Background: The aim of this study was to investigate changes in serum levels of growth hormone and thyroids hormone after 12 weeks of endurance training and GnRH agonist and detraining in grils with progressive puberty. Methods: 25 girls (age 6-8) with precocious puberty were randomly divided into Three groups (medication, training, medication+training). and 10 healthy girls (No precocious puberty) as a control group were considered. at the beginning, blood samples from all subjects were prepared and serum levels of GH (growth hormone), T3 (thyrotrounin) and T4 (thyroxin) were measured by ELISA. The experimental groups did aerobic program prolonged for 12 weeks 3 days a week 20-75 min a day with 45-75% of Maximum heart rate and consumption GnRH agonists monthly (1 ml every four weeks) by a subcutaneous injection. 48 hours after completing the training program second phase of blood samples were collected and the third phase after 4 weeks of detraining was collected. Results: The Anova with repeated measures showed that 12 weeks of aerobic training alone, as well as 12 weeks of aerobic training + consumption of GnRH agonists reduced the levels of GH, T3 and T4, this decrease was significant only in T3 (in training + medication group) and after 4 weeks of detraining, levels of growth hormone and thyroid hormones return to pre-workout levels. Conclusion: According to the findings of this study, aerobic training and the use of the GnRH agonists can reduce GH, T3 and T4 and prevent the process of puberty.
