Abstract
<jats:p>The purpose of the study is to determine the relationship between functional state indicators and competitive performance in the 800-meter run among qualified female athletes aged 12–14. Research methods and organization. In the study, tests by Conconi, the Stange test, the Genche test, and the Stange-Serkin test were used to assess the functional state of female athletes; heart rate (HR) and vital capacity (VC) were measured using instrumental methods. The analysis of performance dynamics in competitive exercises was carried out, and coaches were surveyed using questionnaires. Methods of mathematical and statistical processing of experimental data were also applied. The study was conducted in March–April 2025 during the preparation of 12–14-year-old female athletes specializing in the 800-meter run for major competitions. Research results and conclusions. Correlations have been established between the studied parameters and the time taken to cover the distance. The results obtained confirm that a high performance in the 800-meter run is determined by a combination of the body's functional capabilities, among which the anaerobic threshold and the efficiency of the oxygen transport system (Stange-Serkina test) play a leading role. Survey results revealed an undervaluation of comprehensive monitoring of athletes' functional state in favor of pedagogical control of current physical fitness. The need for the implementation of regular comprehensive functional diagnostics into the system of sports selection and orientation, as well as into the training process of female middle-distance runners, is substantiated in order to optimize training and improve the accuracy of performance prediction.</jats:p>