RESUMO
OBJECTIVE: The aim of this study was to evaluate the isolated and associated effects of aerobic training and estrogen therapy on sympathetic nerve activity and hemodynamics in healthy postmenopausal women. METHODS: Forty-five postmenopausal women (mean [SD] age, 51 [3] y) were randomly divided into four groups: sedentary-placebo (SED-PLA; n = 11), sedentary-estrogen therapy (SED-ET; n = 14), aerobic training-placebo (AT-PLA; n = 12), and aerobic training-estrogen therapy (AT-ET; n = 8). The ET groups received oral estradiol valerate (1 mg/d), whereas the PLA groups received placebo. The AT groups performed aerobic exercise three times a week on a cycle ergometer for 50 minutes, whereas the SED groups remained sedentary. All participants were evaluated before and after 6 months. Muscle sympathetic nerve activity (MSNA; microneurography), forearm blood flow (plethysmography), blood pressure (oscillometry), and heart rate (HR) were measured at rest for 10 minutes. Data were analyzed by three-way analysis of variance. RESULTS: Estrogen administration itself did not change any of the studied parameters. AT improved forearm blood flow (AT-PLA, 2.02 [0.85] vs 2.92 [1.65] mL min(-1) 100 mL(-1), P = 0.03; AT-ET, 1.68 [1.11] vs 2.27 [0.76] mL min(-1) 100 mL(-1), P = 0.03), reduced MSNA in the AT-PLA group (39 [6] vs 34 [5] bursts/min(-1), P = 0.01), and decreased HR in the AT-ET group (65 [8] vs 62 [7] beats/min, P = 0.01). CONCLUSIONS: AT reduces sympathetic nerve activity and improves muscle blood flow in healthy hysterectomized postmenopausal women. Moreover, AT decreases HR when combined with ET. However, ET abolishes the reducing effect of AT on MSNA.
Assuntos
Terapia de Reposição de Estrogênios , Exercício Físico , Histerectomia , Consumo de Oxigênio/fisiologia , Pós-Menopausa , Sistema Nervoso Simpático/fisiologia , Pressão Sanguínea/fisiologia , Método Duplo-Cego , Estradiol/administração & dosagem , Estradiol/análogos & derivados , Teste de Esforço , Feminino , Frequência Cardíaca/fisiologia , Hemodinâmica , Humanos , Pessoa de Meia-Idade , Consumo de Oxigênio/efeitos dos fármacos , Projetos Piloto , Placebos , Sistema Nervoso Simpático/efeitos dos fármacosRESUMO
The aim of this study was to determine whether estrogen therapy enhances postexercise muscle sympathetic nerve activity (MSNA) decrease and vasodilation, resulting in a greater postexercise hypotension. Eighteen postmenopausal women received oral estrogen therapy (ET; n=9, 1 mg/day) or placebo (n=9) for 6 mo. They then participated in one 45-min exercise session (cycle ergometer at 50% of oxygen uptake peak) and one 45-min control session (seated rest) in random order. Blood pressure (BP, oscillometry), heart rate (HR), MSNA (microneurography), forearm blood flow (FBF, plethysmography), and forearm vascular resistance (FVR) were measured 60 min later. FVR was calculated. Data were analyzed using a two-way ANOVA. Although postexercise physiological responses were unaltered, HR was significantly lower in the ET group than in the placebo group (59+/-2 vs. 71+/-2 beats/min, P<0.01). In both groups, exercise produced significant decreases in systolic BP (145+/-3 vs. 154+/-3 mmHg, P=0.01), diastolic BP (71+/-3 vs. 75+/-2 mmHg, P=0.04), mean BP (89+/-2 vs. 93+/-2 mmHg, P=0.02), MSNA (29+/-2 vs. 35+/-1 bursts/min, P<0.01), and FVR (33+/-4 vs. 55+/-10 units, P=0.01), whereas it increased FBF (2.7+/-0.4 vs. 1.6+/-0.2 ml x min(-1) x 100 ml(-1), P=0.02) and did not change HR (64+/-2 vs. 65+/-2 beats/min, P=0.3). Although ET did not change postexercise BP, HR, MSNA, FBF, or FVR responses, it reduced absolute HR values at baseline and after exercise.