Background: It is known that high sports performances are based upon optimization of adaptation process. In order to achieve the above, one should provide a maximal account of individual vivid features of athlete's abilities, peculiarities of his/her physiological reactivity. The aim was to study individualities of sensitivity to shifts in respiratory homeostasis and responsiveness to high intensity physical exercises in homogeneous groups of high performance endurance athletes.Material/Methods: Individual peculiarities of the cardiorespiratory system (CRS) physiological reactivity were evaluated in 118 high performance endurance athletes (cyclists, runners and rowers) aged 20-27 years (competing regularly in sports for 6.8 ± 1.1 years). The sensitivity of response to CO2-H+ (rebreathing), fast kinetics and the peak response of CRS to various physical loads were measured. The level of VO2max and accumulated oxygen deficit were determined as well.Results: The results indicate distinctive individual peculiarities of CRS response to the shifts of respiratory homeostasis in homogeneous groups of endurance athletes with respect to sensitivity and stability of responses to CO2-H+. Sensitivity to CO2-H+ demonstrated a positive correlation with fast kinetics and peak levels in responses to physical loads and anaerobic potential realization.Conclusions: Hyperkinetic and hypokinetic types of an individual physiological responsiveness of CRS to shifts in the respiratory homeostasis and physical exercise in homogeneous groups of high performance athletes were revealed as a premise for athletes' high specific work capacity.