Document Detail


Effect of hyperoxia on aerobic and anaerobic performances and muscle metabolism during maximal cycling exercise.
MedLine Citation:
PMID:  10712578     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The hyperoxia-improved tolerance to maximal aerobic performance was studied in relation to exercising muscle metabolic state. Five students were submitted to four different tests on a cycle ergometer, each being conducted under normoxia and hyperoxia (60% FiO2) on separate days: Test 1, a progressive exercise until exhaustion to determine the maximal work load (Wmax) which was unchanged by hyperoxia; Test 2, an exercise at Wmax (287 +/- 12 W) until exhaustion to determine the performance time (texh) which was elevated by 38% under hyperoxia but exhaustion occurred at the same arterial proton and lactate concentrations; Test 3 (S-Exercise test) consisted of cycling at Wmax for 90% normoxic-texh (4.8 +/- 0.5 min under both O2 conditions) then followed by a 10-s sprint bout during which the total work output (Wtot) was determined; Wtot was elevated by 15% when exercising under hyperoxia; Test 4 (M-Exercise test) consisted also of cycling at Wmax for 4.8 +/- 0.5 min with blood and muscle samples taken at rest and at the end of the exercise to compare the level of different metabolites. During hyperoxic M-Exercise test, glycogen was twice more depleted whereas glucose-6-phosphate and lactate were less accumulated when compared with normoxia. No significant differences were observed for pyruvate, phosphocreatine and muscle/blood lactate ratio between the two conditions. Conversely to normoxia, levels of ATP, ADP and total NADH were maintained at their resting level under 60% FiO2. These data lead us to suppose a higher oxidation rate for pyruvate and NADH in mitochondria, thereby lowering the metabolic acidosis and allowing a better functioning of the glycolytic and contractile processes to delay the time to exhaustion.
Authors:
M T Linossier; D Dormois; L Arsac; C Denis; J P Gay; A Geyssant; J R Lacour
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Acta physiologica Scandinavica     Volume:  168     ISSN:  0001-6772     ISO Abbreviation:  Acta Physiol. Scand.     Publication Date:  2000 Mar 
Date Detail:
Created Date:  2000-04-21     Completed Date:  2000-04-21     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0370362     Medline TA:  Acta Physiol Scand     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  403-11     Citation Subset:  IM; S    
Affiliation:
Laboratoire de Physiologie - GIP Exercice, Faculté de Médecine Saint-Etienne, 15 rue Ambroise Paré, Saint-Etienne Cedex 2, France.
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MeSH Terms
Descriptor/Qualifier:
Adult
Aerobiosis
Anaerobiosis
Blood / metabolism
Exercise / physiology*
Exercise Test
Glycolysis
Humans
Hydrogen-Ion Concentration
Hyperoxia / blood,  metabolism*,  physiopathology
Lactic Acid / blood
Male
Muscle Contraction / physiology
Muscle, Skeletal / metabolism*,  physiopathology
Chemical
Reg. No./Substance:
50-21-5/Lactic Acid

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