Endurance training-induced changes in the GH-IGF-I axis influence maximal muscle strength in previously untrained men

• Published in: Growth hormone & IGF research Vol. 32; pp. 41 - 48
• Main Authors: Grandys, Marcin, Majerczak, Joanna, Kuczek, Piotr, Sztefko, Krystyna, Duda, Krzysztof, Zoladz, Jerzy A
• Format: Journal Article
• Language: English
• Published: Scotland Elsevier Ltd 01.02.2017
• Subjects: Adult; Advanced Basic Science; Endocrinology & Metabolism; Exercise - physiology; Human Growth Hormone - blood; Humans; Insulin-like growth factor; Insulin-Like Growth Factor Binding Protein 3 - blood; Insulin-Like Growth Factor I - analysis; Interleukin-6; Interleukin-6 - blood; Male; Muscle strength; Muscle Strength - physiology; Muscle, Skeletal - physiology; Physical Endurance - physiology; Running; Training; Young Adult; I nsulin-like growth factor; T raining; R unning; M uscle strength; I nterleukin-6; Training; Running; Muscle strength; Insulin-like growth factor; Interleukin-6
• ISSN: 1096-6374; 1532-2238
• DOI: 10.1016/j.ghir.2016.12.003

A bstract Objective In this study we have determined the effects of 20 weeks of endurance running training on the GH-IGF-I axis changes in the context of the skeletal muscle performance and physical capacity level. Design Before and after the endurance training program a maximal incremental exercise tests, a 1500 m race and a muscle strength measurements were performed and the blood samples were taken to determine both resting as well as end-exercise serum growth hormone (GH), insulin-like growth hormone-I (IGF-I), insulin-like growth hormone binding protein-3 (IGFBP-3) and plasma interleukin-6 (IL-6) concentrations. Results 20 weeks of endurance running training improved power output generated at the end of the maximal incremental test by 24% ( P < 0.012), 1500 m running time by 13% ( P < 0.012) and maximal muscle strength by 9% ( P < 0.02). End-exercise IGF-I/IGFBP-3 ratio was decreased by 22% after the training ( P < 0.04) and the magnitude of IGF-I/IGFBP-3 ratio decrease (ΔIGF-I/IGFBP-3ex ) was 2.3 times higher after the training ( P < 0.04). The magnitude of the exercise-induced changes in IGFBP-3 concentration was also significantly higher ( P < 0.04) and there was a trend toward lower end-exercise IGF-I concentration ( P = 0.08) after the training. These changes were accompanied by a significantly higher (30%) end-exercise IL-6 concentration ( P < 0.01) as well as by a 3.4 times higher magnitude of IL-6 increase ( P < 0.02) after the training. Moreover, there were strong positive correlations between changes in resting serum IGF-I concentration (ΔIGF-Ires ) and IGF-I/IGFBP-3 ratio (ΔIGF-I/IGFBP-3res ) and changes in muscle strength (ΔMVC) (r = 0.95, P = 0.0003 and r = 0.90, P = 0.002, respectively). Conclusions The training-induced changes in the components of the GH-IGF-I axis may have additive effects on skeletal muscle performance and physical capacity improvement.