CHANGE OF ECG PARAMETERS DEPENDING ON THE LOAD LEVEL IN ATHLETES

The influence of physical training on bodies of athletes leads to changes that can be characterized as morphological, functional, electrophysiological and psychological. Dynamic exercise, such as running, swimming and riding a bicycle, leads to volume load of heart. Static exercise (gymnastics, weightlifting, wrestling) leads to the development of relatively large muscle force, with or without changes in muscle length and movement of the joint. Given the frequent number of sudden cardiac death cases in sport, it is important to distinguish between changes of the heart that occur as a result of adaptation to physical activity and changes due to some pathological conditions. The aim of this paper is to present the latest information on changes in ECG parameters depending on the load of athletes while performing aerobic trainings in order to better identify markers of adverse cardiovascular events, particularly sudden death in athletes. It is common to see on the ECG of athletes at rest hypertrophy of the left and right ventricle, interventricular conduction disorder, positive ST changes, and short-term tachycardia. Changes that occur in athletes are due to increased vagal tone and suppression of sympathetic nerve regulation. Many changes can be attributed to intrinsic cardiac component that is responsible for the lower frequency of athlete's heart deinnervation (with atropine or propranolol), which means that intense training influences how the autonomic regulation and the intrisic cardiac pacemaker function. It is common for athletes to have sinus bradycardia, sinus arrhythmia, first degree AV block and Mobitz I, as well as junctional rhythm, ST segment elevation, high and sharp, or biphasic T-waves, while ST depression or isolated T-wave inversion are less common. They can also have increased amplitude of P-wave and QRS complex, QRS axis rotation to the right and incomplete right branch block. Some but insufficient data tell about the presence of the third-degree AV block and atrial and ventricular ectopic beats and their predictive role for malignant rhythm disorders.