title: IGF-I polymorphism is associated with lean mass, exercise economy, and exercise performance among premenopausal women.
abstract: BACKGROUND
  We undertook this study to investigate the association of a genetic polymorphism of the insulin-like growth factor, IGF-I(189), on body composition, exercise performance and exercise economy, after controlling for the independent effect of race as assessed by African genetic admixture (AFADM).
  
  
  METHODS
  A total of 114 premenopausal sedentary women were genotyped for IGF-I189, obtaining measures of fat mass, lean body mass, VO2 during cycling and stairclimbing, time on treadmill and leg strength. A quantitative value for AFADM was derived from genotypic information of approximately 40 ancestry informative markers and used as covariate in statistical models.
  
  
  RESULTS
  After adjusting for AFADM, IGF-I189 was negatively associated with lean body mass (p = 0.029) and lean leg mass (p = 0.050). Leg strength was not associated with the presence/absence of IGF-I189 (p = 0.380), but carriers of the allele demonstrated a longer time on the treadmill (p = 0.015) after adjusting for AFADM. There was also a negative relationship between oxygen uptake during cycling and presence of the IGF-I189 independent of AFADM (p = 0.010).
  
  
  CONCLUSIONS
  Independent of AFADM, individuals with IGF-I189 are more likely to have low leg lean mass and to perform better in activities requiring exercise economy and endurance performance.
authors.affiliation: Medical Nutrition Research Unit, Pediatric Hospital, Siglo XXI, National Medical Center, Mexico City, Mexico.
authors.forename: Mardya
authors.initials: M
authors.lastname: López-Alarcón
authors.forename: Gary R
authors.initials: GR
authors.lastname: Hunter
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Gower
authors.forename: José R
authors.initials: JR
authors.lastname: Fernández
mesh_terms: D000328:Adult; D001741:Black or African American / Q000235:genetics; D001823:Body Composition / Q000235:genetics*; D015444:Exercise; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007866:Leg / Q000033:anatomy & histology; D008875:Middle Aged; D009929:Organ Size; D010101:Oxygen Consumption / Q000235:genetics; D010809:Physical Fitness; D011110:Polymorphism, Genetic; D017697:Premenopause; D044465:White People / Q000235:genetics
chemical_list: D007334:Insulin-Like Growth Factor I