The Pituitary-Testicular Axis in Non-Professional Soccer Players

Summary

In European countries, football is one of the most popular forms of physical exercise. However, the possibility that endocrine changes can arise in football players has not been investigated completely. Therefore, the aim of the present study was to evaluate the effects of a training program and the consequences of a football match on the pituitary-testicular axis in ten trained non-professional soccer players. Basal levels of LH, FSH, PRL and T, as well as LH, FSH and PRL responses to an iv bolus of GnRH (0.1 mg) plus TRH (0.2 mg), were measured in each subject. The endocrine evaluation was performed before the beginning of the seasonal training (after a 30 days rest period), and repeated on 2 consecutive days at the end of a 3 months regular training program, 14–15 h from the end of both a customary 3 h training session and a 90 min strenuous soccer match. In 5 out of the 10 athletes a semen analysis was performed after each endocrine evaluation. Ten age-matched, healthy, sedentary men served as a control group. Basal serum levels of LH (10.4 ± 1.3 mIU/ml), FSH (8.7 ± 1.1 mIU/ml), PRL (9.7 ± 1.6ng/ml) and T (6.3 ± 0.9ng/ml) measured in the soccer players before the beginning of the seasonal training were similar to those found in the control subjects (LH = 9.2 ± 1.7 mIU/ml, FSH = 8.5 ± 1.4mIU/ml, PRL = 8.8 ± 1.8 ng/ml, T = 6.4 ± 1.1 ng/ml). The relative maximum responses (RMRs) of FSH and PRL to GnRH-TRH (peak values/basal values) were also similar in the athletes (1.9 ± 0.1 and 4.0 ± 0.8, respectively) and the controls (1.8 ± 0.6 and 3.8 ± 0.6, respectively), whereas the LH RMR was significantly lower in the former group (3.7 ± 0.3 vs. 6.8 ± 0.7, P > 0.001). A 3 h training session, performed after 3 months of regular training, did not affect significantly basal hormone values (LH =10.1 ± 1.0 mIU/ml, FSH = 8.7 ± 0.8 mIU/ml, PRL = 10.2 ± 1.5 ng/ml, T = 6.6 ± 0.8 ng/ml), as well as the RMRs of LH (4.0 ± 0.4), FSH (1.9 ± 0.2) and PRL (3.7 ± 0.5). In contrast, in response to the soccer match, a significant rise in basal T (7.1 ± 0.6 ng/ml) and PRL (17.1 ± 1.8 ng/ml) concentrations (P < 0.05 and P < 0.01 vs. resting values, respectively) was observed. There were no significant changes, however, in circulating LH (9.6 ± 1.0 mIU/ml) and FSH (8.9 ± 1.0 mIU/ml). The LH RMR rose significantly from the resting values (4.1 ± 0.3, P < 0.05), but it remained significantly lower than that of the controls. The FSH RMR (1.8 ± 0.2) was not significantly affected, whereas the PRL RMR (2.3 ± 0.4) showed a significant decrease in comparison with both the resting (P < 0.01) and the control (P < 0.001) values. Although semen volume and sperm concentration were similar in the soccer players (3.7 ± 1.ml and 56.2 ± 16.0 × 10⁶/ml, respectively) and the control subjects (3.5 ± 0.8 ml and 63.9 ± 20.9× 10⁶/ml, respectively), sperm motility was significantly lower in the former group (54.0 ± 6.0% vs. 66.7 ± 6.8%, P < 0.01). Neither the training program nor the soccer match did affect significantly the seminal parameters. Our results suggest that in long-term trained male non-professional soccer players there is some derangement in the control of LH secretion, possibly due to repeated increases in stress hormones and gonadal steroids in response to football competitions. In addition, a small but significant decrease in sperm motility is present in these subjects.

Key words

Soccer players - Physical training - Gonadotropins - Prolactin - Testosterone- Spermatogenesis - Stress