Aerobic Fitness is not Protective of Endothelial Function with Menopause

Abstract

Endothelial dysfunction is a pre-clinical marker for cardiovascular disease (CVD). In most populations, aerobic fitness is protective of endothelial function. Whether this protection remains during and after menopause is unclear. PURPOSE: To evaluate differences in endothelial function before and after acute exercise in women at different menopausal stages with disparate levels of aerobic fitness. METHODS: Brachial artery flow-mediated dilation (FMD) was evaluated before and after 30min of treadmill exercise (60-64% VO2peak) in healthy high (HIGH) and low (LOW) fit perimenopausal (PERI: HIGH, n=12, 50.8±1.0 yr, 49.1±2.5 ml/kg/min; LOW, n=7, 47.3±1.5 yr, 30.1±1.6 ml/kg/min) and postmenopausal (POST: HIGH, n=13, 60.5±1.0 yr, 43.8±1.8 ml/kg/min; LOW, n=8, 58.9±1.4 yr, 28.3± 1.1 ml/kg/min) women. High fit premenopausal (PRE: n=6, 44.6±1.3 yr, 50.5±3.6 ml/kg/min) women were included as a reference group. Data were evaluated with repeated measure ANOVAs and post hoc testing, where appropriate, and are presented as mean±SEM. FMD data in LOW were previously published (Serviente et al., 2016). RESULTS: Overall, there was a main effect of menopause on FMD (p=0.024), with lower FMD in POST compared to PERI (p=0.007). There was a main effect of fitness (p=0.031) with lower FMD in HIGH compared to LOW. Within HIGH, PRE had higher FMD than POST (p=0.018), but not PERI (p=0.737). FMD was lower in HIGH vs. LOW POST (4.2±0.8% vs. 6.51±0.5%, p=0.047) before, but not after acute exercise (4.31±0.6% vs. 6.2±1.0%, p=0.103). After acute exercise, FMD was lower in HIGH POST compared to PRE (6.2±1.0% vs. 7.7±1.1%, p=0.011). There was no difference in FMD in HIGH vs. LOW PERI before exercise (7.1±1.5% vs. 6.5±0.5%, p=0.73); however, FMD was higher in LOW after exercise (5.7±0.6 % vs. 8.5±1.1%, p=0.029). CONCLUSIONS: While endothelial function does not appear to decline until postmenopause, the protective effect of aerobic fitness is not apparent in perimenopausal or postmenopausal women; although, fitness appears to modulate the response to acute exercise. These data suggest that targets other than aerobic fitness may be important for improving endothelial function, and therefore CVD risk, in menopausal women. Funding: ACSM Foundation Doctoral Student Research Grant (Serviente) & UMass Amherst Faculty Research Grant (Witkowski)