title: Inverse relationship between percentage body weight change and finishing time in 643 forty-two-kilometre marathon runners.
abstract: OBJECTIVE
  The purpose of this study was to determine the relationship between athletic performance and the change in body weight (BW) during a 42 km marathon in a large cohort of runners.
  
  
  METHODS
  The study took place during the 2009 Mont Saint-Michel Marathon (France). 643 marathon finishers (560 males and 83 females) were studied. The change in BW during the race was calculated from measurements of each runner's BW immediately before and after the race.
  
  
  RESULTS
  BW loss was 2.3 ± 2.2% (mean±SEM) (p<0.01). BW loss was -3.1 ± 1.9% for runners finishing the marathon in less than 3 h; -2.5 ± 2.1% for runners finishing between 3 and 4 h; and -1.8 ± 2.4% for runners who required more than 4 h to complete the marathon. The degree of BW loss was linearly related to 42 km race finishing time (p<0.0000001). Neither age nor gender influenced BW loss during the race.
  
  
  CONCLUSIONS
  BW loss during the marathon was inversely related to race finishing time in 643 marathon runners and was >3% in runners completing the race in less than 3 h. These data are not compatible with laboratory-derived data suggesting that BW loss greater than 2% during exercise impairs athletic performance. They match an extensive body of evidence showing that the most successful athletes in marathon and ultra-marathon running and triathlon events are frequently those who lose substantially more than 3-4% BW during competition.
authors.affiliation: Movement, Sport, Health and Sciences Laboratory (M2S), UFRAPS, University of Rennes 2-ENS Cachan, Rennes, France.
authors.forename: Hassane
authors.initials: H
authors.lastname: Zouhal
authors.forename: Carole
authors.initials: C
authors.lastname: Groussard
authors.forename: Guenolé
authors.initials: G
authors.lastname: Minter
authors.forename: Sophie
authors.initials: S
authors.lastname: Vincent
authors.forename: Armel
authors.initials: A
authors.lastname: Cretual
authors.forename: Arlette
authors.initials: A
authors.lastname: Gratas-Delamarche
authors.forename: Paul
authors.initials: P
authors.lastname: Delamarche
authors.forename: Timothy David
authors.initials: TD
authors.lastname: Noakes
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012420:Running / Q000502:physiology*; D013997:Time Factors; D015431:Weight Loss / Q000502:physiology*