THE RATE OF INCREASE IN BLOOD-PRESSURE IN CHILDREN 5 YEARS OF AGE IS RELATED TO CHANGES IN AEROBIC FITNESS AND BODY-MASS INDEX

Objective. To determine whether changes in aerobic fitness and body ma ss index are related to the age-related rise in blood pressure in heal thy preschool children. Study design. Longitudinal analyses of 196 fre e-living children aged 5 years at baseline who were followed over a me an of 19.7 months. Aerobic fitness was assessed using a treadmill. All measures were obtained on multiple occasions at scheduled visits as p art of a longitudinal cohort study. Setting. An inner-city medical cen ter. Outcome measures. Blood pressure was measured using an automated Dinamap device. Results. Mean systolic blood pressure was 95.3 mmHg (S D 8.38) at baseline and increased by 4.46 mmHg per year. Mean diastoli c blood pressure was 53.9 mmHg (SD 5.81) at baseline and did not chang e significantly. Children in the highest quintile of increase in fitne ss had a significantly smaller increase in systolic blood pressure com pared to children in the lowest quintile (2.92 vs 5.10 mmHg/year; P = .03). Children in the lowest quintile of increase in body mass index d id not differ significantly in rate of increase in systolic blood pres sure compared to children in the highest quintile (3.92 vs 4.96 mmHg/y ear). In a multiple regression model including baseline systolic blood pressure, fitness, height, body mass index, and other covariates, gre ater increase in fitness (P = .03) and lesser increase in body mass in dex (P < .01) were associated with lower rates of increase in systolic blood pressure. In a similar multivariate analysis, an increase in fi tness was also associated with a lower rate of increase in diastolic b lood pressure (P = .02) Conclusion. Young children who increase their aerobic fitness or decrease their body mass index reduce the rate of t he age-related increase in blood pressure. These observations may have implications for development of interventions directed at the primary prevention of hypertension.