Overtraining and Underfueling: The Female Athlete Triad
We’re here because we love to run. The thrill of a steep descent after a grueling climb, the “runner’s high” that carries us through the rest of the day, and the social network that running creates and maintains are addicting. Chasing our running goals often leads to dramatically increased training volumes, which can result in short-term improvements in performance, but long-term negative effects on the body. There are so many wonderful things that running brings to our lives. However, there are also consequences from overtraining and under-fueling. The most well-known of these consequences: The Female Athlete Triad.
Female Athlete Triad
The Female Athlete Triad is a combination of three conditions: low energy availability, menstrual disturbances, and low bone density(1).
Low Energy Availability
There are a couple of ways in which an athlete’s delicate energy balance can become derailed(2). Even as we promote body positivity both within and outside of sport, many sports (especially running) continue to celebrate lean bodies and highlight low body weight as a performance advantage. Pressure from teammates and coaches often leads to decreased caloric intake even in the setting of increasing energy demands from progressively longer or more difficult workouts. It can also be difficult to gauge how much to eat after a given workout. As a last caveat, it’s common for athletes to have decreased hunger cues following a tough workout, which makes refueling correctly an even trickier feat.
Low energy availability has classically been explained as an imbalance between “calories in” and “calories out.” The math isn’t as simple as it initially sounds - the body adapts to reduced caloric intake by “cutting corners” in other areas. For example, this manifests as a loss of ability to sustain a set resting metabolic rate (RMR) and maintain muscle mass2. This adaptation allows the body to change its “calories out,” given that it has no control over “calories in.” An athlete should be eating approximately 45 calories per kilogram of fat free body mass per day (45 cal/kg FFM/day) to maintain muscle mass(2). Under 30 cal/kg FFM/day, the body not only begins to fail to maintain RMR and muscle mass, but it also is unable to keep up the hormone levels that preserve regular periods and healthy bones (among other things!).
Menstrual Disturbances
One of the first signs of low energy availability is irregular periods(3). Typically, women have periods on 28-day cycles, but menstrual cycle lengths can range anywhere between 21-35 days. Low energy availability can trigger irregular periods and eventually loss of periods by altering the pattern of hormone release from the brain that ultimately signals the ovaries to produce estrogen. This is called the hypothalamic-pituitary-gonadal axis. Low energy availability over time leads to low body fat. Importantly, body fat both produces estrogen and signals the ovaries to produce estrogen(4). Consequently, athletes with low levels of body fat are increasingly vulnerable to menstrual irregularities. Over time, these changes in hormone levels can lead to loss of periods (amenorrhea) and can affect fertility.
Low Bone Density
Decreased estrogen levels also significantly impact bone health. There are two types of cells that maintain bone density: cells that build bone, and cells that absorb bone. The delicate balance between both types of cells creates strong, healthy bones. Estrogen normally decreases the activity of the bone-absorbing cells, preventing excessive bone loss. Therefore, in estrogen-deficient states, bone-absorbing cells become more active. This leads to decreased bone density. Over time, this can result in stress fractures in athletes. Irregular periods are often noticed prior to a stress fracture, and amenorrhea greatly increases the chance of developing a stress fracture over time.
Male Athlete Triad
Low energy availability doesn’t just impact female athletes! Female Athlete Triad has been recognized for years in part because it is relatively easy for athletes to notice their menstrual irregularities. However, in men, the same hormonal axis is affected. This manifests as lower testosterone, lower libido, and lower sperm counts, which together are known as “hypogonadism”(5). The combination of low energy availability with low bone density and hypogonadism in men is called the “Male Athlete Triad”(5).
Relative Energy Deficiency in Sport
More recently, it has been recognized that there are many additional effects of low energy availability on the various body systems, besides those described in the Female and Male Athlete Triads. The term “Relative Energy Deficiency in Sport,” or “RED-S,” is used to describe the constellation of symptoms that are seen in athletes with low energy availability, and includes gastrointestinal dysfunction, impaired cardiovascular health, and mental health disturbances(6). RED-S further expands upon the definition of Female and Male Athlete Triad, and highlights the performance-limiting consequences of low energy availability, such as decreased concentration, decreased training response, and decreased muscle strength.
So... Now What?
Be mindful of changes in your body as you increase your training load. A new pain in your shin or foot, for example, might be from a new workout or from crushing your run the day before, but it might also be the first symptom of a stress fracture. A change in your period could be from many things, including stress, pregnancy, or other hormone disruptions. But it could also be the initial sign of low energy availability and the Female Athlete Triad. It is important to talk with your primary care provider as you notice new symptoms, so that new symptoms can be evaluated and treated before issues progress.
In the meantime, remember to fuel! The Female and Male Athlete Triads and Relative Energy Deficiency in Sport stem from inadequate food intake, and the treatment is to fuel enough to account for 1) calories lost during exercise and 2) calories burned by the body at rest(3). Using an activity tracker to estimate calories burned during a workout can be helpful to determine how many additional calories to eat in a day5. The issues we see in athletes with Female Athlete Triad, including menstrual irregularities and low bone density, begin to resolve as energy availability normalizes(3).
We get so many mixed messages about sport: work out more, but not too much. Eat less, but still enough. A good rule of thumb: pay attention to your body - eat when hungry, work out when energized, and rest when tired. Most importantly, be kind to yourself!
Some Helpful Resources:
The Female and Male Athlete Triad Coalition:
https://www.femaleandmaleathletetriad.org/athletes/female-athlete-triad/
British Association of Sport and Exercise Medicine:
http://health4performance.co.uk/
The American College of Obstetricians and Gynecologists:
References:
De Souza, MJ., Nattiv, A., Joy, E., Misra, M., Williams, N., et al. 22014 Female Athlete Triad Coalition Consensus Statement on Treatment and Return to Play of the Female Athlete Triad: 1st International Conference held in San Francisco, California, May 2012 and 2nd International Conference held in Indianapolis, Indiana, May 2013.” Br J Sports Med. 2014. 48:289. Accessed Nov 2020 at: https://bjsm.bmj.com/content/48/4/289.full
Holtzman, B., Ackerman, K. “Measurements, Determinants, and Implications of Energy Intake in Athletes.” Nutrients. 2019. 11(3): 665. Accessed Nov 2020 at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6472042/
Gharib Nazem, T., Ackerman, K. “The Female Athlete Triad.” Sports Health. 2012. 4(4): 302-311. Accessed Nov 2020 at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3435916/#:~:text=The%20female%20athlete%20triad%20(the,young%20women%20participating%20in%20sports.
Christo K, Cord J, Mendes N, et al. “Acylated ghrelin and leptin in adolescent athletes with amenorrhea, eumenorrheic athletes and controls: a cross-sectional study.” Clin Endocrinol. 2008. 69(4):628-633. Accessed Nov 2020 at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206259/
The Female and Male Athlete Triad Coalition. “What is the Triad.” 2020. Accessed Nov 2020 at: https://www.femaleandmaleathletetriad.org/athletes/what-is-the-triad/
Mountjoy, M., Sundgot-Borgen, J., Burke, L., Carter, S., Constantini, N., et al. “Relative Energy Deficiency in Sport (RED-S) Clinical Assessment Tool (CAT).” Br J Sports Med. 2015. 49:421-423. Accessed Nov 2020 at: https://bjsm.bmj.com/content/bjsports/49/7/421.full.pdf
