DIAGNOSTIC VALUE AND INTERRELATIONSHIPS OF FUNCTIONAL PARAMETERS IN ATHLETES WITH DIFFERENT LEVELS OF HYPOXIC-HYPERCAPNIC TOLERANCE

Abstract

Aim. This paper aims to investigate the features of functional adaptations in highly skilled cross-country skiers compared to healthy students and to evaluate the diagnostic value of functional parameters used in calculating the hypoxic-hypercapnic tolerance index. Materials and methods. This paper involved 32 male participants, including 14 physical education university students (mean age: 19.3 ± 0.3 years; mean BMI: 24.4 ± 1.0 kg/m²) and 18 highly skilled cross-country skiers from the Russian national teams (mean age: 22.0 ± 1.2 years; mean BMI: 23.0 ± 0.4 kg/m²). The rebreathing test without CO₂ absorption was used. Heart rate (HR), blood pressure (BP), O₂ and CO₂ content in the breathing circuit bag (measured by a gas analyzer), and hemoglobin oxygen saturation (measured by a finger pulse oximeter) were obtained at baseline and after rebreathing. Results. Body tolerance to progressive hypoxic-hypercapnic exposure can be quantified using the newly developed hypoxic tolerance index. Factor analysis demonstrated that, in elite cross-country skiers, tolerance to combined acute hypoxia and hypercapnia depends on gas exchange and cardiovascular hemodynamics, as well as BMI. Conclusion. The functional response of cardiovascular hemodynamics and gas exchange to the rebreathing test confirmed the diagnostic value of the proposed express assessment of body tolerance to combined О₂ deficiency and CО₂ excess exposure. This enables individual functional monitoring in athletes using the hypoxic-hypercapnic tolerance index.