Secondary Logo

Journal Logo

Competitive Sports and Pain Management: Section Articles

Eating Disorders Among Male Athletes

Glazer, James L.

Author Information
doi: 10.1249/JSR.0b013e31818f03c5
  • Free

Abstract

INTRODUCTION

Eating disorders among male athletes have been studied lightly, in part because of the widely held assumption that these conditions are rare among men and boys. Yet recently some well publicized deaths among male wrestlers have highlighted the role that eating disorders and associated aberrant eating behaviors play among men and boys at all levels of sport. Increased awareness has led to improved surveillance, and some surprising data have emerged.

In general, recent research seems to suggest that eating disorders are a rapidly growing problem among male athletes, that male risk factors may be different than those for their female counterparts, and that the natural course of eating disorders may differ between men and women.

ETIOLOGY

The connections between eating disorders and participation in sport have been debated for some time. It is thought that involvement in some sports may promote disordered attitudes and behaviors around eating, either through the competitive advantage that some athletes gain through maintaining a lean appearance or through the mechanical advantage of being able to maintain strength at a lighter weight. Attempts to clarify these associations have generally produced conflicting results. In 1988, a study among intercollegiate athletes at Midwestern colleges in the United States found that 21.5% of participants met Diagnostic and Statistical Manual of Mental Disorders, III (DSM-III-R) criteria for bulimia, while 3% met criteria for anorexia nervosa (AN) (1). A subsequent study failed to replicate those results, finding no cases of AN, and only 1.1% incidence of bulimia in women as compared with 0% in men (2). Among the athletes sampled, males reported more bingeing behaviors, whereas women tended to report more purging behaviors (3,4).

Subclinical eating disorders generally seem to be more prevalent among men than women, which may explain some of the differences in data between the two groups (5). This term recently has been adopted to describe patients who are not in treatment for an eating disorder and do not show all clinical aspects of anorexia or bulimia as described in the DSM. Nonetheless, individuals considered to have subclinical eating disorders demonstrate patterns of disturbance in body image and self-perception that are pathological (6). Observations of patients with these characteristics have led to the adoption in the DSM of a third category of patient: those with an eating disorder not otherwise specified (ED - NOS).

Sport-specific eating behaviors may be relatively more significant in the genesis of eating disorders among men. The association between weight-class competition in certain sports (e.g., wrestling, rowing, boxing) and restrictive eating behaviors has been well described, and in a recent study among German lightweight rowers and wrestlers, 52% were found to engage in binge eating behaviors, while 11% met criteria for subclinical eating disorders (7). These data correlate well with previous findings among women in high-risk activities such as ballet or lightweight rowing, and imply that some athletes may be engaged in aberrant behaviors as a rational response to the demands of their sport rather than as a manifestation of a preexisting psychological disease. This implication is further borne out by unpublished data suggesting that males may rapidly recover normal weights and normal eating behaviors after ending their competitive athletic careers (Beals, K., personal communication, May 27, 2008).

Coaching styles also may influence the genesis of eating disorders in athletes. One study examined athletes' responses to two coaching vignettes, one that emphasized health, while the other focused more strictly upon performance. Athletes were asked to respond to the vignettes with specific reference to their attitudes toward their own body weight. Both male and female athletes responded more negatively to the performance-dominated vignette. Those athletes preferentially exhibited body image anxiety, desire to lose weight, and fear of being fat (8). These findings support the implication that coaching styles may have a profound influence upon the genesis of eating disorders among athletes.

Another theory of eating disorders posits that athletes with preexisting eating disorders may preferentially gravitate to sports that serve their desire for a lean physique, either through the norms of the sport or through its typical training regimens. Termed the "attraction to sport" hypothesis, it can provide one explanation for theobservation that concentrations of eating disordered athletes exist in certain sports (9).

A competing theory holds that participation in physique-salient sports may predispose an otherwise normal athlete to develop an eating disorder. A recent study among Finnish athletes confirmed previous studies in identifying significant correlations between eating disorders and weight-class athletes. Fully 93% of the total weight reduction behavior was observed in weight-class athletes (P < 0.05) (10). The study's authors endorsed the suggestion that a balance between protective and promoting factors may determine the prevalence of eating disorders in a group (11). According to this theory, the pressure to reduce weight might tip the balance toward pathology in an athlete struggling under the pressure to maintain an excessively low weight.

There also is evidence supporting a corresponding concept. If certain sports have the potential to influence the balance toward eating disorders, athletes participating in other sports might enjoy a protective effect. This concept of sport as having the potential to be either protective or harmful with respect to eating disorders is borne out by recent research. Among a sample of over 1000 adolescents, athletes in physique-salient sports had significantly more abnormal scores on two widely accepted instruments used to diagnose aberrant attitudes around food and body image. Those athletes scored higher on the Eating Attitudes Test (EAT) and the Social Physique Anxiety Scale (SPAS) as compared with nonathletic controls. Among athletes in physique-salient sports, average EAT scores were 7.55, as opposed to 4.11 among those in non physique-salient sports (P < 0.05). SPAS scores were found to be 20.08 and 19.35, respectively (P < 0.05) (12). These data indicate a greater propensity toward eating disorders among this subset, while those athletes in non-physique salient sports (e.g., basketball, softball, and soccer) had less abnormal EAT and SPAS scores as compared with controls. This suggests that some sports (e.g., soccer, basketball, and other non-physique salient sports) may provide a protective effect against eating disorders, while other sports (e.g., diving or ballet) may influence individuals towards eating disorders.

INCIDENCE

The prevalence of eating disorders in males classically has been thought to be negligible. In fact, one survey of physicians conducted in 1994 found that 40% of internists and fully 25% of psychiatrists thought that eating disorders could not exist in males (13). The last major revision of the DSM (DSM-IV), published in 1994, was the first iteration to exclude amenorrhea as a diagnostic criterion for anorexia, for the first time enabling males to meet the DSM criteria for this condition.

Studies examining the prevalence of eating disorders generally focus upon either males of a certain age or athletes participating in a given sport. Among all adolescent males, the prevalence of eating disorders seems to be rising. In 1993, one group found the prevalence of bulimia nervosa (BN) in young men to be 0.2% (14). By 1999, a similar study found a 50% greater prevalence of BN (15). A more recent study now estimates the prevalence of BN at 0.4% among males (16). Similar data exist for AN, which appears to have increased in incidence from 0.16% in 2001 to 0.20% in 2004 (17).

Other authors investigating athletes have found a prevalence of eating disorders that is higher than has been reported previously. One group identified reports of binge eating behaviors in 52% of athletes, while 11% of the same sample met criteria for subclinical eating disorders (18). More recent data from Sundgot-Borgen reveal a slightly lower incidence of subclinical eating disorders among elite athletes, but these data still reflect rates 10-50 times those typically reported in the literature (19).

Among athletes participating in certain sports, the prevalence of eating disorders may be alarmingly high. A recent study using the EAT found that cyclists scored significantly higher (reflecting more abnormal attitudes) than their nonathletic peers (20). These trends were apparent in subscales measuring binge eating and dieting behavior. Another similar study compared data among cyclists competing at regional, national, and elite levels. In general, elite cyclists were most likely to demonstrate aberrant behaviors and attitudes, although regional cyclists scored more poorly than their national-level peers (21). Although it was not designed as a diagnostic tool, scores above 20 on the EAT have been associated with the presence of an eating disorder. Of the cyclists surveyed in the Ferrand study, 50% met this criterion for the presence of an eating disorder. These cyclists were found to have manifested their abnormal eating patterns with correspondingly low body mass indexes (BMIs). A similar study among triathletes identified that 11% of participants demonstrated food and weight preoccupation, 23% were engaging in restrictive calorie-controlling behaviors, and fully 100% of the sample endorsed unhappiness with their present BMI (22).

Any athlete for whom lowered weight can confer a competitive advantage may be at increased risk for an eating disorder. Studies among jockeys find myriad instances of dangerous behavior. One study revealed that 69% of jockeys skip meals, 67% use "hot box" sauna techniques for cutting weight, 30% induce vomiting, and 14% use laxatives to control their body weight (23). Three recent deaths among wrestlers attempting to cut weight prompted the National Collegiate Athletic Association (NCAA) to develop strict rules designed to limit dieting behaviors (24).

In general, most recent data seem to suggest that eating disorders are underreported among males. Other disorders seen among male athletes may have related etiologies. Preoccupation with body image among males is on the rise, accompanied by other potentially harmful behaviors. Nationwide, 1% of adolescents and adults are thought to have body dysmorphic disorder (25). In 2002, a survey of high school seniors revealed that at least 4% used steroids. More recently, the NCAA found that almost 50% of college athletes who had used steroids began their use in high school (26).

TREATMENT

Most studies on treatment protocols for eating disorders fail to draw a distinction between males and females. Consequently, it is not known whether optimal strategies for treating eating disorders differ among men. Consistent evidence supports the use of cognitive behavioral therapy (CBT) to reduce binge frequency and maintain weight in patients with bulimia (27). Most evidence suggests that remission rates among patients undergoing CBT are equivalent to those taking medications, and the positive effects of CBT persist for up to 4 yr after the treatment. This treatment may be preferable for athletes, many of whom may find the side effects of medications to interfere with their training. If medications are used among bulimics, both tricyclic antidepressants (TCA) and selective serotonin reuptake inhibitors (SSRIs) have been shown in multiple double-blinded, placebo controlled trials to reduce binge frequency and improve symptoms associated with the disease (28). SSRIs generally are preferred because of improved compliance related to their favorable side effect profile. Because SSRIs do not affect electrical conduction in the heart like TCAs, they also are associated with a lower risk of cardiac arrhythmias. This is a particularly important feature, especially among eating-restricted patients who may have existing conduction abnormalities resulting from malnutrition.

First-line pharmacologic treatment of athletes with anorexia should involve use of selective serotonin reuptake inhibitors. While they have not been shown to help patients gain weight, SSRIs have been successful in helping individuals with anorexia maintain their weight (29). CBT may have a role in the treatment of athletes with anorexia as well. In one randomized controlled trial, 93 weight-restored patients with anorexia receiving CBT were compared with those on fluoxetine (30). No differences were observed in BMI and time to relapse between the two groups. Haldol has been studied in hospitalized patients with AN and has been shown to improve bone mineral density, as well as scores on the Eating Disorders Index (EDI) and the Drive for Thinness (DFT) subscale of the EAT (31).

More recent research has focused upon the role that atypical antipsychotics may play in the treatment of anorexia. One study demonstrated increased weight as well as improved anxiety, depression, and other symptoms associated with eating disorders in patients with anorexia treated with olanzapine (32). The current evidence supporting the use of atypical antipsychotics was sufficient to a level that in 2004 the Australian and New Zealand psychiatric community added it to their official treatment recommendations (33).

Several large-scale clinical trials currently are exploring the uses of augmentation therapies for eating disorders. In these protocols, psychotropic medications are used in an attempt to enhance the effects of an antidepressant. Among the medications studied in this context, lithium has shown the most promising results, with 50% response rates over 2-6 wk when combined with SSRIs or TCAs (34). Doses over 600 mg·d−1 have been used most widely for augmentation. Thyroid hormone also has been used and, in small studies, has been found to be efficacious for augmenting TCAs at low doses of 25-50 mcg·d−1 (35). In general, augmentation approaches are still experimental, and they have been studied most widely in hospitalized patients. Augmentation's role in the treatment of athletes with anorexia is still not clear, and such medications are best prescribed in coordination with a psychiatrist.

Lack of adequate nutrition, especially in an athlete in training and competition, can create secondary dangers to the individual's health. Some special considerations apply to the treatment of eating disorder complications in male athletes. The female athlete triad has been well described in women. It consists of eating disorders, low bone mineral density (BMD), and amenorrhea. All three are thought to be related from epidemiological and pathophysiological standpoints. The relationships between the first two in male athletes are less clear. There is good evidence that male athletes with anorexia demonstrate low BMD. Among male athletes in one recent study, low BMD was correlated significantly with lower BMI, higher activity levels, and low calcium intake (36). Similar other studies have shown lower BMD in adult male distance runners and cyclists (37-39). Low spine BMD has been linked with nutrient energy deprivation in male distance runners, and low-normal testosterone has also been posited as a etiologic factor in low BMD (40,41). Although the evidence suggests that low BMD may be present in male athletes with anorexia, this condition is not equivalent to the osteopenia of the female athlete triad. While female athletes with osteopenia rarely are able to regain significant BMD, data suggest that males recover their BMD as their weights returned to baseline (42).

This observation may have important implications upon treatment of eating disordered male athletes, many of whom may eventually return to normal weights. Many experts observe that male athletes' eating disorders are frequently motivated by the desire to obtain a competitive advantage through weight restriction. These individuals may no longer demonstrate unhealthy eating habits when they are out of season or retire from their sports. Prevention of loss of BMD in both male and female athletes should rest on avoidance of energy deprivation (43). The Energy Availability hypothesis is a helpful tool in counseling athletes around issues related to diet. It postulates that sequelae of eating disorders in athletes result from an imbalance between energy availability from dietary energy intake and energy expenditures from training (44). At-risk athletes should have dieticians available to them to help calculate their energy expenditures so that their energy intake can be matched. Data from Castro et al. (36) additionally imply that supplementing male athletes' diets with calcium may be all that is necessary to ensure their long-term bone health.

RETURN TO COMPETITION

Because of the importance that energy availability plays to the recovery of individuals with eating disorders, issues around an athlete's return to training and competition are complex. An athlete who has been maintaining his weight and is showing signs of recovery might have that progress jeopardized by an early return to a training schedule in which his energy expenditure increases. Currently, no consensus exists around return to play criteria for an athlete with an eating disorder.

In practice, the most successful approach to an athlete with an eating disorder is to avoid restricting practice and play unless the athlete is under an imminent threat of harm from his or her condition. Many athletes, especially those competing on an elite level, will find it more difficult to successfully control their eating disorders if they are removed from their sports. Similarly, team physicians may encounter difficulties in successfully partnering with athletes who are restricted from sport. Instead of pulling the athlete from the emotional support structures within their team, most clinicians find it more helpful to emphasize successful management of these chronic conditions. Instead of threatening disqualification, clinicians can emphasize increasing energy intake to a level that the athlete can maintain participation. It also is important to work with the athlete, coaches, nutritionists, and athletic trainers to determine an athletes' safe weight range. In general, men may tolerate lower body fat more safely than women. While most women must maintain body fat greater than 12% to maintain menstrual function and avoid sequelae of the female athlete triad, it is thought that men typically can safely train and compete at body fats of approximately 5% (45). Regardless of the absolute value of their weight or body fat percentage, the use of regular and accurate training logs can often provide concrete evidence for identifying when insufficient reserves of strength and energy are hindering an athlete's performance. Discussions about nutrition can thus be focused upon performance and not weight gain.

To safely practice and compete, athletes with disordered eating must meet several requirements. They must be willing to partner with their health care team in undergoing regular monitoring and treatment, and they must be able to place their health at a priority over their participation. They must be free of potentially lethal complications of anorexia, and clinicians must monitor them regularly to detect the appearance of any new abnormalities, like signs of cardiac deconditioning, arrhythmias, and electrophysiological abnormalities. Athletes must be able and willing to maintain an adequate diet, and they must successfully replete electrolytes, fluids, and nutrients lost during training and competition (see Table 1 for a complete list of suggested participation criteria). Nutritional markers also should be monitored to alert clinicians when athletes are losing control of their disease. Fluid balance, electrolytes, and other markers for eating disorders should all be regularly checked in afflicted athletes (Table 2).

TABLE 1
TABLE 1:
Suggested guidelines for participation among athletes with eating disorders.
TABLE 2
TABLE 2:
Typical lab abnormalities associated with bulimia and anorexia.

Issues of communication frequently complicate the team physician's care of athletes with eating disorders. Disagreements often emerge in times of crisis. Commonly, when an athlete is showing signs of losing control of his illness and is in danger of disqualification, he may either attempt to appeal individually to members of the health care team or even go outside the normal care team in an attempt to gain permission to continue with participation.

It is essential to establish open and regular communication among all members of the athlete's support group before such challenges arise. Typically, eating disorders are cared for by a team of professionals, including a physician, a mental health professional, and a nutritionist, all of whom see the athlete regularly. Coaches, athletic training staff, and athletic administrative personnel also should be included in regular communication about the athlete's condition. Team physicians must establish and maintain clarity around confidentiality issues so that the entire care team knows what information will be shared and how it will be conveyed.

CONCLUSION

The incidence of eating disorders is increasing rapidly among men, and male athletes represent a special population of those affected. Athletes are most at risk in sports emphasizing leanness or those in which eligibility to compete in a lighter weight category confers an advantage. Long-term complications of eating disorders may differ between men and women, as male athletes may recover to physiologic weights more frequently once factors inciting their disorder are removed. Studies have shown that low bone mineral density tends to resolve in male athletes once their "normal" weight is restored. Treatment approaches generally focus on avoidance of life-threatening complications of eating disorders, maintaining conditions that permit participation, and emphasizing a team approach to the athlete's care. Both psychotherapeutic and psychopharmacologic approaches have shown success in treating eating disorders, although as of yet, no specific studies describe optimum treatments among athletes. More research is needed to describe the causes and treatment of eating disorders among male athletes, and especially to establish safe return to play guidelines for athletes with eating disorders.

References

1. Burckes-Miller, M.E., and D. Black. Male and female college students: prevalence of anorexia nervosa and bulimia nervosa. Athl. Train. J. Natl. Athl. Train. Assoc. 23:137-140, 1988.
2. Johnson, C., P.S. Powers, and R. Dick. Athletes and eating disorders: The National Collegiate Athletic Association Study. Int. J. Eat. Disord. 26:179-188, 1999.
3. Baum, A. Eating disorders in the male athlete. Sports Med. 36:1-6, 2006.
4. Sundgot-Borgen, J. Eating disorders among male and female elite athletes. Br. J. Sports Med. 33:434, 1999.
5. Woodside, D.B., P.E. Garfinkel, E. Lin, et al. Comparisons of men with full or partial eating disorders, men without eating disorders, and women with eating disorders in the community. Am. J. Psychiatry. 158:570-574, 2001.
6. Bruch, H. Obesity, Anorexia Nervosa and the Person Within. New York: Basic Books, 1973.
7. Thiel, A., H. Gottfried, and F.W. Hesse. Subclinical eating disorders in male athletes: a study of the low weight category in rowers and wrestlers. Acta. Psychiat. Scand. 88:259-265, 1993.
8. Biesecker, A.C., and D.M. Martx. Impact of coaching style on vulnerability for eating disorders: an analog study. Eating Disord. 7:235-244, 1999.
9. Thompson, R.A., and R.T. Sherman. Helping Athletes with Eating Disorders. Champaign, IL: Human Kinetic Publishers, 1993.
10. Fogelholm, M., and H. Hilloskorpi. Weight and diet concerns in Finnish female and male athletes. Med. Sci. Sports Exerc. 31:229-235, 1999.
11. O'Connor, P.J., J.D. Lewis, and E.M. Kirschner. Eating disorder symptoms in female college gymnasts. Med. Sci. Sports Exerc. 27:550-555, 1995.
12. Glazer, J.L. Body image and self-esteem in adolescent athletes. Presented at the 17th Annual Meeting of the American Medical Society for Sports Medicine, Albuquerque, NM; April, 2007.
13. Vandereycken, W., and S. Van den Broucke. Anorexia nervosa in males. A comparative study of 107 cases reported in the literature (1970 to 1980). Acta Psychiatr. Scand. 70:447-454, 1984.
14. McCallum, K. Eating disorders. Curr. Opin. Psychiat. 6:480-485, 1993.
15. Patton, G.C., R. Selzer, C. Coffey, et al. Onset of adolescent eating disorders: population based cohort study over 3 years. BMJ. 318:765-768, 1999.
16. Kjelsas, E., K.G. Bjornstrom Cgotestam. Prevalence of eating disorders in female and male adolescents (14-15 years). Eat. Behav. 5:13-25, 2004.
17. Woodside, D., P.E. Garfinkel, E. Lin, et al. Comparison of men with full or partial eating disorders, men without eating disorders, and women with eating disorders in the community. Am. J. Psychiat. 158:570-574, 2001.
18. Thiel, A., H. Gottfried, F.W. Hesse. Subclinical eating disorders in male athletes: a study of the low weight category in rowers and wrestlers. Acta Psychiat. Scand. 88:259-265, 1993.
19. Sundgot-Brogen, J. Weight and eating disorders in elite athletes. Scand. J. Med. Sci. Sports. 12:259-260, 2002.
20. Ribel, S.K., A.W. Subudhi, J.P. Broker, et al. The prevalence of subclinical eating disorders among male cyclists. J. Am. Diet. Assoc. 107:1214-1217, 2007.
21. Ferrand, C., and E. Brunet. Perfectionism and risk for disordered eating among young French male cyclists of high performance. Percept. Mot. Skills. 99:959-967, 2004.
22. DiGioacchino DeBate, R., H. Wethington, and R. Sargent. Sub-clinical eating disorder characteristics among male and female triathletes. Eat. Weight Disord. 7(3):210-220, 2002.
23. King, M.B., and B. Mezy. Eating behavior of male racing jockeys. Psychol. Med. 17:249-253, 1987.
24. National Collegiate Athletic Association: 2002 NCAA Wrestling Rules and Interpretations. Available at: http://www.ncaa.com/uploadedFiles/Sports/Wrestling/wres_2002rulesbook.pdf. Accessed July 20, 2008.
25. Phillips, K.A. The Broken Mirror: Understanding and Treating Body Dysmorphic Disorder. New York: Oxford University Press, 2005.
26. Longeman, J. An athlete's dangerous experiment: using steroids enhanced his physique, but he died trying to stop. New York Times. 26:C15-C16, 2003.
27. Wilson, G.T. Psychological treatment of eating disorders. Annu. Rev. Clin. Psychol. 1:439-465, 2005.
28. Steffen, K.J., J.L. Roerig, J.E. Mitchell, and S. Uppala. Emerging drugs for eating disorder treatment. Expert. Opin. Emerg. Drugs. 11:315-336, 2006.
29. Santonastaso, P., S. Friederici, and A. Favaro. Sertraline in the treatment of restricting anorexia nervosa: an open controlled trial. J. Child. Adolesc. Psychopharmacol. 11:143-150, 2001.
30. Walsh, B.T., A.S. Kaplan, E. Attia, et al. Fluoxetine after weight restoration in anorexia nervosa: a randomized controlled trial. JAMA. 295:2605-2612, 2006.
31. Cassano, G.B., M. Miniati, S. Pini, et al. Six-month open trial of haloperidol as an adjunctive treatment for anorexia nervosa: a preliminary report. Int. J. Eat. Disord. 33:172-177, 2003.
32. Barbarich, N.C., C.W. McConaha, J. Gaskill, et al. An open trial of olanzapine in anorexia nervosa. J. Clin. Psychiatry. 65:1480-1482, 2004.
33. Beumont, P., P. Hay, D. Beumont, et al. Australian and New Zealand clinical practice guidelines for the treatment of anorexia nervosa. Aust. N. Z. J. Psychiatry. 38:659-670, 2004.
34. Bauer, M., M. Adli, C. Baethge, et al. Lithium augmentation therapy in refractory depression: clinical evidence and neurobiological mechanisms. Can. J. Psychiatry. 48:440-448, 2003.
35. Aronson, R., H.J. Offman, R.T. Joffe, et al. Triiodothyronine augmentation in the treatment of refractory depression. A meta-analysis. Arch. Gen. Psychiatry. 53:842-848, 1996.
36. Castro, J., J. Toro, L. Lazaro, et al. Bone mineral density in male adolescents with anorexia nervosa. J. Am. Acad. Child Adolesc. Psychiatry. 41:613-618, 2002.
37. Hetland, M.L., J. Haarbo, and C. Christiansen. Low bone mass and high bone turnover in male long distance runners. J. Clin. Endrinol. Metab. 77:770-775, 1993.
38. Stewart, A.D., and J. Hannan. Total and regional bone density in male runners, cyclists, and controls. Med. Sci. Sports Exerc. 32:1373-1377, 2000.
39. Nichols, J.F., J.E. Palmer, and S.S. Levy. Lower bone mineral density in highly trained master male cyclists. Osteoporos Int. 14:644-649, 2003.
40. Hind, K., A.J. Evans, and J.G. Truscott. Low lumbar spine bone mineral density in both male and female endurance runners. Bone. 39:880-885, 2006.
41. Bilanin, J.E., M.S. Blanchard, and E. Russek-Cohen. Lower vertebral bone density in male long distance runners. Med. Sci. Sports Exerc. 2:66-70, 1989.
42. Castro, J., J. Toro, L. Lazaro, et al. Bone mineral density in male adolescents with anorexia nervosa. J. Am. Acad. Child Adolesc. Psychiatry. 41:613-618, 2002.
43. Zanker, C., and K. Hind. The effect of energy balance on endocrine function and bone health in youth. Med. Sci. Sports Exerc. 51:81-101, 2007.
44. Loucks, A.B., M. Verdun, and E.M. Heath. Low energy availability, not stress of exercise, alters LH pulsatility in exercising women. J. Appl. Physiol. 84:37-46, 1998.
45. Claessens, M., C. Claessens, P. Claessens, et al. Importance of determining the percentage body fat in endurance-trained athletes. Ind. Heart J. 52:307-314, 2000.
© 2008 American College of Sports Medicine