Document Detail

Increase characteristics of the cumulated excess-CO2 and the lactate concentration during exercise.
MedLine Citation:
PMID:  10961517     Owner:  NLM     Status:  MEDLINE    
The so-called excess-CO2 in physical exertion results stoichiometrically directly from the quantity of protons bound in bicarbonate buffering. This situation is used in determining the ventilatory threshold (VT). However, the extent to which the degree and increase characteristics of excess-CO2 can be used as an equivalent to blood lactate concentrations is uncertain. To investigate this relationship, 21 healthy men exercised on a cycle ergometer (starting at 50 watt, increases of 50 watt every 3 minutes) to subjective exhaustion. To evaluate the characteristics of this increase, a slope constant lambda was calculated in relation to performance for both the blood lactate concentration (lambda lactate) and the cumulated excess-CO2 (lambda CO2 excess). The start of the lactate increase (LT) and excess-CO2 (VT) showed good intercorrelation (VT=2.27+0.98 x LT; r=0.914; P<0.001). Mean lambda lactate and lambda CO2 excess were of similar dimensions in all subjects (69.3 +/- 39.8 watt vs. 80.11 +/- 15.7 watt), but a minority of the subjects (n=7) showed a considerably more gradual increase for the excess-CO2 to the maximum. Since in addition there was no significant correlation between the absolute values for maximum lactate concentrations and the cumulative excess-CO2, an interindividual prediction of lactate concentrations from the excess-CO2 would be difficult. It is an open question, however, whether perhaps additional performance-limiting factors, such as the ventilation or the buffering capacity, may be included when measuring the excess-CO2 so that this parameter could be more a measure for the formation rate of new lactate than the blood lactate concentration alone.
K Roecker; F Mayer; H Striegel; H H Dickhuth
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  International journal of sports medicine     Volume:  21     ISSN:  0172-4622     ISO Abbreviation:  Int J Sports Med     Publication Date:  2000 Aug 
Date Detail:
Created Date:  2000-12-04     Completed Date:  2000-12-28     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8008349     Medline TA:  Int J Sports Med     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  419-23     Citation Subset:  IM    
Med. Clinic and Policlinic, University of Tuebingen, Dept. of Sports Medicine, Germany.
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MeSH Terms
Carbon Dioxide / blood*
Exercise / physiology*
Exercise Test
Lactic Acid / blood*
Oxygen Consumption
Regression Analysis
Reg. No./Substance:
124-38-9/Carbon Dioxide; 50-21-5/Lactic Acid

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