HORMONAL CHANGES AT REST IN OVERTRAINED ENDURANCE ATHLETES

Resting levels of testosterone, luteinising hormone, cortisol, prolactin, and the testosterone/cortisol ratio were studied in a group of endurance athletes before and throughout a high intensity-volume phase of their yearly training cycles. During this period four athletes developed overtraining characteristics. These subjects were physically matched with control subjects conducting comparable training but exhibiting no overtraining symptoms. Hormonal comparisons between the groups revealed no significant differences existed prior to beginning the intensive training; nor did the hormonal levels of the control subjects alter significantly (P>0.05) due to the training. The overtrained subjects, however, did have a significant (P<0.01) decline in testosterone (6.8±1.0 to 4.4±1.0 ng/ml; MEAN ± SE). Furthermore, prolactin was found to significantly (P<0.05) elevate in the overtrained subjects (8.1±2.0 to 13.2±1.1. ng/ml), while the testosterone/cortisol ratio showed a significant (P<0.005) decline (0.83±0.26 to 0.36±0.08). No other significant changes were noted. These findings support the theory that the overtraining syndrome in athletes may represent a neuroendocrine dysfunction.