1 Department of Pediatrics and the Children's Memorial Hospital, University of Oklahoma Medical Center, Oklahoma City, Oklahoma
The electrocardiographic patterns of 152 adolescents at rest and at maximal exercise were obtained. This included both sexes in approximately equal numbers. At rest, most exhibited sinus arrhythmia, a mean QRS frontal plane vector from 0 to +90°, and a resting rate from 80 to 90 per minute. The response to exercise was consistently that of tachycardia, reaching a rate from 180 to 220 per minute. All subjects did not attain a rate of 200 per minute, but several exceeded this. Changes in the T wave morphology with exercise were common and consisted of an increase in amplitude with peaking. Sex differences were noted in that girls had a slightly faster resting rate, required a shorter time to reach maximal exercise, had more rapid duration of exercise, and had faster recovery rates. Also, more girls than boys had an electrical axis of greater than 90°.
Submitted on January 31, 1967