Blood Pressure And Heart Rate At Rest And During Exercise In 6-year-old Children

Abstract

PURPOSE: Even in children an increase in cardiovascular risk profile and especially in high blood pressure (BP) can be observed in industrialized countries. Therefore 6-year-old children were included in a study to assess BP at rest and BP and heart rate (HR) reaction during exercise. METHODS: In 180 children (aged 6.4±0.5 years) BP and HR were measured indirectly with a mercury sphygmomanometer according to the Riva-Rocci-Korotkoff cuff method in a sitting position at rest and during standardized ergometric exercise on a bicycle ergometer (2 minutes 25 watts) and at rest after exercise testing. During the bicycle ergometry BP readings were taken the last 15 seconds of the 2nd minute and 5 minutes at rest after exercise. HR was monitored by ECG continuously during the test. RESULTS: Average BP at rest was 100±10.3/68.4±8.1 mmHg. According to 115/75 mmHg as upper limit of normal pressure in this age group 34 children (16.8%) could be detected as being hypertensive due to BP at rest. During exercise at a workload of 25 watts BP was 125±13.4/74±8.4 mmHg. Corresponding HR was 155.4±22.3 beats / minute. There was a significant positive correlation between BP and HR during exercise (p<0.001). According to definition of upper BP limit during exercise in adults upper limit in children was defined as 140/85 mmHg (average + 1 standard deviation). Taking this into account 31 children (17.2%) had abnormal BP increases during exercise. In 21 children both BP at rest and during exercise were above normal. HR at rest did not differ between children with normal and elevated BP. In contrast, HR during exercise was significantly higher (p<0.001) in children with elevated BP when compared with normotensive subjects(165±22 /minute versus 151±21/minute). Consequently, the product of HR x systolic BP, a measure of myocardial oxygen consumption, was 32% higher (p<0.001) in hypertensives when compared with their normotensive counterparts. CONCLUSIONS: Even in young children a high percentage has elevated BP at rest and during exercise demonstrating an impaired vasodilatation during exercise. Furthermore, elevated BP is associated with an increased heart rate during exercise, which might be due to increased sympahto-adrenergic activity, which elevates myocardial oxygen consumption during exercise.