Prior sustained hypoxia attenuates interaction between hypoxia and exercise as ventilatory stimuli in humans

Wood, Helen E.; Fatemian, Marzieh; Robbins, Peter A.

doi:10.1113/expphysiol.2006.033159

Cited by 3 publications

(2 citation statements)

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“…Indeed, Wood et al (2007) have demonstrated that this interaction is itself affected (reduced) by a period of prior VAH, and conclude that there may be some interrelation between these processes.…”

Section: Discussionmentioning

confidence: 95%

Respiratory control during air-breathing exercise in humans following an 8h exposure to hypoxia

Herigstad

Fatemian

Robbins

2008

Respiratory Physiology & Neurobiology

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Hypoxic exposure lasting a few hours results in an elevation of ventilation and a lowering of end-tidal PCO2(PETCO2) that persists on return to breathing air. We sought to determine whether this increment in ventilation is fixed (hypothesis 1), or whether it increases in proportion to the rise in metabolic rate associated with exercise (hypothesis 2). Ten subjects were studied on two separate days. On 1 day, subjects were exposed to 8 h of isocapnic hypoxia (end-tidal PO2 55 Torr) and on the other day to 8 h of euoxia as a control. Before and 30 min after each exposure, subjects undertook an incremental exercise test. The best fit of a model for the variation in PETCO2 with metabolic rate gave a residual squared error that was ∼20-fold less for hypothesis 2 than for hypothesis 1 (p < 0.005, F-ratio test). We conclude that the alterations in respiratory control induced during early ventilatory acclimatization to hypoxia better reflect those associated with hypothesis 2 rather than hypothesis 1.

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Section: Discussionmentioning

confidence: 95%

Respiratory control during air-breathing exercise in humans following an 8h exposure to hypoxia

Herigstad

Fatemian

Robbins

2008

Respiratory Physiology & Neurobiology

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“…Both exercise and hypoxia increase pulmonary ventilation. However, the combined effects of the two stimuli are more than additive, such that exercise may be considered to potentate the acute ventilatory response to hypoxia [20]. These data contribute to a better understanding of important aspects of alteration of respiratory system reactive features in the process of sustained physical loads which are closely connected with special work capacity manifestation under different environmental conditions.…”

Section: Discussionmentioning

confidence: 98%

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

Мищенко

Pavlik

Suchanowski

2009

Baltic Journal of Health and Physical Activity

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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, VO 2max 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, VO 2max 74.5±1.5 ml.kg-1 ,min-1 ,11.2±1.4 yrs of experience) were examined by isocapnic progressive hypoxia and CO 2 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 O 2 arterial blood saturation (SaO 2) 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 CO 2 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 CO 2 had to be taken into account, but only an alpinist's aerobic power. Word count: 2 851 Tables: 3 Figures:-References: 20

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The Ventilatory Response to Hypoxia in Mammals: Mechanisms, Measurement, and Analysis

Teppema

Dahan

2010

Physiological Reviews

311

332

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The respiratory response to hypoxia in mammals develops from an inhibition of breathing movements in utero into a sustained increase in ventilation in the adult. This ventilatory response to hypoxia (HVR) in mammals is the subject of this review. The period immediately after birth contains a critical time window in which environmental factors can cause long-term changes in the structural and functional properties of the respiratory system, resulting in an altered HVR phenotype. Both neonatal chronic and chronic intermittent hypoxia, but also chronic hyperoxia, can induce such plastic changes, the nature of which depends on the time pattern and duration of the exposure (acute or chronic, episodic or not, etc.). At adult age, exposure to chronic hypoxic paradigms induces adjustments in the HVR that seem reversible when the respiratory system is fully matured. These changes are orchestrated by transcription factors of which hypoxia-inducible factor 1 has been identified as the master regulator. We discuss the mechanisms underlying the HVR and its adaptations to chronic changes in ambient oxygen concentration, with emphasis on the carotid bodies that contain oxygen sensors and initiate the response, and on the contribution of central neurotransmitters and brain stem regions. We also briefly summarize the techniques used in small animals and in humans to measure the HVR and discuss the specific difficulties encountered in its measurement and analysis.

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Prior sustained hypoxia attenuates interaction between hypoxia and exercise as ventilatory stimuli in humans

Cited by 3 publications

References 47 publications

Respiratory control during air-breathing exercise in humans following an 8h exposure to hypoxia

Respiratory control during air-breathing exercise in humans following an 8h exposure to hypoxia

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

The Ventilatory Response to Hypoxia in Mammals: Mechanisms, Measurement, and Analysis

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