title: Evaluation of serum concentrations of biochemical markers of bone metabolism and insulin-like growth factor I associated with treadmill exercise in young horses.
abstract: OBJECTIVE
  To evaluate changes in serum concentrations of biochemical markers of bone metabolism and insulin-like growth factor I (IGF-I) associated with treadmill exercise in young horses.
  
  
  METHODS
  12 two-year-old Thoroughbred mares.
  
  
  METHODS
  During a 20-week study period, 6 horses were exercised on a treadmill 3 times a week (exercise group) and 6 horses received walking exercise 6 days a week (controls). Serum concentrations or activity of biochemical markers and IGF-I were assessed biweekly. Bone mineral density and content of the first phalanx were measured by dual-energy X-ray absorbiometry (DEXA) on completion of the study.
  
  
  RESULTS
  Compared with values in controls, bone mineral density and content were higher and serum concentrations of osteocalcin (a marker of bone formation) and the carboxy-terminal telopeptide of type I collagen (a marker of bone resorption; ICTP) were lower in exercised horses. Serum concentration and activity of the bone formation markers carboxy-terminal propeptide of type I collagen and bone-specific alkaline phosphatase (BAP) were not different between the 2 groups. Serum IGF-I concentration was lower in the exercise group, compared with control values; there was a significant correlation between change in IGF-I values and changes in osteocalcin, ICTP, and BAP values at the end of the study.
  
  
  CONCLUSIONS
  Treadmill exercise over 20 weeks induced adaptive changes in bones of 2-year-old Thoroughbreds; training appears to increase bone mineral density, thereby enhancing mechanical strength of bone, but decreases bone turnover. Results indicated an association between changes in serum IGF-I concentration and bone cell activity in horses.
authors.affiliation: The Royal Veterinary College, Royal College St, London, NW1 OUT.
authors.forename: Brendan F
authors.initials: BF
authors.lastname: Jackson
authors.forename: Allen E
authors.initials: AE
authors.lastname: Goodship
authors.forename: Richard
authors.initials: R
authors.lastname: Eastell
authors.forename: Joanna S
authors.initials: JS
authors.lastname: Price
mesh_terms: D015502:Absorptiometry, Photon; D000469:Alkaline Phosphatase / Q000097:blood; D000596:Amino Acids / Q000097:blood; D000818:Animals; D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000502:physiology; D001842:Bone and Bones / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D024042:Collagen Type I; D005260:Female; D006736:Horses / Q000097:blood* / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D015675:Osteocalcin / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011347:Procollagen / Q000097:blood
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D024042:Collagen Type I; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C042813:procollagen type I carboxy terminal peptide; D015675:Osteocalcin; D007334:Insulin-Like Growth Factor I; C036020:deoxypyridinoline; D000469:Alkaline Phosphatase