Introduction. Maintaining and strengthening young athletes' health is very important since a growing body is more sensitive than an adult one. The overload on young athletes' bodies' functional systems is much higher compared to their peers who do not engage in intense physical activities and sports. This study aimed to assess the functional changes in the body of young athletes practicing sports games in the training process. Materials and methods. The functional state of the body of young athletes practicing five types of sports (volleyball, basketball, football, tennis, and handball) was studied on a representative group of 94 people, of which 50 (53.2%) males and 44 (46.8%) females with an average age of 17.7 ± 0.19 years. The cardiovascular system, central nervous system, respiratory system, and musculoskeletal system were investigated. The functional state assessment was carried out, taking into account the degree and direction of changes in the dynamics of training of individual indicators and integral indicators. It was determined the degree of risk of developing adverse functional changes. To identify premorbid states, we establish the type of self-regulation of blood circulation. Results. The obtained results in this study indicate that significant changes express the biological significance of the response of athletes to the conditions of training in the indices of the functions of the cardiovascular and central nervous systems and the musculoskeletal system. The indices of the functional state of the young athletes' body at the end of the training changed in both directions. The degree of their severity fluctuated within limits from little too clearly expressed values. On the part of the cardiovascular system, an acceleration of heart rate from 60.1 ± 0.93 to 123.1 ± 0.93 beats/min (p < 0.001) was noted, an increase of systolic blood pressure from 101.1 ± 2.84 to 129.2 ± 1.40 mm Hg. (p <0.001), diastolic arterial pressure from 65.8 ± 1.60 to 76.3 ± 1.20 mm Hg. (p < 0.001), pulse pressure from 33.5 ± 2.35 to 71.5 ± 0.85 mm Hg. (p < 0.001), systolic pressure from 78.3 ± 1.75 to 84.2 ± 1.06 ml (p < 0.001), minutes volume from 4.3 ± 0.22 to 10.3 ± 0.11 l (p < 0.001), total peripheral resistance from 934.2 ± 42.11 to 1646.4 ± 37.61 dyn•s/cm⁵ (p < 0.001). On the part of the central nervous system, there was an increase in visual motor reaction from 236 ± 20.0 to 389 ± 5.3 ms (p < 0.001) and the auditory-motor reaction from 160 ± 3.8 to 256 ± 7.7 ms (p < 0.001). Young athletes who play volleyball have a higher load on the cardiovascular system. Functional changes are more pronounced in female athletes. The risk of developing unfavorable functional changes was noted for 15 physiological indices. The relative risk varied within 1.03-2.45 for boys and 1.04-2.90 for girls. The most pronounced risk is characteristic for total peripheral resistance (RR = 1.60), minutes volume (RR = 1.58), systolic pressure (RR = 1.55) in boys and systolic pressure (RR = 2.35), minutes volume (RR = 2.21), systolic arterial pressure (RR = 1.75), diastolic arterial pressure (RR = 1.73) and peripheral blood pressure (RR = 1.52) in girls. Conclusions. When playing sports games, a specific professional environment for different types of sports games is formed, this harming the functional state, performance, and health of young athletes.