A Gynecologic Perspective of

 The Young Female Athlete

By Susan J. Spencer, M.D.

Several decades ago, in a year that shall remain nameless, I attended a local, private all-girls’ high school. I remember wondering then, “Why is it that my PE classes consist of volleyball or swimming, but my brothers (at the local, private all-boys’ high school) have a choice of football, baseball, basketball, tennis, track and field, swimming, and wrestling?” It’s not that I aspired to the wrestling team, but I was bothered by the inequality of access to sports for women.

Thankfully, things have changed. Although my high school hadn’t quite caught up, the passage of Title IX of the Federal Educational Assistance Act in 1972 mandated equal support for male and female sports. Now girls are participating in a wide variety of sports in grade school and high school. Given the epidemic of obesity in the United States, this is fabulous. In fact, in the last 20 years, the NHANES (National Health and Nutrition Examination Survey) studies have shown a doubling of the prevalence of individuals over the 95th percentile in childhood and adolescence. The concept of “super-size me” is alive and unwell in our country.

Exercise is good, but are there potential health concerns for the young female athlete?

From the gynecologic perspective, there are potential reproductive health concerns for the adolescent engaged in strenuous sports. Back in 1970, Rose Frisch published in Science the seminal paper on the link between body fat and the initiation of menstruation (menarche).1 Her key observation was that late-maturing girls gain fat more slowly. Her research established the hypothesis that menarche, as well as maintenance of menstrual function, is related to the per-centage and absolute amount of body fat. We now recognize that there is a link between extremely vigorous physical activity in female athletes and menstrual dysfunction. The term “exercise-induced amenorrhea” has been used to describe the suppression of central nervous system pulsatile hormone secretion by the stress of vigorous exercise and concomitant negative energy balance.

Female Athlete Triad

In 1992 The American College of Sports Medicine coined the term “Female Athlete Triad.” This syndrome is defined as disordered eating, osteoporosis, and amenorrhea that occurs in women engaged in regular strenuous exercise or sports activities.2 For those of you accustomed to acronyms, I do not believe the authors wish to refer to the syndrome as “FAT.”

In the young female athlete, weight can become a preoccupation. Abnormal eating behaviors may arise in young women, but most vulnerable are those involved in athletic activities that are weight-bearing and favor leanness for performance, such as ballet and gymnastics.

At what age are these young girls becoming concerned with weight? By the age of 10 years there is a demonstrable difference in concern about eating and weight between girls and boys.3 One study showed that by fifth grade 31 percent of girls are dieting, and by sixth grade, 62 percent are dieting to lose weight.4 Thus it appears that attempts to diet in an effort to control weight are common in prepubertal and pubertal girls. All it takes is a glance at Teen Vogue or Britney Spears’ latest video to realize that young girls are bombarded with images that reinforce abnormal eating patterns. Other factors thought to increase a young athlete’s risk for the disordered eating component of this triad include frequent weigh-ins, an overcontrolling parent or coach, and the social isolation of individual sports compared with team sports.2,5

As one might expect with peripubertal dieting, nutrition suffers and calcium intake is decreased.3,6 Since this is a time of bone accrual, lowering of peak bone mass can occur, with long-term implications for predisposition to osteopenia, osteoporosis, and bone fracture. Low bone density predisposes to stress fractures. Joint architecture in the female athlete may predispose her to orthopaedic injuries, such as anterior cruciate ligament tears. These concerns are discussed by the orthopaedic expert’s article in this issue (See Page 7).

Weight-Bearing Sports

Young women in weight-bearing sports that require leanness for peak performance (e.g., ballet, gymnastics, long-distance running) report a higher incidence of delayed menarche and menstrual irregularities compared with nonweight-bearing sports (e.g., swimming) that do not emphasize leanness.7 It appears that body fat composition (as suggested by Rose Frisch) as well as intensity of exercise are important in causing menstrual disruption. With regard to gynecologic manifestations of the female athlete triad, menstrual disruption is a continuum. With progressive weight loss, there may at first be a subtle luteal phase inadequacy, or shortening of the interval from ovulation to menses. As exercise intensity increases and weight decreases, there is increased frequency of anovulation, and the young woman begins “skipping cycles” (oligomenorrhea). Over time, estrogen levels can decline to the point that menstruation ceases (amenorrhea).

Regular menstrual cycles require rhythmic pulsatile release of gonadotropin releasing hormone (GnRH) from the hypothalamus. Disruption of hypothalamic GnRH signals reduces FSH (follicle stimulating hormone) release from the pituitary, which reduces ovarian folliculogenesis, which reduces estrogen production. Low body fat means reduced peripheral (adipocyte) aromatization of androgen precursors to estrogen, further lowering total estrogen levels.

What signals in the young athlete initiate the disruption of GnRH pulsatility? In other words, how is excessive exercise linked with reproductive dysfunction? It is known that nutritional and other metabolic stresses suppress GnRH pulsatility. Neuroendocrine adaptation to marginal energy intake is the basis of cycle disruption seen in young athletes. Recently, research has focused on leptin, a hormone secreted by adipocytes, which has been implicated in the initiation of puberty and may play an important role in hypothalamic amenorrhea.8,9,10 Leptin levels are lower in women who exercise and have low body fat. Leptin receptors also have been found in bone and may have a regulatory role in osteoblast function, which portends great significance for the young amenorrheic athlete. Replenishment of leptin to food-restricted primates restores GnRH pulsatility, underscoring the reversible nature of the neuroendocrine dysregulation.

How Might a Young Woman with the Female Athlete Triad Present?

The first element of the triad is disordered eating. Women are nine times more likely than men to develop eating disorders. Of the general female population, 1 percent to 3 percent has anorexia or bulimia nervosa, and 15 percent to 62 percent of young female athletes suffer from disordered eating.2 Young women with disordered eating are generally thin and focused on their food and fat intake. Identification of disordered eating in an adolescent is extremely important and requires expert intervention.

The second element of the triad is skeletal problems. Development of osteopenia is a silent process. Young women with Female Athlete Triad who experience delayed menarche because of exercise may fail to reach their peak bone mass. Neither calcium nor weight-bearing exercise compensate for lack of bone accrual in late maturing adolescents.11 Stress fractures may occur in weight-bearing cortical bone. Painful fractures can sometimes be dismissed as “shin splints” or growing pains but can be identified radiographically.

The third element of the Female Athlete Triad is amenorrhea. Girls who exercise heavily at a young age (training as young as age 8 or 9) may present with primary amenorrhea. Primary amenorrhea is the absence of menses by age 16 years in a female with secondary sex characteristics. Secondary amenorrhea is the cessation of menses for three or more consecutive cycles. The prevalence of amenorrhea in the general population is around 5 percent. However, the prevalence in competitive athletes ranges from 25 percent to 65 percent. 12 All appropriate differential diagnoses must be considered; exercise-induced amenorrhea is a diagnosis of exclusion. It is important to rule out pregnancy as well as thyroid dysfunction, ovarian failure, polycystic ovarian syndrome, and CNS tumors such as prolactinoma. The diagnosis of hypothalamic amenorrhea is suggested by low FSH and LH levels. If a progestin challenge (10 days of oral progestin) fails to induce withdrawal bleeding, the patient is likely hypoestrogenemic, lacking sufficient endogenous estrogen to grow enough endometrium to shed.

Management of menstrual dysfunction depends on several factors, including the athlete’s age, intensity of training, and caloric intake. Decreasing intensity of training and improving nutritional status are crucial steps in reversing the pattern of menstrual irregularity. Since oligomenorrhea is correlated with low bone density, calcium supplementation and adequate vitamin D intake are essential for bone health. Consideration should also be given to hormonal therapy, such as a low dose oral contraceptive, for cycle regulation and bone density protection.

In summary, there are potential health risks for young women in strenuous sports and exercise programs. Physicians and parents need to be cognizant of the Female Athlete Triad. Supportive care for the adolescent, with collaboration between pediatrician, gynecologist, orthopaedist, and parents, greatly enhances recovery. 

Dr. Spencer practices obstetrics, gynecology, and reproductive endocrinology in San Mateo.

References:

1. Frisch, RE; Revelle, R. Height and weight at menarche and a hypothesis of critical body weights and adolescent events. Science 1970; 169:397-399.

2. Nattiv, A et al. The female athlete triad. The inter-relatedness of disordered eating, amenorrhea, and osteoporosis. Clin Sports Med 1994; 13(2):405-418.

3. Javier-Nieto, F et al. Childhood weight and growth rate as predictors of adult mortality. Am J Epidemiol 1992; 136:201-213.

4. Neumark-Sztainer, D; Hannan, PJ. Weight-related behaviors among adolescent girls and boys: results from a national survey. Arch Pediatr Adolesc Med 2000; 154:569-577.

5. Schreiber, GB et al. Weight modification efforts reported by black and white preadolescent girls: National Heart, Lung and Blood Institute Growth and Health Study. Pediatrics 1996; 98:63-70.

6. Warren, MP; Shantha, S. The female athlete. Ballieres Clin Endo Metab 2000; 14(1):37-53.

 7. Hobart, JA; Smucker, DR. The female athlete triad. Am Fam Phys 2000; 61:3357-3364.

8. Warren MP et al. Functional hypothalamic amenorrhea: hypoleptinemia and disordered eating. J Clin Endocrinol Metab 1999; 84:873-877.

9. Laughlin, GA; Yen, SSC. Hypoleptinemia in women athletes: absence of a diurnal rhythm with amenorrhea. J Clin Endocrinol Metab 1997; 82:318-321.

10. Miller, KK et al. Decreased leptin levels in normal weight women with hypothalamic amenorrhea. J Clin Endocrinol Metab 1998; 83:2309-2312.

11. Jonnavithula, S et al. Bone density is compromised in amenorrheic females despite return of menses: A 2-year study. Obstet Gynecol 1993; 81:669-674.

12. Warren, MP. Health issues for women athletes: Exercise-induced amenorrhea. J Clin Endocrinol Metab 1999; 84(6):1892-1898.