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- Title
No Evidence of Insulin-Like Growth Factor-Binding Protein 3 Proteolysis during a Maximal Exercise Test in Elite Athletes.
- Authors
DALL, ROLF; WIBORG LANGE, KAI HENRIK; KJÆR, MICHAEL; LUNDE JØRGENSEN, JENS OTTO; CHRISTIANSEN, JENS SANDAHL; ØRSKOV, HANS; FLYVBJERG, ALLAN
- Abstract
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.
- Publication
Journal of Clinical Endocrinology & Metabolism, 2001, Vol 86, Issue 2, p669
- ISSN
0021-972X
- Publication type
Article
- DOI
10.1210/jcem.86.2.7180