title: Impact of acute exercise on bone turnover and growth hormone/insulin-like growth factor axis in boys.
abstract: OBJECTIVE
  The aim of this study was to investigate the response of N-terminal propeptide of type I procollagen, crosslinked telopeptide of type I collagen and the growth hormone/insulin-like growth factor-I axis to acute aerobic exercise in boys at different pubertal stages
  
  
  METHODS
  The subjects were 60 healthy boys (group I - Tanner stage 1, N=20; group II - Tanner stages 2 and 3, N=20; group III - Tanner stages 4 and 5, N=20) who exercised 30 minutes at constant load on cycle ergometer at the level of ~95% of their individual ventilatory threshold. Venous blood samples were obtained before, immediately after and after 30 minutes of recovery for the measurement of serum testosterone, growth hormone (GH), insulin-like-growth factor-I, insulin-like-growth factor binding protein-3, N-terminal propeptide of type I procollagen (PINP) and crosslinked telopeptide of type I collagen.
  
  
  RESULTS
  Acute exercise did not affect significantly serum testosterone, insulin-like-growth factor-I, insulin-like-growth factor binding protein-3 or bone turnover markers concentrations in any of study groups. The rise in growth hormone concentration during exercise was highest in group III (62.3+/-41.7 mU/L vs 15.5+/-11.4 in group I and 41.8+/-20.0 in group II). The increment in serum growth hormone level during exercise was positively correlated (r=0.64; P<0.001) to basal serum testosterone concentration.
  
  
  CONCLUSIONS
  It can be concluded that growth hormone response to exercise was directly dependent on serum testosterone concentration. Acute exercise did not affect serum testosterone, insulin-like-growth factor-I, insulin-like-growth factor binding protein-3 or bone markers levels.
authors.affiliation: Centre of Behavioral and Health Sciences, University of Tartu, Tartu, Estonia.
authors.forename: T
authors.initials: T
authors.lastname: Pomerants
authors.forename: V
authors.initials: V
authors.lastname: Tillmann
authors.forename: K
authors.initials: K
authors.lastname: Karelson
authors.forename: J
authors.initials: J
authors.lastname: Jürimäe
authors.forename: T
authors.initials: T
authors.lastname: Jürimäe
mesh_terms: D000293:Adolescent; D016723:Bone Remodeling / Q000502:physiology*; D002648:Child; D016552:Ergometry; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D008297:Male; D011627:Puberty / Q000502:physiology*; D013002:Somatomedins / Q000032:analysis*; D013739:Testosterone / Q000097:blood
chemical_list: D013002:Somatomedins; D019382:Human Growth Hormone; D013739:Testosterone