Relative Energy Deficiency in Sport (RED-S) is a relatively common, but poorly recognised condition, that can have a significant impact on a young athlete’s sporting career and health. The condition can result in a series of potential health and performance consequences as a result of low energy availability.

The term ‘energy availability’ refers to the energy available to an athlete once the energy expended through exercise is subtracted from their energy intake through diet. This energy is needed for body systems to function. RED-S is a broader term which includes the previous concept of the Female Athlete Triad (disordered eating, menstrual abnormalities and issues with low bone density) and acknowledges the more widespread impacts of energy deficiency beyond menstrual dysfunction, and bone density issues as well as the inclusion of male athletes.

RED-S can affect athletes of any gender and across all sports. It is more common in sports in which a lean figure or low body weight is encouraged or athletes are required to meet weight class restrictions e.g. dancers, gymnasts, cyclists, rowers, runners, jockeys and weight class combat sports. Whilst it may be associated with or driven by, disordered eating behaviour or eating disorders, it may also be the result of an athlete struggling to meet the high energy demands of their sport especially in endurance sports, through lack of understanding and nutritional education and may be impacted by social factors or financial constraints. Likewise, although a low body mass index (BMI <17.5kg/m2 or <85% expected body weight for adolescents) may be one surrogate marker of reduced energy availability, athletes may still experience RED-S symptoms at normal, or even elevated, BMI. As a result, a high degree of vigilance is needed.

Athletes with RED-S are at increased risk of hormonal dysfunction which can affect their periods (loss of or reduced periods), and delay puberty in adolescents. When a young woman presents with irregular periods (oligomenorrhea) or absent periods (amenorrhoea) the diagnosis of RED-S should always be considered. Reduced testosterone levels in male athletes can also occur. There is a potential impact on fertility and bone health if low energy availability is prolonged. These athletes are at risk for stress fractures, more frequent overuse injuries and illnesses (especially respiratory tract and gastrointestinal illnesses), iron-deficiency anaemia and gastrointestinal effects including constipation. RED-S can also have significant psychological consequences and poor mental health may either precede or be a result of RED-S.

For many athletes, a diagnosis of a stress fracture, recurrent injury or illness or poor training and competition performance is the presenting feature indicating an energy deficit and should serve as a warning sign for coaching staff and medical practitioners that further specialist input and investigation is warranted. It is very important that clinicians consider an athlete’s energy balance when diagnosing and treating a wide range of medical and musculoskeletal problems. Failing to identify this problem may mean that it is not possible to adequately treat these issues. Early diagnosis and treatment are also essential for preventing the long-term impacts to health and sporting performance.

The diagnosis of RED-S involves a multidisciplinary approach and requires medical review. A useful screening tool has been developed to help clinicians identify those who may be at risk of RED-S (The RED-S Clinician Assessment Tool or RED-S CAT). This uses a traffic light approach to assist identifying at-risk athletes and guide return to sport decisions. Should you be concerned an athlete may be suffering from RED-S consider referring these patients for a specialist medical assessment. The treatment of RED-S can be very challenging and can require a multi-disciplinary team approach. Axis Sports Medicine’s Dr Sarah Beable runs specialist Women’s Health and RED-S clinics in both Auckland and Queenstown and athletes can be referred for a thorough assessment and treatment plan.

By Dr Caroline Stuary on