Shane Seroyer MD
Robin West MD
Since the initiation of Title IX of the Educational Assistant Act of 1972, requiring institutions receiving federal funds to provide equal access and funding to males and females in extracurricular activities, there has been an increase in the number of female participants in organized sports. The National Collegiate Athletic Association (NCAA) participation rate increased 69% for females versus 13% for males in a 15-year period after Title IX was passed. This increase in female participation in sports occurred at all levels of competition, from youth through the professional. Female participation in high school sports has increased 10-fold from the 1971–1972 to the 1998–1999 school years. This has been associated with more sports-related injuries in females and heightened awareness of the significance of proper physical training and conditioning in preventing injuries.
As the female athlete has flourished, a variety of gender-specific problems have emerged. The female athlete must contend with some issues unfamiliar to her male counterpart including several disturbing medical and musculoskeletal conditions. In 1993, the American College of Sports Medicine released the results of a consensus conference and coined the term the “female athlete triad,” referring to the troubling syndrome of amenorrhea, disordered eating, and osteoporosis. Compared to males, female Naval Academy cadets were found to have a higher risk for injury from competition in intercollegiate athletics as well as from their military training. And compared to her male counterpart, the female athlete is more commonly affected by patellofemoral disorders, stress fractures of the pelvis and hip, spondylolysis, and noncontact anterior cruciate ligament (ACL) injuries (Table 10-1). The reasons for this predilection to injury remain uncertain. Once known, changes may be possible to improve safety for the female athlete.
Anderson J: The female athlete triad: disordered eating, amenorrhea, and osteoporosis. Connecticut Med 1999;60(11):647.
Arendt E: Anterior cruciate ligament injuries. Curr Women's Health Rep 2001;1:211.
Gwinn DE et al: The relative incidence of anterior cruciate ligament injury in men and women at the United States Naval Academy. Am J Sports Med 2000;28:98.
The Female Athlete Triad
The female athlete triad has received heightened consideration in the past 10 years. The three tenets of this condition—amenorrhea, disordered eating, and osteoporosis—are interrelated. Disordered eating in the athlete can vary from caloric restriction in excess of metabolic requirements to frank anorexia or bulimia nervosa. The latter may consist of self-induced vomiting, diuretic or laxative abuse, or fasting. Current societal pressures, especially the emphasis on appearance, impel many of the athletes to believe that they must sustain a thin, elegant body appearance to succeed or to be accepted. The form-fitting uniforms worn in certain sports such as swimming, gymnastics, and track may compound the issues. Sports in which the contestants are judged may also place an added pressure on the athlete to maintain a certain physical appearance.
There has been a long-noted association between weight loss and amenorrhea. The diagnostic criterion of anorexia nervosa is a weight loss resulting in a total body weight that is below 85% of ideal body weight. Primary amenorrhea, the absence of menstruation in females 16 years of age or older, must be differentiated from secondary amenorrhea, which is defined as the absence of three or more consecutive menstrual cycles after menarche. Athletic amenorrhea is thought to occur as a result of hypothalamic dysfunction. The loss in the normal pulsatile release of the gonadotropins, leutinizing hormone and follicle-stimulating hormone, may be induced by a negative caloric balance. This loss of the pulsatile release of leutinizing hormone and follicle-stimulating hormone acts at the ovaries to suppress the release of estradiol, resulting in the loss or absence of menses.
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Table 10-1. Conditions affecting female more commonly than male athletes.1 |
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Specific fat deposits rather than overall body weight may greatly influence the menstrual status of athletes. Weight regulation practices can reduce fat stores in regions around the hips, buttocks, and thigh, which may be essential for menstruating purposes. Eumenorrheic (ie, normal menstruating) college gymnasts have significantly greater fat stores in the lateral thigh than amenorrheic gymnasts. Menstrual irregularities occur with increasing frequency as exercise loads increase during competitive seasons, and are more prevalent in female athletes who experienced weight loss when compared to those who have maintained their weight during competition.
Much is known about the deleterious health affects of postmenopausal osteoporosis and its associated morbidities. The long-term effects of amenorrhea on the bones of young female athletes are unknown, but may be similar to postmenopausal effects. Amenorrhea is surprisingly common in strenuously exercising females, with a prevalence of nearly 20%. Amenorrheic athletes have significantly lower whole-body bone mineral density than control subjects, placing them at higher risk for injury. Decreases in bone mineral density in athletes who have been amenorrheic for more than 6 months resemble losses seen after menopause. These losses may be irreversible and lead to long-term sequela. Stress fractures have been shown to be significantly more prevalent in amenorrheic runners when compared to eumenorrheic runners, over the same time period with the same training mileage. A recent, large prospective study involving elite endurance athletes found that the rate of femoral bone loss in amenorrheic athletes was twice that found in the first year after menopause in nonathletic women.
Although their risk for stress fracture of the tibia may be equal to their male counterparts, female athletes are at increased risk for stress fractures of the pelvis and hip and for spondylolysis. Although controversial, support exists for the use of oral contraceptives to combat amenorrhea in female athletes in hopes of protecting them from stress fractures. Intervention through changes in life-style, training habits, and caloric intake, or through pharmacologic treatments such as calcium supplementation or hormone replacement, should be undertaken in the amenorrheic athlete to diminish further bone loss and reestablish a normal menstrual cycle.
The criteria for initiating estrogen replacement and the optimal dosing schedule have not been determined. However, the American Academy of Pediatrics
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recommends estrogen supplementation for amenorrheic adolescents if they are 3 years postmenarche and older than 16 years of age. Estrogen replacement should be considered in amenorrheic athletes who are unwilling to make life-style changes, who have been unsuccessful in reestablishing menses with life-style changes, who have been amenorrheic for 6 months or longer, and who have a history of a stress fracture.
Education concerning the dangers of the female athlete triad, as well as preventative strategies to combat its associated disorders, should be provided to all female athletes by their coaches and trainers. Attempts should be made to deemphasize physical appearance related to athletic performance and body fat measurements. A nutritionist should be available to educate athletes as to proper dietary habits and the dangers of inadequate nutrition. Peers should also be made aware of certain physical and behavioral clues that may indicate that a particular athlete is having a problem and may need help. Common warning signs include excessive criticism of body weight or shape, sudden noticeable weight loss, mood swings, depression, compulsive exercise or preoccupation with caloric intake, bathroom visits after meals, use of laxatives, chronic fatigue, anemia, abdominal bloating or upset, delayed wound healing, and frequent musculoskeletal injuries. Websites offered by the NCAA, American College of Sports Medicine, National Eating Disorder Organization, and National Association of Anorexia Nervosa and Associated Disorders provide helpful information on these issues.
Beals KA et al: Understanding the female athlete triad. J School Health 1999;69(8):337.
Braam L et al: Factors affecting bone loss in female endurance athletes. Am J Sports Med 2003;31(6):889.
Anterior Cruciate Ligament Injuries
Anterior cruciate ligament (ACL) injuries occur two to eight times more frequently in female than in male athletes. A study of male and female midshipmen at the United States Naval Academy, all engaged in similar activities, has confirmed this. Although extensively studied, the reasons for this increased risk of ACL injuries in females remain unknown. Possible reasons include hormonal changes during the menstrual cycle, increased joint laxity, a knee structure that includes a narrow femoral intercondylar notch width, improper training and conditioning, and muscle activation patterns, all of which make females more prone to injury.
The role hormones play in ACL injuries is not known. Human ACL cells have estrogen receptors and fluctuations in the circulating concentration of estradiol may contribute to knee stability through the regulation of fibroblasts and collagen synthesis. Female athletes who sustained noncontact ACL injuries and had urine assays taken within 24 hours of injury to confirm the phase of the menstrual cycle had a much higher than expected rate of ACL injury during the ovulatory phase of the menstrual cycle. This phase coincides with a surge in estradiol that could relate to the effect of estrogen on the suppression of fibroblast function and collagen synthesis. But these findings are contradicted by the lack of association between ACL injury and the phase of the menstrual cycle in women taking oral contraceptives. In addition, ACL injuries are more common during the follicular phase of the menstrual cycle and knee laxity does not vary throughout the menstrual cycle.
Factors related to the structure of the knee, including notch width, the Q angle, and knee laxity, may contribute to ACL injury. The mean femoral intracondylar notch width is narrower in females, probably because they are, on average, smaller than males. Patients who sustained ACL tears may have had significantly narrower femoral intracondylar notch widths than uninjured controls. But a concensus conference in 1999 that addressed current available studies regarding notch width and its relation to gender found that the available data were inconclusive with regard to its relationship to ACL injury. It may be that the ratio of ACL size to femoral intracondylar notch width, rather than just the absolute width, is the relevant factor as cross-sectional area of the ACL in female athletes is significantly smaller than in male athletes. Or the femoral intracondylar notch may simply be proportional to the size of the athlete and not be important in causing ACL injury. Further study is needed. The Q angle is the angle created by the line connecting the anterior superior iliac spine and the midpoint of the patella and the line connecting the tibial tubercle and the midpoint of the patella. This angle may be larger in females, possibly due to a wider pelvic base. An increase in this angle may lead to increased medial stress on the knee. No definitive evidence has linked the Q angle to the increased incidence of ACL injuries in females. Joint laxity may also be greater in female athletes, but no causative relationship to ACL injuries has been established.
Many noncontact ACL injuries occur when an athlete lands from a jump, is decelerating, or is executing a cutting maneuver, all of which are performed, on average, in a more erect position in females than in males. These movements are associated with eccentric contraction of the quadriceps muscle. And high velocity, eccentric activation of the quadriceps muscle has long been thought to result in high ACL loads, especially with the knee in extension. Muscle activation patterns during proprioceptive activities and jump training have been studied to determine if there is a correlation with injury. The muscle activation theory contends that there are two main muscular activation or response patterns to anterior tibial translation or stress. In the first, which is quadriceps
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dominant and seemingly more prevalent in female athletes, preferential activation of the quadriceps occurs in response to anterior tibial translation. This action may accentuate the anterior translation and increase the ACL load. In the second, involving muscular activation or response patterns that may be more common in male athletes, hamstring dominant activation or simultaneous hamstring and quadriceps activation occurs. This muscular activation would decrease the anterior translation of the tibia and decrease the ACL load.
If improper training and conditioning as well as muscle activation patterns make females prone to ACL injury, then prevention programs with muscle training with special attention to the hamstrings as well as with proprioceptive training and plyometrics can be instituted. One study involving female high school soccer players showed that formal training of athletes with cardiovascular conditioning, plyometrics, speed drills, strength training, and agility decreased ACL injuries in the trained group compared to an untrained control group. A jump training program was tested to determine its effects on landing mechanics and muscular forces in female athletes. Plyometric training decreases the landing forces and increases the hamstring muscle power in these athletes. These programs may significantly affect knee stabilization and prevent knee injuries in female athletes.
Anderson AF et al: Correlation of anthropometric measurements, strength, anterior cruciate ligament size, and intercondylar notch characteristics to sex differences in anterior cruciate ligament tear rates. Am J Sports Med 2001;29:58.
Arendt E: Anterior cruciate ligament. Curr Women's Health Rep 2001;1:211.
Belanger MJ et al: Knee laxity does not vary with the menstrual cycle, before or after exercise. Am J Sports Med 2004;32(5): 1150.
Griffin LY et al: Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg 2000;8:141.
Heidt RS et al: Avoidance of soccer injuries with preseason conditioning. Am J Sports Med 2000;28(5):659.
Huston LJ et al: Anterior cruciate ligament injuries in the female athlete. Clin Orthop Rel Res 2000;372:50.
Myklebust G et al: Prevention of anterior cruciate ligament injuries in female team handball players: a prospective intervention study over three seasons. Clin J Sport Med 2003;13:71.
Wojtys EM et al: The effect of the menstrual cycle on anterior cruciate ligament injuries in women as determined by hormone levels. Am J Sports Med 2002;30(2):182.
Patellofemoral Disorders
Patellofemoral disorders, described in more detail in Chapter 3, are more common in female than male athletes and are multifactorial in origin. This may be related to an increased Q angle, femoral anteversion, ligamentous laxity, external tibial rotation, forefoot pronation, and vastus medialis obliquus (VMO) dysplasia. Patellar disorders including lateral patellar compression syndrome and patellar instability are more common in females than males. These disorders are diagnosed by clinical examination, radiographs, and sometimes additional tests such as computed tomography (CT), magnetic resonance imaging, and bone scans.
Acute patellar dislocations can be treated with rehabilitation if there is no evidence of osteochondral injury and the patella is well centered after closed reduction. Recurrent instability often requires surgical intervention, including a proximal (eg, release of the lateral parapatellar retinaaculum and occasionally an imbrication of the medial parapatellar retinaaculum) and a distal (eg, tibial tubercle) realignment. Isolated lateral patellar compression syndrome can usually be treated with VMO strengthening, orthotics, patellar taping, and mobility. If after 3 months of rehabilitation the symptoms of lateral patellar compression do not improve, syndrome, a release of the lateral parapatellar retinaaculum can be performed. Hamstring stretching is also important in the treatment of patellofemoral disorder as it may decrease joint contact forces.
Multidirectional Shoulder Instability
Multidirectional shoulder instability (MDI), described in more detail in Chapter 5, is another problem more common in female than male athletes. It is a complex entity characterized by glenohumeral instability in two or more directions: anterior, inferior, or posterior. It may be more common in gymnasts and swimmers than in other athletes. A thorough physical examination reveals the sulcus sign and evidence of anterior and/or posterior instability. Imaging may reveal a patulous capsule that allows an increase in capsular volume. An incompetent rotator interval may also contribute. Rehabilitation aimed at improving muscle tone and coordination may result in a nearly 90% success rate. Failure after 6 months of such therapy in a compliant patient may be an indication that a surgical procedure, done with either an open or arthroscopic technique, should be performed. A goal is to tighten the patulous capsule.
Beasley L et al: The athletic woman: multidirection instability of the shoulder in the female athlete. Clinics Sports Med 2000;19(2):331.
Stress Fractures
Another problem more common in female than male athletes is stress fractures. Stress fractures of the spine are discussed in more detail in Chapter 7. Spondylolysis, a stress fracture of the pars interarticularis of the vertebra, is more
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common in persons who participate in hyperextension activities such as dance, gymnastics, and diving. Progression to spondylolisthesis (ie, slippage of the vertebra) is also more prevalent in females. Athletes with this problem present with intermittent back pain that is usually associated with a specific activity. It may be diagnosed with plain radiographs and is most common at L5. Low-grade spondylolisthesis may be responsive to nonoperative treatment including rest, bracing, and physical therapy in up to 80% of athletes. The athlete may return to play when she is pain and symptom free. Higher grade slips (25–50%) may preclude an athlete from participating in hyperextension-type activities. Spondylolisthesis, with slips greater than 50%, and persistent pain with spondylolysis are conditions that may require surgical intervention, such as a spinal fusion. Athletes with spondylolisthesis may need to have their condition evaluated by a spine specialist before being allowed to return to play.
Stress fractures of the pelvis and hip are also more common in female than in male athletes. Pubic rami and femoral neck fractures are of particular concern in female athletes. The athlete with either of these conditions may present with pain in the groin, pain with activity, and limited ability to participate in particular activities. They can be easily mistaken for muscle strains or soft tissue injuries. Athletes affected by the “female athlete triad” are predisposed to stress fractures as decreased bone mineral density puts them at risk for these fractures. The etiology of the vertical stress fracture in the pubic rami is thought to be multifactorial and related to tight adductor musculature, crossover running style, and overstriding with running. Athletes with femoral neck stress fractures may, in addition, complain of anterior thigh pain in the distribution of the obturator nerve. Clinically they may have an adductor lurch with gait and experience pain with passive range of motion. They should remain nonweightbearing pending orthopedic evaluation. A stress fracture on the laterally based tension side (as opposed to the medial compression side) of the femoral neck has an increased risk of progression into complete fracture and warrants surgical intervention. Rest, physical therapy, and temporary withdrawal from participation in sport are the mainstays of treatment. The patient should not be allowed to return to play until she is pain free and has clinical and radiologic evidence of healing. This may take up to 3–4 months.
Pregnancy & Exercise
In the past there had been concern that the physiologic responses to exercise during pregnancy could lead to fetal malformation, poor fetal growth, and premature labor. There were also concerns that poor fetal and maternal outcomes could result from the combined effects of exercise and the pregnancy-induced changes in hemodynamics, body temperature, circulating stress hormones, and caloric expenditure. However, these concerns have not been validated.
The physiologic effects of combining exercise and pregnancy are different than anticipated. The combination of pregnancy and exercise produces a maternal physiologic change in response to conditions of metabolic, thermal, cardiovascular, and mechanical stress. This change produces an extended margin of safety for both the mother and baby. Exercise and pregnancy have a synergistic effect by increasing maternal blood volume, heart chamber volumes, maximum cardiac output, the ability to dissipate heat, and the delivery of oxygen and nutrients to the tissue. Not only are cardiovascular, thermal, and oxygenation improvements made by both exercise and pregnancy, glucose and oxygen supplies for the baby are improved under most circumstances if the mother eats adequately and regularly. The musculoskeletal and ligamentous effects of regular exercise also protect the mother from injury and symptoms.
The maternal benefits of regular exercise during pregnancy are numerous. Fit women who continue to perform weight-bearing exercise throughout pregnancy and lactation at or above 50% of their prepregnancy levels have less weight gain, deposit and retain less fat, feel better, have shorter and less complicated labors, and recover more quickly postpartum.
The fetal benefits of regular maternal exercise are also plentiful. Infants of mothers who exercised during pregnancy have been shown to have fewer signs of distress, a decreased incidence of meconium-stained amniotic fluid, and a decreased risk in abnormal fetal heart rate patterns. APGAR scores of infants born to mothers who exercise are similar or higher than scores of infants born to sedentary mothers. Infants born to mothers who exercise when compared to infants born to sedentary mothers are more alert and more able to quiet themselves after exposure to stimuli. At 1 year of age, children of mothers who exercise had slightly better motor skills. At age 5, they were leaner and performed better on standardized tests of intelligence than the controls.
Healthy women with an uncomplicated pregnancy may safely continue or begin a regular exercise program during pregnancy. Maternal symptoms should dictate the intensity of exercise. The supine position should be avoided since it may lead to decreased cardiac output. Activities such as martial arts, which may cause abdominal trauma, should be avoided. Relative contraindications to exercise during pregnancy include bleeding in early pregnancy, anemia, arrhythmias, and an extremely overweight or underweight mother. Absolute contraindications include preterm labor, ruptured membranes, pregnancy-induced hypertension, persistent
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bleeding after 12 weeks, incompetent cervix, poor fetal growth, or multiple-birth pregnancy (Table 10-2).
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Table 10-2. Absolute contraindications to exercise in pregnancy.1 |
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ACOG Committee Opinion No. 267: Exercise during pregnancy and the postpartum period. Obstet Gynecol 2002;99:171.
Clapp JF: Exercise during pregnancy: a clinical update. Clinics Sports Med 2000;19:273.
Clapp JF et al: Neonatal behavioral profile of the offspring of women who continued to exercise regularly throughout pregnancy. Am J Obstet Gynecol 1999;180:91.
Conclusion
The Title IX Education Assistant Act of 1972 has had a profound impact on female athletes. Marketing of their sports has resulted in female athletes who are sports icons and role models. Female youth now share the same professional athletic dreams and ambitions as their male counterparts. Increased opportunities for these young women have also contributed to a healthier, more fit society. But this is not without consequence. Several musculoskeletal and medical conditions that frequently occur in females have resulted. Most alarming of these trends is the “female athlete triad.” This condition, with devastating medical, physical, and emotional consequences, can be life-threatening. Fortunately, it is preventable through education, close monitoring, and deemphasizing certain societal pressures. The female athlete also has a predilection for ACL injuries as well as an increased incidence of stress fractures and patellofemoral disorders.
As the population of female athletes has increased, more research has been done to study their medical and musculoskeletal disorders. Our understanding of these conditions has already increased dramatically. For example, the healthy pregnant female with an uncomplicated pregnancy is now encouraged to exercise. Significant maternal and fetal benefits from exercise have been identified. In the future, a better understanding of injuries that have a predilection for female athletes will aid in preventing and treating these injuries in athletes of both genders.