TY - JOUR
T1 - No evidence of insulin-like growth factor-binding protein 3 proteolysis during a maximal exercise test in elite athletes
AU - Dall, R
AU - Lange, K H
AU - Kjaer, M
AU - Jørgensen, J O
AU - Christiansen, J S
AU - Orskov, H
AU - Flyvbjerg, A
PY - 2001/2
Y1 - 2001/2
N2 - The aim of the present study was to examine the GH/insulin-like growth factor (IGF) axis, post exercise, with emphasis on IGF-binding protein (IGFBP)-3 proteolysis. Sixteen elite rowers (8 female/8 male) performed a stepwise submaximal rowing test followed by a 6- to 7-min-long maximal test. Blood samples were drawn at baseline, t = 0 (end of exercise) and t = 15, 30, 60, 90, and 120 min. GH and IGFBP-1 levels increased post exercise (P < 0.0005). Total IGF-I and IGF-II increased significantly post exercise (P < 0.0005) but not after albumin correction. Free IGF-I decreased after exercise with nadir coincidently with the IGFBP-1 peak, and free IGF-II decreased post exercise coincidently with the IGFBP-6 peak. IGFBP-3, measured by immunoradiometric assay, increased after exercise (P < 0.0005) but not after albumin adjustment. IGFBP-3 proteolysis (%) (measured by a specific in vitro proteolytic activity assay) and IGFBP-3 (measured by Western ligand blotting) were unchanged post exercise. Albumin-adjusted levels of IGFBP-6 increased by 18% (P < 0.0005), whereas IGFBP-2 and IGFBP-4 did not change significantly post exercise. Our findings do not support the hypothesis that short-term strenuous exercise induces major acute changes in the GH/IGF axis. To what degree the protein anabolic effects of regular exercise are associated with acute alterations in the GH/IGF axis remains unclear.
AB - The aim of the present study was to examine the GH/insulin-like growth factor (IGF) axis, post exercise, with emphasis on IGF-binding protein (IGFBP)-3 proteolysis. Sixteen elite rowers (8 female/8 male) performed a stepwise submaximal rowing test followed by a 6- to 7-min-long maximal test. Blood samples were drawn at baseline, t = 0 (end of exercise) and t = 15, 30, 60, 90, and 120 min. GH and IGFBP-1 levels increased post exercise (P < 0.0005). Total IGF-I and IGF-II increased significantly post exercise (P < 0.0005) but not after albumin correction. Free IGF-I decreased after exercise with nadir coincidently with the IGFBP-1 peak, and free IGF-II decreased post exercise coincidently with the IGFBP-6 peak. IGFBP-3, measured by immunoradiometric assay, increased after exercise (P < 0.0005) but not after albumin adjustment. IGFBP-3 proteolysis (%) (measured by a specific in vitro proteolytic activity assay) and IGFBP-3 (measured by Western ligand blotting) were unchanged post exercise. Albumin-adjusted levels of IGFBP-6 increased by 18% (P < 0.0005), whereas IGFBP-2 and IGFBP-4 did not change significantly post exercise. Our findings do not support the hypothesis that short-term strenuous exercise induces major acute changes in the GH/IGF axis. To what degree the protein anabolic effects of regular exercise are associated with acute alterations in the GH/IGF axis remains unclear.
KW - Adult
KW - Analysis of Variance
KW - Blotting, Western
KW - Female
KW - Human Growth Hormone/blood
KW - Humans
KW - Insulin-Like Growth Factor Binding Protein 1/blood
KW - Insulin-Like Growth Factor Binding Protein 3/blood
KW - Insulin-Like Growth Factor Binding Protein 6/blood
KW - Insulin-Like Growth Factor Binding Proteins/blood
KW - Insulin-Like Growth Factor I/analysis
KW - Insulin-Like Growth Factor II/analysis
KW - Male
KW - Physical Exertion/physiology
KW - Reproducibility of Results
KW - Serum Albumin/analysis
KW - Sex Characteristics
KW - Sports/physiology
KW - Time Factors
U2 - 10.1210/jcem.86.2.7180
DO - 10.1210/jcem.86.2.7180
M3 - Journal article
C2 - 11158029
SN - 0021-972X
VL - 86
SP - 669
EP - 674
JO - Journal of Clinical Endocrinology and Metabolism
JF - Journal of Clinical Endocrinology and Metabolism
IS - 2
ER -