To improve the health of modern youth, regular training is needed to further assessment the influence of different types of physical activity on the young organism, especially in the process of adaptation of the heart of young athletes. The purpose of this study is to trace the dynamics of the physiological parameters of the heart in adolescent tennis players. This study was performed on 27 clinically healthy adolescent tennis players with at least two years of training experience. The control group consisted of 22 clinically healthy young men who had never been involved in physical culture or sports. The observation was performed using the SSD-80 "Aloka" ultrasonic device (Japan). With its help, several functional indicators of the heart were taken into account. Statistical analysis of the results of the work was performed using Student's t-test. The examined tennis players showed signs of slight hypertrophy of the left ventricular muscle. This was indicated by an increase in the diameter of the muscle in its posterior wall and an increase in the mass of the left ventricle of the heart. In all tennis players, the left cardiac ventricle volume was perfectly normal. Tennis players also had an optimum diastole time. Regular tennis lessons strengthen all of a person's internal organs. They increase left ventricle muscle mass, which increases its function.