Aerobic Fitness Does Not Improve Endothelial Function and Responses to Acute Exercise in Perimenopausal Women

Endothelial function, a pre‐clinical marker for cardiovascular disease, is generally better in those with high aerobic fitness; however, this benefit appears to be lost in postmenopausal women. It is unclear whether this loss is also present during the transitional (i.e. perimenopausal) years. PURPOSE To determine if there are differences in endothelial function before and after acute exercise in high‐ and low‐fit perimenopausal women. METHODS Perimenopausal women were defined as experiencing irregular menstrual cycles or 2–11 months of amenorrhea. Women were healthy and were classified as high‐ (n=7) or low‐ (n=7) fit based on self‐reported physical activity and verified by a treadmill VO 2 max test. Endothelial function was assessed using flow‐mediated dilation (FMD). Brachial artery diameter was continuously imaged during 2 min of rest, 5 min of forearm blood flow occlusion (200mmHg), and 4 min following the end of occlusion. FMD (%) was calculated as (Diameter peak − Diameter baseline )/ Diameter baseline × 100. The response to acute exercise was calculated as FMD post‐exercise −FMD pre‐exercise. Pre‐ and post‐exercise FMD differences were analyzed by group using a 2‐way repeated measures ANOVA (aerobic fitness × exercise). Group characteristics and the FMD response to acute exercise were assessed using t‐tests and Mann‐Whitney Rank Sum tests. Pearson correlations were used to assess if any baseline characteristics were associated with pre‐ or post‐exercise FMD. Data are presented as mean ± SEM. Data from low‐fit women has been previously published. RESULTS Groups were matched for most CVD risk factors; however, high‐fit women were slightly older (high: 51.7±1.1yr vs. low: 47.3±4.0yr, p=0.037), had higher VO 2 peak (high: 51.2±3.48 ml/kg/min vs. low: 30.1±4.3 ml/kg/min, p<0.001) and lower body fat percentage (high: 25.1±3.3% vs. low: 40.8±7.0%, p=0.007) compared to low‐fit women. There was no difference in FMD before (high: 5.07±2.0% vs. low: 6.4±1.6%, p=0.44) or after exercise in high‐ vs. low‐fit women (high: 5.36±0.5% vs. low: 8.5±3.2%, p=0.085). There was also no difference between groups in the FMD response to acute exercise (high: 0.28±2.2% vs. low: 2.1±1.2%, p=0.483). Baseline artery diameter did not differ before or after exercise in either group (high, pre: 3.49±0.12mm vs. post: 3.53±0.12mm, p=0.444; low, pre: 3.2±0.3mm vs. post: 3.16±0.4mm, p=0.416). Pre‐ and post‐ exercise FMD were not related to age (pre: r=−0.316, p=0.272; post: r=−0.421, p=0.134) or body fat percentage (pre: r=0.331, p=0.247; post: r=0.289, p=0.317). VO 2 peak was negatively related to post‐exercise FMD (r=−0.527, p=0.0526). CONCLUSION High aerobic fitness does not have a positive impact on endothelial function in healthy perimenopausal women, nor does it enhance endothelial function in response to acute exercise. In fact, higher aerobic fitness may be associated with a lower post‐exercise FMD. The lack of benefit of aerobic fitness on endothelial function during perimenopause suggests that other interventions or intervention targets may need to be identified to improve cardiovascular risk in this population. Support or Funding Information American College of Sports Medicine Foundation Doctoral Student Research Grant (Serviente) & University of Massachusetts Amherst Faculty Research Grant (Witkowski).