title: Acute regulation of IGF-I by alterations in post-exercise macronutrients.
abstract: This investigation sought to examine the contributions of exercise and nutrient replenishment on in vivo regulation of the insulin-like growth factor-I (IGF-I) axis components. Eight college-aged males completed three high-intensity interval training (HIIT) protocols followed by three post-exercise nutritional protocols: (1) placebo (EX); (2) carbohydrate only (CHO); and (3) essential amino acid/carbohydrate (EAA/CHO). Samples were analyzed for growth hormone (GH), free IGF-I, IGFBP-1, IGFBP-2, insulin, hematocrit, hemoglobin, serum leucine, matrix metalloproteinase-9 (MMP-9) proteolytic activity, and presence of IGFBP-3 protease activity. No evidence for IGFBP-3 proteolysis was observed. Significant increases in [free IGF-I] and [leucine] were observed in the EAA/CHO group only. Significant differences were noted in [IGFBP-1] and [IGFBP-2] across conditions. Significant increases in [GH] and MMP-9 activity were observed in all groups. These results indicate that post-exercise macronutrient ratio is a determinant of [free IGF-I], [IGFBP-1 and -2] and may play a role in modulating the IGF-I axis in vivo.
authors.affiliation: Department of Kinesiology, Auburn University, Auburn, AL, USA. ebyronf1@gmail.com
authors.forename: E B
authors.initials: EB
authors.lastname: Foster
authors.forename: G
authors.initials: G
authors.lastname: Fisher
authors.forename: J L
authors.initials: JL
authors.lastname: Sartin
authors.forename: T H
authors.initials: TH
authors.lastname: Elsasser
authors.forename: G
authors.initials: G
authors.lastname: Wu
authors.forename: W
authors.initials: W
authors.lastname: Cowan
authors.forename: D D
authors.initials: DD
authors.lastname: Pascoe
mesh_terms: D000328:Adult; D000601:Amino Acids, Essential / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D019587:Dietary Supplements / Q000032:analysis / Q000706:statistics & numerical data*; D015444:Exercise; D005786:Gene Expression Regulation; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000378:metabolism; D008297:Male; D055815:Young Adult
chemical_list: D000601:Amino Acids, Essential; D007328:Insulin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone