european college of sport science

Saturday, June 27th, 2009
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what have we learned from human studies? Pflugers Arch., 451, 319-327.
EFFECTS OF AGING AND LONG-TERM RESISTANCE TRAINING ON TESTICULAR TESTOSTERONE PRODUCTION CAPAC-
ITY
AHTIAINEN, J.P., HELSTE, M., NYMAN, K., RANNIKKO, A., HUHTANIEMI, I., KRAEMER, W.J., PARVIAINEN, T., HÄKKINEN, K.
JYU (JYVÄSKYLÄ, FINLAND), CENTRAL FINLAND HOSPITAL (JYVÄSKYLÄ, FINLAND), UH (HELSINKI, FINLAND), UTU (TURKU, FINLAND), UCONN
(STORRS, CT, USA)
Introduction: Testosterone production is regulated by the function of the hypothalamic–pituitary–testicular (HPT) axis. The hypothalamus
releases gonadotrophin-releasing hormone (GnRH), which in turn stimulates pulsatile release of luteinizing hormone (LH) from the anterior
pituitary gland, and this subsequently, induces testicular testosterone production. The HPT axis can be assessed using exogenous
GnRH agonist as well as human chorionic gonadotropin (hCG) that mimics the normal surge of LH. Previously it has been shown that
acute and chronic endurance training induces suppressed testosterone responses to GnRH agonist and hCG (1,2,3). However, the effects
of resistance training on the HPT axis have not been examined. Therefore, GnRH and hCG stimulation were used to investigate traininginduced
changes in testicular production of testosterone before and after long-term systematic resistance training.
Methods
Healthy untrained young (28.0 (2.9) yrs., n = 5) and old men (69.5 (2.3) yrs., n = 8) volunteered to the study. Before and after the 1-year
resistance training (2-3/wk) the nasal solution of GnRH agonist (Synarela 200 mikrog) or hCG injection (Pregnyl 5000 IU) were dosed in a
randomized order with a two week interval. Basal serum total testosterone (T) and sex-hormone binding globulin (SHBG) concentrations
were measured before and 24h after the administration of GnRH as well as before and 48h, 72h and 96h after the administration of
hCG.
Results: Serum free androgen index (FAI; T/SHBG) was greater (p