Aims: The aim of this investigation was to examine the thyroid hormone levels of professional cyclists during a 3-week stage competition (Vuelta a España 1998). Methods: 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. Results: 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. Conclusion: In conclusion, 3 weeks of competition provokes changes in basal thyroid hormone concentrations in professional road cyclists.

Keywords:
Triiodothyronine, Thyroxine, Thyrotropin, Cycling, Exercise
1.
Basu M, Pal K, Malhotra AS, Prasad R, Sawhney RC: Free and total thyroid hormones in humans at extreme altitude. Int J Biometeorol 1995;39:17–21.
2.
Caralis DG, Edwards L, Davies J: Serum total and free thyroxine and triiodothyronine during dynamic muscular exercise in man. Am J Physiol 1977;2:E115–E118.
3.
Chicharro JL, Legido JC, Alvarez J, Serratosa L, Bandres F, Gamella C: Saliva electrolytes as a useful tool for anaerobic threshold determination. Eur J Appl Physiol 1994;68:214–218.
4.
Chopra IJ, Solomon DH, Chopra U, Sing YW, Fisher DA, Nakamura Y: Pathways of metabolism of thyroid hormones. Horm Res 1981;34:521–567.
5.
Coplan NL, Gleim GW, Nicholas JA: Exercise-related changes in serum catecholamines and potassium: Effect of sustained exercise above and below lactate threshold. Am Heart J 1989;117:1070–1075.
6.
Deligiannis A, Karamouzis M, Kouidi E, Mougios V, Kallaras C: Plasma TSH, T3, T4 and cortisol responses to swimming at varying water temperatures. Br J Sports Med 1993;27:247–250.
7.
Dill DB, Costill DL: Calculation of percentage changes in volume of blood plasma and red cells in dehydration. J Appl Physiol 1974;37:247–248.
8.
Galbo H, Hummer L, Peterson IB, Christensen NJ, Bie N: Thyroid and testicular hormonal responses to graded and prolonged exercise in men. Eur J Appl Physiol 1977;36:101–106.
9.
Garcia-Roves PM, Terrados N, Fernandez SF, Patterson AM: Macronutrient intake of top level cyclists during continuous competition-change in the feeding pattern. Int J Sports Med 1998;19:61–67.
10.
Hackney AC, Feith S, Pozos R, Seale J: Effects of high altitude and cold exposure on resting thyroid hormone concentrations. Aviat Space Environ Med 1995;66:325–329.
11.
Hackney AC, Gulledge T: Thyroid hormone responses during an 8-hour period following aerobic and anaerobic exercise. Physiol Res 1994;43:1–5.
12.
Hesse V, Vilser C, Scheibe J, Jahreis G, Foley T: Thyroid hormone metabolism under extreme body exercises. Exp Clin Endocrinol 1989;94:82–88.
13.
Hohtari H, Pakarinen A, Kauppila A: Serum concentrations of thyrotropin, thyroxine, triiodothyronine and thyroxine binding globulin in female endurance runners and joggers. Acta Endocrinol 1987;114:41–46.
14.
Humpeler E, Skrabal F, Bartsch G: Influence of exposure to moderate altitude on the plasma concentration of cortisol, aldosterone, renin, testosterone, and gonadotropins. Eur J Appl Physiol Occup Physiol 1980;45:167–176.
15.
Katzeff HL, O’Connell M, Horton ES, Danforth Jr E, Young JB, Landsberg L: The impact of over and underfeeding on energy expenditure in lean and obese men: Response to graded infusions of norepinephrine. Metabolism 1986;35:166–175.
16.
Koistinen P, Martikkala V, Karpakka J, Vuolteenaho O, Leppäluoto J: The effects of moderate altitude on circulating thyroid hormones and thyrotropin in training athletes. J Sports Med Phys Fitness 1996;36:108–111.
17.
Kotchen TA, Mougey EH, Hogan RP, Body III AE, Pennington LL, Mason JW: Thyroid responses to simulated altitude. J Appl Physiol 1973;2:165–168.
18.
Limanova Z, Sonka J, Kratochvil O, Sonka K, Kanka J, Sprynarova ST: Effects of exercise on serum cortisol and thyroid hormones. Exp Clin Endocrinol 1983;81:308–314.
19.
Lucía A, Díaz B, Hoyos J, Fernández C, Villa G, Chicharro JL: Hormone levels of world class cyclists during the Tour of Spain stage race. Br J Sports Med 2001;35:424–430.
20.
Lucía A, Hoyos J, Carvajal A, Chicharro JL: Heart response to professional road cycling: The Tour de France. Int J Sports Med 1999;20:167–172.
21.
Lucia A, Hoyos J, Perez M: Thyroid hormones may influence the slow component of VO2 in professional cyclists. Jpn J Physiol 2001;51:239–4240.
22.
McMurray RG, Hackney RG: Endocrine responses to exercise and training; in Garrett E Jr, Kinkerdall DT (eds): Exercise and Sport Science. Philadelphia, Lippincott Williams & Wilkins, 2000, pp 135–161.
23.
Melander A, Ericson LE, Ljunggren JG, Norberg KA, Persson B, Sundler F, Tibblin S, Westgren U: Sympathetic innervation of the normal human thyroid. J Clin Endocrinol 1974;39:713–718.
24.
Mena P, Maynar M, Campillo JE: Changes in plasma enzyme activities in professional racing cyclists. Br J Sports Med 1996;30:122–124.
25.
O’Connell M, Robbins DC, Horton ES, Sims EAH, Danforth E Jr: Changes in serum concentrations of 3,5′,3′-triiodothyronine during prolonged moderate exercise. J Clin Endocrinol Metab 1979;49:242–246.
26.
Refsum HE, Strømme SB: Serum thyroxine, triiodothyronine and thyroid stimulating hormone after prolonged heavy exercise. Scand J Clin Lab Invest 1979;39:455–459.
27.
Rone JK, Dons RF, Reed HL: The effect of endurance training on serum triiodothyronine kinetics in man: Physical conditioning marked by enhanced thyroid hormone metabolism. Clin Endocrinol (Oxf) 1992;37:325–330.
28.
Saris WHM, van Erp-Baart MA, Brouns F, Westertep KR, ten Hoor F: Study on food intake and energy expenditure during extreme sustained exercise: The Tour de France. Int J Sports Med 1989;10:S26–S31.
29.
Sawhney RC, Malhotra AS: Thyroid function in sojourners and acclimatised low landers at high altitude in man. Horm Metab Res 1991;23:81–84
30.
Scanlon MF: Neuroendocrine control of thyrotropin secretion; in Braverman LE, Utiger RD (eds): The Thyroid. Philadelphia, Lippincott Williams & Wilkins, 1991, pp 230–256.
31.
Spaulding SW, Chopra IJ, Sherwin RS, Lyall SS: Effect of caloric restriction and dietary composition on serum T3 and rT3 in man. J Clin Endocrinol Metab 1976;42:197–200.
32.
Stock MJ, Chapman C, Stirling JL, Campbell IT: Effects of exercise, altitude, and food on blood hormone and metabolite levels. J Appl Physiol 1978;45:350–354.
33.
Terjung RL, Tipton CM: Plasma thyroxine and thyroid-stimulating hormone levels during submaximal exercise in humans. Am J Physiol 1971;220:1840–1845.
34.
Vagenakis AG, Burger A, Portnary GI, Rudolph M, O’Brian JR, Azizi F, Arky RA, Nicod P, Ingbar SH, Braverman LE: Diversion of peripheral thyroxine metabolism from activating to inactivating pathways during complete fasting. J Clin Endocrinol Metab 1975;41:191–194.
35.
Zarzeczny R, Pilis W, Langfort J, Kaciuba U, Cilko H, Nazar K: Influence of thyroid hormones on exercise tolerance and lactate threshold in rats. J Physiol Pharmacol 1996;47:503–513.
36.
Wirth A, Holm G, Lindstedt G, Lundberg PA, Bjorntorp P: Thyroid hormones and lipolysis in physically trained rats. Metabolism 1981;30:237–241.
© 2002 S. Karger AG, Basel
2002
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.