| Changes in ventricular twist and untwisting with orthostatic stress: endurance athletes versus normally active individuals. | |
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MedLine Citation:
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PMID: 20203066 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Endurance-trained individuals exhibit larger reductions in left ventricular (LV) end-diastolic volume in response to lower body negative pressure (LBNP) compared with normally active individuals. However, the relationship between LV torsion and untwisting and the LV volume response to LBNP in endurance athletes is unknown. Eight endurance-trained athletes [maximal oxygen consumption (VO2max): 66.4+/-7.2 ml.kg(-1).min(-1)] and eight normally active individuals (VO2max: 41.9+/-9.0 ml.kg(-1).min(-1)) (all men) underwent two cardiac magnetic resonance imaging (MRI) assessments, the first during supine rest and the second during -30 mmHg LBNP. Right ventricular (RV) and LV volumes were assessed, myocardial tagging was applied in order to quantify LV peak torsion and peak untwisting rate, and filling rates were measured with phase-contrast MRI. In response to LBNP, endurance-trained individuals had greater reductions in RV and LV end-diastolic volume and stroke volume (P<0.05). Endurance athletes had reduced untwisting rates (20.3+/-8.7 degrees/s), while normally active individuals had increased untwisting rates (-16.2+/-32.1 degrees/s) in response to LBNP (P<0.05). Changes in peak untwisting rate were significantly correlated with change in peak torsion (R=-0.87, P<0.05), with the change in early filling rate and VO2max, but not with changes in end-diastolic or end-systolic volume (P>0.05). We conclude that increased untwisting rates in normally active subjects may mitigate the drop in early filling rate with LBNP and thus may be a compensatory mechanism for the reduction in stroke volume with volume unloading. The opposite response in athletes, who showed a decreased untwisting rate, may contribute to their larger reductions in LV end-diastolic and stroke volumes with volume unloading and their orthostatic intolerance. |
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Authors:
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Ben T Esch; Jessica M Scott; Mark J Haykowsky; Ian Paterson; Darren E R Warburton; June Cheng-Baron; Kelvin Chow; Richard B Thompson |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't Date: 2010-03-04 |
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 May |
Date Detail:
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Created Date: 2010-05-05 Completed Date: 2010-08-12 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: 1259-66 Citation Subset: IM |
Affiliation:
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University of British Columbia, Vancouver, British Columbia, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adaptation, Physiological Adult Humans Lower Body Negative Pressure Magnetic Resonance Imaging, Cine Male Orthostatic Intolerance / physiopathology* Oxygen Consumption Physical Endurance* Stroke Volume Time Factors Torsion, Mechanical* Ventricular Function, Left* Ventricular Function, Right Young Adult |
| Grant Support | |
ID/Acronym/Agency:
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//Canadian Institutes of Health Research |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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