Document Detail

Coincidental changes in ventilation and electromyographic activity during consecutive incremental exercise tests.
MedLine Citation:
PMID:  8162924     Owner:  NLM     Status:  MEDLINE    
These experiments examined the effect of metabolic acidosis, induced as a result of dynamic exercise, on ventilation, lactate concentration and electromyographic activity. Seven subjects performed two consecutive incremental exercise tests until volitional exhaustion was achieved. The two tests were identical and were separated by a 7-min period of light exercise. During the tests, ventilation, mixed expired oxygen and carbon dioxide, arterialized venous blood and electromyographic activity from the vastus lateralis was sampled. The results showed that the ventilation and electromyographic measurements followed a similar time course during both tests, although ventilation during the initial 6 min of the second test was significantly greater than the values recorded during the first test. In addition, throughout the first test lactate concentration increased with time, and pH, bicarbonate concentration and partial pressure of carbon dioxide decreased. In contrast, during the second test, lactate concentration decreased, and pH and bicarbonate concentration increased; during a period of time when ventilation and electromyographic activity were increasing. These findings have led us to conclude that changes in ventilation and electromyographic activity observed during incremental exercise are not related to changes in blood lactate concentration. It is suggested that such a conclusion supports the hypothesis that the changes in ventilation are mediated by an increase in neural activity originating from the subthalamic motor region or exercising limbs, induced in response to the need to progressively recruit fast twitch muscle fibres as exercise work rate is increased and as individual muscle fibres begin to fatigue.
J H Mateika; J Duffin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of applied physiology and occupational physiology     Volume:  68     ISSN:  0301-5548     ISO Abbreviation:  Eur J Appl Physiol Occup Physiol     Publication Date:  1994  
Date Detail:
Created Date:  1994-05-26     Completed Date:  1994-05-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0410266     Medline TA:  Eur J Appl Physiol Occup Physiol     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  54-61     Citation Subset:  IM; S    
Department of Anaesthesia, University of Toronto, Ontario, Canada.
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MeSH Terms
Bicarbonates / blood
Carbon Dioxide / metabolism
Exercise / physiology*
Exercise Test
Hydrogen-Ion Concentration
Lactates / blood
Lactic Acid
Muscle Contraction / physiology*
Oxygen Consumption / physiology
Respiration / physiology*
Reg. No./Substance:
0/Bicarbonates; 0/Lactates; 124-38-9/Carbon Dioxide; 50-21-5/Lactic Acid

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

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