Document Detail


Reduction in LBNP tolerance following prolonged endurance exercise training.
MedLine Citation:
PMID:  1435175     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
G H Stevens; B H Foresman; X Shi; S A Stern; P B Raven
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
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:
Created Date:  1992-12-14     Completed Date:  1992-12-14     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1235-44     Citation Subset:  IM; S    
Affiliation:
Department of Physiology, Medicine and Anesthesiology, Texas College of Osteopathic Medicine, Fort Worth 76107.
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MeSH Terms
Descriptor/Qualifier:
Adult
Blood Volume
Exercise*
Hemodynamics*
Humans
Lower Body Negative Pressure*
Male
Oxygen Consumption
Physical Endurance*
Grant Support
ID/Acronym/Agency:
HL34397/HL/NHLBI NIH HHS; T32HL07652/HL/NHLBI NIH HHS
Comments/Corrections
Erratum In:
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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