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

100%

Mishchenko V., Suchanowski A., Lysenko O.

Baltic Journal of Health and Physical Activity

2009

vol. 1

issue 1

27-32

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 notedConclusions: 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.

Specifics of Ventilatory and Heart Rate Chemosensitivity Related to Special Endurance Capacity in High Performance Alpinists and Endurance Athletes

86%

Mishchenko V., Pavlik A., Suchanowski A.

Baltic Journal of Health and Physical Activity

2009

vol. 1

issue 2

97-104

Background: The aim was to compare ventilatory and heart rate chemosensitivity to hypoxia and hypercapnia in homogenous groups of high performance alpinists and endurance athletes and its relation to special work endurance.Material/Methods: Thirty-two male best national alpinists (30.7±2.7 yrs, VO2max 63.7±1.9 ml. kg-1,min-1, 14.3±2.4 yrs of experience) and 24 high performance male road cyclists of national team (25.7±1.1 yrs, VO2max 74.5±1.5 ml.kg-1,min-1, 11.2±1.4 yrs of experience) were examined by isocapnic progressive hypoxia and CO2 rebreathing tests. Maximal oxygen uptake, lung ventilation and heart rate peak responses were measured in an incremental ergometric test at sea level. Special work capacity of 23 alpinists was evaluated as the best time of non complicated mountain climbing between the point at 3,290 and 4,300 m above the sea level. Special work capacity of cyclists was evaluated as the best time of the individual 50 km race at the sea level.Results: The results showed no significant differences of the hypoxic ventilatory response in groups of alpinists and cyclists (p<0.05) But circulatory response evaluated by response of HR increase in answer to a decrease in O2 arterial blood saturation (SaO2) in alpinists was lower (p<0.05). Results showed that the evaluation of ventilatory and heart rate chemosensitivity in addition to measure of aerobic power may give important information for prevision of specific working capacity of high performance alpinists. Maximal oxygen uptake (ml/kg body mass) of the four best alpinists did not differ from the values of other alpinists. Special work capacity of alpinists was significantly related to tidal volume increase for the hypoxia test (r=-0.60) and to CO2 sensitivity (r=-0.67).Conclusions: The long-term exposure to environmental hypoxia and hypocapnia in alpinists generates specific changes in respiratory control. To evaluate special work capacity potential possibilities in a homogenous group of high performance alpinists first of all heart rate response sensitivity to hypoxia as well ventilatory response sensitivity to CO2 had to be taken into account, but only an alpinist's aerobic power.

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2 Baltic Journal of Health and Physical Activity

2 2009

2 Mishchenko V.

2 Suchanowski A.

1 Lysenko O.

1 Pavlik A.

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

Specifics of Ventilatory and Heart Rate Chemosensitivity Related to Special Endurance Capacity in High Performance Alpinists and Endurance Athletes