Correlations of growth hormone (GH) and insulin-like growth factor I (IGF-I): effects of exercise and abuse by athletes

The importance of hormones on body metabolism when physical exercise is car ried out has been established for a long time. Growth hormone (GH) is cruci al in energy metabolism as well as in body anabolism. Recent studies have i ncreased our knowledge of GH's mechanisms of action. In particular, insulin -like growth factor I (IGF-I), the main hormone mediating the principal GH effects and other protein structures (i.e, the binding proteins related to these two hormones), has been recognized as playing a crucial role. The bio chemical aspects relating to the molecules of the GH/IGF-I axis have been d escribed here. Furthermore, the belief that GH and IGF-I enhance performanc e has induced an 'abuse' of GH land possibly of IGF-I) by competitive sport s athletes and amateurs. The present study outlines the best methods availa ble to uncover abuse, as well as a series of potential research projects to recognize doping. The review also underlines the principal variables measu rable in the laboratory and summarizes published reference ranges of these parameters. These biochemical and laboratory profiles describe principal ex perimental approaches, with the hope that this will stimulate new ideas on the subject of detecting doping practices. (C) 2001 Elsevier Science B.V. A ll rights reserved.