Document Detail

Effect of hypoxia and carbon monoxide on muscle oxygenation during exercise.
MedLine Citation:
PMID:  9001317     Owner:  NLM     Status:  MEDLINE    
We used near-infrared spectroscopy (NIRS) to test the hypothesis that reducing oxygen availability during exercise would affect the rate of muscle oxyhemoglobin (O2Hb) desaturation when performing work above the lactic acidosis threshold (LAT), but not below it. Seven healthy men each performed two constant work intensities (60%LAT and the LAT plus 40% of the difference between the LAT and VO2max [40%delta]) four times under the following conditions: (1) 10 min air; (2) 5 min 15%O2 + 5 min air; (3) 5 min air + 5 min 15%O2; (4) 5 min after carbon monoxide (CO) loading to increase the carboxyhemoglobin (COHb) saturation to 15%. During each test, cardiorespiratory parameters and muscle oxygenation measured with NIRS were continuously monitored. Forearm venous blood lactate was measured every 2 to 3 min. Hypoxia and CO accelerated muscle deoxygenation only for exercise above the LAT; for exercise below the LAT, neither progressive deoxygenation nor lactate accumulation occurred after initital, rapid muscle deoxygenation. The rate of decrease in muscle oxygenation between 3 to 5 min of exercise correlated with the increase in VO2 (r = 0.61, p < 0.01) and blood lactate (r = 0.70, p < 0.01) over the same period. These results support the hypothesis that progressive muscle deoxygenation occurs above the LAT and that the rate of deoxygenation is sensitive to oxygen delivery.
K Maehara; M Riley; P Galassetti; T J Barstow; K Wasserman
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  155     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1997 Jan 
Date Detail:
Created Date:  1997-02-11     Completed Date:  1997-02-11     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  229-35     Citation Subset:  AIM; IM; S    
Harbor-UCLA Medical Center, Division of Respiratory and Critical Care Physiology and Medicine, Torrance, California 90509-2910, USA.
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MeSH Terms
Anoxia / metabolism*
Carbon Monoxide / administration & dosage,  pharmacology*
Carboxyhemoglobin / metabolism
Lactic Acid / metabolism
Muscle, Skeletal / metabolism*
Oxygen / blood
Oxygen Consumption*
Oxyhemoglobins / metabolism
Physical Exertion*
Spectroscopy, Near-Infrared
Reg. No./Substance:
0/Oxyhemoglobins; 50-21-5/Lactic Acid; 630-08-0/Carbon Monoxide; 7782-44-7/Oxygen; 9061-29-4/Carboxyhemoglobin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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