Hemodynamics of supine bicycle exercise in "normal" children.

Sixty children age 5 to 16 years with normal or nearly normal hearts performed submaximal and maximal supine bicycle exercise. Submaximal cardiac output was linearly correlated with work load (r = 0.80). After 2 minutes' exercise cardiac output was over 90 per cent of the value for 6 minutes' exercise. Maximal cardiac index was 10.1 +/- 1.8 for boys and 8.6 +/- 1.8 L. per minute per square meter for girls. Stroke volume was highest during the recovery period after maximal exercise. Pulmonary artery PO2 fell to 24 mm. Hg, oxygen saturation to 33 per cent, and pH to 7.21. During maximal exercise mean pulmonary artery pressure was 24 +/- 5 mm. Hg and mean brachial artery pressure was 113 +/- 8. There were no major differences between children aged 5 to 9 years of age and those 10 to 16 years, except for higher hemoglobin values in postpubertal children.