Document Detail

Hypervolemia in men from fluid ingestion at rest and during exercise.
MedLine Citation:
PMID:  9561285     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Plasma osmolality (Osm) is important for controlling and maintaining plasma volume (PV) and body water. The effect of oral rehydration fluids for ameliorating dehydration is well-established; but optimal composition and Osm of fluids for hyperhydrating normally hydrated subjects is less clear. METHODS: Six treatments were used without and with oral fluids of varying ionic and constituent concentrations for hyperhydrating six previously euhydrated men (30 +/- SD 8 yr, 76.84 +/- 16.19 kg, 73 +/- 12 PV, 40 +/- 10 peak VO2) sitting at rest for 90 min (VO2 = 0.39 +/- SE 0.02 L.min-1) and during subsequent 70 min of submaximal exercise (VO2 = 2.08 +/- SE 0.33 L.min-1, 70 +/- 7% peak VO2). The hypothesis was that the fluid composition is more important than plasma Osm for increasing PV in euhydrated subjects at rest and maintaining it during exercise. Drink formulation compositions, given at 10 body wt, (mean = 768 ml), for the sitting period were: Performance 1 (P1; 55 mEq Na+, 365 H2O-1), P2 (97 mEq Na+, 791, P2G (113 mEq Na+, 4% glycerol, 1382, AstroAde (AA; 164 mEq Na+, 253, and 01 and 02 (no drinking). The exercise drink (10, 768 ml) was P1 for all treatments except 02 (no drinking); thus, drink designations were: P1/P1, P2/P1, P2G/P1, AA/P1, 0/P1, and 0/0. RESULTS: PV at rest increased (p < 0.05) by 4.7% with P1 and by 7.9% with AA. Percent change in PV during exercise was +1% to +3% (NS) with AA/P1; -6% to 0% (NS) with P1/P1, P2/P1, P2G/P1, and 0/P1; and -8% to -5% (p < 0.05) with 0/0. AA, with the lowest Osm of 253, increased PV at rest (as did P1) and maintained it during exercise, whereas the other drinks with lower Na+ and higher Osm of 365-1382 did not. CONCLUSION: Drink composition appears to be more important than its Osm for increasing PV at rest and for maintaining it during exercise in previously euhydrated subjects.
J E Greenleaf; R Looft-Wilson; J L Wisherd; C G Jackson; P P Fung; A C Ertl; P R Barnes; C D Jensen; J H Whittam
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  69     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  1998 Apr 
Date Detail:
Created Date:  1998-06-04     Completed Date:  1998-06-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  374-86     Citation Subset:  IM; S    
Gravitational Research Branch (239-11), NASA, Ames Research Center, Moffett Field, CA 94035-1000, USA.
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MeSH Terms
Body Temperature Regulation
Dehydration / metabolism,  physiopathology,  therapy*
Erythrocyte Indices
Exercise / physiology*
Exercise Test
Osmolar Concentration
Physical Endurance
Plasma Volume / drug effects*
Rehydration Solutions / chemistry*,  therapeutic use*
Rest / physiology*
Water-Electrolyte Balance / drug effects*
Reg. No./Substance:
0/Rehydration Solutions
J E Greenleaf / ARC

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

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