title: Training and overtraining markers in selected sport events.
abstract: OBJECTIVE
  Varieties of symptoms are supposed to detect overtraining (OT). Besides the problems of diagnosis and analysis in elite athletes, a daily monitoring of training status takes place with measurement of the parameters serum urea (SU) and serum creatine kinase (CK); therefore, their meaningfulness will be examined, with special respect inter- and intra-individually.
  
  
  METHODS
  Data were obtained from determinations during training from athletes in rowing and athletes of international level.
  
  
  RESULTS
  For 6981 SU determinations (male, N = 717; female, N = 285), a slightly asymmetric normal distribution was found (male, 80%, 5-7 mmol x L(-1); female, 75%, 4-6 mmol x L(-1)). Values for women were approximately 1.5 mmol x L(-1) lower. Individual variability was enormous; there seems little point in setting fixed value as 8.3 mmol x L(-1) for men and 7.0 mmol x L(-1) for women as a critical limit for OT. CK has also been measured and evaluated in sports as an essential parameter for determination of muscular stress. Frequency distributions of CK in 2790 samples (male, N = 497; female, N = 350) presented an asymmetric normal distribution with distinct trend toward higher values being evident for the range between 100 and 250 U x L(-1). Conspicuously elevated values occurred in the ranges 250-350 U x L(-1) and 1000-2000 U x L(-1). Men's maximal values were 3000 U x L(-1) and 1150 U x L(-1) for women. Individual variability was enormous. Athletes with chronically low CK exhibited mainly low variability; those with chronically higher values exhibited considerable variability.
  
  
  CONCLUSIONS
  Establishment of both parameters should be useful to determine individual baselines from a large number of samples. Determinations should be made at least every 3 d in standardized conditions. If a large increase is observed in combination with reduced exercise tolerance after a phase of exertion (2-4 d), then the possibility of a catabolic/metabolic activity or insufficient exercise tolerance becomes much more likely.
authors.affiliation: Institute for Theory in Training and Movement, German Sport University-Cologne, Köln. u.hartmann@hrz.dshs-koeln.de
authors.forename: U
authors.initials: U
authors.lastname: Hartmann
authors.forename: J
authors.initials: J
authors.lastname: Mester
mesh_terms: D015415:Biomarkers / Q000097:blood; D003402:Creatine Kinase / Q000097:blood*; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology; D012737:Sex Factors; D013177:Sports / Q000193:education / Q000502:physiology*; D013312:Stress, Physiological / Q000097:blood / Q000503:physiopathology; D013997:Time Factors; D014508:Urea / Q000097:blood*
chemical_list: D015415:Biomarkers; D014508:Urea; D003402:Creatine Kinase