Serum IGF-I concentrations are low in female bodybuilders in the pre-contest phase

Abstract

Bodybuilding involves athletes performing a series of poses/postures on the stage so that they can be classified according to their best esthetic and physical appearance during the competition. In the weeks prior to the target competition, the athletes subject themselves to restrictive diets and different physical training methods, as well as using dietary supplementation and, in some cases, anabolic steroids, to reduce body fat to low levels and maintain or increase muscle mass. On the other hand, it is known that physical training is a potent stimulator for releasing the components of the GH/IGF-I axis that are directly linked to the anabolic process. Based on these assumptions, this study aimed to verify the kinetics of IGF-I and of its binding protein IGFBP-3 in female bodybuilders. Serum IGF-I and IGFBP-3 concentrations were recorded before and after standardized training sessions at two different times: in the initial phase (phase 1) and in the final phase of the pre-contest (phase 2) of a 12-week training season. It was possible to conclude that there was a significant reduction in serum IGF-I values at the end of the pre-contest phase that preceded the athletes' participation in a competition. With relation to the serum IGF-I and IGFBP-3 values measured before and after the standardized training session, it was only possible to verify significant changes in the IGF-I values in the initial phase of the pre-contest. It seems reasonable to suggest that the caloric restriction used by bodybuilders may be related to the decrease in IGF-I values verified at the end of the pre-contest phase.