Abstract
Horse-racing jockeys are a group of weight-restricted athletes, who have been suggested as undertaking rapid and extreme weight cycling practices in order to comply with stipulated body-mass standards. The aim of this study was to examine bone mass, turnover and endocrine function in jockeys and to compare this group with age, gender and body mass index matched controls. Twenty male professional jockeys and 20 healthy male controls participated. Dual energy X-ray absorptiometry scans and early morning fasting blood and urine samples were used to measure bone mass, turnover and a hormonal profile. Total body bone mineral density (BMD) was significantly lower in jockeys (1.143 ± 0.05 vs. 1.27 ± 0.06 g cm−3, p < 0.01). Bone resorptive activity was elevated in the jockey group as indicated by significantly higher urinary NTx/creatinine (76.94 ± 29.52 vs. 55.9 ± 13.9 nmol mmol−1, p < 0.01), resulting in a significantly negative uncoupling index between bone resorption and formation. Sex hormone binding globulin (SHBG) levels were significantly higher in jockeys (41.21 ± 9.77 vs. 28.24 ± 9.98 nmol L−1, p < 0.01) with a lower percentage of bioavailable testosterone (48.89 ± 7.38 vs. 59.18 ± 6.74 %, p < 0.01). SHBG and insulin-like growth factor-1 were independent predictors of total body and femoral neck BMD, respectively (p < 0.05). In conclusion, it appears that professional jockeys have an elevated rate of bone loss and reduced bone mass that appears to be associated with disrupted hormonal activity. It is likely that this may have occurred in response to the chronic weight cycling habitually experienced by this group.
Similar content being viewed by others
References
Dolan E, O’Connor H, O’Loughlin G, McGoldrick A, Warrington G (2011) Nutritional, lifestyle and weight-control practices of professional jockeys. J Sports Sci 29:791–799
Moore JM, Timperio AF, Crawford DA, Cameron-Smith D (2002) Weight management and weight loss strategies of professional jockeys. Int J Sport Nutr Exerc Metab 12:1–13
Leydon MA, Wall C (2002) New Zealand jockeys’ dietary habits and their potential impact on health. Int J Sport Nutr Exerc 12:220–237
Warrington GD, Dolan E, McGoldrick A, McEvoy J, MacManus C, Griffin M, Lyons D (2009) Chronic weight control impacts on physiological function and bone health in elite jockeys. J Sports Sci 27:543–550
Dolan E, Crabtree N, McGoldrick A, Ashley DT, McCaffrey N, Warrington GD (2011) Weight regulation and bone mass: a comparison between professional jockeys, elite amateur boxers and age. gender and bmi matched controls. J Bone Miner Metab. doi:10.1007/s00774-001-0297-1
Frost HM (2003) Bone’s Mechanostat: A 2003 Update. Anat Rec Part A 275:1081–1101
Cure–Cure C, Capozza RF, Cointry GR, Meta M, Cure-Ramirez P, Ferretti JL (2005) Reference chart for the relationships between dual energy X-ray absorptiometry assessed bone mineral content and lean mass in 3,063 healthy men and premenopausal and postmenopausal women. Osteoporos Int 16:2095–2106
De Souza MJ, Williams NI (2004) Physiological aspects and clinical sequelae of energy deficiency and hypoestrogenism in exercising women. Human Reprod Update 10:433–448
Loucks AB, Thuma JR (2003) Luteinizing hormone pulsatility is disrupted at a threshold of energy availability in regularly menstruating women. J Clin Endocrinol Metab 88:297–311
Haspolat K, Ece A, Gurkan F, Atamer Y, Tutanc M, Yolbas I (2007) Relationship between leptin, insulin, IGF-1 and IGFBP3 in children with energy malnutrition. Clin Biochem 40:201–205
Misra M, Miller KK, Bjornsen J, Hackman A, Aggarwal A, Chung J, Ott M, Herzog DB, Johnson ML, Klibanski A (2003) Alterations in growth hormone secretory dynamics in adolescent girls with anorexia nervosa and effects on bone metabolism. J Clin Endocrinol 88:5615–5623
Solomon AM, Bouloux PMG (2006) Modifying muscle mass: the endocrine perspective. J Endocrinol 191:349–360
Proteau S, Pelle A, Collomp K, Benhamou L, Courteix D (2006) Bone density in elite judoists and effects of weight cycling on bone metabolic balance. Med Sci Sports Exerc 38:694–700
Vermeulen A, Verdonck L, Kaufman JM (1999) A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab 84:3666–3672
Boot AM, de Ridder MAJ, van der Sluis IM, van Slobbe I, Krenning EP, de Muinick Keizer-Schrama SMBF (2009) Peak bone mineral density, lean body mass and fractures. Bone 46:336–341
Kroger H, Kotaniemi A, Vainio P, Alhava E (1992) Bone densitometry of the spine and femur in children by dual energy X-ray absorptiometry. Bone Miner Bone Mineral 17:75–85
Molgaard C, Thomsen BL, Prentice A, Cole TJ, Michaelsen KF (1997) Whole body bone mineral density in healthy children and adolescents. Arch Dis 76:9–15
Prentice A, Parsons TJ, Cole TJ (1994) Uncritical use of bone mineral density in absorptiometry may lead to size-related artifacts in the identification of bone mineral determinants. Am J Clin Nutr 60:837–842
Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad MH, Weaver CM, Endocrine Society (2011) Evaluation, treatment and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 96:1911–1930
Waller AE, Daniels JL, Weaver NL, Robinson P (2000) Jockey injuries in the United States. J Am Med Assoc 283:1326–1328
Bass SL, Eser P, Daly R (2005) The effect of exercise and nutrition on the mechanostat. J Musculoskelet Neuronal Interact 5:239–254
Ferry B, Duclos M, Burt L, Therre P, LeGall F, Jaffre C, Courteix C (2011) Bone geometry and strength adaptations to physical constraints inherent in different sports: comparison between elite female soccer players and swimmers. J Bone Miner Metab 29:342–351
Garnero P, Sornay-Rendu E, Claustrat B, Delmas PD (2000) Biochemical markers of bone turnover, endogenous hormones and the risk of fractures in postmenopausal women: the OFELY study. J Bone Miner Res 15:1526–1536
Mora S, Gilsanz V (2003) Establishment of peak bone mass. Endocrinol Metab Clin North Am 32:39–63
Hansen MA, Overgaard K, Riis BJ, Christiansen C (1991) Role of peak bone mass and bone loss in postmenopausal osteoporosis: 12 year study. BMJ 303:961–964
Waldron-Lynch F, Murray BF, Brady JJ, McKenna MJ, McGoldrick A, Warrington G, O’Loughlin G, Barragry JM (2009) High bone turnover in irish professional jockeys. Osteoporos Int 21:521–525
Iuliano Burns S, Wang XF, Ayton J, Jones G (2009) Skeletal and hormonal responses to sunlight deprivation in Antarctic expeditioners. Osteoporos Int 20:1523–1528
Ihle R, Loucks AB (2004) Dose response relationships between energy availability and bone turnover in young exercising women. J Bone Miner Res 19:1231–1240
Kahn SM, Hryb DJ, Nakhla AM, Romas NA (2002) Sex hormone binding globulin is synthesized in target cells. J Endocrinol 175:113–120
Khosla S, Melton LJ, Atkinson EJ, O’Fallon WM, Klee GG, Riggs BL (1998) Relationship of serum sex steroid levels and bone turnover markers with bone mineral density in men and women: a key role for bioavailable estrogen. J Clin Endocrinol Metab 83:2266–2274
Frystyk J, Delhanty PJD, Skjerbek C, Baxter RC (1999) Changes in the circulating IGF system during short term fasting and refeeding. Am J Physiol Endocrinol Metab 40:245–252
Rajaram S, Baylink DJ, Mohan S (1997) Insulin like growth factor binding proteins in serum and other biological fluids: regulation and functions. Endocr Rev 18:801–831
Aimaretti G, Corneli G, Di Somma C, Baldilli R, Gasco V, Rovere S, Migliaretti G, Colao A, Tamburrano G, Lombardi G, Chigo E, Camami F (2005) Different degrees of gh deficiency evidenced by GHRH + arginine test and IGF-1 levels in adults with pituitary disease. J Endocrinolol Invest 28:247–252
Holt RIG, Webb E, Pentecost C, Sonksen PH (2001) Aging and physical fitness are more important than obesity in determining exercise-induced generation of GH. J Clin Endocrinol Metab 86:5715–5720
Nindl BC, Pierce JR, Durkot MJ, Tuckow AP, Kennett MJ, Nieves JW, Cosman F, Alemany JA, Hymer WC (2008) Relationship between growth hormone in vivo bioactivity, the insulin like growth factor 1 system and bone mineral density in young, physically fit men and women. Growth Horm IGF Res 18:439–445
Rubin J, Ackert-Bicknell CL, Zhu L, Fan X, Murphy TC, Nanes MS, Marcus R, Holloway L, Beamer WG, Rosen CJ (2002) IGF-1 regulates osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand in vitro and OPG in vivo. J Clin Endocrinol Metab 87:4273–4279
Ueland T (2004) Bone metabolism in relation to alterations in systemic growth hormone. Growth Horm IGF Res 14:404–417
Garnero P, Sornay E, Rendu E, Delmas PD (2000) Low serum IGF-1 and recurrence of osteoporotic fractures in postmenopausal women. Lancet 355:898–899
Sjogren KS, Sheng M, Moverare S, Liu JL, Wallenius K, Tornell J, Isaksson O, Jansson J, Mohan S, Ohlsson C (2002) Effects of liver derived insulin-like growth factor 1 on bone metabolism in mice. J Bone Miner Res 17:342–351
Nattiv A, Loucks AB, Manore MM, Sunborn CF, Sundgot-Borgen J, Warren MP (2007) The female athlete triad: ACSM position stand. Med Sci Sports Exerc 39:1867–1882
Acknowledgments
This research was supported by an unrestricted grant from the Irish Turf Club.
Conflict of interest
The authors have nothing to declare regarding any potential conflicts of interest which may be perceived as prejudicing the impartiality of the research reported.
Author information
Authors and Affiliations
Corresponding author
About this article
Cite this article
Dolan, E., McGoldrick, A., Davenport, C. et al. An altered hormonal profile and elevated rate of bone loss are associated with low bone mass in professional horse-racing jockeys. J Bone Miner Metab 30, 534–542 (2012). https://doi.org/10.1007/s00774-012-0354-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00774-012-0354-4