purpose: to study the peculiarities of adaptive changes in high-class athletes to the effect of significant physical loads in middle mountain conditions. Material & Methods: determination of the level of urea and the concentration of hemoglobin in the blood was carried out using a biochemical analyzer “Diaglobal” (Germany) using ready-made kits of reagents from the same company. results: the article discusses the ways to improve the efficiency of training process management in athletics (race walking) and modern pentathlon, based on the use of biochemical control over the development of adaptation in various climatic conditions of the body of highly qualified athletes under the influence of training and control-competitive activities. conclusions: the reaction to the load of the blood system on the hemoglobin in the second microcycle of modern pentathletes showed an unwillingness to perform these loads, due to the fact that most athletes perform training loads at this height for the first time, while in athletes engaged in race walking in the second microcycle adaptive polycythemia was developing. This ensures the formation of sustainable adaptation, which allows you to perform the planned program of training loads. A blood test of race walking athletes showed that the concentration of urea, which was determined before exercise at rest, gradually increased within normal limits, and characterized the tolerability of training loads.