At the 2021 Olympics, 26 year old swimmer Simone Manuel was suffering from Overtraining Syndrome (11). In 2020, ultra-sensation Mimi Kotka announced she was taking a break from competing because she was suffering from RED-S (2). In 2019, Mary Cain exposed her Nike training as contributing to her unhealthy relationship with food and her body, ultimately causing her to suffer from the Female Athlete Triad (3).

All three athletes complained of similar symptoms, including decreased performance, anxiety and depression, and a lack of period. So what exactly is the difference between the three, seemingly identical, syndromes?

The Female Athlete Triad

The “simplest” of the bunch is the Female Athlete Triad. As indicated in the name, this disorder is made of three (triad) symptoms: low bone density, menstrual irregularities (i.e., missing or irregular period), and a lack of fuel to match the demand (with or without an eating disorder) (4).

The suspected driving force in the Female Athlete Triad, is a lack of fuel to match the demand, i.e., not eating enough for the exercise you’re doing, otherwise known as low energy availability. Essentially, failing to adequately fuel the body leads to a shut down in processes not directly involved in metabolism, such as maintaining a menstrual cycle for reproduction. This leads to decreased hormone concentrations that are essential for bone remodeling, leading to a decrease in density (5). Crazy how smart your body is at adapting to its environment!


Image from Justin, 2019 (6).

Because the Female Athlete Triad is not an entirely black and white disorder (i.e., you don’t suddenly go from being healthy to being affected by it), this disorder is often depicted as a pyramid. One side having “healthy” symptoms, the other having Triad symptoms, and in between representing the spectrum of symptoms individuals could experience.

Relative-Energy Deficiency in Sport (RED-S)

Almost 22 years after the first description of the Female Athlete Triad, researchers expanded the effects that low energy availability (remember that lack of fuel) has on the athlete (7). This redefined condition was now referred to as Relative Energy Deficiency in Sport, RED-S for short.


Image from Mountjoy et al. (8)

The effects of low energy availability now include symptoms such as decreased performance, mood changes, decreased concentration and coordination, weakness, decreased recovery, immune impairment, and others (9). The Female Athlete Triad is now a smaller subgroup of a much larger condition.

More on this in a future article 😉


The effects of exercise on the body are complex (so complex that I have dedicated my life to studying it), but to understand why too much exercise is bad, we need to break things down.

When you exercise, particularly at high intensities for long periods, your body needs to recover. In addition to needing to physically repair the muscle you damaged, you have to replace the fuels you used, allow your brain and heart to relax, and a lot of other things. This not only takes a lot of energy (hence the hunger after exercise), but it also requires time.


Image from Etherton 2015 (10).

Sometimes we want to push our bodies a little over the limit of what we’re used to, just to give it that little push to adapt to higher intensities, distances, weights, etc. However, if we ask our bodies to do too much too often, we are not giving ourselves time to repair and reset. This leads to overtraining.

A lot of the symptoms associated with Overtraining Syndrome (OTS) are shared with that of RED-S. Namely, change in mood, immune dysfunction, missed or irregular periods, increased risk of injury, muscle weakness, etc. (11). However, OTS differs from RED-S in that the leading cause of OTS is a drastic increase in training with inadequate recovery, rather than a lack of energy to support the demand.

This article only scrapes the surface at the nuances, symptoms, and impacts that each of these syndromes has on athletic performance, but more importantly daily health.

Tracking your workouts, nutritional intake, and feelings with Wild.AI daily check-ins is a great way to be sure that you are taking care of your body to be your best self! Also using wearable devices like Garmin or Oura can help you track more quantitative measures, like resting heart rate and heart rate variability (HRV) that can help you be more in tune with your body!

We hope that this article helped shed light on the importance of fueling your body and taking the adequate time to recover.

Image adapted from: Stellingwerff, Trent, et al. 2021 (12) and Malcolm 2022 (13).

Originally published: 26.01.2023


  1. McLaughlin, Kelly, and Anna Medaris Miller. “Olympic Athletes Are Being More Open than Ever about Mental Health and Pressures of Competing.” Business Insider, 28 July 2021,
  2. “RED-S Syndrome – What Athletes Need to Know.” Iancorless, 31 Aug. 2020,
  3. Landsverk, Gabby. “A Once-Olympic Hopeful Who Said Her Body Broke Down After Working with a Nike Coach Had a Disturbingly Common Condition.” Insider, Accessed 19 Jan. 2023.
  4. Nazem, Taraneh Gharib, and Kathryn E. Ackerman. “The Female Athlete Triad.” Sports Health, vol. 4, no. 4, July 2012, pp. 302–11,
  5. Raj, Marc A., et al. “Female Athlete Triad.” StatPearls, StatPearls Publishing, 2022,
  6. Justin. “Female Athlete Triad – Real Life Scenario.” Feldman Physical Therapy and Performance, 9 May 2019,
  7. Brown, Kelly A., et al. “The Female Athlete Triad: Special Considerations for Adolescent Female Athletes.” Translational Pediatrics, vol. 6, no. 3, July 2017, pp. 144–49,
  8. Mountjoy, Margo, et al. “The IOC Relative Energy Deficiency in Sport Clinical Assessment Tool (RED-S CAT).” British Journal of Sports Medicine, vol. 49, no. 21, 2015, pp. 1354–1354,
  9. Medicine, BMJ Publishing Group Ltd and British Association of Sport and Exercise. “Relative Energy Deficiency in Sport (RED-S).” British Journal of Sports Medicine, vol. 49, no. 7, Apr. 2015, pp. 421–23,
  10. Etherton, Lucy. “Over-Training Syndrome.” TRAIL Magazine South Africa, 14 Aug. 2015,
  11. Kreher, Jeffrey B., and Jennifer B. Schwartz. “Overtraining Syndrome.” Sports Health, vol. 4, no. 2, Mar. 2012, pp. 128–38,
  12. Stellingwerff, Trent, et al. “Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared Pathways, Symptoms and Complexities.” Sports Medicine, vol. 51, no. 11, Nov. 2021, pp. 2251–80,
  13. Malcolm, Corrine. “Is Your Overtraining Syndrome Really Relative Energy Deficiency in Sport?” IRunFar, 19 Apr. 2022,


Be the first to leave a comment.
User is typing...
No Name
4 years ago
This is the actual comment. It's can be long or short. And must contain only text information.
No Name
2 years ago
This is the actual comment. It's can be long or short. And must contain only text information.
Load More
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.
Load More