title: Plasma electrolyte and hematological changes after marathon running in adolescents.
abstract: OBJECTIVE
  The objective of this research is to study plasma electrolyte and hematological changes in adolescent runners completing a standard 42.2-km marathon run.
  
  
  METHODS
  Fifty adolescents (30 healthy males and 20 healthy females) between ages 13 and 17 yr participated in the study. The participants had to undergo a routine physical examination including ECG records. Blood was taken before the race, immediately after the race, and 24 h after the race to determine complete blood cell count and electrolyte concentration.
  
  
  RESULTS
  Forty-seven runners completed the race with a mean finishing time of 4 h 57 min (range: 3 h 17 min 09 s to 6 h 14 min). None of the participants experienced an adverse medical event during or after the race. Only slight changes in plasma electrolytes without any cases of hyper- or hyponatremia and a marked increase in white blood cell count were demonstrated immediately after the race. At this time, the hemoglobin concentration and hematocrit were decreased (P < 0.05), indicating an approximately 11% increase in plasma volume. Some of these changes were still present 24 h postrace. No differences were observed between sexes.
  
  
  CONCLUSIONS
  This is the first study evaluating plasma electrolyte and hematological changes in a relatively large sample of young runners completing a standard marathon. The presented findings indicate that well-trained and educated adolescent marathon runners are not at risk to develop clinically significant electrolyte or hematological changes.
authors.affiliation: Department of Sport Science, Medical Section, University of Innsbruck, Innsbruck, Austria.
authors.forename: Natthapon
authors.initials: N
authors.lastname: Traiperm
authors.forename: Hannes
authors.initials: H
authors.lastname: Gatterer
authors.forename: Martin
authors.initials: M
authors.lastname: Burtscher
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D001772:Blood Cell Count; D004573:Electrolytes / Q000097:blood*; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007964:Leukocytosis / Q000097:blood / Q000209:etiology*; D008297:Male; D012420:Running / Q000502:physiology*
chemical_list: D015415:Biomarkers; D004573:Electrolytes; D006454:Hemoglobins