Proceedings of the International scientific and practical conference ―New York Global Science Conference 2026‖ (May 18-20, 2026) / Publisher website: www.naukainfo.com. – New York, USA, 2026. - 322 p.

288 Immunological reactivity reflects the body’s ability to form an adequate response to physical load. In promising young futsal players, the immune response should be sufficiently active to provide protection, but at the same time controlled, without excessive hyperreactivity or signs of immune exhaustion. This type of response indicates the formation of a more economical adaptation mechanism, in which the body responds effectively to training influence without excessive tension of regulatory systems. The obtained results suggest that the combined assessment of hematological indicators, cellular resistance and immunological reactivity increases the objectivity of the selection of promising futsal players. Unlike the traditional approach, which mainly focuses on physical, technical and game preparedness, biological criteria make it possible to assess the internal adaptive resource of the athlete. This is especially important during adolescence, when external sports results do not always fully reflect the real functional potential of the body. Thus, the prospects of a young futsal player should be determined not only by the level of development of speed, coordination, strength and technical-tactical qualities, but also by the body’s ability to maintain hematological stability, a high level of cellular stability and balanced immunological reactivity. The combination of these features may indicate high adaptive potential, good tolerance of training loads and the ability for further sports growth. In practical terms, the results of the study indicate the expediency of including indicators of the blood system, cellular resistance and immunological reactivity in a comprehensive program for assessing young futsal players. Their use may contribute to early identification of athletes with high functional reserves and allow timely detection of individuals with signs of adaptive tension who require correction of training load or additional recovery. Thus, adaptive mechanisms of the blood system, cellular resistance and immunological reactivity act as important biological indicators of sports prospects in young futsal players. Their comprehensive assessment deepens the content of sports