Hypothalamic-Pituitary-Testicular Axis Function in Endurance-Trained Males

Hackney, Anthony C.; Sinning, W. E.; Bruot, Brent C.

doi:10.1055/s-2007-1024811

Cited by 117 publications

(76 citation statements)

References 7 publications

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“…For example, Wheeler et al (1984) reported that basal testosterone concentrations of long-distance runners were only 55-70% of those found in age-matched controls. Many later studies have replicated this finding (Ayers et al 1985;Gulledge and Hackney 1996;Hackney et al 1988Hackney et al , 1990Wheeler et al 1991).…”

Section: Introductionmentioning

confidence: 50%

“…The research studies attempting to explain these lowered basal testosterone findings have suggested a central adaptation has occurred in the H-P-T regulatory axis (Hackney 1996;Hackney et al 1988Hackney et al , 1990MacConnie et al 1984;Wheeler et al 1991). Wheeler et al (1984) were the first to propose this hypothesis.…”

Section: Introductionmentioning

confidence: 94%

“…These authors concluded that this finding meant that the hypothalamic-pituitary central unit was unresponsive to the lack of adequate circulating testosterone. Some years later, Hackney et al (1990) showed that endurance-trained men with low basal testosterone concentrations have a dramatically blunted pituitary LH response to an exogenous GnRH stimulus, pointing to another form of central adaptation (i.e., anterior pituitary insensitivity to GnRH or suppressed synthesis capacity). In this aforementioned study (Hackney et al 1990), testicular testosterone responsiveness of the endurance-trained men to the LH response of the GnRH stimuli seemed normal and appropriate.…”

Section: Introductionmentioning

confidence: 97%

“…Some years later, Hackney et al (1990) showed that endurance-trained men with low basal testosterone concentrations have a dramatically blunted pituitary LH response to an exogenous GnRH stimulus, pointing to another form of central adaptation (i.e., anterior pituitary insensitivity to GnRH or suppressed synthesis capacity). In this aforementioned study (Hackney et al 1990), testicular testosterone responsiveness of the endurance-trained men to the LH response of the GnRH stimuli seemed normal and appropriate. In a similar fashion, MacConnie et al (1986) used human chorionic gonadotropin (hCG, a LH-like agent) to stimulate testicular testosterone production in endurance-trained men and they saw normal responses.…”

Section: Introductionmentioning

confidence: 97%

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Basal testicular testosterone production in endurance-trained men is suppressed

2003

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Research indicates that endurance-trained men have lower basal testosterone concentrations than age-matched sedentary control men. The physiological cause for this finding is uncertain. Therefore, we examined the peripheral component in the hypothalamic-pituitary-testicular (H-P-T) axis in endurance-trained men to determine if their basal testicular production of testosterone was compromised. The study design was retrospective, with a case-control approach. Age-matched, trained (n=5, TRN) and sedentary control men (n=6, SED) were infused with gonadotrophin-releasing hormone (GnRH) to induce testicular testosterone production via subsequent luteinizing hormone elevations. Testosterone production rate was statistically analyzed with adjustments for confounding factors and compared between groups. The basal testosterone concentrations differed significantly between the TRN and SED groups [pooled mean values; 13.9 (3.0) nmol x l(-1) vs 23.4 (3.2) nmol x l(-1), P<0.05]. The testosterone production rate was significantly lower (approximately 20-30%; P<0.05) in the TRN men as compared with the SED men following GnRH infusion. It was concluded that the exogenous stimulated testicular production rate of endurance-trained men is suppressed. This finding may account, in part, for the lower circulating basal testosterone concentrations found in these men. The present evidence supports the hypothesis that endurance exercise training induces a degree of peripheral adaptation (i.e., testicle) in the H-P-T axis. Whether this adaptation in the axis is a permanent or transient phenomenon in these men remains to be determined.

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Section: Introductionmentioning

confidence: 50%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

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Basal testicular testosterone production in endurance-trained men is suppressed

2003

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“…The decrease in both LH pulse frequency and amplitude found by MacConnie et al (1986) and Hackney et al (1990) represents strong evidence that the hypothalamo-pituitary-testicular axis can be inhibited in male athletes. However, the decreased LH response to GnRH (Hackney et al, 1990) contrasts with the increased response seen in amenorrhoeic female athletes (Veldhuis et al, 1985). The reproductive function in male athletes seems less sensitive to chronic exercise than that of females.…”

mentioning

confidence: 92%