This study will investigate the isolated and the associated effect of estrogen therapy and physical exercise in the function, regulation and cardiovascular risk markers of 60 postmenopausal women, (45 - 60 years old). The volunteers will be randomaized into two groups: estrogen therapy (estradiol valerate 1 mg/day oraly) and placebo. The two groups will be randomaized into two subgroups: exercise group (aerobic trainning,cicle-ergometre, 50 minutes, 3 x week) and sedentary group. At 0, 6 and 12 months the volunteers will be submited to: clinical analise, cardiorespiratory analise (ergoepirometric test), quality of life questionare (Short Form-36 [SF-36]), ambulatory blood pressure monitoring during 24 hours and to 2 experimental sessions where the cardiovascular responses to insulin action (euglicemic/hiperinsulinemic clamp) and to physical and mental stress (microneurography) will be accessed. Besides these, the volunteers of the sedentary group will be submited to an extra session at 6 months of study evaluate the physiological answer to insulin infusion after an acute session of exercise.