title: Exercise-induced insulin-like growth factor I system concentrations after training in women.
abstract: BACKGROUND
  This study examined the effects of short-term physical training on the acute hormonal response (i.e., growth hormone, total and free insulin-like growth factor I [IGF-I], and IGF binding proteins [IGFBP]-1, IGFBP-2, and IGFBP-3) to resistance exercise (RE) in women.
  
  
  METHODS
  Forty-six women (20.3 ± 0.3 yr, mass = 64.1 ± 7.3 kg, height = 165.7 ± 1.0 cm) were randomly assigned to an endurance training (E), resistance training (R), combined training (R + E), or control (C) group for 8wk. Subjects completed a standardized bout of RE (six sets of back squats at 10 repetition maximum) before and after training. Blood samples were obtained at rest (PRE), after the third set, immediately postexercise (POST), and at 15 min and 30 min after exercise.
  
  
  RESULTS
  Acute RE significantly increased (P < 0.05) serum growth hormone (mean ± SD; change from PRE to POST = +10.9 ± 7.5 μg·L-1), total IGF-I (+66.1 ± 25.4 μg·L-1), IGFBP-1 (+2.5 ± 3.1 μg·L-1), IGFBP-2 (+86.0 ± 86.8 μg·L-1), and IGFBP-3 (+0.69 ± 0.25 mg·L-1) concentrations and decreased free IGF-I concentrations (-0.14 ± 0.21 μg·L-1). After 8 wk of training, total IGF-I concentrations were significantly increased (change in POST concentrations from week 0 to week 8 = +82.5 ± 120.8 μg·L-1), and IGFBP-1 concentrations were significantly decreased (-6.7 ± 13.6 μg·L-1) during exercise in groups that participated in resistance training (R and R + E); no significant changes were seen after E or C.
  
  
  CONCLUSIONS
  Participation in resistance training increased total IGF-I and reduced IGFBP-1 concentrations during acute RE, indicating exercise mode-specific adaptations in the circulating IGF-I system.
authors.affiliation: Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA, USA.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Gregory
authors.forename: Barry A
authors.initials: BA
authors.lastname: Spiering
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Alemany
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Tuckow
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Rarick
authors.forename: Jeffery S
authors.initials: JS
authors.lastname: Staab
authors.forename: Disa L
authors.initials: DL
authors.lastname: Hatfield
authors.forename: William J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: Carl M
authors.initials: CM
authors.lastname: Maresh
authors.forename: Bradley C
authors.initials: BC
authors.lastname: Nindl
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology; D055070:Resistance Training; D012420:Running / Q000502:physiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone