J Exerc Nutrition Biochem Search

CLOSE


Phys Act Nutr > Volume 22(3); 2018 > Article
Jeon, Cho, Ok, Lee, and Park: Weight loss practice, nutritional status, bone health, and injury history: A profile of professional jockeys in Korea

Abstract

[Purpose]

The purpose of this study was to investigate the impact of weight loss practices on nutritional status, bone health, and injury history among Korean professional jockeys.

[Methods]

Forty-three male jockeys completed a questionnaire to assess their weight loss practices. Of these, 10 jockeys were selected for in-depth assessment of their nutritional status, bone health, and injury history.

[Results]

The questionnaires revealed that 81.4% of jockeys lost weight every week mainly by dieting and/or exercising. None of the jockeys consumed enough food during the weight loss period. Two jockeys were diagnosed with osteopenia and one was diagnosed with osteoporosis. Only history of fracture showed a significant correlation with low bone mineral density. All jockeys had more than one injury experience throughout their career. Fracture was the most common type of injury, occurring during practice and/or competition and caused mainly by difficulties in handling the horses.

[Conclusion]

Professional jockeys in Korea use extreme weight loss methods. Their repeated periods of poor nutritional intake may result in seriously low bone mineral density, which may aggravate injuries sustained during horse races. Implementation of balanced dietary programs and delivery of health education on weight management are urgently required.

INTRODUCTION

Horse racing is one of the oldest sports in the world. The speed of the horse is key in competition. To achieve maximal speed in racehorses, the body weight of jockeys must be less than 49 kg in Korea (2016 Guideline for Korean Trainee Jockeys of the Korea Racing Authority (KRA)). Many jockeys endeavor to comply with the strict weight restrictions before each competition by adopting unhealthy weight loss practices that are relatively quick, such as restricting food and fluid consumption, taking laxatives or diuretics, and even vomiting after meals1-6. Of concern is the issue that racing competitions take place every weekend all year round, except for one month during the off season. Therefore, jockeys repeatedly engage in these unhealthy weight loss practices throughout the year.
Unhealthy weight loss practices can negatively affect the health condition of jockeys. A poor diet cannot properly fulfil the nutritional intake required for the human body to function and have good performance7-17. Dehydration caused by restricting fluid intake or promoting perspiration can decrease total plasma volume in the body, which has adverse effects on overall physiological functions including hormonal imbalance, kidney and cardiovascular dysfunction, electrolyte imbalance, and impaired thermoregulation11,13,18-21. In addition, repeated unhealthy weight loss practices lead to a lack of vital mineral and vitamin intake that can persist for many years. This insufficient nutrient intake hampers the maintenance of proper bone mineral density (BMD)12,14,22-25. Relatively low BMD among professional jockeys has been reported in numerous studies2,4,5,26-28.
Not only physiological functions but also psychological and cognitive functions are negatively influenced by extreme dietary regimens9,11-13,15. Previous studies have reported that jockeys who undergo rapid weight loss sometimes feel fatigue, confusion, a lack of concentration, and experience depression1,4,29-31. A marked decline in cognitive function may distract their attention during horse racing, which increases the possibility of falling during competition.
Falling accidents happen frequently in horse racing, and even death can occur in the worst case32-37. In general , jockeys have relatively low BMD, which is not only likely to cause more severe injury if a fall occurs, it also significantly influences jockeys’ overall health, even after their professional racing career is over32.
Despite the fact that jockeys consistently practice unhealthy weight loss strategies, there is no systematic education and management of weight control practices for this population in Korea. Therefore, the purpose of this study was to investigate the impact of weight loss practices on nutritional status, bone health, and injury history among Korean professional jockeys who often engage in extreme weight loss. We expect to provide baseline data regarding Korean professional jockeys through this study.

METHODS

Participants

Forty-three professional male jockeys from the KRA completed a questionnaire on their weight loss practices. Of these, we selected 10 jockeys who reported using extreme weight loss practices for more than 5 years, to examine their nutritional status, bone health, and injury history in greater detail. Prior to starting our study, all participants were given a full explanation of all procedures, and they provided their written informed consent. This study was approved by the Texas A&M University-San Antonio Institutional Review Board (2017-22).

Weight loss practices questionnaire

In this study, we used a modified weight loss practices questionnaire, adopted from previous studies1,38. This modified questionnaire contained 13 open-and closed-ended questions on general characteristics, weight loss practices, psychological and physiological changes after weight control, and recovery methods. Some questions had more than one possible answer. The questionnaire was self-administered by the respondents.

Anthropometric and body composition assessment

Height, body mass, and total body water were measured using a multi-frequency bioelectrical impedance analysis (BIA) device (X-SCAN PLUS 2; Jawon Medical, Korea). Body mass index (BMI) was calculated as weight divided by height squared (kg/m2). Lean and fat mass and percent body fat were assessed using dual-energy X-ray absorptiometry (DEXA) (QDR-4500; Hologic, USA).

Nutritional assessment

Jockeys' nutritional status was assessed on two different days (weight loss day vs. non-weight loss day) using a 24-hour dietary recall. All participants filled out dietary logs after being provided with detailed instructions, and a researcher reviewed the logs together with each jockey. The data were analyzed using a computer-aided nutritional analysis program (CAN-Pro 2.0; The Korean Nutrition Society, Korea). The estimated average requirement (EAR) and recommended daily allowance (RDA) were based on the Dietary Reference Intakes for Koreans in 2015.

Bone health

BMD and bone mineral content (BMC) of the total body were assessed using DEXA scans (QDR-4500). BMD was reported as grams of absolute BMC per cm2. Osteopenia and osteoporosis were based on the criteria of the World Health Organization. Osteopenia was defined as T-score between −1.0 and −2.5, and osteoporosis was defined as T-score of −2.5 or lower. To analyze the correlation between BMD and osteoporosis risk factors, data on previous fracture history, smoking, and alcohol consumption were collected using a separate questionnaire22,39.

Injury history questionnaire

The injury history questionnaire contained nine open-and closed-ended questions on the number of injuries experienced, time and cause of injury, body sites of injury and diagnosis, therapeutic period, number of recurrences, and degree of influence on competition32,33,36. All questions, except for the number of injuries, had more than one possible answer. The questionnaire was self-administered by respondents.

Statistical analysis

All data are presented as mean ± standard deviation and were analyzed with IBM SPSS Statistics 24 (IBM Corp., Armonk, NY, USA). Frequency analysis was performed for data collected using the weight loss practices questionnaires. Jockeys’ nutritional status between weight loss days and non-weight loss days were compared using paired t-tests, with effect sizes calculated as Cohen’s drm40. Spearman’s rank correlation coefficient was used to test the association between BMD and osteoporosis risk factors: age, fracture history, smoking, alcohol consumption, calories and calcium consumption on weight loss days, and calories and calcium consumption on non-weight loss days. Statistical significance was set at p < .05.

RESULTS

Weight loss practices questionnaire

Forty-three professional jockeys responded to the weight loss practices survey (age 32.3 ± 7.2 years, career 10.5 ± 7.8 years, height 158.3 ± 4.8 cm, body mass 49.8 ± 2.3 kg). More than 80% of jockeys underwent a routine weight loss regimen every week, 1 and 3 days prior to race days, mainly by extreme dieting, exercising, and/or using a sauna. Around 70% of jockeys reported severe fatigue during weight loss days. They consumed high caloric foods and/or rested to recover their condition after each competition (Table 1).
Table 1.

Results of weight loss practices questionnaires among Korean professional jockeys.

n (%) n (%)
Weight control status (n=42) Psychological changes after weight loss (n=35)
Trying to lose weight 35 (81.4) Irritation 22 (62.9)
Not trying to lose weight 8 (18.6) No change 7 (20.0)
Number of weight loss days per week (n=35) Anger
1 day 11 (31.4) Depression 5 (14.3)
2 days 10 (28.6) Anxiety 3 (8.6)
3 days 12 (34.3) Tiredness 3 (8.6)
More than 4 days 3 (8.6) Physiological changes after weight loss (n=35)
Amount of weight usually lost (n=35) Fatigue 25 (71.4)
Less than 1 kg 25 (71.4) Hunger 21 (60.0)
1 to 2 kg 7 (20.0) Thirst 18 (51.4)
More than 2 kg 3 (8.6) Muscle cramps 8 (22.9)
Weight loss methods (n=35) Dizziness 7 (20.0)
Restricting calories 22 (62.9) Dehydration 4 (11.4)
Increased exercise 21 (60.0) No change 2 (5.7)
Sauna 18 (51.4) Recovery methods after competitions (n=35)
Fasting 9 (25.7) Consuming calories 33 (94.3)
Restricting fluids 7 (20.0) Resting 23 (65.7)
Vomiting after meals 2 (5.7) Nutritional supplements 8 (22.9)
Diuretics or laxatives 0 (0.0) Other 4 (11.4)

Anthropometric and body composition

Anthropometric and body composition data of the 10 jockeys is presented in Table 2.
Table 2.

Anthropometric and body composition profiles of Korean professional jockeys.

Jockeys (n = 10)
Age (years) 31.8±3.7
Career (years) 11.6±3.8
Height (cm) 157.5±4.52
Body mass (kg) 50.6±1.87
BMI (kg/m2) 20.5±1.38
Lean body mass (kg) 43.3±1.67
Fat mass (kg) 7.3±1.24
Percent body fat (%) 14.4±2.27
Total body water (kg) 31.2±1.20

Note. Data presented as mean ± SD.

Nutritional status

The results of nutritional assessment are presented in Table 3. On weight loss days, jockeys not only consumed around half the calories and EAR consumed on non-weight loss days, they also did not eat the RDA of micronutrients. Most nutrients were consumed in significantly lower amounts during weight loss days compared with non-weight loss days: total calories (t(9) = −5.09, p < .001), carbohydrate (t(9) = −2.93, p = .017), protein (t(9) = −4.01, p = .003), fat (t(9) = −3.08, p = .013), vitamin E (t(9) = −2.81, p = .020), thiamine (t(9) = −3.48, p = .007), riboflavin (t(9) = −2.53, p = .032), niacin (t(9) = −3.91, p = .004), vitamin B6 (t(9) = −3.59, p = .006), phosphorus (t(9) = −3.84, p = .004), sodium (t(9) = −5.90, p < .001), potassium (t(9) = −2.73, p = .023), and zinc (t(9) = −4.59, p = .001).
Table 3.

Nutritional analysis of Korean professional jockeys.

Weight loss days n (%) < RDA Non-weight loss days n (%) < RDA d
Total calories (kcal) 1046.0 ± 590.86 2086.5 ± 374.76*** 1.65
EAR (kcal) 2806.7 ± 74.81 2806.7 ± 74.81
Carbohydrate (g) 156.9 ± 118.76 251.6 ± 95.98* 0.95
Protein (g) 38.3 ± 18.39 89.3 ± 36.26** 1.34
Fat (g) 29.0 ± 14.59 61.8 ± 26.59* 1.00
Vitamin A (μg) 443.6 ± 367.47 8 (59.2) 883.0 ± 866.20 7 (117.7) 0.60
Vitamin E (μg) 6.3 ± 5.41 11.1 ± 5.56* 0.89
Vitamin C (mg) 59.7 ± 54.76 9 (59.7) 92.9 ± 60.55 6 (92.9) 0.41
Thiamine (mg) 0.62 ± 0.42 1.46 ± 0.84** 1.22
Riboflavin (mg) 0.61 ± 0.41 1.18 ± 0.57* 1.07
Niacin (mg) 8.1 ± 3.10 9 (50.7) 20.0 ± 8.03** 5 (124.8) 1.25
Vitamin B6 (mg) 1.2 ± 0.85 9 (62.0) 2.4 ± 0.77** 3 (120.0) 1.17
Folate (μg) 157.2 ± 132.87 10 (39.3) 220.7 ± 116.54 9 (55.2) 0.58
Calcium (mg) 266.1 ± 184.33 9 (38.0) 385.3 ± 157.56 6 (55.0) 0.63
Phosphorus (mg) 532.9 ± 307.55 8 (76.1) 1061.1 ± 394.73** 1 (151.6) 1.23
Sodium (g) 1.9 ± 0.47 4.3 ± 1.49*** 2.58
Potassium (g) 1.6 ± 1.03 2.6 ± 0.94* 0.83
Iron (mg) 13.0 ± 17.69 7 (130.5) 13.8 ± 2.93 2 (138.0) 0.08
Zinc (mg) 5.2 ± 2.38 9 (54.3) 10.0 ± 2.59** 4 (105.3) 1.44

Note. Data presented as mean ± SD unless otherwise indicated.

d = Cohen’s d effect size, EAR = estimated average requirement, RDA = recommended daily allowance.

n (%) < RDA refers to the number of people who consumed less than the RDA and the average proportion of the RDA represented by the intake amount.

* p < .05, ** p < .01, *** p < .001 between weight loss days and non-weight loss days.

Bone health

Results of DEXA scans are presented in Table 4. Two jockeys were diagnosed with osteopenia and one was diagnosed with osteoporosis. All jockeys had experienced fractures more than once (2.2 ± 1.23). Six jockeys were non-smokers, one usually smoked 6 to 10 cigarettes a day, another smoked 11 to 15 cigarettes a day, and two jockeys smoked a pack per day. As for alcohol consumption, three jockeys never drank, four drank alcohol less than once a week, one drank 2 to 3 times a week, and two jockeys drank more than 4 times a week. Figure 1 shows the Spearman's correlation coefficients between BMD and risk factors for osteoporosis. Only fracture history had a significantly strong correlation: r(8) = −75 , p = .013. Other risk factors showed no significant correlations with BMD: age (r(8) = −.51, p = .136), smoking (r(8) = −.15, p =.678), alcohol (r(8) = −.13, p = .726), non-weight loss calories (r(8) = −.13, p = .726), weight loss calories (r(8) = −.08, p = .829), non-weight loss calcium (r(8) = −54 , p = .108), and weight loss calcium (r(8) = .20, p = .580).
Table 4.

Mean values for bone mass among Korean professional jockeys.

Area (cm2) BMC (g) BMD (g/cm2)
Left arm 159.44 ± 9.63 128.32 ± 12.53 0.804 ± 0.049
Right arm 172.59 ± 10.64 139.02 ± 13.25 0.806 ± 0.058
Left ribs 116.83 ± 11.95 80.04 ± 11.10 0.688 ± 0.092
Right ribs 119.28 ± 13.10 81.14 ± 12.71 0.679 ± 0.066
Thoracic spine 107.78 ± 14.39 97.37 ± 16.18 0.906 ± 0.102
Lumbar spine 46.90 ± 6.92 54.36 ± 17.89 1.150 ± 0.297
Pelvis 186.87 ± 22.38 194.72 ± 38.70 1.035 ± 0.090
Left leg 302.06 ± 20.28 353.62 ± 52.12 1.167 ± 0.110
Right leg 295.93 ± 22.29 353.51 ± 56.60 1.196 ± 0.114
Subtotal 1507.67 ± 67.35 1482.10 ± 186.27 0.908 ± 0.085
Head 267.19 ± 20.17 574.43 ± 129.85 2.145 ± 0.401
Total 1774.06 ± 77.59 2056.53 ± 306.71 1.155 ± 0.126
T-score −0.29 ± 1.41
Z-score 0.00 ± 1.35

Note. Data presented as mean ± SD.

BMC = bone mineral content, BMD = bone mineral density.

Fig. 1.

Correlation between total bone mineral density (BMD) and risk factors for osteoporosis. WL = weight loss days, NWL = non-weight loss days.

JENB_2018_v22n3_27_f001.jpg

Injury history questionnaire

The results of the questionnaire on jockeys’ injury history throughout their career are presented in Table 5. All jockeys had experienced more than one injury. Two jockeys were injured more than 10 times. Most injuries took place during practice or competition and were mainly caused by difficulties in handling the horses. The most frequently injured body parts were the shoulder and lower back. Fractures happened most frequently, but recurrence of these injuries was rare. In most cases, jockeys were unsatisfied with the length of their recovery period and felt that their injuries negatively affected future competitions.
Table 5.

Injury history among Korean professional jockeys.

n n
Number of injuries experienced Injury of lower body site
1 to 3 times 1 Knee 1
4 to 6 times 3 Calf 1
7 to 9 times 3 Ankle 1
More than 10 time 2 Toe 2
Time of injury Diagnosis
Warm-up 2 Fracture 13
Practice 15 Dislocation 5
Competition 20 Strain 3
Cause of injury Sprain 5
Horse 29 Myositis 3
Facilities 3 Tendinosis 1
Another person 1 Herniated disc 2
Poor conditions 2 Abrasion 4
Nervousness 1 Laceration 2
Excessive competitiveness 3 Recurrence
Ineptitude while riding the horse 2 Never 18
Injury involving upper body site 1 time 3
Head 1 More than 2 times 4
Face 3 Therapeutic period
Neck 4 Very short 4
Shoulder 6 Short 14
Chest 3 Neutral 7
Back 2 Sufficient 8
Low back 6 Influence on competition
Elbow 3 Not at all 3
Wrist 2 Somewhat 5
Finger 5 Definitely 15

DISCUSSION

The aim of this study was to investigate the weight loss practices of Korean professional jockeys and to scrutinize jockeys’ characteristics including nutritional status, bone health, and injury history, targeting jockeys who had engaged in more than 5 years of extreme weight loss practices.
Our findings on the questionnaire survey for weight loss practices of jockeys were in line with those of previous studies1-3,6,30,31,41. We confirmed that many jockeys have extreme weight loss routines that mainly involve restricting calories and/or inducing dehydration. A large number of studies have pointed out that this eating disorder pattern, including starvation, exercise-induced dehydration, binge eating, and vomiting has a high association with numerous disorders8,12,23. People with eating disorders are not only more likely to have various health problems such as gastrointestinal disorders, low bone density, and hormonal problems in later life, they are less likely to reach peak athletic performance owing to low available energy10,15. Mental disorders, such as mood disorders, anxiety, and depression, are additional consequences of eating disorders43,44. For these reasons, the National Athletic Trainers’ Association (NATA) announced guidelines to manage and reduce disordered eating in athletes45. Because most jockeys in this study also reported one or more negative physiological and psychological changes after weight loss, finding proper ways to protect jockeys’ health in consideration of the unique requirements of their sport is urgently needed.
As reported in numerous jockey-related studies, not consuming enough of the nutrients needed for good health is typical among jockeys1-5. Our study also found that while losing weight, all jockeys consumed about half the calories consumed on non-weight loss days, and most nutrients consumed did not reach the EAR or RDA on both weight loss and non-weight loss days. Korean jockeys tend to start weight loss just 1 or 2 days before competition, usually by restricting food and fluid intake. In addition, jockeys cannot replenish food and water before or during competition because their weight must match before and after each race. Such low energy availability induced by extreme weight loss practices makes it hard for these athletes to focus on racing and to reach peak physical performance levels46. At worst, poor physical condition on the day of competition may result in falling accidents.
The negative effects of low calorie consumption can be either acute or chronic. A repetitive pattern of poor calorie intake among jockeys can enervate overall health. In Joint Position Statements , it is highly recommended that athletes consume at least the RDA of all micronutrients because low energy intakes can result in failure to achieve peak bone density and can lead to increased fatigue, injury, and illness14. People aged 19-70 years are recommended to intake at least 1,000 mg of calcium a day for bone health25, and athletes with disordered eating or at risk for early osteoporosis are recommended 1,500 mg of calcium intake a day14. The average daily dietary calcium intake of Korean jockeys in this study was less than half their RDA. Jockeys’ unhealthy diet regimen may arise from poor nutritional knowledge due to a lack of nutritional education for these athletes in Korea. Therefore, it is essential to improve nutritional education as a collaborative effort among nutritionists, counselors, and jockeys, to forestall adverse effects caused by chronic undernourishment in this population.
As for bone health, peak bone mass typically occurs in the early 30s47. According to a population-based cross-sectional analysis among 398 women and 222 men aged 20-89 years, the average total BMD of men aged 20-29 years was 1.26 ± 0.10 g/cm2, and the average total BMD of men aged 20-39 was 1.24 ± 0.11 g/cm247. In comparison with this study, Korean jockeys in our study had relatively low total BMD (1.155 ± 0.126 g/cm2), which did not seem to reach its peak value. Similarly, Dolan et al.26 showed that 20 Irish professional jockeys had an average 1.134 ± 0.05 g/cm2 total BMD, and Warrington et al.28 reported an average 1.049 ± 0.07 g/cm2 total BMD among a population of 17 Irish professional flat jockeys. Clearly, many previous studies have ascertained that jockeys have significantly lower BMD that can lead to increased susceptibility to fractures, which could even bring their professional career to an end2,4,5,26-28,31,42.
In the present study, the results of correlation analysis between BMD and osteoporosis risk factors showed that only fracture history had a significantly strong correlation. Even though other risk factors did not show significant relationships, future studies that include a larger sample size are needed to corroborate this result.
Horse racing is a high-risk sport in which accidents happen frequently32-37,48. All Korean jockeys in this study experienced more than one injury, and two jockeys had more than 10 injuries during an average career span of 11.6 ± 3.8 years. Fractures are the most common type of injury among jockeys. Given the high speed at which horses run in a race and the elevated position of the jockey atop the horse , accidents that occur during a horse race can be very serious and even fatal to jockeys. With the high rate of serious accidents during horse races, low BMD owing to continually poor nutrient consumption can aggravate injuries sustained by jockeys 23. For these reasons, unhealthy dietary habits among jockeys must be rectified and adequate nutritional supplementation, especially of calcium and vitamin D, should be ensured14,23.

CONCLUSION

Korean professional jockeys engage in extreme weight loss practices throughout their careers, and such chronic exposure to undernourished states may result in serious health problems, especially regarding bone health. Given the high rate of accidents in horse racing, the relatively low BMD among jockeys can have very serious consequences. Therefore, efforts should be made to stop and/or regulate repeated extreme weight loss practices among Korean jockeys.

Acknowledgments

We thank all the jockeys who volunteered for this study. No potential conflict of interest was reported by the authors.

REFERENCES

1. Dolan E, O'Connor H, McGoldrick A, O'Loughlin G, Lyon D, Warrington G. Nutritional, lifestyle, and weight control practices of professional jockeys. J Sports Sci 2011;29:791PMID: 10.1080/02640414.2011.560173. PMID: 21506039.
crossref
2. Leydon MA, Wall C. New Zealand jockeys’ dietary habits and their potential impact on health. Int J Sport Nutr Exerc Metab 2002;12:220-37. PMID: 10.1123/ijsnem.12.2.220. PMID: 12187620.
crossref
3. Moore JM, Timperio AF, Crawford DA, Burns CM, Cameron-Smith D. Weight management and weight loss strategies of professional jockeys. Int J Sport Nutr Exerc Metab 2002;12:1-13. PMID: 10.1123/ijsnem.12.1.1. PMID: 11993617.
crossref
4. O’Reilly J, Cheng HL, Poon ETC. New insights in professional horse racing; “in-race” heart rate data, elevated fracture risk, hydration, nutritional and lifestyle analysis of elite professional jockeys. J Sports Sci 2017;35:441-8. PMID: 10.1080/02640414.2016.1171890. PMID: 27070776.
crossref
5. Poon ETC, O’Reilly J, Sheridan S, Cai MM, Wong SHS. Markers of bone health, bone-specific physical activities, nutritional intake and quality of life of professional jockeys in Hong Kong. Int J Sport Nutr Exerc Metab 2017;28:440.
crossref
6. Wilson G, Hawken MB, Poole I, Sparks A, Bennett S, Drust B, Morton J, Close GL. Rapid weight-loss impairs simulated riding performance and strength in jockeys: Implications for making-weight. J Sports Sci 2014;32:383-91. PMID: 10.1080/02640414.2013.825732. PMID: 24015787.
crossref
7. Cullen S, Dolan E, O Brien K, McGoldrick A, Warrington G. Lack of effect of typical rapid-weight-loss practices on balance and anaerobic performance in apprentice jockeys. Int J Sports Physiol Perform 2015;10:972-7. PMID: 10.1123/ijspp.2014-0506. PMID: 25756312.
crossref
8. Dede AD, Lyritis GP, Tournis S. Bone disease in anorexia nervosa. Hormones(Athens) 2014;13:38-56. PMID: 10.1007/bf03401319. PMID: 24722126.
crossref pdf
9. Franchini E, Brito CJ, Artioli GG. Weight loss in combat sports: Physiological, psychological and performance effects. J Int Soc Sports Nutr 2012;9:52PMID: 10.1186/1550-2783-9-52. PMID: 23237303.
crossref pdf
10. Joy E, Kussman A, Nattiv A. 2016 update on eating disorders in athletes: A comprehensive narrative review with a focus on clinical assessment and management. Br J Sports Med 2016;50:154-62. PMID: 10.1136/bjsports-2015-095735. PMID: 26782763.
crossref
11. Khodaee M, Olewinski L, Shadgan B, Kiningham RR. Rapid weight loss in sports with weight classes. Curr Sports Med Rep 2015;14:435-41. PMID: 10.1249/jsr.0000000000000206. PMID: 26561763.
crossref
12. Meczekalski B, Podfigurna-Stopa A, Katulski K. Long-term consequences of anorexia nervosa. Maturitas 2013;75:215-20. PMID: 10.1016/j.maturitas.2013.04.014. PMID: 23706279.
crossref
13. Rankin JW. Weight loss and gain in athletes. Curr Sports Med Rep 2002;1:208-13. PMID: 10.1249/00149619-200208000-00004. PMID: 12831697.
crossref
14. American Dietetic Association. Dietitians of Canada. American College of Sports Medicine. Rodriguez NR, Di Marco NM, Langley S. American College of Sports Medicine position stand. Nutrition and athletic performance. Med Sci Sports Exerc 2009;41:709-31. PMID: 19225360.
crossref
15. Sundgot-Borgen J, Meyer NL, Lohman TG, Ackland TR, Maughan RJ, Stewart AD, Müller W. How to minimise the health risks to athletes who compete in weight-sensitive sports review and position statement on behalf of the Ad Hoc Research Working Group on Body Composition, Health and Performance, under the auspices of the IOC Medical Commission. Br J Sports Med 2013;47:1012-22. PMID: 10.1136/bjsports-2013-092966. PMID: 24115480.
crossref
16. Tarnopolsky MA, Cipriano N, Woodcroft C, Pulkkinen WJ, Robinson DC, Henderson JM, MacDougall JD. Effects of rapid weight loss and wrestling on muscle glycogen concentration. Clin J Sport Med 1996;6:78-84. PMID: 10.1097/00042752-199604000-00003. PMID: 8673580.
crossref
17. Turocy PS, DePalma BF, Horswill CA, Laquale KM, Martin TJ, Perry AC, Somova MJ, Utter AC. National Athletic Trainers’ Association. National athletic trainers' association position statement: Safe weight loss and maintenance practices in sport and exercise. J Athl Train 2011;46:322-36. PMID: 10.4085/1062-6050-46.3.322. PMID: 21669104.
crossref pdf
18. Popkin BM, D'Anci KE, Rosenberg IH. Water, hydration, and health. Nutr Rev 2010;68:439-58. PMID: 20646222.
crossref pdf
19. Ritz P, Berrut G. The importance of good hydration for day-to-day health. Nutr Rev 2015;63:S6-13.
crossref pdf
20. American College of Sports Medicine. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc 2007;39:377-90. PMID: 17277604.

21. Shirreffs SM. The importance of good hydration for work and exercise performance. Nutr Rev 2005;63:S14-21. PMID: 10.1111/j.1753-4887.2005.tb00149.x. PMID: 16028568.
crossref pdf
22. Conde FA, Aronson WJ. Risk factors for male osteoporosis. Urol Oncol 2003;21:380-3. PMID: 14670549.
crossref
23. Drabkin A, Rothman MS, Wassenaar E, Mascolo M, Mehler PS. Assessment and clinical management of bone disease in adults with eating disorders: a review. J Eat Disord 2017;5:42PMID: 10.1186/s40337-017-0172-0. PMID: 29214023.
crossref pdf
24. Goolsby MA, Boniquit N. Bone health in athletes: The role of exercise, nutrition, and hormones. Sports Health 2017;9:108-17. PMID: 27821574.
crossref
25. Ross AC, Manson JE, Abrams SA, Aloia JF, Brannon PM, Clinton SK, Durazo-Arvizu RA, Gallagher JC, Gallo RL, Jones G, Kovacs CS, Mayne ST, Rosen CJ, Shapses SA. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: What clinicians need to know. J Clin Endocrinol Metab 2011;96:53-8. PMID: 10.1210/jc.2010-2704. PMID: 21118827.
crossref
26. Dolan E, Crabtree N, McGoldrick A, Ashley DT, McCaffrey N, Warrington GD. Weight regulation and bone mass: A comparison between professional jockeys, elite amateur boxers, and age, gender and BMI matched controls. J Bone Miner Metab 2012;30:164-70. PMID: 10.1007/s00774-011-0297-1. PMID: 21773703.
crossref pdf
27. Waldron-Lynch F, Murray BF, Brady JJ, McKenna MJ, McGoldrick A, Warrington G, O'Loughlin G, Barragry JM. High bone turnover in Irish professional jockeys. Osteoporos Int 2010;21:521-5. PMID: 10.1007/s00198-009-0887-0. PMID: 19271097.
crossref pdf
28. Warrington G, Dolan E, McGoldrick A, McEvoy J, Macmanus C, Griffin M, Lyons D. Chronic weight control impacts on physiological function and bone health in elite jockeys. J Sports Sci 2009;27:543-50. PMID: 10.1080/02640410802702863. PMID: 19337879.
crossref
29. Caulfield MJ, Karageorghis CI. Psychological effects of rapid weight loss and attitudes towards eating among professional jockeys. J Sports Sci 2008;26:877-83. PMID: 10.1080/02640410701837349. PMID: 18569553.
crossref
30. Dolan E, Cullen S, McGoldrick A, Warrington GD. The impact of making weight on physiological and cognitive processes in elite jockeys. Int J Sport Nutr Exerc Metab 2013;23:399-408. PMID: 10.1123/ijsnem.23.4.399. PMID: 23436623.
crossref
31. Wilson G, Drust B, Morton JP, Close GL. Weight-making strategies in professional jockeys: Implications for physical and mental health and well-being. Sports Med 2014;44:785-96. PMID: 10.1007/s40279-014-0169-7. PMID: 24682950.
crossref pdf
32. Balendra G, Turner M, McCrory P. Career-ending injuries to professional jockeys in British horse racing (1991-2005). Br J Sports Med 2008;42:22-4. PMID: 17510227.
crossref
33. Hitchens PL, Blizzard CL, Jones G, Day LM, Fell J. The incidence of race-day jockey falls in Australia, 2002-2006. Med J Aust 2009;190:83-6. PMID: 19236295.
crossref
34. Hitchens PL, Hill AE, Stover SM. Jockey falls, injuries, and fatalities associated with Thoroughbred and Quarter Horse racing in California, 2007-2011. Orthop J Sports Med 2013;1:1-7. PMID: 10.1177/2325967113492625.
crossref
35. O'Connor S, Warrington G, McGoldrick A, Cullen S. Epidemiology of injury due to race-day jockey falls in professional flat and jump horse racing in Ireland, 2011-2015. J Athl Train 2017;52:1140-6. PMID: 10.4085/1062-6050-52.12.17. PMID: 29154693.
crossref pdf
36. Waller AE, Daniels JL, Weaver NL, Robinson P. Jockey injuries in the United States. JAMA 2000;283:1326-8. PMID: 10.1001/jama.283.10.1326. PMID: 10714733.
crossref
37. Wylie CE, McManus P, McDonald C, Jorgensen S, McGreevy P. Thoroughbred fatality and associated jockey falls and injuries in races in New South Wales and the Australian Capital Territory, Australia: 2009-2014. Vet J 2017;227:1-7. PMID: 10.1016/j.tvjl.2017.06.008. PMID: 29031324.
crossref
38. Brito CJ, Roas A FC, Brito I SS, Marins J CB, Córdova C, Franchini E. Methods of body-mass reduction by combat sport athletes. Int J Sport Nutr Exerc Metab 2012;22:89-97. PMID: 10.1123/ijsnem.22.2.89. PMID: 22349031.
crossref
39. Grainge MJ, Coupland CA, Cliffe SJ, Chilvers CE, Hosking DJ. Cigarette smoking, alcohol and caffeine consumption, and bone mineral density in postmenopausal women. Osteoporos Int 1998;8:355-63. PMID: 10.1007/s001980050075. PMID: 10024906.
crossref pdf
40. Cohen J. Statistical Power Analysis for the Behavioral Sciences. New York, NY: Routledge Academic. 1969. PMID: 10.4324/9780203771587.

41. Cotugna N, Snider OS, Windish J. Nutrition assessment of horse-racing athletes. J Community Health 2011;36:261-4. PMID: 10.1007/s10900-010-9306-x. PMID: 20803166.
crossref pdf
42. Dolan E, McGoldrick A, Davenport C, Kelleher G, Byrne B, Tormey W, Smith D, Warrington GD. 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 2012;30:534-42. PMID: 10.1007/s00774-012-0354-4. PMID: 22491874.
crossref pdf
43. Javaras KN, Pope HG, Lalonde JK, Roberts JL, Nillni YI, Laird NM, Bulik CM, Crow SJ, McElroy SL, Walsh BT, Tsuang MT, Rosenthal NR, Hudson JI. Co-occurrence of binge eating disorder with psychiatric and medical disorders. J Clin Psychiatry 2008;69:266-73. PMID: 10.4088/jcp.v69n0213. PMID: 18348600.
crossref
44. Meng X, D'Arcy C. Comorbidity between lifetime eating problems and mood and anxiety disorders: Results from the Canadian Community Health Survey of Mental Health and Well-being. Eur Eat Disord Rev 2015;23:156-62. PMID: 10.1002/erv.2347. PMID: 25604862.
crossref
45. Bonci CM, Bonci LJ, Granger LR, Johnson CL, Malina RM, Milne LW, Ryan RR, Vanderbunt EM. National athletic trainers' association position statement: preventing, detecting, and managing disordered eating in athletes. J Athl Train 2008;43:80-108. PMID: 10.4085/1062-6050-43.1.80. PMID: 18335017.
crossref
46. Wilson G, Lucas D, Hambly C, Speakman JR, Morton JP, Close GL. Energy expenditure in professional flat jockeys using doubly labelled water during the racing season: Implications for body weight management. Eur J Sport Sci 2019;18:235-42.
crossref
47. Warming L, Hassager C, Christiansen C. Changes in bone mineral density with age in men and women: A longitudinal study. Osteoporos Int 2002;13:105-12. PMID: 10.1007/s001980200001. PMID: 11905520.
crossref pdf
48. Yim VW, Yeung JH, Mak PS, Graham CA, Lai PB, Rainer TH. Five year analysis of Jockey Club horse-related injuries presenting to a trauma centre in Hong Kong. Injury 2007;38:98-103. PMID: 10.1016/j.injury.2006.08.026. PMID: 17049524.
crossref
TOOLS
Share :
Facebook Twitter Linked In Google+ Line it
METRICS Graph View
  • 8 Crossref
  •     Scopus
  • 3,289 View
  • 11 Download
Related articles in Phys Act Nutr


ABOUT
ARTICLE CATEGORY

Browse all articles >

BROWSE ARTICLES
EDITORIAL POLICY
FOR CONTRIBUTORS
Editorial Office
Korea University, 145 Anam-Ro, Seongbuk-gu,Seoul 02841, Republic of Korea
Tel: +82-10-2235-0018    Fax: +82-2-3290-2315    E-mail: jenbedit@gmail.com                

Copyright © 2024 by Korean Society for Exercise Nutrition.

Developed in M2PI

Close layer
prev next