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Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,111
Online ISSN 1827-1928
Hackney A. C., Fahrner C. l., Gulledge T. P.
Endocrine Section, Applied Physiology Laboratory, University of North Carolina, Chapel Hill, North Carolina, USA
Objective. The purpose was to examine the basal reproductive hormonal profiles in age-matched groups of endurance trained (ET) and sedentary (SED) men under controlled conditions.
Experimental design. Resting basal blood samples were obtained from groups of ET and SED men after a 24-hr control period. Blood specimens were analyzed for testosterone (T), free-testosterone (fT), sex-hormone binding globulin (SHBG), luteinizing hormone (LH), cortisol, and prolactin. The design of the study was retrospective and cross-sectional in nature.
Setting. Laboratory setting at the University of North Carolina, North Carolina USA.
Participants. ET men (n=53) who had been involved with chronic endurance exercise training for ≥ 5 years. SED men (n=35) were selected of comparable ages and the fact that they had done no formal exercise training.
Results. Results indicated that the basal T and fT of the ET men were significantly (p<0.01) lower than that of the SED men. The levels of these hormones in the ET men where in the normal clinical range, but represented only 55% to 85% of those seen in the SED men. For SHBG, LH, cortisol, and prolactin, no significant differences (p>0.05) were found between the ET and SED men.
Conclusions. ET men have lowered basal T and fT levels and this suppression may be related to an alteration in the hypothalamic-pituitary-testicular regulatory axis since the LH of the ET was not elevated. Whether these hormonal changes have any significant beneficial (i.e., protective cardiovascular) or negative (i.e., decrease anabolic-androgenic processes) physiologic consequences remains to be determined.