ELECTROCARDIOGRAPHIC FINDINGS OF HEART-RATE AND CONDUCTION TIMES IN ATHLETIC STUDENTS AND SEDENTARY CONTROL SUBJECTS

We have investigated resting electrocardiograms in 1,299 athletic stud ents and 151 sedentary control subjects. Bradycardia was significantly more common in athletes. The athletic group was divided according to a heart rate <50, 50-100, and above 100 beats/min. Atrioventricular co nduction time, prevalence of ectopic beats and other rhythms, paramete rs of right and left ventricular hypertrophy, ST elevation, and T wave amplitude were increased in the sinus bradycardia group. A significan t negative correlation was found between heart rate and PQ duration in athletes. In the sinus tachycardia group, the PQ duration was shorter and the ST depression more prominent than in the other groups. The su bjects were also divided according to PQ greater than or equal to 0.22 , 0.21-0.12, and <0.12 s. Parameters of left ventricular hypertrophy w ere markedly increased in athletes with PQ greater than or equal to 0. 22 s, while the heart rate was only slightly decreased, suggesting an association between prolonged atrioventricular conduction time and lef t ventricular hypertrophy. Incomplete right bundle branch block was as sociated with a lower heart rate, increased duration of QRS and QT(c), voltage of precordial Q waves, indices of right ventricular hypertrop hy, and negative T waves. These findings are typical of right ventricu lar hypertrophy, indicating a close relation of incomplete right bundl e branch block to right ventricular hypertrophy.