The influence of exercise on the functioning of the pituitary–gonadal axis in physically active older and younger men

Abstract

Age is a meaningful factor modulating the functioning of the human endocrine system. In our research, the factor stimulating the pituitary–gonadal axis was a 400 m race. In this type of effort, glycolyticand lactic acid transformations are dominant and a fundamental increase in lactic acid concentration is noted.The aim of the research was to compare the response of the pituitary–gonadal axisin physically active men of various ages after a 400 m race. Nine men aged 21.7 ± 0.7 years and nine men aged 60.0 ± 3.4 years took part in the study. Blood samples were taken from the elbowvein before the race at 08.00 and immediately after the effort. The levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), total testosterone and free testosterone were determined in bloodsera. The concentration of lactic acid was measured in full blood at 5 min after the race.Before the effort, statistically significant differences in the concentration of FSH and free testosteronebetween the two age groups were observed (higher FSH in older men but lower free testosterone). No differences in the level of LH, total testosterone and lactic acid were observed. Immediately after theeffort, no changes in the level of FSH were found in both groups; a statistically significant decrease in LH concentration was noted only in the group of younger men. In both groups, statistically significantincreases in total testosterone, free testosterone and lactic acid concentrations were observed after the race. In the group of younger men, compared to the older, larger increases in free testosteroneand lactic acid concentrations, as well as shorter race time, were revealed after the effort test.Analysis of the two groups after the race showed statistically significant differences in FSH, freetestosterone and lactic acid concentrations. A positive correlation (r = 0.57) was demonstrated between the after-effort increase in the concentration of free testosterone and lactic acid, and negativecorrelation (r = –0.66) between the after-effort increase in the concentration of free testosterone and the time of the 400 m race.In older men, the concentration of free testosteronemay play an important function in lowering strength capacities. It must be stressed that the 400 m race was a more significant stimulus for changes in hormone concentrations of the pituitary–gonadalaxis in younger men (greater changes in the level of the investigated parameters) than in the older. The results obtained allow us to conclude that, in older men, as compared to the younger ones, the responseof the pituitary–gonadal axis to an effort stimulus is to some extent different.