title: Rapid rather than gradual weight reduction impairs hemorheological parameters of Taekwondo athletes through reduction in RBC-NOS activation.
abstract: OBJECTIVE
  Rapid weight reduction is part of the pre-competition routine and has been shown to negatively affect psychological and physiological performance of Taekwondo (TKD) athletes. This is caused by a reduction of the body water and an electrolyte imbalance. So far, it is unknown whether weight reduction also affects hemorheological properties and hemorheology-influencing nitric oxide (NO) signaling, important for oxygen supply to the muscles and organs.
  
  
  METHODS
  For this purpose, ten male TKD athletes reduced their body weight by 5% within four days (rapid weight reduction, RWR). After a recovery phase, athletes reduced body weight by 5% within four weeks (gradual weight reduction, GWR). Each intervention was preceded by two baseline measurements and followed by a simulated competition. Basal blood parameters (red blood cell (RBC) count, hemoglobin concentration, hematocrit, mean corpuscular volume, mean cellular hemoglobin and mean cellular hemoglobin concentration), RBC-NO synthase activation, RBC nitrite as marker for NO synthesis, RBC deformability and aggregation parameters were determined on a total of eight investigation days.
  
  
  RESULTS
  Basal blood parameters were not affected by the two interventions. In contrast to GWR, RWR decreased activation of RBC-NO synthase, RBC nitrite, respective NO concentration and RBC deformability. Additionally, RWR increased RBC aggregation and disaggregation threshold.
  
  
  CONCLUSIONS
  The results point out that a rapid weight reduction negatively affects hemorheological parameters and NO signaling in RBC which might limit performance capacity. Thus, GWR should be preferred to achieve the desired weight prior to a competition to avoid these negative effects.
authors: Institute of Training Science and Sport Informatics, German Sport University Cologne, Cologne, Germany; Olympic Training Centre Rhineland, Cologne, Germany.
authors: Woo Hwi
authors: WH
authors: Yang
authors: Olympic Training Centre Rhineland, Cologne, Germany.
authors: Oliver
authors: O
authors: Heine
authors: Department of Molecular and Cellular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University Cologne, Cologne, Germany.
authors: Sebastian
authors: S
authors: Pauly
authors: Department of Molecular and Cellular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University Cologne, Cologne, Germany.
authors: Pilsang
authors: P
authors: Kim
authors: Department of Molecular and Cellular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University Cologne, Cologne, Germany; German Research Centre for Elite Sports, German Sport University, Cologne, Germany.
authors: Wilhelm
authors: W
authors: Bloch
authors: Institute of Training Science and Sport Informatics, German Sport University Cologne, Cologne, Germany; German Research Centre for Elite Sports, German Sport University, Cologne, Germany.
authors: Joachim
authors: J
authors: Mester
authors: Department of Molecular and Cellular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University Cologne, Cologne, Germany; German Research Centre for Elite Sports, German Sport University, Cologne, Germany.
authors: Marijke
authors: M
authors: Grau
mesh_terms: D056352:Athletes; D004903:Erythrocyte Aggregation; D004907:Erythrocyte Deformability; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D016139:Martial Arts; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D009573:Nitrites / Q000032:analysis; D010766:Phosphorylation; D015431:Weight Loss
chemical_list: D009573:Nitrites; D019001:Nitric Oxide Synthase