Besides the obvious physical and physiological differences between the genders, there is also a difference in terms of acquired problems that can be associated with sport and activity. One such difference is the “female athlete triad”. The triad consists of three different problems , including eating disorders (anorexia and/or bulimia), menstrual irregularities and reduced bone mass.

Eating disorders, and their less problematic counterparts, disordered eating, are a constellation of symptoms that centre around abnormal food intake. There has been considerable discussion regarding the relationship between intense athletic activity and eating disorders. While a direct connection is unlikely i.e. one does not cause the other, the emphasis on thinness, especially in sports like gymnastics, ballet, figure skating and endurance athletics, may lead to an increased incidence of these disorders in susceptible individuals. Pressure from coaches, parents and other competitors may also contribute to disordered eating, and eventually to the full blown syndromes of anorexia and/or bulimia, the classic eating disorders. Hallmarks of anorexia include abnormal preoccupation with and perception of body image, over-exercising, use of diuretics/laxatives/stimulants for weight control and abnormally low body mass index (BMI). Bulimia is known mostly for the binge and purge cycles common in afflicted individuals, which may include ingestion of large amounts of calories followed by self-induced vomiting. It may also be accompanied by use of laxatives/diuretics/stimulants. There is often overlap between these two classic eating disorders.

Menstrual irregularities include amenorrhea (absent menstruation, fewer than three cycles per year or no cycles for the past six months) and oligomenorrhea (irregular menstruation, three to six cycles per year). In a pre-menopausal female who is athletic, menstrual irregularities should not automatically be assumed to be exercise related. The most common cause of this problem is pregnancy, but other potential causes include anorexia nervosa, thyroid disease, psychological stress, various drugs and post birth control pill, among others. It should always be borne in mind by any female that normal menstruation is an important indicator of health and hormonal balance. While this process poses some obvious disadvantages and problems known well to most women, normal, cyclical menstruation is a hallmark of female health.

The incidence of these problems is increased in sporting populations in that 10-20% of female athletes in general and as many as 50% of distance runners experience menstrual problems; this is contrasted to 5% in the general population. Assuming that an active ammenorrheic female has no other reason for this problem, why does this condition happen at all? One theory proposes that there is inhibition of the normal hormonal secretion (follicle stimulating hormone and leutinizing hormone) required for menstruation secondary to elevated cortisol levels, a stress hormone secreted by the adrenal gland. Cortisol may be elevated in response to both psychological and physiological stress, features of many athletes. There does appear to be a relationship between menstrual irregularities and the level of exercise performed. Another theory suggests that caloric intake may not match output, again having an inhibiting effect on normal hormonal secretion. And yet another theory proposes that body fat in these athletes may be too low to support normal hormone profiles, as fat is responsible for producing some of the active form of estrogen (estradiol) that circulates in females. Normal estrogen levels are important in optimizing menstrual function. In all probability, all of these proposed mechanisms play some role.

Complications of Exercise Associated Menstrual Cycle Irregularities

There are two major problems associated with menstrual cycle irregularities:

Reduced Fertility

There is an increased incidence of reduced fertility in intensely exercising females compared with their sedentary counterparts. These females may have trouble ovulating (anovulatory cycles), even in spite of having the appearance of a normal period with normal menstrual blood flow. A good indication that ovulation has occurred mid-cycle is a rise in basal body temperature of .2-.6 degrees Celsius that remains elevated until menstruation. If repeated anovulatory cycles occur, and pregnancy is desired, a reduction in activity levels and/or allowing an increase in body fat percentage are the first steps. Failing this, fertility counselling for both partners is indicated, as the male may contribute to infertility from 20-30% of the time.

Reduced Bone Mass

The third part of the female athlete triad is reductions in bone mass, either minimal (osteopenia) or moderate to severe (osteoporosis). Several studies have confirmed the presence of lower axial (spine/pelvis) bone density in oligomenorrheic and amenorrheic athletes. Peripheral bone mass (limbs) may also be affected, but this has been a less consistent finding.

Bone is lost rapidly in the first two-three years following onset of menstrual disturbances at a rate of approximately 4%/year. After this time, bone loss slows down, but nonetheless continues. It is thought that below normal estrogen levels are the most important determinate of this phenomenon. Compared to normally menstruating females, estradiol (the active form of estrogen) levels in amenorrheic athletes resemble post-menopausal women. An additional important contributor is under nutrition.

Reduced bone mass in these athletes is important from the perspective of increasing the risk of both stress fractures and post-menopausal osteoporosis. It should be emphasized that the higher one’s bone mass is to begin with, the lower the risk for development of these problems. Bone mass accrues mostly during the period between 10-30 years old, with peak accrual usually by the late teens/early twenties. Abnormal menstrual cycles during this period is, therefore, most problematic from a bone formation point of view. Besides estrogen levels, other related factors determining peak bone mass include genetics, nutrition (especially calcium intake) and exercise. Once lost, it appears possible to regain at least some of the lost mass over a several year period after resumption of normal menstrual cycles. However, it is questionable as to whether or not full recovery of lost mass occurs. As always, prevention is the best approach!

Preventing the Female Athlete Triad

In summary, the female athlete triad is a prevalent problem amongst active females. Eating disorders, menstrual irregularities and reduced bone mass are all conditions to be avoided, and avoidance starts with education. Understanding the pressures on female athletes regarding body image and body weight is important. Most major centres have eating disorder specialists/clinics to help those affected-these problems are difficult to treat at the best of times.

The influence of excess activity and abnormal nutritional intake on menstruation, fertility and bone mass is also important to understand. In athletic women especially, emphasis on appropriate caloric intake for activity levels, coupled with sufficient calcium intake to support normal bone formation, are important. Active premenopausal females should aim for 1000-1250 mg/day of elemental calcium, along with 400 IU/day of vitamin D, especially in winter months when lack of sunlight reduces our natural ability to make our own vitamin D. This vitamin is instrumental in helping our bodies absorb calcium. Counselling on these issues is best provided by naturopaths or dieticians with an interest in the needs of athletes.

Ensuring ovulation is occurring via basal body temperature readings is helpful in assessing normal menstrual function. If abnormal menstrual function exists, and the athlete is unwilling to change eating habits and/or activity levels to try to correct this, one way to increase estrogen levels is via use of the oral contraceptive pill. This should be guided by blood work that shows deficient estrogen levels. Pharmacological manipulation of estrogen levels is, of course, less desirable than allowing menstruation to occur normally, unless contraception is also desired. Also, use of the pill in this regard to try to raise estrogen levels may not always have a positive effect on bone mass, according to some studies. Finally, in some circumstances, medication to directly enhance the accrual of bone mass can be prescribed. Collectively known as “bisphosphonates”, these medications are currently being used in the treatment of osteoporosis. Your sports medicine specialist or family doctor can help direct you in these matters.

Douglas Stoddard  MD, M Sport Med, Dip Sport Med, ES
Medical Director-e load Corporation
Medical Director-Toronto Sports & Exercise Medicine Institute (SEMI)  Printed: September 2001
Copyright ©2001 SEMI