Document Detail


Women hydrate more than men during a marathon race: hyponatremia in the Houston marathon: a report on 60 cases.
MedLine Citation:
PMID:  15867557     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: To examine the relationship between gender and the development of hyponatremia in marathon runners. DESIGN: A retrospective analysis of prerace and postrace data collected on 117 runners completing the Houston Marathon from 2000 to 2003. SETTING: The Houston Marathon. PARTICIPANTS: A total of 117 marathon runners (63 male and 54 female) who consented to participate in hyponatremia research. MAIN OUTCOME MEASURES: Prerace and postrace body weight and serum sodium ([Na+]) concentrations were measured. Total fluid intake was self-reported immediately following the race. RESULTS:: Of the runners tested, 28% developed hyponatremia ([Na+] < or = 135 mmol/L). Hyponatremic runners (n = 33) drank significantly more fluid (31.70 versus 18.90 cups; P < 0.001), lost the least weight (-0.14 versus -1.61 kg; P < 0.001), and dropped serum [Na+] levels further (-7.48 versus -1.92; P < 0.001) compared with nonhyponatremic runners. Female runners (n = 54) were significantly lighter (62.46 versus 80.73 kg; P < 0.001), ran slower (303.02 versus 269.06 minutes; P < 0.001), lost the least weight (-0.62 versus -1.68 kg; P < 0.001), dropped serum [Na+] levels further (-4.44 versus -2.67; P < 0.01), and had lower postrace serum [Na+] values (136.87 versus 138.50; P < 0.01) compared with male runners while consuming the same total amount of fluid during the race (22.87 versus 22.30 cups; P = 0.83, NS). There were significant inverse relationships between serum [Na+] change versus body weight change (r = -0.65; P < 0.001) and between postrace [Na+] versus body weight change (r = -0.60; P < 0.001), with significant sex differences noted only between nonhyponatremic female and male runners (-0.91 versus -0.2.05 kg; P < 0.001) and between hyponatremic and nonhyponatremic male runners (-0.11 versus -2.05 kg; P < 0.001). CONCLUSIONS: Female marathon runners drink more fluid than male runners in proportion to body size. A loss of 3 kg body weight corresponds to a 0 change in serum [Na+] from prerace to postrace, suggesting that a loss of 3 kg during a marathon represents euhydration and not dehydration. All cases of hyponatremia reported in this study are a result of overhydration based on this convention.
Authors:
Tamara D Hew
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Publication Detail:
Type:  Comparative Study; Journal Article; Retracted Publication    
Journal Detail:
Title:  Clinical journal of sport medicine : official journal of the Canadian Academy of Sport Medicine     Volume:  15     ISSN:  1050-642X     ISO Abbreviation:  Clin J Sport Med     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-05-03     Completed Date:  2005-08-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9103300     Medline TA:  Clin J Sport Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  148-53     Citation Subset:  IM    
Affiliation:
MRC/UCT Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town Sport Science Institute of South Africa, Newlands, South Africa. thew@sports.uct.ac.za
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MeSH Terms
Descriptor/Qualifier:
Adult
Analysis of Variance
Anthropometry
Drinking
Female
Fluid Therapy / methods*
Follow-Up Studies
Humans
Hyponatremia / epidemiology*,  etiology
Incidence
Male
Middle Aged
Physical Endurance
Probability
Retrospective Studies
Risk Assessment
Running / physiology*
Sampling Studies
Sex Factors
Texas
Water-Electrolyte Imbalance / epidemiology,  etiology
Comments/Corrections
Retraction In:
Hew TD. Clin J Sport Med. 2005 Jul;15(4):286   [PMID:  16003050 ]

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


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