Jan 29, 2015
Triple Threat

Twenty years ago, no one knew the female athlete triad existed. Ten years ago, we started to understand its significance. Today, new research is bringing it even more into focus.

By Dr. Nancy Williams

Nancy Williams, ScD, is Associate Professor of Kinesiology and Co-Director of the Women’s Health and Exercise Laboratory at Pennsylvania State University. She has conducted over 20 years of research into the effects of exercise on the menstrual cycle, and has published numerous papers on the female athlete triad. She currently serves as the interim President of the Female Athlete Triad Coalition (www.femaleathletetriad.org), and can be reached at: [email protected].

Since the female athlete triad was first identified in the early 1990s, the sports medicine community has learned a great deal about its causes, symptoms, and risk factors. Studies involving many different types of athletes have provided valuable and sometimes surprising insight that has helped females perform better, and more importantly, stay healthier. And the best news is that the inquiry continues.

In this article, I’ll provide an overview of the latest research and explain what it has taught us about the nature, prevalence, and progression of the triad. I’ll also discuss how this new knowledge can improve the way you approach prevention and treatment of triad symptoms with athletes in your program.


A major step forward in recent years has been the emergence of a new model for understanding the triad. Originally, the three components of the illness–disordered eating, low bone mass, and amenorrhea–were thought of as parts of the same sequence. If an athlete suffered from one component of the triad and didn’t address it, the condition would likely progress until she developed the other two. In the new model, however, each component exists on its own independent spectrum. Whether an athlete has an eating disorder, for instance, is not a “yes” or “no” proposition. Instead, her nutritional intake must be evaluated, accounting for her metabolism and activity level to determine whether she is fully meeting her energy demands.

At the healthy ends of the three spectrums are optimal energy availability, optimal bone health, and eumenorrhea (the presence of normal, ovulatory menstrual cycles). At the opposite ends are the pathological conditions associated with each triad component: low energy availability (with or without an eating disorder), osteoporosis, and functional hypothalamic amenorrhea.

Studies have shown that many female athletes display intermediate or “subclinical” presentations of one or more triad conditions, and that progression along the three spectrums can occur at different rates. For example, an athlete may show signs of restrictive eating but not meet the clinical criteria for an eating disorder. She may also display subtle menstrual abnormalities, such as anovulation, luteal phase defects, and/or changes in cycle length, but not consider herself amenorrheic. Likewise, she may be losing bone, but not yet have dropped below her age-matched normal range for bone density.

While each of the three spectrums is unique, there are clear correlations between them, and the presence of one element of the triad raises the likelihood an athlete is suffering from others (see The Triad Spectrums for an illustration of these relationships). For instance, stress fractures and overuse injuries are not necessarily part of the bone health spectrum, but the strong association between these injuries and menstrual disorders suggests that they can be a symptom of the triad.


In light of this new model, researchers have also taken a fresh look at the prevalence of the triad’s three conditions, though more research is still needed in this area. Not surprisingly, the data vary widely depending on the sport and the definitions used.

One study that used the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) to define eating disorders found that such disorders were present in 31 percent of elite female athletes in “thin-build” sports (such as gymnastics and distance running), compared to 5.5 percent of non-athletes. Another study found that 25 percent of elite female athletes in aesthetic, weight class, and endurance sports had clinical eating disorders compared to nine percent of the general population. Overall, disordered eating occurs most frequently in sports where leanness and low body weight are most emphasized and valued.

Delayed menarche, or primary amenorrhea, affects less than one percent of the general population, yet research has found that it is experienced by 22 percent of gymnasts, divers, and cheerleaders. Secondary amenorrhea (disordered menstruation post-menarche) rates vary widely depending on the sport, and are also affected by age and body weight. In runners less than 15 years from the time of menarche, amenorrhea is much more common (affecting 67 percent of athletes) than among those whose reproductive age is greater than 15 years (nine percent). Some studies have found amenorrhea rates to be as high as 69 percent in dancers and 65 percent in long-distance runners, while affecting only two to five percent of the general population. Subclinical (less pronounced) menstrual disturbances, such as anovulation and luteal phase defects, can occur even in women who have normal-length menstrual cycles. One study found that up to 78 percent of exercising women experienced such disturbances.

In numerous studies, bone mineral density (BMD) has been lower in amenorrheic athletes than in eumenorrheic athletes. Bone loss has also been observed with more subtle menstrual abnormalities. While no research has yet determined the minimum number of normal menstrual cycles per year necessary to prevent bone loss, irregular cycle lengths–as well as a history of irregular cycle lengths–have been associated with reduced BMD.

When researchers evaluate bone loss and low bone mass, they often use the criteria established by the World Health Organization, which are based on comparing individuals’ bone density with that of an average healthy 30-year-old of the same gender and ethnicity. Osteopenia (low bone mass, a common precursor to osteoporosis) is diagnosed if someone’s BMD falls between 1.0 and 2.5 standard deviations below the mean (T score: -1.0 to -2.5). Osteoporosis is diagnosed if BMD falls 2.5 standard deviations below the mean or lower (T score: < -2.5).

Using this standard, recent studies have found that between 22 and 50 percent of female athletes suffer from osteopenia (compared with 12 percent of the general population), and up to 13 percent of female athletes suffer from osteoporosis (compared with 2.3 percent of the population). While these statistics are certainly cause for concern, it’s important to note that there are currently no epidemiological data directly linking fracture risk to low BMD in adolescents and pre-menopausal women. More research needs to be done to determine the risk of fracture in young athletes as it relates to BMD.

In terms of bone health assessment, the International Society of Clinical Densitometry (ISCD) recently redefined its osteoporosis criteria for pre-menopausal women. Now, osteoporosis can be diagnosed if an individual’s bone density falls at least two standard deviations below average (Z score: < -2.0) and there is at least one secondary clinical risk factor, such as chronic malnutrition, an eating disorder, hypogonadism, glucocorticoid use, or previous fractures.

This new standard has been widely accepted in some medical fields, but it may not be a perfect fit for female athletes, whose average bone density should be greater than that of the general population. The American College of Sports Medicine recommends that athletes whose bone density falls one to two standard deviations below average (Z score: -1 to -2) should be diagnosed as having low bone mass. A bone density (DXA) test result in this range is serious enough to warrant a referral for treatment.


These statistics show the prevalence of each element of the female athlete triad, but for a more complete understanding, we must also consider how the three components relate to one another. An important feature of the new model is the way it acknowledges a connection between the triad’s individual parts.

How many athletes suffer from the full triad? Using the new ISCD criteria, one study found the prevalence of all three components in elite athletes from a wide variety of sports to be similar to the control group (4.3 vs. 3.4 percent). But in that study, the control subjects were not strictly “non-athletes”–they exercised an average of five hours per week. Additionally, every triad-positive control group member was overweight and had a history of pathological weight loss behavior. Two other studies have found the existence of all three triad components among 2.7 percent of female college athletes and 1.2 percent of high school athletes.

Researchers are also examining the relationships between the triad components. Studies have determined that a primary cause of triad-related menstrual abnormalities and bone loss is chronic energy deficiency and low energy availability. This demonstrates how an athlete suffering from one element of the triad is putting herself at risk for the other two.

Because an athlete’s energy supply can be consciously manipulated (unlike bone density and menstrual regularity), it deserves special attention in this discussion. Low energy availability occurs when there is a negative imbalance between energy intake and energy expenditure–it doesn’t matter if the imbalance is due to restriction of calories or increased training. Recent studies have attempted to define a threshold of energy availability below which the body attempts to suppress reproductive function, resulting in amenorrhea, but no firm conclusion has been reached.

Some research suggests that if an athlete eats “normally” (the average amount for her body weight), she should be able to perform the equivalent of running up to eight miles per day without compromising reproductive hormone secretion. However, other studies have shown menstrual irregularities in recreationally active women who run about 12 km (about 7.5 miles) per week, which most people would not consider intense training. In those studies, the women’s diets did show some evidence of restriction, which further reinforces the idea that nutrition plays a key role in triggering other triad-related symptoms.

For good reason, then, most educational efforts aimed at preventing the triad focus on disordered eating. A comprehensive approach should include not only clinically recognized eating disorders, such as anorexia nervosa and bulimia nervosa, but also subclinical disordered eating. The latter category includes many athletes who don’t meet the criteria for an eating disorder but display a preoccupation with body weight and a poor body image, which can lead to practicing pathological eating behaviors.

Furthermore, it’s important to remember that athletes can experience low energy availability even if they’re not consciously restricting their diet at all. These athletes simply don’t take in enough calories to match their energy expenditure. A busy class schedule, travel, stress, and other factors can prevent female athletes from maintaining adequate energy for training, and because reliable biomarkers for low energy availability aren’t available for practical use in the field, these athletes (who do not present with disordered eating symptoms or behaviors) are often overlooked in discussions of the triad.

The importance of energy deficiency as a cause of menstrual disruptions is now more apparent than ever. Conventional wisdom used to hold that the stress of physical exercise itself was the cause of menstrual disturbances and bone loss, but the latest research is challenging those assumptions. In fact, we now know that exercise is a positive stimulus for bone, and female athletes should score higher on average than their age-matched non-athletic peers in measurements of bone density.


What does this new research mean for those who work with competitive female athletes every day? One key finding is that an athlete does not need to reduce her training to avoid the triad or to resume normal menstrual cycles if she is amenorrheic. It’s a natural reaction to want to scale back activity in response to triad symptoms, but the fact is most athletes can effectively address triad-related health problems with adequate fueling. That said, if training can be reduced, for example by adding one day of rest per week, resumption of normal menstruation will likely occur more quickly.

Studies are ongoing to determine just how many “extra” calories are needed for normal menses to resume, but thus far it appears even small increases in body weight, which can lead to subtle changes in metabolic hormones (reflecting modest positive changes in energy balance), may be all that’s required to resume normal, ovulatory menstrual cycles. Some studies suggest that when an individual reaches the body weight that was associated with the stopping of menstruation, it will likely resume again.

An important goal in triad education is to improve our identification of not only athletes with the full-blown triad, but also those who may be moving in an unhealthy direction–to catch athletes before they slide further down the three spectrums. Sports medicine professionals and athletes themselves should be aware that even subtle menstrual cycle changes, such as the development of very light or spotting periods, or moderate caloric restriction (with or without weight loss), can be early signs in the progression to serious triad complications. If an athlete exhibits one aspect of the triad, the other two should be inquired about. This might mean, for instance, a bone density test and nutrition counseling for an athlete who reports experiencing irregular menstruation.

Obviously, one of the best times to catch potential triad-related problems is during pre-participation physicals and yearly check-ups. Female athletes should be asked about their eating habits and their menstrual regularity as part of basic screening, and people with a history of stress fractures may warrant special attention. These recommendations extend to all female athletes–not just those in sports that emphasize leanness.

It’s also important to remember that many physicians are not familiar with the triad and are dismissive of its signs and symptoms (though considerable progress has been made in this area). Amenorrheic athletes are still frequently prescribed hormonal contraceptives to prevent or slow bone loss, but this does not address the underlying problem–it only addresses the symptom. Contraceptives may normalize menstrual periods and provide exogenous estrogen, but they will not aid bone health. In fact, long-acting progesterone-only contraceptives like Depo-Provera have been shown to cause bone loss, and the packaging now includes a warning to this effect. Nevertheless, this particular drug remains popular among athletes who feel normal menstruation impairs their performance.

Worse yet, athletes on birth control pills often believe they have addressed their triad-related problems, and thus are likely not being counseled to improve dietary habits. As a result, they may continue to fall further down the energy availability spectrum, which can have negative consequences for performance, bone formation, and overall health.

When should a more formal intervention occur? Current thinking is that if an athlete has been amenorrheic for six months or more, has suffered fractures, or has current or previous irregular menstrual cycles (more than 36 days between periods), she should be given a DXA test. If the result is a Z score below -2, the athlete should be referred for hormonal treatment and should meet with a dietician or nutritionist. If the result is a Z score between -1 and -2, the athlete should be referred to a dietician or nutritionist, but not immediately put on hormonal therapy. In either case, if menses does not resume, the DXA test should be repeated in 12 months.

Finally, it’s important to remember that not all triad-related symptoms are caused by an energy deficit or dietary problem. Amenorrhea might also be due to an anatomic defect, premature ovarian failure, a prolactin-secreting tumor, polycystic ovarian syndrome (PCOS), or pregnancy. Low bone mass, too, can have other causes. A physician’s evaluation and testing can determine whether another health problem is present. If not, energy deficit is the most logical place to look.

Athletic trainers, physicians, and other healthcare and sports medicine professionals should strive to stay current on the female athlete triad, and to educate athletes and coaches on an ongoing basis. Athletes often view weight loss as synonymous with improved performance, and they must be informed of the serious short- and long-term health risks of dietary restriction. Armed with the latest information and research, you may be the first and best line of defense in keeping athletes safe from the triad.

References for this article can be found here.

Shop see all »

75 Applewood Drive, Suite A
P.O. Box 128
Sparta, MI 49345
website development by deyo designs
Interested in receiving the print or digital edition of Training & Conditioning?

Subscribe Today »

Be sure to check out our sister sites: