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  • Deborah Thomas BPT MCSP MAPPI Chartered Physio

RED-S: Relative Energy Deficiency in Sport

Some of you may have heard about the ‘female triad’: The ‘female athlete triad’ was officially described in 1997, by the Task Force on Women’s Issues of the American College of Sports Medicine (ACSM), as a syndrome often observed in physically active girls and women with three distinct medical disorders: Disordered eating, Amenorrhea (the absence of menstruation — one or more missed menstrual periods) and Osteoporosis. In 2007 they redefined the triad to include three interrelated components to energy availability (EA), menstrual function, and bone health.

The syndrome of RED-S refers to ‘impaired physiological functioning caused by relative energy deficiency and includes, but is not limited to, impairments of metabolic rate, menstrual function, bone health, immunity, protein synthesis and cardiovascular health’.

Low energy availability (LEA), which is at the base of the concept of RED-S, is a mismatch between an athlete’s energy intake (diet) and the energy expended in exercise, leaving inadequate energy to support the functions required by the body to maintain optimal health and performance. Currently, there is no practical tool for the measurement of Energy

Availability (EA). Energy availability directly affects menstrual status, and in turn, energy availability and menstrual status directly influence bone health. In 2014, the International Olympic Committee (IOC) working group coined the phrase Relative Energy Deficiency in Sports (RED-S) to emphasize that the syndrome affects all athletes, both female and male,

individuals who do not identify as athletes, such as performing artists, and further many health parameters in addition to the bone health and menstrual dysfunction depicted in the triad model.

I will outline the systemic effects of RED-S associated in the short and long term. It is important to highlight, that although not a part of RED-S, Urinary incontinence and pelvic floor dysfunction are even more prevalent in elite sportswomen with eating disorders (5).

The clinical presentation of RED-S can include:

  • Menstrual dysfunction

  • Delayed menarche (the first occurrence of menstruation)

  • Subfertility

  • Disordered eating

Long-term considerations: several bone-health related complications that may remain asymptomatic until the damage is irreversible, such as the development of osteoporosis or stress fractures.

Health effects of low energy availability

RED-S has both short- and long-term effects on many systems of the body; Hypoestrogenemia (very low oestrogen levels) associated with prolonged reproductive suppression can negatively impact the spectrum of the Female Athlete Triad. There are potential alterations in thyroid function, decreases in insulin resistance and elevations in cortisol. I will outline a few of the symptoms and causes here, these are mainly the ones I will see in the clinic, in more detail:

  • Bone health

    • LEA contributes to impaired bone health in athletes, particularly women; studies have demonstrated decreased Bone Mass Density (BMD), altered bone microarchitecture and bone turnover markers, decreased bone strength and increased risk for bone stress injuries, often known as ‘shin splints’ and osteoporosis. Women with amenorrhoea are also at greater risk of developing stress fractures. This risk extends into the future, even following return of menstruation, where women with a previous history of amenorrhoea continue to be at two to four-times greater risk, highlighting the potential irreversible damage caused by RED-S.

  • Haematological

    • Iron deficiency, often seen in female athletes, can contribute directly and indirectly to energy deficiency.

  • Gastrointestinal

    • Altered sphincter function, delayed gastric emptying, constipation and increased intestinal transit time.

  • Immunological

    • The immune system may be altered by LEA: upper respiratory tract infection, muscular and joint aches and pains, and head complaints

  • Psychological

    • LEA in athletes has been shown to have negative correlates with various aspects of psychological well-being.

  • Disordered eating and eating disorders

Red-S and Pelvic Floor Dysfunction (PFD):

Low-energy availability in female athletes may play a role in the development of PFD such as urinary incontinence, faecal incontinence, and pelvic organ prolapse. Nutritional factors have been identified as a predisposing causal factor of PFD (4).

The prevalence of urinary incontinence among female athletes of different sport modalities has been shown to be 36% (4) but it can be as high as 76% (5). A significant correlation between eating disorders and urinary incontinence was found in a group of 37 female long-distance runners. Further research has found that athletes with disordered eating were three times more likely to present with urinary leakage than athletes without disordered eating; Urinary incontinence also has been found to be more prevalent in adolescent female athletes (15 to 19 years of age) with low-energy availability; A significant prevalence of

PFD especially urinary incontinence (37%), anal incontinence (28%), and pelvic girdle pain (18%) was described in a population of 311 adult female triathletes; Stress urinary incontinence is the most prevalent PFD found in female athletes.

Several factors may be related to the contribution of developing PFD in RED-S athletes:

Neuromuscular (as decreased muscle strength, decreased glycogen stores, and decreased endurance performance), Nutrition (Pelvic floor skeletal muscle efficiency, which is crucial for urethral function, may be compromised when vitamin D concentrations are deficient; vitamin D insufficient concentrations likely could impact the contractility and function of the pelvic floor muscles); Endocrine (may experience alterations in normal sex hormone concentrations and function, a decrease in systemic oestrogen levels). Oestrogen receptors have been identified in all major supporting structures of the pelvic floor. The hypoestrogenic state may increase the risk of PFD by influencing the connective tissue properties and the overall neuromuscular functionality of the pelvic floor.

Prevention of LEA and RED-S:

The IOC states that ‘Surveys have reported that less than 50% of physicians, coaches, physiotherapists and athletic trainers could identify the triad components (LEA with or without an eating disorder, menstrual dysfunction and low BMD)’. By writing this blog I hope to help raise further awareness.

Screening for relative energy deficiency in sport

Early detection of athletes at risk for energy deficiency is critical to prevent long-term health

consequences. Several measures have been proposed:

  • Periodic Health Examination

  • LEAF-Q

  • Low Energy Availability in Males Questionnaire

  • The RED-S Clinical Assessment Tool (RED-S CAT) – validation is still required

A suggested screening questionnaire like this may be helpful: (adapted from De Souza et al. 2014)

  1. When did you start having periods?

  2. When was your last menstrual period?

  3. How long is your menstrual cycle?

  4. Are you presently taking contraception or hormone replacement therapy?

  5. Have you ever missed a menstrual period for a year or longer?

  6. Is your body mass index <18.5?

  7. Do you worry about your weight?

  8. Have you ever had an eating disorder?

  9. Have you lost more than 5 kg in the last 3 months?

  10. Have you ever had a stress fracture?

  11. Have you ever experienced low bone mineral density or osteoporosis?

  12. Do you leak urine when training or competing?

  13. Have you ever had a problem becoming pregnant?

The IOC recommends ‘improved awareness of RED-S is required through educational initiatives’, and stresses that ‘there is still much to be learned about the psychological and physiological health risks and long-term consequences of RED-S in all athletes.’ In regards to urinary incontinence, ‘Sportswomen with urinary incontinence require intervention, particularly if there is evidence it is impeding performance or affecting quality of life. The mainstay of treatment is an individually tailored pelvic floor muscle training regime’ and these have been shown to ‘significantly improve the condition in 67–74% of sportswomen with urinary incontinence involved in high impact sports.’ RCOG 2019

Within physiotherapy, we must get better at identifying the symptoms and highlighting these to the patient and their medical or athletic team, to support them through improving energy intake, lifestyle, education, and training. I am very well positioned to address rehabilitation goals with structured, tailored exercise programmes, as well as treatment and rehab for pelvic floor dysfunction.

Written by: Deborah Thomas BPT MCSP MAPPI

For any queries about this topic, contact me via my website:


  1. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update Mountjoy M, Sundgot-Borgen JK, Burke LM, et al. Br J Sports Med 2018;52:687–697

  2. Female Athlete Triad or Relative Energy Deficiency in Sports (RED-S): Is There a Difference? Wendy Marcason, 2016, JOURNAL OF THE ACADEMY OF NUTRITION AND DIETETICS,

  3. Relative Energy Deficiency in Sport: The Tip of an Iceberg. Margo L. Mountjoy et al : International Journal of Sport Nutrition and Exercise Metabolism, 2018, 28, 313-315

  4. APA Rebullido, Tamara Rial PhD, CSPS1; Stracciolini, Andrea MD, FAAP, FACSM2 Pelvic Floor Dysfunction in Female Athletes: Is Relative Energy Deficiency in Sport a Risk Factor? Current Sports Medicine Reports: July 2019 - Volume 18 - Issue 7 - p 255-257 doi: 10.1249/JSR.0000000000000615

  5. Jones BP, L’Heveder A, Saso S, Yazbek J, Smith JR, Dooley M. Sports gynaecology. The Obstetrician & Gynaecologist. 2019;21:85–94. 2014 Female Athlete Triad Coalition Consensus Statement on Treatment and Return to Play of the Female Athlete Triad De Souza MJ, Nattiv A, Joy E, et al. Br J Sports Med 2014;48:289.

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