Endurance training and its effect upon the activity of the GH-IGFs system in the elderly

There is an age-associated decline in the activity of the GH-IGFs system. However, so far, it has not been studied, whether this decline in somatotrophic activity might be preventable by intensive exercising. We studied 11 elderly male (50-78 years) marathon runners and 10 age-matched male (52-73 years) sedentary controls to evaluate plasma concentrations of GH, total and free IGF-I and IGF-II and of IGF-binding protein-1 (IGFBP-1), IGFBP-2, IGFBP-3 and insulin. When comparing the two groups (runners vs controls) no differences were found in GH (1.0 +/- 1.2 vs 1.3 +/- 1.3 microg/l [mean +/- SD]), IGF-1 (115 +/- 23 vs 113 +/- 21 microg/l), IGF-II (961 +/- 192 vs 864 +/- 125 microg/l), free IGF-1 (227 +/- 80 vs 318 +/- 146 ng/l), free IGF-II (563 +/- 249 vs 492 +/- 108 ng/l), IGFBP-3 (2403 +/- 515 vs 2307 +/- 326 microg/l) or insulin (26 +/- 13 vs 27 +/- 18 mU/l). However, IGFBP-1 (4.44 +/- 2.61 vs 2.28 +/- 0.93 microg/l) and IGFBP-2 (493 +/- 143 vs 340 +/- 186 microg/l) were found to be significantly increased in marathon runners. In conclusion, our findings do not support the hypothesis that the age-associated decline in GH, IGF-1 and IGFBP-3 may be preventable by intensive endurance training. However, marathon running affects the regulation of the GH-IGFs system activity at the level of IGFBP-1 and -BP-2.