| Kinetics of O2 uptake, leg blood flow, and muscle deoxygenation are slowed in the upper compared with lower region of the moderate-intensity exercise domain. | |
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MedLine Citation:
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PMID: 16037398 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Six male subjects [23 yr (SD 4)] performed repetitions (6-8) of two-legged, moderate-intensity, knee-extension exercise during two separate protocols that included step transitions from 3 W to 90% estimated lactate threshold (thetaL) performed as a single step (S3) and in two equal steps (S1, 3 W to approximately 45% thetaL; S2, approximately 45% thetaL to approximately 90% thetaL). The time constants (tau) of pulmonary oxygen uptake (Vo2), leg blood flow (LBF), heart rate (HR), and muscle deoxygenation (HHb) were greater (P < 0.05) in S2 (tauVo2, approximately 52 s; tauLBF, approximately 39 s; tauHR, approximately 42 s; tauHHb, approximately 33 s) compared with S1 (tauVo2, approximately 24 s; tauLBF, approximately 21 s; tauHR, approximately 21 s; tauHHb, approximately 16 s), while the delay before an increase in HHb was reduced (P < 0.05) in S2 (approximately 14 s) compared with S1 (approximately 20 s). The Vo2 and HHb amplitudes were greater (P < 0.05) in S2 compared with S1, whereas the LBF amplitude was similar in S2 and S1. Thus the slowed Vo2 response in S2 compared with S1 is consistent with a mechanism whereby Vo2 kinetics is limited, in part, by a slowed adaptation of blood flow and/or O2 transport when exercise was initiated from a baseline of moderate-intensity exercise. |
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Authors:
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Shelley L MacPhee; J Kevin Shoemaker; Donald H Paterson; John M Kowalchuk |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2005-07-21 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 99 ISSN: 8750-7587 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2005 Nov |
Date Detail:
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Created Date: 2005-10-17 Completed Date: 2005-12-14 Revised Date: 2008-11-21 |
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: 1822-34 Citation Subset: IM |
Affiliation:
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Canadian Centre for Activity and Aging, 3M Centre, The University of Western Ontario, London, Ontario, Canada N6A 3K7. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Pressure / physiology Heart Rate / physiology Humans Kinetics Leg / blood supply, physiology Male Muscle, Skeletal / blood supply, physiology* Oxygen / metabolism* Oxygen Consumption / physiology* Physical Exertion / physiology* Regional Blood Flow / physiology* Spectroscopy, Near-Infrared |
| Chemical | |
Reg. No./Substance:
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7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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