Exercise restores impaired resistance vessel function in hypothalamic hypoestrogenic premenopausal women in association with increased resting cardiac output and decreased systemic vascular resistance

Objectives: To determine the hemodynamic effects of an acute bout of exercise on previous findings of impaired resistance vessel function in physically active premenopausal women with hypothalamic hypoestrogenemia (ExHH). Methods: Two groups of similarly trained recreationally active premenopausal women were studied: ExHH (n=12; aged 25±1 years; body mass index 20.3±0.7 kg/m2; mean±SEM), and eumenorrheic ovulatory women (ExOv; n=14; 24±1years; 21.4±0.5 kg/m2). Blood pressure (BP), heart rate (HR), stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR; 2D echocardiography) and resting and peak-ischemic calf blood flow (CBF; plethysmography) were assessed at baseline and 60 minutes after 45 minutes of moderate aerobic exercise. Results: In ExHH, baseline HR (47±2 beats/min), systolic BP (90±2 mmHg) and CO (3.4±0.1 L/min) were lower (p<0.05) than in ExOv (54±2 beats/min; 101±1 mmHg; 4.1±0.1 L/min; respectively). Resting and peak-ischemic CBF were also lower (p<0.05) in ExHH (1.5±0.1 and 20.5±1.5 ml/100ml/min) than ExOv women (2.4±0.2 and 28.8±2.9 ml/100ml/min). Conversely, TPR was higher (p<0.05) in ExHH (1606±69 dynes/sec/cm5) than eumenorrheic women (1400±47 dynes/sec/cm5). Post-exercise: HR and CO were increased (p<0.05), and TPR decreased (p<0.05) in both groups. However, in ExHH, HR (58±2 beats/min) and CO (3.90±0.1 L/min) remained lower (p<0.05) and TPR (1365±65 dynes/sec/cm5) higher (p<0.05) than in ExOv women. Resting CBF was increased (p<0.05) to a similar value (3.3±0.2 ml/100ml/min; overall mean) in both groups. Peak CBF was increased (p<0.05) in ExHH only (26.4±2.0 ml/100ml/min). Using pooled data, CO was positively, and TPR inversely, associated (p<0.05,) with resting CBF both pre- and post-exercise. Conclusion: Compared with eumenorrheic women, ExHH women demonstrate impaired regional blood flow in association with low CO and elevated TPR. Dynamic exercise acutely restores CBF in ExHH women in association with increased CO and decreased TPR. While the effects of estrogen deficiency per se are unclear, these data suggest that impaired resistance vessel function in ExHH is: i) reversible, and ii) associated in part with increased vascular tone and altered hemodynamic characteristics.