title: Influence of promoter region variants of insulin-like growth factor pathway genes on the strength-training response of muscle phenotypes in older adults.
abstract: To examine the influence of insulin-like growth factor (IGF) pathway gene polymorphisms on muscle mass and strength responses to strength training (ST), we studied 128 White and Black men and women before and after a 10-wk single-leg knee extension ST program. One-repetition maximum strength, muscle volume (MV) via computed tomography, and muscle quality (MQ) were assessed at baseline and after 10 wk of ST. There was a significant combined IGF1 cytosine adenine (CA) repeat gene effect, which included both the IGF1 CA repeat main effect and IGF1 CA repeat x PPP3R1 insertion-deletion (I/D) gene x gene interaction effect, on the changes in strength (P < 0.01) and MQ (P < 0.05) with ST. There was a trend for a significant gene x gene interaction between IGF1 CA repeat and PPP3R1 I/D for changes in strength (P = 0.07) and MQ (P = 0.06) with ST. The influence of the PPP3R1 A-202C gene polymorphism on change in MV with ST approached significance (P = 0.06). The IGF1 CA repeat polymorphism had a significant influence on the change in strength and MV combined with ST (P < 0.05), whereas the influence of the PPP3R1 I/D polymorphism approached significance (P = 0.08). There were no associations between the IGFBP3 A-202C gene polymorphism and the muscle phenotypic responses to ST. These data suggest that two of the three IGF pathway gene polymorphisms identified in this study influence muscle phenotypic responses to ST in both black and white older men and women.
authors.affiliation: Dept. of Kinesiology, Univ. of Maryland, College Park, MD 20742, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Hand
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Kostek
authors.forename: Robert E
authors.initials: RE
authors.lastname: Ferrell
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Delmonico
authors.forename: Larry W
authors.initials: LW
authors.lastname: Douglass
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Roth
authors.forename: James M
authors.initials: JM
authors.lastname: Hagberg
authors.forename: Ben F
authors.initials: BF
authors.lastname: Hurley
mesh_terms: D001741:Black or African American / Q000235:genetics; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics*; D019703:Calcineurin; D018900:Dinucleotide Repeats; D015444:Exercise / Q000502:physiology*; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins / Q000235:genetics / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000378:metabolism*; D010641:Phenotype; D010749:Phosphoprotein Phosphatases / Q000235:genetics* / Q000378:metabolism; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D012737:Sex Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D044465:White People / Q000235:genetics
chemical_list: C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D019703:Calcineurin; C503672:PPP3R2 protein, human; D010749:Phosphoprotein Phosphatases