Total body surface potential mapping during exercise: QRS-T-wave changes in normal young adults.

Total body surface potential distributions were recorded from 20 normal young adults, 20-35 years old, during multistage maximal exercise testing on a bicycle ergometer. Using a system for measuring total body surface potential distributions from measurements at 24 locations, high-quality potential maps were obtained during exercise without requiring wave form averaging or special modes of exercise. Serial maps recorded at 1-msec intervals throughout QRS-T during exercise and during recovery from exercise were compared with corresponding maps recorded with the subjects at rest. During and after exercise, consistent changes appeared in the map patterns during early QRS and the ST segment and in the magnitude of the T-wave potentials. Increases in QRS duration (0-10 msec) also appeared during exercise. The changes in map patterns during early QRS in exercise strongly suggested changes in the initial sequence of activation in the ventricles. The results demonstrate the importance of analyses of total body surface potential distributions in understanding ECG changes during exercise.