| Blood lactate accumulation and muscle deoxygenation during incremental exercise. | |
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MedLine Citation:
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PMID: 10409594 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Near-infrared spectroscopy (NIRS) could allow insights into controversial issues related to blood lactate concentration ([La](b)) increases at submaximal workloads (). We combined, on five well-trained subjects [mountain climbers; peak O(2) consumption (VO(2peak)), 51.0 +/- 4.2 (SD) ml. kg(-1). min(-1)] performing incremental exercise on a cycle ergometer (30 W added every 4 min up to voluntary exhaustion), measurements of pulmonary gas exchange and earlobe [La](b) with determinations of concentration changes of oxygenated Hb (Delta[O(2)Hb]) and deoxygenated Hb (Delta[HHb]) in the vastus lateralis muscle, by continuous-wave NIRS. A "point of inflection" of [La](b) vs. was arbitrarily identified at the lowest [La](b) value which was >0.5 mM lower than that obtained at the following. Total Hb volume (Delta[O(2)Hb + HHb]) in the muscle region of interest increased as a function of up to 60-65% of VO(2 peak), after which it remained unchanged. The oxygenation index (Delta[O(2)Hb - HHb]) showed an accelerated decrease from 60- 65% of VO(2 peak). In the presence of a constant total Hb volume, the observed Delta[O(2)Hb - HHb] decrease indicates muscle deoxygenation (i.e., mainly capillary-venular Hb desaturation). The onset of muscle deoxygenation was significantly correlated (r(2) = 0.95; P < 0.01) with the point of inflection of [La](b) vs., i.e., with the onset of blood lactate accumulation. Previous studies showed relatively constant femoral venous PO(2) levels at higher than approximately 60% of maximal O(2) consumption. Thus muscle deoxygenation observed in the present study from 60-65% of VO(2 peak) could be attributed to capillary-venular Hb desaturation in the presence of relatively constant capillary-venular PO(2) levels, as a consequence of a rightward shift of the O(2)Hb dissociation curve determined by the onset of lactic acidosis. |
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Authors:
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B Grassi; V Quaresima; C Marconi; M Ferrari; P Cerretelli |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 87 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 1999 Jul |
Date Detail:
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Created Date: 1999-08-27 Completed Date: 1999-08-27 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8502536 Medline TA: J Appl Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 348-55 Citation Subset: IM; S |
Affiliation:
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Istituto di Tecnologie Biomediche Avanzate, Consiglio Nazionale delle Ricerche, I-20090 Segrate (MI), Italy. grassi@itba.mi.cnr.it |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acidosis, Lactic
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blood,
etiology,
metabolism Adult Exercise / physiology* Exercise Test Hemoglobins / metabolism Humans Lactic Acid / blood* Male Muscle, Skeletal / blood supply, metabolism* Oxygen / metabolism* Oxygen Consumption Oxyhemoglobins / metabolism Spectroscopy, Near-Infrared |
| Chemical | |
Reg. No./Substance:
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0/Hemoglobins; 0/Oxyhemoglobins; 50-21-5/Lactic Acid; 7782-44-7/Oxygen; 9008-02-0/deoxyhemoglobin |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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