Variations in normal electrocardiographic response to treadmill testing

Forty healthy young men at low risk for coronary artery disease underwent progressive maximal treadmill testing. Four bipolar electrocardiographic leads including CM 5, CC 5, inferior-superior Y, anterior-posterior Z, and a standard V 5 were recorded and later computer-processed. Measurements included amplitudes of the Q, R, S, J junction and T wave, R-T and Q-S intervals and S-T segment slope. These variables are presented as the 10th, 50th (median) and 90th percentiles throughout the testing procedure to define reference values for the electrocardiographic response to maximal treadmill testing. The medians are presented graphically so that the exercise-induced changes can be visualized. In addition, the percent change of R wave amplitude in V 5 compared with the supine pretest value is displayed for each subject during and after testing.