Background: The present study was performed to clarify fatigue-induced effects of a strenuous and moderate intensity endurance training session on temporary changes of cardiopulmonary (CP) chemosensitivity and fast kinetics response. Material/Methods: Eleven high performance (national level) male rowers participated in this study [age 21.8 ±1.7 (range 18-25 years), 89.3 ±2.0 kg, 190.1 ±1.7 cm, VO2 max 67.9 ±1.1 ml·kg-1·min-1]. The studies involved three steps: 1) a study of effects related to a training session of moderate intensity, 2) effects of a high intensity session, and 3) an impact of a high intensity session on values of peak response. The high intensity session consisted of intermittent training loads made up of five sets of four repetitions of sixty-second work intervals (HR of 149-186 bt·min-1). The moderate intensity session consisted of unvarying type of exercise (HR of 138-167 bt·min-1). Measurements were made at rest before, 13-15, and 37-39 hours after the training session. In rebreathing tests ventilatory sensitivity to CO2 and HR response sensitivity to normocapnic hypoxia were measured. Fast kinetics of ventilation, oxygen uptake, CO2 production and the heart rate were measured in a 5-min standard power test (0.7 VO2 max, 5 min, transition from 25 w) and in a 6-min test (1.12 ±0.11 VO2max). Results: We found that a training session of high intensity resulted in a significant decrease in sensitivity to hypercapnia, an increase in CP sensitivity to hypoxia, a decrease in CP fast kinetics and stability of peak response 13-15 hours after the session vs. baseline. Mean power in a 6-min maximum test decreased, which was mainly determined by a decrease in mean power during the first 3 min and utilization of VO2max for a 6-min test. Moderate intensity of a training session resulted in an increase in ventilatory sensitivity to hypercapnia whereas sensitivity CP to hypoxia and fast kinetics remained unaffected. Conclusions: These results suggest that not only CP chemosensitivity to hypoxia but also CP chemosensitivity to hypercapnia are variable in high intensity endurance training. The variability related to the effect of fatigue in the recovery phase (up to 15-15 hours) after strenuous training sessions.