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To determine whether responses to exercise in children with sickle cell trait (AS) are different from those of normal children, we performed dynamic cycle ergometer stress testing in 48 children with AS, aged 4 to 21 years. We compared these data with those obtained from 184 healthy black children. No subject with AS demonstrated definite ischemia on the exercise ECG, but four (8.3%) had equivocal ischemia. Population statistics derived from Z score values showed that the subjects with AS had lower exercise values for heart rate and work load than the controls. The BP response to exercise was normal in subjects with AS. Since no ischemia or complications occurred, exercise in subjects with AS appears to be safe. Further studies are needed to define the mechanism for the impaired pulse rate and work load variables.

The measurement of systolic and diastolic blood pressure during exercise is often difficult to perform due to patient motion and environmental noise. We evaluated an automated system of blood pressure determination in 121 children undergoing cycle ergometer stress testing. The system (Critikon Model 1165) utilized acoustic transduction, with electrocardiogram gating and microprocessor signal filtering. One observer measured the blood pressure values from the same arm as the automated system; this observer was blinded to the readout of the system. The correlation coefficients for systolic blood pressure at rest, during exercise, and during recovery were all greater than 0.91, and improved with the use of a stethophone adapter. This system can eliminate intraobserver variation as well as the necessity for the technician or physician to direct attention away from the electrocardiogram and patient during stress testing.

To determine the frequency of significant complications of exercise testing in children, we reviewed 1,730 studies performed over a 9-year period, 1973 to 1982. The protocol used a graded, continuous test to maximal effort on a cycle ergometer. The overall incidence of complications was 1.79%, similar to the 1.7% previously reported by Freed [4]. No deaths occurred. Complications were classified into 4 groups with their frequency of occurrence as follows: chest pain (0.69%), dizziness or syncope (0.29%), decreased blood pressure (0.35%), hazardous arrhythmias (0.46%). These data confirm that exercise testing in children has low morbidity and mortality. We believe that the safety of stress testing should encourage physicians to expand its use in the assessment of functional ability.

To determine normal values for the exercise variables heart rate, blood pressure, maximal workload, physical working capacity index, J point displacement, and ST segment slope, we stress tested 405 healthy children. We analyzed the data for four body surface area-determined groups, to discover whether there were any racial differences between healthy white children and black children. There were numerous racial differences in blood pressure, maximal workload, and physical working capacity index; there were no differences in the heart rate values. The incidence of false-positive J point displacement was less than or equal to 3% when the PR isoelectric line method was used. The ST segment slope in healthy children was always greater than zero at maximal exercise. Thus, norms for exercise variables must be expressed in relation to both sex and race. The nomograms presented in this report provide an easy-to-use set of normative data for cycle ergometer stress testing in children.