African Americans have the highest rates of hypertension in the world. Effective therapies and awareness of hypertension in African Americans have declined this past decade contributing to further racial disparities in cardiovascular (CV) disease rates and mortality compared to Caucasians. Further, the traditional recommendation for lifestyle management of hypertension with diet and aerobic exercise is based on data obtained from studies involving mostly Caucasians. There are no exercise prescription guidelines for improving blood pressure specific for African Americans and the management of hypertension in this population continues to be problematic. A recent study in our laboratory showed divergent effects of resistance exercise training on blood pressure and arterial function in African Americans compared to Caucasians indicating that resistance exercise may exert more beneficial effects than aerobic exercise on early vascular risk. Thus, the goal of our research program is to determine novel exercise interventions, designed to optimally target arterial function and lower blood pressure in African Americans with pre and stage 1 hypertension. The overall hypothesis of this proposal is that is that African Americans with pre-hypertension and stage 1 hypertension will show greater benefit from resistance exercise training on arterial function and blood pressure and retain the benefit longer than aerobic exercise. Conversely, in Caucasians, aerobic exercise will improve arterial function and reduce cardiovascular risk more than resistance exercise.
Aim 1 will test the comparative effectiveness of 8-weeks of resistance or aerobic exercise training and de-training on blood pressure in African Americans with pre- and stage 1 hypertension compared to Caucasians. This will be tested with a prospective, randomized, 8 week resistance vs. aerobic exercise training intervention followed by 8 weeks of detraining in African American and Caucasian adults (18-45 years old).
Aim 2 will test the comparative effectiveness of 8-weeks of resistance or aerobic exercise training and de-training on 24 hour ambulatory blood pressure and arterial stiffness in central and peripheral arteries in African Americans compared to Caucasians.
Aim 3 will determine the effectiveness of 8-weeks of resistance or aerobic exercise training and de-training on arterial function in conduit and resistance arteries of pre- and stage 1 hypertensive African Americans compared to Caucasians. This will be determined in large (brachial artery FMD) and in small (dilation of isolated resistance arteries to acetylcholine and flow) arteries obtained from subcutaneous fat. In vivo determination of arterial function and physiologic approaches of resistance artery functioning are highly relevant to the pathogenesis of hypertension. These studies will serve determine the site and source of improved vascular health after resistance training in African Americans and Caucasians. Relevance: This study will provide clinically important data on how blood pressure can be optimally lowered by exercise and may show that resistance exercise training is the lifestyle intervention of choice for blood pressure lowering in African Americans.
Compared with Caucasians, African Americans have a higher prevalence of hypertension and with earlier onset of arterial dysfunction associated with increased rates of cardiovascular disease mortality. Consequently, the cardiovascular disease burden is considerably greater in African-Americans than in Caucasians. This application is relevant to public health because it will determine the impact of exercise training paradigms on protecting the circulation and lowering blood pressure and vascular risk thereby preventing overt cardiovascular disease in this high risk population.
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