Document Detail

The influence of a respiratory acidosis on the exercise blood lactate response.
MedLine Citation:
PMID:  1915334     Owner:  NLM     Status:  MEDLINE    
The purpose of the present study was to examine the influence of a respiratory acidosis on the blood lactate (La) threshold and specific blood La concentrations measured during a progressive incremental exercise test. Seven males performed three step-incremental exercise tests (20 W.min-1) breathing the following gas mixtures; 21% O2 balance-nitrogen, and 21% O2, 4% CO2 balance-nitrogen or balance-helium. The log-log transformation of La oxygen consumption (VO2) relationship and a 1 mmol.l-1 increase above resting values were used to determine a La threshold. Also, the VO2 corresponding to a La value of 2 (La2) and 4 (La4) mmol.l-1 was determined. Breathing the hypercapnic gas mixtures significantly increased the resting partial pressure of carbon dioxide (PCO2) from 5.6 kPa (42 mm Hg) to 6.1 kPa (46 mm Hg) and decreased pH from 7.395 to 7.366. During the incremental exercise test, PCO2 increased significantly to 7.2 kPa (54 mm Hg) and 6.8 kPa (51 mm Hg) for the hypercapnic gas mixtures with nitrogen and helium, respectively, and pH decreased to 7.194 and 7.208. In contrast, blood PCO2 decreased to 4.9 kPa (37 mm Hg) at the end of the normocapnic exercise test and pH decreased to 7.291. A blood La threshold determined from a log-log transformation [1.20 (0.28) l.min-1] or as an increase of 1 mmol.l-1 [1.84 (0.46) l.min-1] was unaffected by the acid-base alterations. Similarly, the VO2 corresponding to La2 and La4 was not affected by breathing the hypercapnic gas mixtures [2.12 (0.46) l.min-1 and 2.81 (0.52) l.min-1, respectively].(ABSTRACT TRUNCATED AT 250 WORDS)
T M McLellan
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  European journal of applied physiology and occupational physiology     Volume:  63     ISSN:  0301-5548     ISO Abbreviation:  Eur J Appl Physiol Occup Physiol     Publication Date:  1991  
Date Detail:
Created Date:  1991-11-21     Completed Date:  1991-11-21     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0410266     Medline TA:  Eur J Appl Physiol Occup Physiol     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  6-11     Citation Subset:  IM    
Environmental Physiology Section, Defence and Civil Institute of Environmental Medicine, North York, Ontario, Canada.
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MeSH Terms
Acidosis, Respiratory / blood*
Carbon Dioxide / administration & dosage,  blood
Exercise / physiology*
Lactates / blood*
Lactic Acid
Oxygen Consumption
Reg. No./Substance:
0/Lactates; 124-38-9/Carbon Dioxide; 50-21-5/Lactic Acid

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