title: Differences in the GH-IGF-I axis in children of different weight and fitness status.
abstract: OBJECTIVE
  To determine if differences in the GH-IGF-I axis exist between children of high and low aerobic fitness who are obese or of normal weight.
  
  
  METHODS
  124 children (ages 8-11) divided into four groups based on BMI and VO₂max (mL O₂/kg fat free mass(FFM)/min): normal weight--high-fit (NH), normal weight--low-fit (NL), obese--high-fit (OH), and obese--low-fit (OL). Height, weight, skinfolds, body mass index (BMI), body fat percentage and predicted VO₂max (both ml/kg/min and ml/kg(FFM)/min) were assessed. Resting growth hormone (GH), total insulin-like growth factor 1 (total IGF-I), free insulin-like growth factor 1(free IGF-I), and insulin were measured using morning fasting blood samples.
  
  
  RESULTS
  GH was greater in the NH group compared to the OL group only (p<0.01). No group differences existed for either total IGF-I (p=0.53) or free IGF-I (p=0.189). Insulin was greater in the OH and OL groups than the NH and NL groups (p<0.01). With groups combined (or overall), insulin and free IGF-I were related to fitness (insulin--ml/kg/min: r=-0.226, p<0.05 and ml/kg(FFM)/min: r=-0.212, p<0.05; free IGF-I--ml/kg/min: r=-0.219, p<0.01 and ml/kg(FFM)/min: r=-0.272, p<0.05).
  
  
  CONCLUSIONS
  Fitness may contribute to the obesity related reduction of GH that may be involved with weight gain.
authors.affiliation: Department of Physiology and Biophysics, University of Mississippi Medical Center, Arthur C. Guyton Research Complex, 2500 N State Street, Jackson, MS 39216-4505, USA. phosick@umc.edu
authors.forename: Peter A
authors.initials: PA
authors.lastname: Hosick
authors.forename: Robert G
authors.initials: RG
authors.lastname: McMurray
authors.forename: A C
authors.initials: AC
authors.lastname: Hackney
authors.forename: Claudio L
authors.initials: CL
authors.lastname: Battaglini
authors.forename: Terry P
authors.initials: TP
authors.lastname: Combs
authors.forename: Joanne S
authors.initials: JS
authors.lastname: Harrell
mesh_terms: D000328:Adult; D001823:Body Composition; D001835:Body Weight; D002648:Child; D005260:Female; D019382:Human Growth Hormone / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008954:Models, Biological; D009765:Obesity / Q000378:metabolism*; D010100:Oxygen / Q000737:chemistry; D010809:Physical Fitness; D015430:Weight Gain
chemical_list: D007328:Insulin; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D010100:Oxygen