Objective of the study was to substantiate the need for a differentiated approach to the correction of the functional state of qualified athletes using hypoxic-hypercapnic training. Methods and structure of the study. The study was carried out at the premises of the state-financed institution "Sports Medicine Center", Crimea, in the period from 2015 to 2017, with the informed consent of the subjects and after the verdict of the ethics committee. Sampled for the study were the 19-22 year-old qualified athletes from team sports (n=100) and combat athletes (n=100). The authors rated their cardiorespiratory system functionality in the transitional period of the one-year training cycle, which was followed by the hypoxic-hypercapnic training course for 83 athletes. The course consisted of 10 training sessions, each with three sets of 5, 6, and 7 minutes (18 minutes in total), respectively, with a 5-minute rest break inbetween. Results and conclusions. When identifying the differences in the functional reserves of the myocardium, it was the T-wave symmetry rates (βT) that were the most informative. There were statistically significant relationships between MOC/kg and PЕТ CO2 in the combat athletes with all breathing patterns. After the hypoxic-hypercapnic training course, the athletes with the initial hypocapnic type of ventilation were found to have expanded myocardial reserve and increased aerobic capacity of the body. The βT value decreased by 6% (p˂0.001), the MOC/ kg value increased by 10% (p˂0.01). In the group with the initial hypocapnic type of ventilation, no changes in MOC/kg were found, but the βT value decreased by 10% (p˂0.001).