Cardiovascular Reactivity During a Fatiguing Exercise in Women: The Influence of Menopause Duration and Age

Abstract

IntroductionThe risk of hypertension (HTN) and cardiovascular disease (CVD) dramatically increases following menopause, and premature and early menopause (<45yr) substantially increase this risk. Greater blood pressure (BP) reactivity to stressors such as exercise can predict future risk of developing HTN. Thus, we aimed to determine if the time since menopause completion contribute to greater BP reactivity during a fatiguing hand grip (HG). We hypothesized that women who have been postmenopausal for a longer duration would exhibit greater cardiovascular reactivity to a fatiguing HG exercise.MethodsWomen who experienced early and typical‐age (>46yr) menopause completed two visits. Visit 1: Informed consent, medical and health questionnaires. Visit 2: Participants rested in a supine position. Three maximum voluntary contractions (MVC) of their left hand were completed followed by a baseline rest (BL) of 10 minutes. Following BL, a HG test at 30% of MVC was performed until time to task failure. Non‐invasive beat‐to‐beat BP and heart rate (HR) were recorded during BL and HG test. Systolic (SAP), diastolic (DAP), mean arterial (MAP), and HR were analyzed as BL averages and in 20‐30s intervals at start, 25%, 50%, 75%, and task failure. Repeated‐measures ANOVA and independent T‐tests were used for the statistical analysis; results are presented as mean±SD.ResultsEighteen postmenopausal females completed the study and were divided into two groups: 1) postmenopause ≤10yrs (PM≤10; 8±2 yrs; body mass index (BMI): 25±3 kg/m2, n=8) and 2) postmenopause ≥11 (PM≥11; 15±5 yrs; BMI: 25±5 kg/m2, n=10). The PM≥11 group was slightly older (64±3yrs) than the PM≤10 (60±4yrs, p=0.005). BL SAP was not different between PM≤10 (133±14mmHg) and PM≥11 (128.75±14mmHg; p=0.95). DAP (85±9 vs 81±10mmHg; p=0.68) and MAP (100±10 vs 96±9mmHG; p=0.40), were not different between PM≤10 and PM≥11, respectively. During the fatiguing contraction, SAP increases were exaggerated in PM≥11 compared with PM≤10 (Δ63±25 vs Δ40±16mmHg; group × time, p=0.03). Similarly, MAP increased more in PM≥11 compared with PM≤10 (Δ49±16 vs Δ31±10mmHg; group × time, p=0.04), but not DAP (group × time, p=0.1) or HR (group × time, p=0.08). When co‐varying for age, however, the interactions were no longer significant (p>0.05, for all). In addition, peak increases in SAP (p=0.04), MAP (p=0.01), and HR (p=0.02) were greater in PM≥11 compared with PM≤10, but these observations were no longer significant when co‐varying for age (p>0.05, for all).ConclusionNovel findings from this study suggest that although the duration of menopause influences BP reactivity during a moderate intensity fatiguing contraction, this greater increase may be explained by older age. This elevated response to submaximal exercise may contribute to the increased risk of HTN and CVD in postmenopausal women.