| Noninvasive determination of exercise-induced hydrodgen ion threshold through direct optical measurement. | |
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MedLine Citation:
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PMID: 18096753 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The intensity of exercise above which oxygen uptake (Vo2) does not account for all of the required energy to perform work has been associated with lactate accumulation in the blood (lactate threshold, LT) and elevated carbon dioxide output (gas exchange threshold). An increase in hydrogen ion concentration ([H+]) is approximately concurrent with elevation of blood lactate and CO2 output during exercise. Near-infrared spectra (NIRS) and invasive interstitial fluid pH (pHm) were measured in the flexor digitorum profundus during handgrip exercise to produce a mathematical model relating the two measures with an estimated error of 0.035 pH units. This NIRS pHm model was subsequently applied to spectra collected from the vastus lateralis of 10 subjects performing an incremental-intensity cycle protocol. Muscle oxygen saturation (SmO2) was also calculated from spectra. We hypothesized that a H+ threshold could be identified for these subjects and that it would be different from but correlated with the LT. Lactate, gas exchange, SmO2, and H+ thresholds were determined as a function of Vo2 using bilinear regression. LT was significantly different from both the gas exchange threshold (Delta = 0.27 +/- 0.29 l/min) and H+ threshold (Delta = 0.29 +/- 0.23 l/min), but the gas exchange threshold was not significantly different from the H+ threshold (Delta = 0.00 +/- 0.38 l/min). The H+ threshold was strongly correlated with LT (R2 = 0.95) and the gas exchange threshold (R2 = 0.85). This initial study demonstrates the feasibility of noninvasive pHm estimations, the determination of H+ threshold, and the relationship between H+ and classical metabolic thresholds during incremental exercise. |
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Authors:
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Babs R Soller; Ye Yang; Stuart M C Lee; Cassie Wilson; R Donald Hagan |
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Publication Detail:
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Type: Comparative Study; Journal Article; Multicenter Study; Research Support, U.S. Gov't, Non-P.H.S.; Validation Studies Date: 2007-12-20 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 104 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2008 Mar |
Date Detail:
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Created Date: 2008-03-10 Completed Date: 2008-05-23 Revised Date: - |
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: 837-44 Citation Subset: IM |
Affiliation:
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Dept. of Anesthesiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA. babs.soller@umassmed.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Anaerobic Threshold Exercise / physiology* Extracellular Fluid / metabolism* Feasibility Studies Female Hand Strength* Humans Hydrogen-Ion Concentration Lactic Acid / metabolism Male Models, Biological Muscle Contraction* Muscle, Skeletal / metabolism* Oxygen Consumption Pulmonary Gas Exchange Quadriceps Muscle / metabolism Spectroscopy, Near-Infrared* United States |
| Chemical | |
Reg. No./Substance:
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50-21-5/Lactic Acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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