title: Hematocrits of triathletes: is monitoring useful?
abstract: OBJECTIVE
  The purpose of this manuscript was to provide a basis for establishing safety cutoffs for hematocrit levels in triathletes and background data for possible future medical control regulations.
  
  
  METHODS
  Competitors from three different distance triathlons participated: Olympic (N = 118), half-Ironman (N = 87), and Ironman (N = 207). Blood samples were drawn within 24-36 h prerace (N = 412) and within minutes of race finish (N = 296). Prerace hematocrits approximated a normal distribution for men (X = 43.2 +/- 2.9) and women (X = 40.2+/-2.6). Prerace hematocrits decreased as competitive distance increased for men (X = 45.0, 43.4, 42.5; respectively; P < 0.01) but not for women (P > 0.05).
  
  
  RESULTS
  Mean race day changes were small but statistically significant for Olympic and Ironman men and for half-Ironman women. Individual responses were more variable with hemoconcentration occurring in 57%, hemodilution in 43%, and no change in 2% of participants. The magnitude of individual responses was also variable with hematocrit changes ranging from -7.1 to + 10%. No athlete in this sample had a hematocrit that would place him/her in the "danger zone" (Hct > 55%).
  
  
  CONCLUSIONS
  Cutoff values (3 SD above the means) of 52% for men and 48% for women are suggested by these data. However, the relationship of these cutoffs to either athlete safety or the ability to detect rules violations remains unknown.
authors: University of Tennessee-Campbell Clinic, Department of Orthopaedic Surgery, Memphis 38163, USA.
authors: M L
authors: ML
authors: O'Toole
authors: P S
authors: PS
authors: Douglas
authors: W D
authors: WD
authors: Hiller
authors: R H
authors: RH
authors: Laird
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006400:Hematocrit; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D012016:Reference Values; D013177:Sports / Q000502:physiology*