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Female Athlete Triad: Background, Pathophysiology, Etiology

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Female athlete triad was originally defined as an interrelation of amenorrhea, osteoporosis, and disordered eating that would exist simultaneously.

More recently, it has been recognized that these 3 conditions exist on a spectrum and they have since been renamed menstrual dysfunction, low bone mineral density, and low energy availability with or without an eating disorder.

It is important to note that not all components of the triad need to be present to make the diagnosis; only one is needed.

Female Athlete Triad

Timely prevention, recognition, and treatment are important at delaying the progression as any one of the 3 triad components puts the individual at a higher risk of incurring all 3.


The female athlete triad occurs in girls and women, especially if they are highly competitive athletes. 

The development of female athlete triad is also possible in those who are sedentary and recreationally active but the prevalence rate is less than that of more competitive athletes.

Younger individuals are greatly impacted by the non-reversible, long-term consequences of this syndrome. In fact, a study on animals found that low energy availability can decrease growth and hinder sexual development.

Unfortunately, due to inconsistencies and limitations in definition criteria and experimental design, it is difficult to determine the prevalence of all three components of the Triad existing simultaneously. 

However, a lot of evidence exists looking at the prevalence of each individual component.

A systematic review by Gibbs and colleagues (2013) compiled available evidence and identified 9 studies investigation prevalence of 3/3, 2/3, and 1/3 of the triad conditions in exercising women. 

Of the 9 included studies, they found a prevalence of 0-15.9% for 3/3 conditions. When it came to determining the prevalence of the combination of any 2 components they found the following:

  • Menstrual dysfunction (MD) and low bone mineral density (BMD) had a prevalence of 0-7.5%
  • MD and disordered eating (DE) had a prevalence of 2.7-50%
  • Low BMD and DE had a prevalence of 0.9 -3.2%
  • MD and low energy availability (EA) had a prevalence of 17.5%, and
  • Low BMD and low EA had a prevalence of 3.75%.

Female Athlete Triad


Becoming aware of how each component can develop and present itself will aid healthcare providers and other stakeholders in sport in the early recognition of the female athlete triad.

Low Energy Availability With or Without an Eating Disorder

A low energy availability (EA) can be due to decreased dietary energy intake and/or increased energy expended during exercise and, when EA is low, this leads to less energy available for body functions. 

Some athletes may participate in restrictive diets or use pills or laxatives. Other athletes may have a diagnosis of an eating disorder including Anorexia Nervosa, Bulimia Nervosa, Binge Eating Disorder, or Other Specified or Unspecified Feeding or Eating Disorders.

Low EA can lead to menstrual dysfunction and low BMD. 

Menstrual Dysfunction

Eumenorrhea is a menstrual cycle occurring after 28 +/- 7 days and amenorrhea is the absence of a menstrual cycle for more than 90 days.

Amenorrhea can be primary, meaning there is a delay in age of the first occurrence of menstruation (15 years or older or within 5 years of breast tissue development), or secondary, meaning it occurs after the individual has begun menstruation.

Oligomenorrhea is an irregularity somewhere in between the two extremes on the spectrum; it is defined as intervals of more than 35 days between menstrual cycles.

Functional hypothalamic amenorrhea (FHA)

It is most relevant in the Triad, can be a primary or secondary amenorrhea caused by low EA and it is classified into the following 3 categories: weight loss-related, stress-related, and exercise-related amenorrhea.

FHA affects gonadotropin-releasing hormone and luteinizing hormone, which leads to estrogen deficiency. 

The low EA, resulting in hypoestrogenism and other metabolic disturbances, can cause anovulation and infertility, miscarriage or preterm birth, low BMD and fractures coronary artery disease, diabetes mellitus, anxiety, and depression.

Low Bone Mineral Density

Low BMD is classified as a z-score between -1.0 and -2.0 and osteoporosis is classified as a z-score of less than or equal to -2.0 along with the presence of a secondary risk factor such as low EA, hypoestrogenism, or a previous history of fractures.

Athletes engaging in weight-bearing sports have been shown to have a BMD that is 5-15% higher than those who are not engaging in any sports at all.

Furthermore, a z-score of -1.0 or less in athletes should lead to more tests regardless of what secondary risk factors are present at the time.

Approximately half of an individual’s peak bone mass (PBM) is formed during puberty and, additionally, hormones and nutrition are thought to contribute 40-60%.

Low EA plays a big role in BMD—as evidenced by a randomized controlled trial that found bone formation in exercising women declined shortly after EA was reduced to less than 30kcal/kg.

A low EA can lead to estrogen deficiency, which plays a key role in bone formation. A loss in BMD may be irreversible so it is important to identify it as early as possible to minimize the risks of stress fractures and osteoporosis.

Female Athlete Triad

Manifestations (including systemic involvement)

  • Weight loss
  • Absent or irregular menstrual cycles (includes primary and secondary amenorrhea, as well as oligomenorrhea)
  • Chronic fatigue
  • Fractures without significant trauma (low force cause); most common location is the tibia
  • Compulsive exercise
  • Increased infections and illnesses
  • Decreased ability to recovery from injuries (slower tissue repair)
  • Anxiety
  • Depression
  • Nutrient deficits
  • Esophagitis and oesophageal perforation if self-induced vomiting
  • Constipation
  • Changes in thyroid function, appetite, decrease in insulin, increase in cortisol, and resistance to growth hormones
  • Increased cardiovascular risk (including atherosclerosis) due to increase in bad lipids and endothelial dysfunction
  • Slowed growth
  • Impaired athletic performance
  • Reduced muscle mass
  • Vaginal dryness

Screening and Risk Factor Stratification

Screening for female athlete triad should occur for all female high school and college athletes as part of the Pre-Participation Physical Evaluation (PPE), at annual check-ups, as well as during evaluation for the signs and symptoms related to the triad (e.g., stress fractures, menstrual dysfunction).

Physiotherapists are often the first clinical encounter for many athletes. Physiotherapists have the ability to refer their patients onwards to undergo further investigations, which may require some advocating. 

Furthermore, having knowledge of the triad and the ability to screen for it is compulsory in primary and secondary prevention. 

Screening questions can be incorporated into the subjective portion of physiotherapy assessments and treatments.

The 2014 Female Athlete Triad Coalition Consensus (Triad Coalition) Statement on Treatment and Return to Play of the Female Athlete Triad, by De Souza and colleagues (2014), identified the following questions that adolescent females should be asked as part of the PPE to screen for the Triad:

  1. "Have you ever had a menstrual period?"
  2. "How old were you when you had your first menstrual period?"
  3. "When was your most recent menstrual period?"
  4. "How many periods have you had in the past 12 months?"
  5. "Are you presently taking any female hormones (estrogen, progesterone, birth control pills)?"
  6. "Do you worry about your weight?"
  7. "Are you trying to or has anyone recommended that you gain or lose weight?"
  8. "Are you on a special diet or do you avoid certain types of foods or food groups?"
  9. "Have you ever had an eating disorder?"
  10. "Have you ever had a stress fracture?"
  11. "Have you ever been told you have low bone density (Osteopenia or Osteoporosis)?"

Full clearance for participation requires 0-1 points, provisional/limited clearance requires 2-5 points, and restricted from training and competition requires 6 or more points

Around the same time, the International Olympic Committee (IOC) Consensus group created an updated term for the triad, called the Relatively Energy Deficiency in Sport (RED-S). 

Mountjoy and colleagues (2014) believe RED-S is more suitable because it is not actually a triad, but a syndrome associated with numerous physiological impairments that affect health and performance. 

The RED-S Clinical Assessment tool can be readily accessed at the following link: RED-S Clinical Assessment Tool for the Evaluation of Athletes. 

With the tool, athletes can be classified into high risk, moderate risk, or low-risk groups, which also correlate with how much sport activity they should participate in. Additionally, the RED-S risk assessment also has a stepwise approach for determining an athlete’s readiness to return-to-play. 

Female Athlete Triad


Athletes with disordered eating or low energy availability may undergo the following laboratory tests:

  • Electrolytes
  • Chemistry profile
  • Complete blood count
  • Erythrocyte sedimentation rate
  • Thyroid function tests
  • Urinalysis

Female Athlete Triad


When approaching the Triad with an affected athlete it is important to recognize this may be a sensitive topic. Treatment requires a multidisciplinary approach.

The team may be comprised of various healthcare providers including a physician, registered dietitian, mental health practitioner, physiotherapist (and/or athletic trainer or exercise physiologist), and coach. 

While interventions can have both pharmacological and non-pharmacological components, non-pharmacological treatment methods are to be the initial course of action. 

Pharmacological interventions should be considered if there is no improvement after a year of non-pharmacological intervention and/or the athlete has a relevant history of fractures.

Pharmacological interventions

Pharmacological interventions may include oral contraceptives, gonadal steroids (estrogen, progesterone, and testosterone), other bone restorative medications, recombinant parathyroid hormone, antidepressants. However, as previously mentioned, pharmacological interventions should not be a first-line therapy. There is a lack of evidence to support them.

Non-pharmacological interventions

Low energy availability (EA) is generally directly related to menstrual dysfunction and low bone mineral density (BMD) so it is addressed first and foremost.

Depending on the cause of low EA, the athlete should be referred to a sports dietitian for nutritional education and counselling. If there is suspicion of a clinical eating disorder, the athlete should be referred to a mental health professional for psychological treatment.

Depending on the severity, inpatient treatment may be needed. Energy expenditure may also need to be altered by reducing or ceasing exercise. 

It is believed that normalizing body weight will promote the return of menses and improve bone health.

When it comes to low BMD, addressing low EA, increasing body weight, having a regular menstrual cycle, and ensuring adequate calcium and vitamin D are recommended.

Role for Physical Therapy in Management

Physiotherapists possess the knowledge and skills to help prevent a condition from happening in the first place or increasing in severity. They also help maintain and restore function in those dealing with particular conditions. 

Through presentations and discussions, physiotherapists can educate stakeholders in sport on the importance of adopting healthy behaviours and the role physiotherapy plays in preventing and treating the triad. 

Physiotherapists can play a role in assessing, modifying and monitoring an athlete’s activity, such that they can help place less focus on cardiovascular training. 

Case studies have shown improvements in bone health after athletes with amenorrhea gained some weight, but it is not likely that this will restore BMD by itself. Resistance exercises, including weight-training, should also be incorporated 2-3 days a week.

While simple low-impact weight-bearing exercise has been shown to increase BMD during menopause, it is likely not enough for younger athletes. 

Additionally, high-impact sports, including running, may increase an athlete’s risk of developing stress fractures if they do not have adequate BMD to withstand the repeated forces. 

Lastly, it is also important to note that physiotherapists have the knowledge and skills to recognize and manage stress fractures and osteoporosis. 

As part of a multidisciplinary team, physiotherapists will work closely with others to determine an athlete’s readiness to return-to-play. If the athlete is not ready to fully return-to-play it is recommended athletes receive a written contract from the physician. 

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