Female Athlete Triad and RED-S In Endurance Runners

The Female Athlete Triad (FAT) is a syndrome involving the interplay between low energy availability, menstrual dysfunction and altered bone mineral density. Elite and recreational endurance runners are at a significantly increased risk of FAT due to the high energy demands in combination with the potential desire for leanness for improved performance (Folscher et al., 2015).

More recently, the acronym RED-S (Relative Energy Deficiency Syndrome) has been used due to the complexity of the condition and that male endurance runners can also experience similar symptoms.

The basic principle of FAT and RED-S is that energy intake is lower than energy expenditure required for general activities of daily living, growth and sporting activities. With this in mind, we can see that endurance athletes are at higher risk of these conditions due to the significant energy expenditure required for endurance training and events.

If the high energy demands required to train for endurance events are consistently not met, then physiological processes are compromised with the suppression of many systems including metabolic rate, menstrual function, new bone formation, protein synthesis, immune responses and cardiovascular health.

The dysfunction of these systems can result in amenorrhoea (absence of menstrual period) and subsequent infertility, osteopenia/osteoporosis, stress fractures, an inability to repair exercise-induced tissues/muscle damage and the inability to recover from illness and injury.

In endurance athletes, the low energy availability that is central to FAT and RED-S is usually from excessive exercise, poor nutritional habits or eating disorders.

Prevention of Female Athlete Triad and RED-S

Preventing FAT and RED-S begins with awareness. In a recent survey of a group of exercising Australian women, one-third believed irregular periods were ‘normal’ for active females. Unfortunately health professionals working in the sports sphere were just as bad, with less than 50% of physicians, coaches, physiotherapists and athletic trainers able to identify triad components (Curry et al., 2015). By writing this article we hope to raise awareness of the FAT and RED-S with recreational athletes themselves.

Athlete coaches are in the best position to identify low energy intake and/or eating disorders amongst athletes, as they are in contact with athletes weekly. However, it can be difficult in endurance sports due to the predisposition of athletes to aim for a leaner body given the perceived performance benefits. This leaves coaches having to distinguish between naturally lean athletes and those that have achieved certain body types via disordered eating habits.

Once an athlete is suspected of having the female athlete triad or RED-S, a consultation with a sports physician is essential. This is because these are conditions of exclusion, meaning other diagnoses need to be ruled out first.

Recognising Female Athlete Triad and Relative Energy Deficiency Syndrome

  • Amenorrhoea (absence or abnormal menstrual period)
  • Recent stress fractures
  • Increasing constipation
  • Disordered or restrictive eating
  • Weight loss
  • Excessive/chronic fatigue
  • Increased frequency of illness

Treatment of Female Athlete Triad and RED-S

I won’t go into treatment of RED-S or FAT here, as it is an individual process which can depend on the cause of the low energy intake. Treatment for an individual who has unintentional low energy intake is completely different to an individual with low energy intake on a background of an eating disorder. A medical consultation with a sports physician is the essential first step in diagnosing treating FAT or RED-S.

Remember that RED-S is not a female only condition. Despite a lack of research, males can also suffer from this condition and it is important for health professional to aware of this when working with athletes.


Folscher, L. L., Grant, C. C., Fletcher, L., & van Rensberg, D. C. J. (2015). Ultra-marathon athletes at risk for the female athlete triad. Sports medicine-open1(1), 29.

Curry, E. J., Logan, C., Ackerman, K., McInnis, K. C., & Matzkin, E. G. (2015). Female athlete triad awareness among multispecialty physicians. Sports medicine-open1(1), 38.

Melin, A., Tornberg, Å. B., Skouby, S., Faber, J., Ritz, C., Sjödin, A., & Sundgot-Borgen, J. (2014). The LEAF questionnaire: a screening tool for the identification of female athletes at risk for the female athlete triad. Br J Sports Med48(7), 540-545.

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