| Reduction in LBNP tolerance following prolonged endurance exercise training. | |
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MedLine Citation:
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PMID: 1435175 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Eight young men underwent an 8-month endurance exercise training program. Prior to and following the training program, the subjects' maximal oxygen uptake (VO2max), total blood volume (TBV) and plasma volume (PV), tolerance to lower body negative pressure (LBNP) assessed by the cumulative stress index (CSI) to presyncope, and their hemodynamic responses to 0 to -45 torr LBNP was determined. Hemodynamic measures included rebreathe carbon dioxide cardiac output (Qc), heart rate (HR), directly measured arterial blood pressures (ABP), and strain gauge determination of forearm blood flow (FBF) and leg volume changes (delta LgV). Calculated values of stroke volume (SV), forearm, vascular resistance (FVR), and peripheral vascular resistance (PVR) were made. Following training, each subject had an increased VO2max (mean = +27.4%, P < 0.001), TBV (mean = +15.8%, P < 0.02), and PV (mean = +16.5%, P < 0.02) and each subject had a decreased tolerance to LBNP (mean CSI = -24%, P < 0.001). Stepwise linear regression identified that the major factors to significantly predict the decreased CSI pre- to post-training were a reduced response of PVR to LBNP from -15 to -45 torr (Model R2 = 0.853), the delta TBV (model R2 = 0.981), and the greater post-training reduction in SBP to LBNP of 0 to -45 torr (model R2 = 1.0). These data suggest that physiologic adaptations associated with the increased VO2max and TBV resulting from a prolonged endurance exercise training program can alter the reflex control of vasomotion and cardiac output during LBNP and reduce the LBNP tolerance. |
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Authors:
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G H Stevens; B H Foresman; X Shi; S A Stern; P B Raven |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Medicine and science in sports and exercise Volume: 24 ISSN: 0195-9131 ISO Abbreviation: Med Sci Sports Exerc Publication Date: 1992 Nov |
Date Detail:
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Created Date: 1992-12-14 Completed Date: 1992-12-14 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8005433 Medline TA: Med Sci Sports Exerc Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1235-44 Citation Subset: IM; S |
Affiliation:
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Department of Physiology, Medicine and Anesthesiology, Texas College of Osteopathic Medicine, Fort Worth 76107. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Volume Exercise* Hemodynamics* Humans Lower Body Negative Pressure* Male Oxygen Consumption Physical Endurance* |
| Grant Support | |
ID/Acronym/Agency:
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HL34397/HL/NHLBI NIH HHS; T32HL07652/HL/NHLBI NIH HHS |
| Comments/Corrections | |
Erratum In:
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Med Sci Sports Exerc 1993 Feb;25(2):307 |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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