title: Absolute and functional iron deficiency in professional athletes during training and recovery.
abstract: BACKGROUND
  Iron deficiency (ID) is one of the most important metabolic dysfunctions. Athletic performance depends on oxygen transport and mitochondrial efficiency, thus on optimal iron balance. We hypothesised that physical extremes result in ID in elite athletes and that the short recovery period may be insufficient to allow a lasting replenishment of iron reserves.
  
  
  METHODS
  Iron metabolism was examined in 20 elite rowing athletes and 10 professional soccer players at the end of a competitive season, after recuperation and during pre-season training. Absolute ID values were defined as ferritin <30 μg/L, functional ID as ferritin 30-99 μg/L or 100-299 μg/L+transferrin saturation <20%.
  
  
  RESULTS
  At the end of season, 27% of all athletes had absolute ID and 70% showed functional ID. Absolute iron depletion was not generally restored after recuperation and observed at all time points in 14% of the athletes. Although athletes with initially low ferritin levels showed a slight increase during recuperation (p<0.09), these increases remained within borderline levels. Furthermore, 10% showed borderline haemoglobin levels, suggestive of mild anaemia, as defined by the World Health Organisation.
  
  
  CONCLUSIONS
  A significant proportion of professional athletes have ID, independent of the training mode. Although recuperation seems to allow a certain recovery of iron storage, particularly in athletes with initially low ferritin levels, this retrieval was insufficient to fully normalise reduced iron levels. Therefore, iron status should be carefully monitored during the various training and competitive periods in elite athletes. An adequate iron supplementation may be needed to maintain balanced iron stores.
authors.affiliation: Division of Applied Cachexia Research, Department of Cardiology, Charité-Universitätsmedizin Berlin, Germany. simon.reinke@charite.de
authors.forename: Simon
authors.initials: S
authors.lastname: Reinke
authors.forename: William R
authors.initials: WR
authors.lastname: Taylor
authors.forename: Georg N
authors.initials: GN
authors.lastname: Duda
authors.forename: Stephan
authors.initials: S
authors.lastname: von Haehling
authors.forename: Petra
authors.initials: P
authors.lastname: Reinke
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Volk
authors.forename: Stefan D
authors.initials: SD
authors.lastname: Anker
authors.forename: Wolfram
authors.initials: W
authors.lastname: Doehner
mesh_terms: D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000097:blood* / Q000175:diagnosis*; D056352:Athletes; D005293:Ferritins / Q000097:blood; D006801:Humans; D007501:Iron / Q000097:blood*; D008297:Male; D009043:Motor Activity / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology*; D055070:Resistance Training; D012916:Soccer / Q000502:physiology; D014168:Transferrin / Q000378:metabolism; D055815:Young Adult
chemical_list: D014168:Transferrin; D005293:Ferritins; D007501:Iron