Influence of marathon running on thyroid hormones.
Thyroid hormones were studied in 16 well-trained male amateur runners (mean age 31.8 years) before, immediately after, and 60 min and 22 h after marathon running. Free thyroxine (fT4), appraised by the free thyroxine index (fT4-I), was significantly increased immediately after and 1 h after the race compared with control values. Thyroid-stimulating hormone (TSH) was significantly increased immediately after the race, returned to the control value 1 h later, and was markedly decreased 22 h after the race. Free triiodothyronine (fT3) and free reverse triiodo-thyronine (frT3), appraised by the ratios triiodothyronine/-thyroxine binding globulin and reverse triiodothyronine/thyroxine binding globulin, respectively, showed contrary results. frT3 increased significantly after exercise, whereas fT3 decreased insignificantly. The peripheral conversion of thyroxine was additionally estimated by the ratios rT3/T3 and rT3/T. Both ratios were increased significantly after the run and remained elevated 22 h after the race. It is concluded that an increased TSH-regulated T4 secretion occurs during prolonged exercise as well as a change of the peripheral conversion process in favor of the hormonal inactive rT3. The latter condition remained still 22 h after the race.
Sander
M
M
Institut für Physiologie, Freien Universität Berlin.
Röcker
L
L
D000293:Adolescent; D000328:Adult; D006801:Humans; D008297:Male; D008875:Middle Aged; D012420:Running; D013963:Thyroid Hormones / Q000097:blood*
D013963:Thyroid Hormones