[Changes in the blood pressure during an exercise test in children and adolescents. Results with reference to height]

The variations of blood pressure (BP) during exercise are important when there is a doubt about the normality of the values or a possibility of future abnormality. This is particularly true in children and adolescents with borderline or variable values, whose capacity of cardiovascular adaptation to sport is to be evaluated or who have a family history of hypertension. This study was undertaken to establish the profile of blood pressure on exercise during bicycle ergometry with reference to the height of the child or adolescent. BP and heart rate were measured in 651 healthy children aged 5 to 18 years during stress testing by bicycle ergometry. The sample was divided according to sex and height (120-139, 140-159, 160-180 cm), and according to resting BP values. During simple progressive exercise, the work required is increased by 10 watts every 2 minutes for children less than 140 cm tall, and by 20 watts when over 140 cm tall. BP and heart rate were measured during the last 30 seconds of each stage. Heart rate and systolic BP increased progressively with work load; on the other hand, the diastolic pressure did not change on exercise. The regression equation and the slope of systolic BP with respect to heart rate are reported, and allow comparison of different groups according to height, sex and resting systolic BP. The increase in systolic BP was the same in all groups except for boys taller than 160 cm in whom it was significantly greater (p less than 0,01). Sex and resting BP had no significant effect on the slope of systolic BP on exercise. The same applied to exercise lasting more than 6 minutes. The mean values and standard deviation of systolic BP at a heart rate of 150/min were, for each height group in ascending order: 121.5 +/- 19, 129 +/- 22 and 151 +/- 26 mmHg for boys, and 118.5 +/- 26, 126 +/- 21 and 137 +/- 26 mmHg for girls. In order to simplify the interpretation of the results obtained individually, charts in the form of an ellipse were plotted containing the usual values (95% of a healthy population) of systolic BP on exercise at the heart rate of 150/min, for each sex. They were established with reference to resting systolic BP and height. The diagnostic and prognostic value of this test will have to be evaluated by comparison with values obtained in hypertensive children.