[Changes in the heart rhythm studied by the PWC170 test following physical loading]

By application of the two-component test PWC170, the changes in the heart rate (HR) and the difference in the duration of the minimal and maximal cardiac cycles (SAr), were studied. The indices (HR and SAr) were recorded by electrocardiography prior to the test (initial values), during the three-minute pause between the two loadings and in the three-minute recovery period following the second loading. It was found that SAr in the pause after the first loading with lower intensity of the test was more markedly expressed with respect to its initial values, while in the recovery period after the more intensive second loading of the test it was not only less expressed but in a number of cases did not reach the initial values. It was assumed that the relationship between the expressed in each moment influences of the vagal and sympathetic neuroregulatory mechanisms of the heart was significant for the expression of the observed rhythmic fluctuations.