AltitudeOmics: Effects of 16 days acclimatisation to hypobaric hypoxia on muscle oxygen extraction during incremental exercise.
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State: Public
Version: Author's accepted manuscript
License: Not specified
Serval ID
serval:BIB_6C2483BABA14
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
AltitudeOmics: Effects of 16 days acclimatisation to hypobaric hypoxia on muscle oxygen extraction during incremental exercise.
Journal
Journal of applied physiology
ISSN
1522-1601 (Electronic)
ISSN-L
0161-7567
Publication state
In Press
Peer-reviewed
Oui
Language
english
Notes
Publication types: Journal Article
Publication Status: aheadofprint
Publication Status: aheadofprint
Abstract
Acute altitude exposure lowers arterial oxygen content (CaO <sub>2</sub> ) and cardiac output ( c) at peak exercise, whilst O <sub>2</sub> extraction from blood to working muscles remains similar. Acclimatization normalizes CaO <sub>2</sub> but not peak c nor peak oxygen consumption ( O <sub>2</sub> p). To what extent acclimatization impacts muscle O <sub>2</sub> extraction remains unresolved.
Twenty-one sea-level residents performed an incremental cycling exercise to exhaustion near sea level (SL), in acute (ALT1) and chronic (ALT16) hypoxia (5,260 m). Arterial blood gases, gas exchange at the mouth and oxy- (O <sub>2</sub> Hb) and deoxyhaemoglobin (HHb) of the vastus lateralis were recorded to assess arterial O <sub>2</sub> content (CaO <sub>2</sub> ), c, and O <sub>2</sub> . The HHb- O <sub>2</sub> slope was taken as a surrogate for muscle O <sub>2</sub> extraction.
During moderate-intensity exercise, HHb- O <sub>2</sub> slope increased to a comparable extent at ALT1 (2.13 ± 0.94) and ALT16 (2.03 ± 0.88) compared to SL (1.27 ± 0.12), indicating increased O <sub>2</sub> extraction. However, the HHb/CaO <sub>2</sub> ratio increased from SL to ALT1 and then tended to go back to SL values at ALT16. During high-intensity exercise, HHb- O <sub>2</sub> slope reached a break point beyond which it decreased at SL and ALT1, but not at ALT16.
Increased muscle O <sub>2</sub> extraction during submaximal exercise was associated with decreased CaO <sub>2</sub> in acute hypoxia. The significantly greater muscle O <sub>2</sub> extraction during maximal exercise in chronic hypoxia is suggestive of an O <sub>2</sub> reserve.
Twenty-one sea-level residents performed an incremental cycling exercise to exhaustion near sea level (SL), in acute (ALT1) and chronic (ALT16) hypoxia (5,260 m). Arterial blood gases, gas exchange at the mouth and oxy- (O <sub>2</sub> Hb) and deoxyhaemoglobin (HHb) of the vastus lateralis were recorded to assess arterial O <sub>2</sub> content (CaO <sub>2</sub> ), c, and O <sub>2</sub> . The HHb- O <sub>2</sub> slope was taken as a surrogate for muscle O <sub>2</sub> extraction.
During moderate-intensity exercise, HHb- O <sub>2</sub> slope increased to a comparable extent at ALT1 (2.13 ± 0.94) and ALT16 (2.03 ± 0.88) compared to SL (1.27 ± 0.12), indicating increased O <sub>2</sub> extraction. However, the HHb/CaO <sub>2</sub> ratio increased from SL to ALT1 and then tended to go back to SL values at ALT16. During high-intensity exercise, HHb- O <sub>2</sub> slope reached a break point beyond which it decreased at SL and ALT1, but not at ALT16.
Increased muscle O <sub>2</sub> extraction during submaximal exercise was associated with decreased CaO <sub>2</sub> in acute hypoxia. The significantly greater muscle O <sub>2</sub> extraction during maximal exercise in chronic hypoxia is suggestive of an O <sub>2</sub> reserve.
Keywords
NIRS, altitude, maximal exercise
Pubmed
Create date
22/08/2023 8:48
Last modification date
26/08/2023 7:11
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