| Perfusion heterogeneity does not explain excess muscle oxygen uptake during variable intensity exercise. | |
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MedLine Citation:
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PMID: 20491840 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The association between muscle oxygen uptake (VO(2)) and perfusion or perfusion heterogeneity (relative dispersion, RD) was studied in eight healthy male subjects during intermittent isometric (1 s on, 2 s off) one-legged knee-extension exercise at variable intensities using positron emission tomography and a-v blood sampling. Resistance during the first 6 min of exercise was 50% of maximal isometric voluntary contraction force (MVC) (HI-1), followed by 6 min at 10% MVC (LOW) and finishing with 6 min at 50% MVC (HI-2). Muscle perfusion and O(2) delivery during HI-1 (26 +/- 5 and 5.4 +/- 1.0 ml 100 g(-1) min(-1)) and HI-2 (28 +/- 4 and 5.8 +/- 0.7 ml 100 g(-1) min(-1)) were similar, but both were higher (P<0.01) than during LOW (15 +/- 3 and 3.0 +/- 0.6 ml 100 g(-1) min(-1)). Muscle VO(2) was also higher during both HI workloads (HI-1 3.3 +/- 0.4 and HI-2 4.1 +/- 0.6 ml 100 g(-1) min(-1)) than LOW (1.4 +/- 0.4 ml 100 g(-1) min(-1); P<0.01) and 25% higher during HI-2 than HI-1 (P<0.05). O(2) extraction was higher during HI workloads (HI-1 62 +/- 7 and HI-2 70 +/- 7%) than LOW (45 +/- 8%; P<0.01). O(2) extraction tended to be higher (P = 0.08) during HI-2 when compared to HI-1. Perfusion was less heterogeneous (P<0.05) during HI workloads when compared to LOW with no difference between HI workloads. Thus, during one-legged knee-extension exercise at variable intensities, skeletal muscle perfusion and O(2) delivery are unchanged between high-intensity workloads, whereas muscle VO(2) is increased during the second high-intensity workload. Perfusion heterogeneity cannot explain this discrepancy between O(2) delivery and uptake. We propose that the excess muscle VO(2) during the second high-intensity workload is derived from working muscle cells. |
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Authors:
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Marko S Laaksonen; Glenn Björklund; Ilkka Heinonen; Jukka Kemppainen; Juhani Knuuti; Heikki Kyröläinen; Kari K Kalliokoski |
Publication Detail:
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Type: Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't Date: 2010-05-11 |
Journal Detail:
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Title: Clinical physiology and functional imaging Volume: 30 ISSN: 1475-097X ISO Abbreviation: Clin Physiol Funct Imaging Publication Date: 2010 Jul |
Date Detail:
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Created Date: 2010-07-28 Completed Date: 2010-11-08 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101137604 Medline TA: Clin Physiol Funct Imaging Country: England |
Other Details:
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Languages: eng Pagination: 241-9 Citation Subset: IM |
Affiliation:
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Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Ostersund, Sweden. marko.laaksonen@miun.se |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Pressure Electromyography Exercise* Heart Rate Humans Isometric Contraction* Male Muscle, Skeletal / blood supply*, metabolism*, radionuclide imaging Oxygen / blood* Oxygen Consumption* Perfusion Imaging / methods Positron-Emission Tomography Regional Blood Flow Resistance Training Time Factors Young Adult |
| 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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