The Impact of Exercise on Thyroid Hormone Metabolism in Children and Adolescents

Abstract

Thyroid hormones are important regulators of energy metabolism and may influence energy processes during physical exercise. 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. Although some studies demonstrate a transient change in thyroid hormones during intense physical performance, most studies agree that these changes are of minor impact, practically reflecting the relative negative energy balance during strenuous exercise. This state of hypometabolism during intense physical performance has also been confirmed in highly trained female young athletes, who may be also characterized by reproductive axis dysfunction, manifested either as luteal-phase deficiency or amenorrhea, alongside the typical constellation of low T₃, insulin and leptin levels. More importantly, strenuous exercise during childhood or adolescence is mostly accompanied by a delay of skeletal maturation, and height and may have a long-lasting negative effect on growth and acquisition of maximum bone mass. In conclusion, although thyroid hormones are only transiently or insignificantly changed during strenuous exercise, adequate caloric intake should be guaranteed in highly performing young athletes in order to counteract the relative negative energy balance and prevent alterations in endocrine-metabolic profile. Moreover, when growth and pubertal progression in very young athletes are significantly impaired, a reduction in the intensity of the physical exercise should be advocated in order to guarantee better final height and adequate acquisition of bone mass.

Key words

Thyroid hormones - Metabolism - Sport - Exercise - Childhood - Adolescence - Female athlete - Hypometabolic state - Growth - Pubertal delay

References

• 1 Caralis D G, Edwards L, Davies J. Serum total and free thyroxine and triiodothyronine during dynamic muscular exercise in man.  Am J Physiol. 1977;  2 E115-E118
• 2 O’Connell M, Robbins D C, Horton E S, Sims E AH, Danforth E. Changes in serum concentrations of 3,5’,3’-triiodothyronine during prolonged moderate exercise.  J Clin Endocrinol Metab. 1979;  49 242-246
• 3 Terjung R L, Tipton C M. Plasma thyroxin and thyroid-stimulating hormone levels during submaximal exercise in humans.  Am J Phyiol. 1971;  220 1840-1845
• 4 Pakarinen A, Hakkinen K, Alen M. Serum thyroid hormones, thyrotropin and thyroxine binding globulin in elite athletes during very intense strength training of one week.  J Sports Med Phys Fitness. 1991;  31 142-146
• 5 Alen M, Pakarinen A, Hakkinen K. Effects of prolonged training on serum thyrotropin and thyroid hormones in elite strength athletes.  J Sports Sci. 1993;  11 493-497
• 6 Kraemer R R, Blair M S, McCaferty R, Castracane V D. Running-induced alterations in growth hormone, prolactin, triiodothyronine and thyroxine concentrations in trained and untrained men and women.  Res Q Exerc Sport. 1993;  64 69-74
• 7 Chicharro J l, Hoyos J, Bandres F, Terrados N, Fernandez B, Lucia A. Thyroid hormone levels during a 3-week professional road cycling competition.  Horm Res. 2001;  56 59-164
• 8 Rone J K, Dons R F, Reed H L. 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
• 9 Hackney A C, Gulledge T. Thyroid hormone responses during an 8-hour period following aerobic and anaerobic exercise.  Physiol Rev. 1994;  43 1-5
• 10 Tremblay A, Poehlman E T, Despres J P, Theriault G, Danforth E, Bouchard C. Endurance training with constant energy intake in identical twins: changes over time in energy expenditure and related hormones.  Metabolism. 1997;  46 499-503
• 11 Jahreis G, Kauf E, Frohner G, Schmidt H E. Influence of intensive exercise on insulin-like growth factor I, thyroid and steroid hormones in female gymnasts.  Growth Regul. 1991;  1 95-99
• 12 Theinz G, Ladame F, Howald H, Weiss U, Torresani T, Sizonenko P C. The child, growth and high-level sport.  Schweiz Z Med Traumatol. 1994;  3 7-15
• 13 American Academy of Pediatrics . Medical concerns in the female athlete.  Pediatrics. 2000;  106 610-613
• 14 Greydanus D E, Patel D R. The female athlete: Before and beyond puberty.  Ped Clinics of North America. 2002;  49 553-580
• 15 Duhamel J F. Nutritional management of highly trained child athlete.  Bull Acad Natl Med. 2001;  185 1495-1503
• 16 Theinz G, Ladame F, Howald H, Weiss U, Torresani T, Sizonenko P C. Evidence for a reduction of growth potential in adolescent female gymnasts.  J Pediatr. 1993;  122 306-313
• 17 Georgopoulos N A, Theodoropoulou A, Leglise M, Vagenakis A G, Markou K B. Growth and skeletal maturation in male and female artistic gymnasts.  J Clin Endocrinol Metab. 2004;  89 4377-4382
• 18 Markou K B, Mylonas P, Theodoropoulou A, Kontogiannis A, Leglise M, Vagenakis A G, Georgopoulos N A. The influence of intensive physical exercise on bone acquisition in adolescent elite female and male artistic gymnasts.  J Clin Endocrinol Metab. 2004;  89 4383-4387
• 19 Georgopoulos N A, Markou K, Theodoropoulou A, Vagenakis G A, Benardot D, Leglise M, Dimopoulos J CA, Vagenakis A G. Height velocity and skeletal maturation in elite female rhythmic gymnasts.  J Clin Endocrinol Metab. 2001;  86 5159-5164
• 20 Chen E C, Brzyski R G. Exercise and reproductive dysfunction.  Fertil Steril. 1998;  71 1-6
• 21 Loucks A B, Laughlin G A, Mortola J F, Girton L, Nelson J C, Yen S S. Hypothalamic-pituitary-thyroidal function in eumenorrheic and amenorrheic athletes.  J Clin Endocriol Metab. 1992;  75 514-518
• 22 Baer J T. Endocrine parameters in amenorrheic and eumenorrheic adolescent female runners.  Int J Sports Med.. 1993;  14 191-195
• 23 Laughlin G A, Yen S S. Nutritional and endocrine-metabolic alterations in amenorrheic athletes.  J Clin Endocrinol Metab. 1996;  81 4301-4309
• 24 Sundgot-Borgen J. Eating disorders. In: Drinkwater BA (ed) Women in sport. Oxford, England; Blackwell Scientific 2000: 364-376
• 25 De Souza M J, Van Heest J, Demers L M, Lasley B L. Luteal phase deficiency in recreational runners: Evidence for a hypometabolic state.  J Clin Endocriol Metab. 2003;  88 337-346