for its cardiovascular benefits. The association between HFs and CVD risk may be through their effect on endothelial health. The objective of this study was to evaluate the relationship between objectively measured HF and endothelial function and determine the effect of physical activity on the relationship in healthy perimenopausal women. We hypothesized that more HF would be associated with lower endothelial function and PA would influence this relationship. Healthy perimenopausal women (n=52, age 43-54) were included in this analysis. Perimenopause was defined as ≥7d difference in the length of consecutive cycles to <12 months of amenorrhea. Hot flashes were measured objectively using sternal skin conductance for 24 hours. The number of HF experienced and HF rate (normalized to actual wear time) were quantified. Endothelial function was assessed with measures of brachial artery flow mediated dilation (FMD, %) on the non-dominant arm. Moderate to vigorous physical activity (MVPA) was assessed with 7-days of actigraphy monitoring on the non-dominant wrist. The R package GGIR and Hildebrand (2016) cut points were used to quantify PA intensity and reported as sum of the average minutes of moderate and vigorous physical activity per day. Pearson correlations and multiple regression analyses were used to evaluate relationships between variables. Data met all assumptions for statistical tests. Modeling was performed to evaluate whether HFs were predictors of the main outcome of FMD (R version 4.2.3 and RStudio version 2023.06.2+561). Age and BMI were included in all models. Lower FMD was significantly correlated with a higher objective HF rate ( r (52) =-0.27, p=0.05). Objective HF rate predicted FMD (β=-3.91, p=0.04) when controlling for age and BMI (adj R2=0.100, F(3,48) =2.892, p=.05). When MVPA was added to the model, MVPA alone was not a significant predictor but the interaction between MVPA and HF was (β=0.12, p=0.04; adj R2=0.147, F(5,46) =2.761, p<0.03). This interaction was such that higher levels of MVPA were related to a less strongly negative relationship between objective HF rate and FMD. A simple slopes analysis found that the HF rate effect at one SD below the mean MVPA was significantly negative, (β=-8.64, p=0.004), whereas the HF rate effect at one SD above the mean MVPA was not significant, (β=0.18, p=0.95). These data provide strong evidence that support the hypothesis that a greater number of objectively-assessed hot flashes is associated with lower endothelial function in perimenopausal women and that higher amount of physical activity serves as a buffer against the negative relation between hot flashes and FMD. NIH NHLBI R15 Grant 1R15HL145650-01A1 (Witkowski); Smith College McKinley s Honors Fellowship (Tha Ra Wun); Smith College STRIDE (Buszkiewicz). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.