Exercise-induced differences in cardiac output, blood pressure, and systemic vascular resistance in a healthy biracial population of 10-year-old boys
F. W. Arensman, F. A. Treiber, M. P. Gruber and W. B. Strong
Department of Pediatrics, Medical College of Georgia, Augusta 30912-3710.
Previous studies have documented systolic blood pressure differences in
response to dynamic exercise when blacks were compared with whites. This
study was performed to validate these data and to determine if the cardiac
output and systemic vascular resistance responses to exercise are different
in a biracial population of 10-year-old boys. Nineteen blacks and 31 whites
underwent maximum supine graded exercise tests with Doppler determination
of cardiac output and measurement of systolic and diastolic blood pressure
and systemic vascular resistance. The blacks had a body surface area that
was marginally larger than that of the whites, but no differences were
noted in height or weight. Working capacities, when indexed by weight, were
virtually identical between the two groups. No differences were noted in
either systolic or diastolic blood pressure during preexercise, maximum
exercise, or early and late recovery. White males had significantly higher
cardiac indexes during preexercise, maximum exercise, and early and late
recovery. Black males had greater systemic vascular resistance during
preexercise, maximum exercise, and early and late recovery. Thus, the black
children's blood pressure responses to exercise were comparable with those
of the white children but they had a greater systemic vascular resistance
and lower cardiac index. These racial differences may serve as potential
markers for the prehypertensive state.
