Does strenuous physical activity affect thyroid hormone metabolism?
['The results of the present study in a unique experimental human model of maximal exposure to altitude and physical exercise demonstrate that extreme HA and strenuous physical exercise are coupled with specific endocrine adaptations. These include increased activity of the GH/IGF-I axis and a low T(3) syndrome', "3,5,3'-triiodothyronine (T3) and T4 levels increase during strenuous exercise, and, at the end of the exercise bout, a decrease of T3 and T4 levels, with an increase in TSH during the following 4-5 days, is seen.", 'the obtained results indicate that in intense exercise, causing the rapid development of fatigue, rapid increases in serum levels of hormones of the pituitary-adrenocortical, pituitary-gonadal and pituitary-thyroid systems occur.', 'Mean levels of fasting plasma estradiol, luteinizing hormone, follicle-stimulating hormone, free thyroxine and triiodothyronine were significantly lower in AR compared to ER and SE.', "Reductions in plasma T4, T3 and T3/T4 ratio are probably due to inhibition of T4 secretion and 5'-monodeiodination with possible conversion of T4 to reverse T3 (rT3). These processes may represent a mechanism for regulation of thyroid hormone metabolism during strenuous and extended flight.", 'Strenuous endurance training seems to have minor changes on the function of the thyroid gland. Depressed T4 levels in runners may rather be due to lowered TBG levels than due to direct effect of training.', 'brief strenuous swimming or moderate bicycle exercise had minor or no effect on thyroid hormone concentrations when consideration was given to the attendant hemoconcentration.', 'thyroxine were determined in 26 men participating in a 90-km cross-country ski race, before, immediately after, and on the following days', 'Total thyroxine and free thyroxine in serum were significantly increased at the end of the race, but had returned to the pre-raced levels during the rest of the observation period.', 'There are controversial results concerning thyroid hormone metabolism during strenuous exercise in adult athletes and only scant data concerning the impact of strenuous exercise on thyroid hormone metabolism in children and adolescents.']
['YES']
['yes']