Document Detail


Hypovolemic intolerance to lower body negative pressure in female runners.
MedLine Citation:
PMID:  11740299     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: An attenuated baroreflex response and orthostatic intolerance have been reported in endurance-trained male athletes; however, it is still unknown whether this occurs also in females. The purpose of the present study was to examine whether endurance exercise-trained women had a predisposition to orthostatic compromise, and if so, what causative factor(s) may induce orthostatic intolerance. METHODS: We studied cardiovascular and hormonal responses to graded lower body negative pressure (LBNP) (0 to -60 mm Hg) in 26 middle-distance female runners (18.6 +/- 0.1 yr) as the exercise-trained (ET) subjects and 23 age-matched untrained (UT) control subjects. On the basis of the occurrence of syncope episodes during LBNP, ET and UT subjects were further allocated to two groups; ET with presyncope (ET+syncope) and without presyncope (ET-syncope) and UT with presyncope (UT+syncope) and without presyncope (UT-syncope). RESULTS: Occurrence of presyncope episodes during LBNP was higher in ET (65.4%, P < 0.05) than that for UT (34.8%). Leg compliance was higher (P < 0.05) in ET than in UT. LBNP reduced stroke volume (SV) more (P < 0.05), increased heart rate (HR) higher (P < 0.05), and increased forearm vascular resistance (FVR) more in ET+syncope as compared with the other groups. Response of vasoactive hormones to LBNP was higher in ET+syncope (P < 0.05) than that of the other groups except for norepinephrine (NE); high in both ET+syncope and UT+syncope. The relationship between SV and NE, an index of sympathetic neuronal response, had no training-related changes during LBNP. CONCLUSION: We conclude that exercise-trained females have a high incidence of orthostatic intolerance during LBNP, with a greater reduction of SV independent of changes in baroreflex and neurohumoral function. A lower incidence of LBNP intolerance in UT may be accounted for by a lower reduction of SV during LBNP. An increase in leg compliance in the exercise-trained females may play an important role in inducing pronounced reduction of SV and hence the intolerance to LBNP.
Authors:
T Morikawa; S Sagawa; R Torii; Y Endo; F Yamazaki; K Shiraki
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Publication Detail:
Type:  Clinical Trial; Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  33     ISSN:  0195-9131     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2001 Dec 
Date Detail:
Created Date:  2001-12-12     Completed Date:  2002-01-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2058-64     Citation Subset:  IM; S    
Affiliation:
Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, 807-8555 Kitakyushu, Japan.
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Baroreflex / physiology
Female
Humans
Hypotension, Orthostatic / blood,  physiopathology*
Hypovolemia / blood,  physiopathology*
Lower Body Negative Pressure*
Norepinephrine / blood
Physical Endurance / physiology
Renin / blood
Running / physiology*
Sex Factors
Stroke Volume / physiology
Syncope / blood,  physiopathology*
Vasopressins / blood
Chemical
Reg. No./Substance:
11000-17-2/Vasopressins; 51-41-2/Norepinephrine; EC 3.4.23.15/Renin

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