title: Insulin-Like Growth Factor-1 and Resistance Exercise in Community Dwelling Old Adults.
abstract: BACKGROUND
  Insulin-like growth factor-1 (IGF-1) is related to the preservation of lean body mass. Its decline during ageing is thought to make old adults more susceptible to sarcopenia and functional dependency. The aim of the present study was to investigate circulating total IGF-1 in old adults who engaged in a 12-weeks of progressive resistance training.
  
  
  METHODS
  Intervention study.
  
  
  METHODS
  Community.
  
  
  METHODS
  Old Icelandic adults (N = 235, 73.7 ± 5.7 years, 58.2% female).
  
  
  METHODS
  Twelve-week resistance exercise program (3 times/week; 3 sets, 6-8 repetitions at 75-80% of the 1-repetition maximum) designed to increase strength and muscle mass of major muscle groups.
  
  
  METHODS
  IGF-1.
  
  
  RESULTS
  At baseline IGF-1 was significantly associated with lean body mass and appendicular muscle mass (also when corrected for age, gender and various covariates). After the training IGF-1 decreased significantly from 112.1 ± 35.6 to 106.1 ± 35.2 µg/L during the course of the study. On and individual level, IGF-1 decreased in 59% and increased in 39% of the participants. Changes in IGF-1 were inversely related to changes in lean body mass (rho = -0.176, P = 0.013 ) and appendicular muscle mass (rho = -0.162, P = 0.019) also when corrected for protein intake, age, gender, and other covariates.
  
  
  CONCLUSIONS
  Serum total IGF-1 decreases after 12 weeks of resistance exercise in community dwelling old adults. When looked at IGF-1 changes for participants individually it becomes clear that IGF-1 response to resistances exercise is highly variable. Changes in IGF-1 are negatively related to changes in lean body mass during training, which supports the hypothesis that IGF-1 is redistributed from circulation into tissue during periods of active muscle building.
authors.affiliation: Alfons Ramel, Unit for Nutrition Research, National University Hospital of Iceland, Eiriksgata 29, 101 Reykjavik, Iceland,Telephone: +354-543-8410, Fax: +354-543-4824, Email: alfonsra@hi.is.
authors.forename: A
authors.initials: A
authors.lastname: Arnarson
authors.forename: O
authors.initials: O
authors.lastname: Gudny Geirsdottir
authors.forename: A
authors.initials: A
authors.lastname: Ramel
authors.forename: P V
authors.initials: PV
authors.lastname: Jonsson
authors.forename: I
authors.initials: I
authors.lastname: Thorsdottir
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001823:Body Composition / Q000502:physiology*; D005260:Female; D006801:Humans; D057187:Independent Living; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D055070:Resistance Training
chemical_list: C583557:IGF1 protein, human; D007334:Insulin-Like Growth Factor I