Relative Energy Deficiency in Sport (RED-S)

Introduction

Relative Energy Deficiency in Sport (RED-S) (the updated model of the female athlete triad) was defined by the International Olympic Committee in 2014 as: ‘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 is the instance in which there is a chronic mismatch between nutritional intake and energy expenditure, thus leaving insufficient energy available for essential physiological functions. As a result, physiological functions are down-regulated in order to preserve energy for more essential functions and for movement.

This term has replaced the female athlete triad as we are now aware that this syndrome impacts both female and male individuals experiencing low energy availability.

Relevant Definitions

Amenorrhea - An abnormal absence of menstruation

Dysmenorrhea - Painful menstruation, typically involving abdominal cramps

The Female Athlete Triad – The interrelationship of menstrual cycle dysfunction, reduced energy availability and reduced bone mineral density

Hypomenorrhea – Abnormally light menstrual bleeding

Menarche – ‘The occurrence of the first menstrual period in the female adolescent’

Menorrhagia – Heavy menstrual blood loss

Menstrual cycle - The process of ovulation and menstruation

Menstruation - The process of discharging blood and other material from the lining of the uterus at intervals of about one lunar month from puberty to the menopause, except during pregnancy

Oligomenorrhea - Menstrual cycle length of greater than 45 days

Osteopenia - A medical condition in which the protein and mineral content of bone is reduced, but less severely than in osteoporosis

Relative Energy Deficiency in Sport (RED-S) - This is impaired physiological function including, but not limited to impairment of: metabolic rate; menstrual function; bone health; immunity; protein synthesis; and cardiovascular health, caused by energy deficiency

Prevalence of RED-S

The prevalence of RED-S is not well documented due to the inherent methodological difficulties in diagnosing true low energy availability.

The understanding of RED-S and its symptoms are poorly known by athletes and coaches, and therefore it is also not commonly recognised. Fewer than 50% of physicians, coaches, physiotherapists and athletic trainers could identify the triad components (Low energy availability +/- disordered eating, menstrual dysfunction, low bone mineral density (IOC update RED-S0.

Prevalence varies between sports and ranges in the literature between 22-58%.

Health Implications of RED-S

Health implications are multi-system, affecting the endocrine, metabolic, skeletal, cardiovascular and immune systems; and in women, the menstrual cycle is disrupted. Not infrequently are also significant ramifications on the psychological state of the individual, given the prevalence of disordered eating in this population.

Performance Implications of RED-S

Health and Performance Implications of RED-S

Performance implications are significant and are the result of the negative influences on training adaptations, coordination, endurance performance, muscle strength, worsened concentration, irritability, impaired judgement, and the increased risk of injury.

Red Flags

The health and performance implications – cardiac abnormalities, recent weight loss, stress fractures, overuse injuries, anxiety/depression, oligomenorrhea/amenorrhea, poor concentration, restrictive eating, worsened performance, and body dysmorphia – are the red flags for RED-S.

Screening tools

RED-S CAT - Relative Energy Deficiency in Sport (RED-S) Clinical Assessment Tool (CAT) https://bjsm.bmj.com/content/bjsports/49/7/421.full.pdf

Can assess males and females]

Assesses risk and return to play

Is a more functional model using a traffic light system

LEAF-Q – Low Energy Availability in Females Questionnaire http://www.diva-portal.org/smash/get/diva2:1303041/FULLTEXT02.pdf

High Sensitivity (78%) and specificity (90%)

For female athletes only

Management

Non-pharmacologic – When a patient is diagnosed with RED-S, the following management strategies should be implemented: education; optimising energy availability; modification of exercise and nutrition; supplementation of vitamin D and calcium; and CBT. An MDT approach should be adopted, including mental health support. Sport participation may be used as leverage.

Pharmacologic – oral contraceptive is not recommended as it creates false menstruation or a ‘pseudo-period’. They are currently reviewing the use of recombinant parathyroid hormones and its role in improving bone mineral density