Muscle and cardiovascular indicators in persons engaged in physical culture and sport at the time of failure to perform strenuous physical exercise
The purpose of the present research was to study the indicators of muscular and cardiovascular systems at the time of failure to perform strenuous exercise. It is shown that the sympathetic influence on the heart sharply increased in the subjects at the time of failure, along with an increase of the hemodynamic characteristics and ECG and EMG changes. All this is testifies to the functional changes that occur at the time of endurance exercise. It has been established that strenuous exercise to failure causes a pronounced increase of the sympathetic effect in the subjects, accompanied by an increase in systolic blood pressure, stroke volume, cardiac output and heart rate. This is accompanied by an increase of the impulse generation in the sinus node of the heart and sharp increase of R wave in the ECG, slowing of the intraventricular conduction of impulses and deepening of Q and S waves caused by the rise of motor hypoxia. The T wave, showing the increase of the sympathetic effects on the heart, is reduced. Reduced average amplitude against the background of stabilization of the number of turns in the EMG indicates of muscle fatigue. It should be stressed that at the time of failure to perform an exercise the changes of P, Q, T waves and the QRS segment reach the level of the marginal compensation, but after 6 minutes of recovery they return to normal. The findings can be the ground for the development of the individual evaluation criteria of physiological capabilities of athletes and, consequently, contribute to to planning their training and competitive activities.