title: Monitoring intensive endurance training at moderate energetic demands using resting laboratory markers failed to recognize an early overtraining stage.
abstract: BACKGROUND
  Aim was to answer the question whether resting laboratory parameters are suitable for monitoring intensive endurance training at moderate energetic demands. This was designed since markers of overtraining at high energetic demands, e.g. mild anemia, leukopenia, iron deficiency, reduced serum albumin, glucose, triglyceride, triglyceride-rich cholesterol (LDL, VLDL), free fatty acid, increased plasma noradrenaline levels, and decreased basal catecholamine excretions were recommended.
  
  
  METHODS
  A prospective 6-wk, 6-dys/wk intensive steady state and interval cycle ergometer training of 40-60 min/dy was performed. Total load was about 6-time pretraining activities followed by a 2-wk, 2-hour/wk regenerative training period. Six recreational athletes (VO2max 51.5 +/- 4.5 ml.kg-1.min-1) participated and finished the study. A large pattern of resting hematological, blood-chemical, and hormonal parameters was tested regarding suitability for monitoring overtraining.
  
  
  RESULTS
  After 3 wks, submaximum and maximum performance were significantly increased, stopped improving between wk 3 and 6, or deteriorated. No supercompensation occurred after regeneration, but a decrease in work output. Lack of progression and supercompensation, and decreased maximum work output indicate a critical stage in the training process.
  
  
  CONCLUSIONS
  All examined resting laboratory parameters failed to reflect this critical stage except for a significant decrease in serum glucose, ferritin, and free fatty acid concentrations.
authors.affiliation: Department of Sports Medicine, University Medical Clinic, Ulm, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Gastmann
authors.forename: K G
authors.initials: KG
authors.lastname: Petersen
authors.forename: J
authors.initials: J
authors.lastname: Böcker
authors.forename: M
authors.initials: M
authors.lastname: Lehmann
mesh_terms: D000328:Adult; D000740:Anemia / Q000097:blood; D015415:Biomarkers / Q000097:blood*; D001786:Blood Glucose / Q000032:analysis; D008078:Cholesterol, LDL / Q000097:blood; D015243:Cholesterol, VLDL / Q000097:blood; D004298:Dopamine / Q000097:blood; D004734:Energy Metabolism / Q000502:physiology*; D004837:Epinephrine / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005293:Ferritins / Q000097:blood; D006801:Humans; D007501:Iron / Q000097:blood; D000090463:Iron Deficiencies; D007970:Leukopenia / Q000097:blood; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D011446:Prospective Studies; D011597:Psychomotor Performance / Q000502:physiology; D012709:Serum Albumin / Q000032:analysis; D013177:Sports / Q000502:physiology*; D014280:Triglycerides / Q000097:blood
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D008078:Cholesterol, LDL; D015243:Cholesterol, VLDL; D005230:Fatty Acids, Nonesterified; D012709:Serum Albumin; D014280:Triglycerides; D005293:Ferritins; D007501:Iron; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine