Effects of endurance exercise on free testosterone concentration and the binding affinity of sex hormone binding globulin (SHBG)

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Bibliographic Details
Title translated into German:Auswirkungen von Ausdauerbelastung auf die Konzentration des freien Testosterons und die Bindungsaffinitaet des sexualhormonbindenden Globulins
Author:Fahrner, C.L.; Hackney, A.C.
Published in:International journal of sports medicine
Published:19 (1998), 1 , S. 12-15, Lit.
Format: Publications (Database SPOLIT)
Publication Type: Journal article
Media type: Print resource
ISSN:0172-4622, 1439-3964
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Identification number:PU199802209847

Author's abstract

Our purpose was to examine the changes in free testosterone concentration following moderately prolonged endurance exercise to determine whether such changes were due to alterations in the binding affinity of sex hormone binding globulin (SHBG). Ten trained men completed control (45 min rest) and exercise (45 min, 70% VO2max) experimental sessions. Blood samples were collected before (pre-) and immediately after (post-) each of the sessions and analyzed for total testosterone, free testosterone, LH, FSH, cortisol, estradiol, SHBG, epinephrine and norepinephrine. The association constant (Ka) of SHBG for testosterone was assessed to evaluate binding affinity. No significant difference was seen between the pre-control and the pre-exercise session values for any of the measures. However, within the exercise session significant (p<0.01) increases in post samples were evident for total testosterone (+32.0%), free-testosterone (+39.6%), cortisol (+38.0%), norepinephrine (+365.2%) and epinephrine (+225.8%). All other hormonal changes and the responses for Ka were non-significant. The results of the correlation analysis indicated that only norepinephrine was significantly (p<0.05) related to the changes observed in free testosterone (r=+0.92). We conclude that the free testosterone increase with moderate, prolonged endurance exercise was not associated with the change in the binding affinity of SHBG. Furthermore, the data suggest that the exercise-induced increase in testosterone involves increased production which may be mediated by sympathetic stimulation of the testicles. Verf.-Referat