| Priming exercise speeds pulmonary O2 uptake kinetics during supine "work-to-work" high-intensity cycle exercise. | |
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MedLine Citation:
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PMID: 19959765 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We manipulated the baseline metabolic rate and body position to explore the effect of the interaction between recruitment of discrete sections of the muscle fiber pool and muscle O(2) delivery on pulmonary O(2) uptake (VO(2)) kinetics during cycle exercise. We hypothesized that phase II VO(2) kinetics (tau(p)) in the transition from moderate- to severe-intensity exercise would be significantly slower in the supine than upright position because of a compromise to muscle perfusion and that a priming bout of severe-intensity exercise would return tau(p) during supine exercise to tau(p) during upright exercise. Eight male subjects [35 +/- 13 (SD) yr] completed a series of "step" transitions to severe-intensity cycle exercise from an "unloaded" (20-W) baseline and a baseline of moderate-intensity exercise in the supine and upright body positions. tau(p) was not significantly different between supine and upright exercise during transitions from a 20-W baseline to moderate- or severe-intensity exercise but was significantly greater during moderate- to severe-intensity exercise in the supine position (54 +/- 19 vs. 38 +/- 10 s, P < 0.05). Priming significantly reduced tau(p) during moderate- to severe-intensity supine exercise (34 +/- 9 s), returning it to a value that was not significantly different from tau(p) in the upright position. This effect occurred in the absence of changes in estimated muscle fractional O(2) extraction (from the near-infrared spectroscopy-derived deoxygenated Hb concentration signal), such that the priming-induced facilitation of muscle blood flow matched increased O(2) utilization in the recruited fibers, resulting in a speeding of VO(2) kinetics. These findings suggest that, during supine cycling, priming speeds VO(2) kinetics by providing an increased driving pressure for O(2) diffusion in the higher-order (i.e., type II) fibers, which would be recruited in the transition from moderate- to severe-intensity exercise and are known to be especially sensitive to limitations in O(2) supply. |
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Authors:
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Fred J DiMenna; Daryl P Wilkerson; Mark Burnley; Stephen J Bailey; Andrew M Jones |
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Publication Detail:
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Type: Journal Article Date: 2009-12-03 |
Journal Detail:
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Title: Journal of applied physiology (Bethesda, Md. : 1985) Volume: 108 ISSN: 1522-1601 ISO Abbreviation: J. Appl. Physiol. Publication Date: 2010 Feb |
Date Detail:
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Created Date: 2010-02-01 Completed Date: 2010-04-23 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: 283-92 Citation Subset: IM |
Affiliation:
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School of Sport and Health Sciences, St. Luke's Campus, Univ. of Exeter, Heavitree Rd., Exeter, Devon EX1 2LU, UK. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Algorithms Electromyography Exercise / physiology* Exercise Test Heart Rate / physiology Hemoglobins / metabolism Humans Kinetics Lactic Acid / blood Leg / physiology Lung / metabolism*, physiology* Male Oxygen Consumption / physiology* Pulmonary Gas Exchange / physiology Respiratory Mechanics / physiology Spectroscopy, Near-Infrared Supine Position / physiology* |
| Chemical | |
Reg. No./Substance:
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0/Hemoglobins; 50-21-5/Lactic Acid; 9008-02-0/deoxyhemoglobin |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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