African-Americans are at greater risk than Caucasians for developing hypertension, cardiovascular disease, stroke and renal disease. This is likely related to arterial dysfunction including greater arterial stiffness, and reduced microvascular reactivity of resistance arteries in African-Americans. In addition, African-Americans have higher levels of inflammatory markers, and a greater sympathoexcitatory response to various stressors. This imbalance between sympathetic and reduced parasympathetic activation may directly affect vascular function and potentiate a greater inflammatory response, further altering key structural and functional properties of the vascular wall. The overall aim of this proposal is to test the effects of endurance exercise training on arterial structure and function, and to examine potential mechanisms producing changes in arterial structure and function in young (18-35 years of age) African Americans when compared to Caucasians. We will examine these effects at rest and following a high intensity (maximal cycle ergometry) sympathoexcitation at both pre- and post-intervention time points, since sympathoexcitation may elucidate changes not evident at rest. Because African-Americans have higher levels of arterial stiffness, lower microvascular reactivity, greater responses to sympathoexcitation, greater levels of inflammatory markers and greater vasoconstrictive tone, we hypothesize that African-Americans will show differential responses to exercise training and benefit more compared to a matched group of Caucasians.
The purpose of this study is to test the effects of endurance exercise training on arterial structure and function, and to examine potential mechanisms producing changes in arterial structure and function in young (18-35 years of age) African Americans when compared to Caucasians.