title: Effect of high- and low-intensity exercise and metabolic acidosis on levels of GH, IGF-I, IGFBP-3 and cortisol.
abstract: OBJECTIVE
  The purpose of the present study was to examine the acute hormonal response of a short term high-intensity training (HIT) versus a high volume endurance training (HVT) and to determine the contribution of the metabolic acidosis as a stimulus for possibly different reactions of circulating hGH, IGF-1, IGFBP-3 and cortisol.
  
  
  METHODS
  Eleven subjects participated in three experimental trials separated by one week. Two times subjects performed four 30s maximal effort exercise bouts on a cycle ergometer separated by 5 min rest each. Before the exercise subjects either received (single-blinded) bicarbonate (HIT (B)) or a placebo (HIT (P)). The third exercise trail consisted of a constant load exercise for 1h at 50% VO₂max (HVT). Venous blood samples were taken under resting conditions, 10 min, 60 min and 240 min after each exercise condition to determine hGH, IGF-1, IGFBP-3 and cortisol serum concentrations. Capillary blood samples were taken to determine lactate concentrations and blood gas parameters.
  
  
  RESULTS
  Power output, mean lactate concentrations and mean pH values were significantly higher during HIT (B) compared to HIT (P). Serum cortisol and hGH concentrations were significantly increased 10 min post exercise in both HIT interventions. IGFBP-3 was only significantly increased after HIT (P), whereas IGF-1 was not affected by any of the interventions. HVT showed no significant effects on cortisol, hGH, IGF-1 and IGFBP-3 levels. Additionally it was shown that the diminished acidosis during HIT (B) attenuates the cortisol and hGH response.
  
  
  CONCLUSIONS
  The present study suggests that HIT/acidosis is a stimulus for exercise-induced cortisol/hGH secretion, but not for IGF-1 and IGFBP-3 under these experimental conditions. These findings might be relevant for arrangements of interval training, due to the fact that active or passive recovery during rest periods influence the acid base status and may therefore influence the hormonal response.
authors.affiliation: Institute of Training Science and Sport Informatics, German Sport University, Cologne, Germany. Wahl@dshs-koeln.de
authors.forename: Patrick
authors.initials: P
authors.lastname: Wahl
authors.forename: Christoph
authors.initials: C
authors.lastname: Zinner
authors.forename: Silvia
authors.initials: S
authors.lastname: Achtzehn
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Bloch
authors.forename: Joachim
authors.initials: J
authors.lastname: Mester
mesh_terms: D000138:Acidosis / Q000097:blood* / Q000503:physiopathology; D000328:Adult; D001639:Bicarbonates / Q000378:metabolism; D001784:Blood Gas Analysis; D015444:Exercise / Q000502:physiology*; D019382:Human Growth Hormone / Q000097:blood* / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000097:blood* / Q000378:metabolism; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000502:physiology*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D055815:Young Adult
chemical_list: D001639:Bicarbonates; C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D019382:Human Growth Hormone; D019344:Lactic Acid; D007334:Insulin-Like Growth Factor I; D006854:Hydrocortisone