OVERTRAINING AFFECTS MALE REPRODUCTIVE STATUS

Objective: To substantiate the hypothesis that strenuous exercise disr upts the hypothalamic-pituitary-gonadal axis in men. Design: Longitudi nal study. Setting: Normal human volunteers in an academic research en vironment. Patients: Five endurance-trained men (maximum oxygen consum ption 65.4 +/- 3.6 mL/kg per minute [means +/- SEM]) with normal sperm atogenic and hormonal profiles. Interventions: Semen and blood samples were collected bimonthly before, immediately after, and 3 months afte r overtraining, which was defined as twice the previous average weekly training volume with unchanged intensity. Main Outcome Measure: Testo sterone, cortisol, and sperm concentration. Results: Basal T levels de creased to 5.37 +/- 67 ng/mL from 8.68 +/- 93 ng/mL (conversion factor to SI unit, 3.47) immediately after overtraining and basal cortisol l evels increased to 215.3 +/- 31 ng/mL from 145.7 +/- 27 ng/mL (convers ion factor to SI unit, 2.76). This inverse relationship was highly cor related (r = -0.92). Both cortisol and T levels returned to pretrainin g values 3 months after resumption of previous training volume. Sperm count (91 +/- 23.3 x 10(6)) decreased significantly by 43% immediately after overtraining (52 +/- 6.8 X 10(6)) and by 52% 3 months after ove rtraining (44.5 +/- 20 x 10(6)). However, all values remained within n ormal range and would not be expected to affect fertility. Conclusions : Our results indicate that overtraining reduces T levels, which is hi ghly correlated with an increase in levels of cortisol and possibly a subsequent decrease in sperm concentration 74 days later.