title: Association of Hematological Variables with Team-Sport Specific Fitness Performance.
abstract: OBJECTIVE
  We investigated association of hematological variables with specific fitness performance in elite team-sport players.
  
  
  METHODS
  Hemoglobin mass (Hbmass) was measured in 25 elite field hockey players using the optimized (2 min) CO-rebreathing method. Hemoglobin concentration ([Hb]), hematocrit and mean corpuscular hemoglobin concentration (MCHC) were analyzed in venous blood. Fitness performance evaluation included a repeated-sprint ability (RSA) test (8 x 20 m sprints, 20 s of rest) and the Yo-Yo intermittent recovery level 2 (YYIR2).
  
  
  RESULTS
  Hbmass was largely correlated (r = 0.62, P<0.01) with YYIR2 total distance covered (YYIR2TD) but not with any RSA-derived parameters (r ranging from -0.06 to -0.32; all P>0.05). [Hb] and MCHC displayed moderate correlations with both YYIR2TD (r = 0.44 and 0.41; both P<0.01) and RSA sprint decrement score (r = -0.41 and -0.44; both P<0.05). YYIR2TD correlated with RSA best and total sprint times (r = -0.46, P<0.05 and -0.60, P<0.01; respectively), but not with RSA sprint decrement score (r = -0.19, P>0.05).
  
  
  CONCLUSIONS
  Hbmass is positively correlated with specific aerobic fitness, but not with RSA, in elite team-sport players. Additionally, the negative relationships between YYIR2 and RSA tests performance imply that different hematological mechanisms may be at play. Overall, these results indicate that these two fitness tests should not be used interchangeably as they reflect different hematological mechanisms.
authors.affiliation: ISSUL, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland.|Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Franck
authors.initials: F
authors.lastname: Brocherie
authors.affiliation: ISSUL, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland.|Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
authors.forename: Grégoire P
authors.initials: GP
authors.lastname: Millet
authors.affiliation: ISSUL, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland.|Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.|Swiss Federal Institute of Sport, Section for Elite Sport, Magglingen, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Hauser
authors.affiliation: Swiss Federal Institute of Sport, Section for Elite Sport, Magglingen, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Steiner
authors.affiliation: Swiss Federal Institute of Sport, Section for Elite Sport, Magglingen, Switzerland.
authors.forename: Jon P
authors.initials: JP
authors.lastname: Wehrlin
authors.affiliation: Faculty of Motor Sciences, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Julien
authors.initials: J
authors.lastname: Rysman
authors.affiliation: ISSUL, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland.|Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.|ASPETAR, Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.
authors.forename: Olivier
authors.initials: O
authors.lastname: Girard
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D005080:Exercise Test; D006454:Hemoglobins / Q000032:analysis*; D006688:Hockey / Q000502:physiology*; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*
chemical_list: D006454:Hemoglobins