Abstract

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 micro-g/l (mean+/-SD)), IGF-1 (115+/-23 vs 113+/-21 micro-g/l), IGF-II (961+/-192 vs 864+/-125 micro-g/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 micro-g/l) or insulin (26+/-13 vs 27+/-18 mU/l). However, IGFBP-1 (4.44+/-2.61 vs 2.28+/-0.93 micro-g/l) and IGFBP-2 (493+/-143 vs 340+/-186 micro-g/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. Verf.-Referat