Independency of acute regulation of IGF-1 system components to growth hormone and insulin in response to resistance exercise

Abstract

Background: The aim of this study was to determine
possible relationship between changes induced by exercise in serum
concentrations of growth hormone and insulin with IGF-1 system components over
time in trained and untrained individuals.
Methods: Nineteen healthy men among physical
education students as trained group and 15 healthy men among non-physical
education students as untrained group voluntarily participated in this study. The
subjects randomly were divided into experimental (trained and untrained) and
control (trained and untrained) groups. Blood samples were obtained just before;
and at immediately, four and seven hours after the end of exercise. Serum
concentrations of GH, Insulin, total IGF-1, IGFBP1 and IGFBP3 were determined.
Results: No significant difference was observed in
the pre-exercise concentrations of variables between the trained and untrained
individuals. However, a strong and positive correlation between areas under
curves of variations in IGF-1 and IGFBP3 was identified in the experimental
trained group (r=0.872 and p=0.001); and also, there was correlation between
areas under curves of variations in Insulin with IGF-1 (r=0.752 and p=0.05) and
in IGF-1 with IGFBP3 (r=0.922 and p=0.003) in the control untrained group, but
no statistically significant relationship was observed in the control trained
and experimental untrained groups.
Conclusion: Overall, there was no relationship
between acute changes in levels of IGF-1 components with GH and insulin after
resistance exercise and the role of each component of the system in mutual
regulation of the other components may be more important than nonmember factors
of the system during exercise and the following recovery period.