Familial history of hypertension : hemodynamic responses to exercise in children

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Authors
Kelsey, Kira Q.
Advisor
Mahon, Anthony D.
Issue Date
1996
Keyword
Degree
Thesis (M.S.)
Department
School of Physical Education
Other Identifiers
Abstract

Hypertension afflicts one in four American adults and is a major risk factor for cardiovascular disease. Studies have shown that a family history of hypertension is an important predictor of future hypertension. Two hemodynamic factors control blood pressure (BP); cardiac output (CO) and total peripheral resistance (TPR). Although children of hypertensive parents may exhibit normal levels of these hemodynamic variables at rest, the response of these variables during exercise stress may differ. Therefore, the present study was designed to investigate whether children with a positive family history of hypertension exhibit an exaggerated BP response due to either an increased CO or an attenuated decrease in TPR during dynamic submaximal exercise compared to children of normotensive parents. Eleven children 12.2 ± 1.8 yr (M ± SE) of normotensive parents and 11 children 12.0 ± 2.4 yr of at least one hypertensive parent completed an orientation session, graded maximal cycle ergometer test, and a submaximal exercise bout consisting of 6 minutes of steady state cycling at 50 and 80% of maximal heart rate reserve. Blood pressure, CO and TPR were measured during the last 3 minutes of each submaximal exercise stage. An independent t-test was used to determine differences in the resting measures. The changes in TPR, BP and CO from rest through 80% intensity stage were examined using a twoway (group x intensity) ANOVA. The groups were evenly matched for age, weight, height, and body fatness. The children with a positive family history of hypertension had significantly higher resting systolic BP, diastolic BP (DBP), and mean arterial pressure (MAP) (p<0.05) compared to those children with a negative family history. Although there were no significant interactions among any of the variables studied, there was a tendency for TPR to be higher (p>0.05) at rest and throughout exercise in the positive history group. MAP and DBP were significantly higher in the positive family history group at rest and remained higher throughout exercise. In conclusion children of hypertensive parents exhibit a modest but significantly higher MAP and DBP at rest and during submaximal exercise. This subtle difference in BP control reflects an early trend toward increased TPR.

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