Cognition is the most important determinant of health status, quality of life and functional ability in older age. Therefore, early interventions that preserve and enhance cognitive function are crucial for ensuring successful aging. The most common treatable risk factor for late-life cognitive impairment is midlife hypertension (HTN). One highly promising intervention strategy is aerobic exercise as it has been associated cognitive benefits in non-demented older adults. However, it is still unclear whether this benefit is due simply to prevention of other risk factors (e.g., reductions in blood pressure) or if exercise can reverse the negative effects of HTN on the brain. The goals of the current study are to employ sensitive measures of neuroimaging and cognition in order to 1).Compare cerebral health in endurance trained versus sedentary middle aged adults with normal or borderline to stage 1 hypertension, 2). measure the effects of exercise training in previously sedentary middle aged adults adults with normal or borderline to stage 1 hypertension, and 3). examine if exercise-related differences and changes in neural integrity and cognition are mediated by systemic vascular health.