Changes Related to Fatigue in Cardiorespiratory Response Sensitivity to Hypoxic and Hypercapnic Stimulation during Strenuous Physical Load

Background: The aim was to study changes in the sensitivity of CRS responses of skilled athletes caused by fatigue during a strenuous physical load. Material/Methods: Response sensitivity to hypoxic and hypercapnic stimuli was analyzed in a group of high performance rowers (n=12) aged 18-22 years during exercising on "Concept-II" rowing ergometer. Two types of loads were used: sustained intensive load at high oxygen consumption (78-83% of VO2max) and relatively easier load (49-62% of VO2max) performed within 5 minutes. The method of rebreathing was used to determine responses sensitivity to CO2. Results: The results showed an increase in respiratory response sensitivity to hypoxia and a decrease in sensitivity to acidosis stimulus of respiration (CO2-H+) at the end of a strenuous load in presence of fatigue. Ventilatory response to hypoxic stimulus increased reliably before the end of work. At high intensity of loads during increment hypercapnia even in highly trained athletes the inhibition of ventilatory response has been noted Conclusions: The data provide additional grounds for correction of fatigue by means of regulating the character and the intensity of physical loads in the process of endurance training. It has been shown that changes in sensitivity of CRS responses and other aspects of reactive features are of importance for special work capacity manifestations.