Document Detail

Restoration of plasma volume after 16 days of head-down tilt induced by a single bout of maximal exercise.
MedLine Citation:
PMID:  8769779     Owner:  NLM     Status:  MEDLINE    
Seven healthy men performed maximal exercise 24 h before the end of 16 days exposure to 6 degrees head-down tilt (HDT) to test the hypothesis that such an exercise technique could restore plasma volume (PV) at the end of a simulated space mission. Exercise consisted of supine cycling with graded work rates increasing by 16 W/min to volitional fatigue and required an average of 16 min. The experimental protocol was a standard cross-over design in which the order of treatment (exercise or control) was counterbalanced across all seven subjects. PV, fluid intake (ad libitum), urine output, renal function, and hormones associated with fluid homeostasis were measured before HDT, 24 h before the end of HDT just prior to exercise, and at the end of HDT 24 h after exercise. HDT reduced PV by 16% in both control and exercise conditions. Maximal exercise completely restored plasma volume within 24 h to 3.9 +/- 3.2% of pre-HDT levels despite continued HDT. Compared with control, exercise induced a 660-ml larger positive fluid balance because of greater fluid intake and reduced urine volume during the 24 h after exercise. These results suggest that one bout of maximal leg exercise before return from 16 days of spaceflight may be completely effective in stimulating thirst and restoring plasma volume to preflight levels.
V A Convertino; K A Engelke; D A Ludwig; D F Doerr
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  270     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1996 Jan 
Date Detail:
Created Date:  1996-12-20     Completed Date:  1996-12-20     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R3-10     Citation Subset:  IM; S    
Physiology Research Branch, Brooks Air Force Base, Texas 78235, USA.
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MeSH Terms
Body Weight
Electrolytes / blood
Head-Down Tilt*
Hormones / blood
Kidney / physiology
Physical Exertion*
Plasma Volume*
Time Factors
Reg. No./Substance:
0/Electrolytes; 0/Hormones
V A Convertino / Armstrong Lab, Brooks AFB, TX

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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