Serum thyroid hormones, thyrotropin and thyroxine binding globulin in elite athletes during very intense strength training of one week.

The effects of a one-week very intense strength training period on maximal strength and pituitary-thyroid function were investigated in eight elite male weight lifters. No statistically significant changes occurred in the maximal isometric leg extension force of the test subjects. Decreased serum concentrations of thyrotropin (TSH), thyroxine (T4) and triiodothyronine (T3) were found during the training period, but no statistically significant changes occurred in the levels of free thyroxine (fT4), reverse T3 (rT3) and thyroxine binding globulin (TBG). The results suggest that the training stress affects at the hypophyseal and/or hypothalamic level decreasing the secretion of TSH, which leads to slightly decreased function of the thyroid gland.