The research of heart electrical activity of sportsmen-swimmers has been carried out using a functional test with physical activity. Standard 12-lead electrocardiograms and the cardioelectric field on the athletes' thorax surface were analyzed at rest and in every minute of a five-minute recovery period after submaximal workload. The changes of amplitude-temporal characteristics of the heart electric field on the athletes' body surface were revealed while performing physical workload. During submaximal physical workload there was no correlation between the changes: the time of achievement of maximum values of the extrema of the heart electric field and the duration of ST-T(II) and QT(II) intervals in the electrocardiogram, an amplitude of the T(II)-wave and an absolute value of the maximum positive extremum of the heart electric field.