López Chicharro, JoséHoyos, J.Bandrés Moya, FernandoTerrados Cepeda, NicolásFernández, BenjamínLucía Mulas, Alejandro2016-09-072016-09-072001López Chicharro, J., Hoyos, J., Bandrés, F., Terrados Cepeda, N., Fernández, B., & Lucía Mulas, A. (2001). Thyroid hormone levels during a 3-week professional road cycling competition. Hormone Research, 56(5-6), 159-164.03010163http://hdl.handle.net/11268/5722The aim of this investigation was to examine the thyroid hormone levels of professional cyclists during a 3-week stage competition (Vuelta a España 1998). The study population was made up of 16 male cyclists from two world-leading professional teams. Four blood samples were drawn (between 07:00 and 09:00 a.m.) from each participant before and at the end of the 1st, 2nd and 3rd weeks of competition. 3,5,3′ (-Triiodothyronine (T3), free T3 (FT3), thyroxine (T4), free T4 (FT4) and thyroid-stimulating hormone (TSH) were determined in each blood sample by radioimmunoassay. Serum T4, FT4 and FT3 levels showed a significant increase (p<0.05) by the last week of competition while concentrations of TSH and T3 remained unchanged. In conclusion, 3 weeks of competition provokes changes in basal thyroid hormone concentrations in professional road cyclists.engjournal article10.1159/000048112restricted accessHormonas tiroideasMedicina deportivaCiclismoHormonaMedicina deportiva