Cardiovascular Response To Aerobic Exercise Training In Perimenopausal Women: Role Of Autonomic Nervous System

The postmenopausal ages has been associated with increased incidence of cardiovascular disease compared with premenopausal period. The related mechanisms are the reduction of heart rate variability (HRV) and increase of oxidative stress during aging. On the other hand, aerobic exercise training (AET) has been associated with improvement antioxidant activity, nitric oxide bioavailability and autonomic control. However, studies evaluating the response HRV front of the AET in perimenopausal women compared to men of similar age are still scarce. Aim: To evaluate the response of autonomic control of blood pressure (office, ambulatory and its variability) and heart rate (resting and its variability) as well as the humoral mechanism of NO production after aerobic exercise training in perimenopausal women and men of the same age. Methodology: Sixteen perimenopausal women (PW) (46.1±1.1 yrs) and fifteen men (M) (48.7±0.9 yrs) underwent this study. The experimental design was 16 weeks of control (8wk) and AET (8wk) respectively. The volunteers were evaluated at initial, before and after AET. Resting heart rate (HR) was analyzed using a beat-by-beat HR monitor (Polar RS800CX) for 15 minutes and HRV was determined later according to the Kubios 2.1 software. Office blood pressure (BP) (Tycos, Raleigh, NC) and ambulatory (Dyna-MAPA) BP monitoring (ABPM) were performed previously and after AET. BP variability was calculated using the average real variability (ARV) index. Venous blood sample were collected after overnight fasting of 12 hours for biochemical analyses at three periods of evaluation. The spectrophotometer analysis (Cayman Chemical kits) were performed to evaluate nitrite/nitrate (NOx-) and malondialdehyde (MDA) concentration, superoxide dismutase (SOD) and catalase activity. AET consisted of walking on a treadmill, 3 times/wk, 30-40 minutes at maximal lactate steady state intensity. Results: AET increased RR interval and RMSSD index (time domain measure of HRV) only in PW (U:11.2% and U: 25.6%, respectively), associated with improvement in aerobic capacity (U: 5.3%) and reduction in resting HR (U: -7.5%). AET decreased office systolic and diastolic BP in PW (USBP: - 3.6% and UDBP: -3.1%). In addition, systolic BP nighttime and its variability decreases in response to AET (USBPN: -3.6% and USBPV: -26.9%). Interestingly, no changes were found in BP (office, ambulatory and its variability) in the M group. On the other hand, AET promoted an up-regulation of SOD activity only for M group (U: 36.0%). Neither catalase activity nor NOxand MDA concentrations were changed in both groups. PW showed a major magnitude of response for aerobic capacity (U: 167.3%) and systolic BP nighttime (U: -232.6%) compared to M group. Conclusion: AET decreases heart rate and blood pressure in perimenopausal women, and these beneficial effects were associated with improved HRV. However, the molecular mechanisms are still unclear.

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