What is the Female Athletic Triad and what are its implications for musculoskeletal medicine?


The female athletic triad has three components: (1) energy deficit, (2) low bone mineral density, and (3) menstrual irregularity. These symptoms exist on a spectrum of severity, but the extreme “textbook” case may be easier to remember: anorexia, amenorrhea, and osteoporosis-related stress fractures.

  • Energy Deficit: Sports that require athletes to be “thin” or “light” (such as long-distance running) or have a special emphasis on physical appearance (such as gymnastics or ballet), place athletes at risk for consuming fewer calories than expended, creating “energy deficit.” Importantly, while eating disorders such as anorexia nervosa (severe limitation of caloric intake) and bulimia nervosa (binging and purging) may, in the extreme, be responsible for energy deficit, these conditions do not have to be present to make the diagnosis. “Innocent” over-exercising relative to intake is sufficient.
  • Menstrual Irregularity: Normally, the hypothalamic-pituitary-ovarian axis controls release of estrogen and progesterone, leading to regular menstrual cycles approximately every 28 days. In low-energy states, this axis is down-regulated, leading to irregular menstrual cycles (oligomenorrhea) or lack of menstruation (amenorrhea).
  • Low Bone Mineral Density: In women, estrogen is the primary mediator of bone remodeling via its effects on osteoblast and osteoclast activity. Low estrogen therefore disrupts bone building, leading to weaker bone. Additionally, athletes at risk typically have low fat mass (a peripheral producer of estrogen) worsening their estrogen deficit. Lastly, low caloric intake can often result in low serum calcium levels (due to low calcium intake). The bones are the body’s primary store of calcium, but metabolic needs are prioritized. This means bones are broken down to increase serum calcium, at the cost of weakening structural integrity.


Clinical Implications

  • Stress fractures: The musculoskeletal practitioner most commonly sees the female athlete triad presenting as a stress fracture. The history and physical exam are important diagnostic tools to detect a stress fracture. For example, Figure 1 below demonstrates a physician performing a heel “squeeze” to detect for calcaneal stress fracture. These are difficult to visualize on standard x-ray, and are best visualized on CT, MRI (Figure 3), or nuclear bone scan (Figure 2).

Figure 1: Squeezing calcaneus side to side may reveal a stress fracture
Figure 2: Calcaneal stress fracture. A nuclear bone scan shows tracer uptake at the stress fracture location. (Case courtesy of Radswiki, Radiopaedia.org, rID: 11969)
Figure 3: MRI showing stress fracture of the inferior femoral neck (compression side) with surrounding edema. (Courtesy of https://radiopaedia.org/cases/femoral-neck-stress-fracture-3)

  • Osteoporosis: Failure to attain peak bone mass in young adulthood predisposes to osteoporosis and associated problems later in life.
  • Eating Disorders: May lead to electrolyte disturbances, arrhythmias, depression, and are associated with OCD and other diagnoses beyond the female athlete triad.
  • Psychologic: Absence from sport, identity, body image and eating disorders contribute to psychological difficulties that may present clinically as well.
  • Infertility: Amenorrhea signals underlying reproductive dysfunction.



  • Stress Fractures: Mainstays of treatment include rest and avoidance. Activity and training is restricted and athletes cannot return to play until pain subsides, tenderness has resolved, and radiographic findings are negative. Some specific fractures (metatarsal, femoral shaft, and tibia) can be managed with modified weight bearing. Fractures in the calcaneus (heel) or navicular may require more strict guidelines. Open reduction and internal fixation (ORIF) may be considered in elite or professional athletes who require a faster recovery and are at high risk of complications, such as displacement or nonunion. Operative treatment is also indicated for fractures in locations at high risk of fracture propagation or poor healing, such as on the tension side of the femoral neck or on the anterior cortex of tibia.  
  • Energy Deficit: While modification of training regimen may be included, increasing caloric intake throughout the day by modifying nutrition is the main component of treatment. Recognizing and treating eating disorders is therefore incredibly important, and experts must be included where appropriate to ensure proper management. 
  • Amenorrhea: In theory, with increased caloric intake amenorrhea should resolve as well. However, this may take some time. Gynecology, endocrinology and other specialists should be consulted where appropriate (and that means any time the presentation is beyond the expertise of the provider).


Additional Points to Consider

  • The female athlete triad is not abbreviated “FAT,” perhaps due to the fact that this condition is usually seen precisely when fat is absent.
  • The use of oral contraceptive pills (OCPs) or other hormonal replacement techniques chosen by many female athletes may confound the symptoms of the triad. For example, OCPs may cause a woman to still bleed monthly without truly ovulating, thus masking this facet of the triad. 
  • The differential diagnosis for stress fracture includes simple muscle strain (common, especially in athletes) or something more insidious such as bone tumors or infection. Radiographs in patients with suspicious symptoms are therefore essential, because the x-ray presentation of stress fractures, tumors and infections can be similar. Therefore, MRI or other advanced testing may also be indicated.