REDs

As discussed in the 2023 International Olympic Committee (IOC) consensus statement, it is well-supported that long-term and/or severe “problematic” low energy availability (LEA) leads to the syndrome of Relative Energy Deficiency in Sport (REDs).¹

REDs can result in an increased risk of injuries, illness or decreased training adaptation (or missed training days), leading to poorer performance.

Hear from elite runner, Pippa Woolven, on her personal connection to REDs

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What is REDs?

REDs is defined as:

“A syndrome of impaired physiological and/or psychological functioning experienced by female and male athletes that is caused by exposure to problematic (prolonged and/or severe) low energy availability. The detrimental outcomes include but are not limited to decreases in energy metabolism, reproductive function, musculoskeletal health, immunity, glycogen synthesis and cardiovascular and hematological health, which can all individually and synergistically lead to impaired well-being, increased injury risk and decreased sports performance.” ¹
[see figures below]

The cause of REDs is problematic (prolonged and/or severe) LEA.

This is where an individual’s dietary energy intake is insufficient to support the energy expenditure required for health, function and daily living, after accounting for energy required for exercise and sport. Problematic LEA can be thought of like a smartphone in Low Power Mode: when the battery runs low, the phone saves power by slowing down or disabling features. When the body does not have enough energy, it slows or shuts down certain functions to conserve energy.

Although the evidence is still emerging for some outcomes, LEA has been associated with many REDs health and performance consequences, as illustrated below.

REDs Conceptual Model - Health

REDs Conceptual Model - Performance

_{Figures reproduced with permission from British Journal of Sports Medicine (BJSM), under license obtained via the BMJ Rights and Licensing clearinghouse. Mountjoy et al., 2023}

Build Your Knowledge: REDs Stats

These wide ranges are primarily due to differences in populations and sports studied, the lack of a singular, definitive diagnostic tool for REDs and variation in the standardization and accuracy of research methodologies. Therefore, the true population-wide prevalence of REDs remains to be determined.

Nevertheless, it is well-established that problematic LEA can cause many impairments in health and performance, including hormonal, metabolic, immune, digestive, psychological, neuromuscular, cardiovascular and bone systems; this includes low bone mineral density and an increased risk for bone stress injuries.^3,14-16

For example, data from elite endurance athletes showed that whole body bone mineral density was inversely related to LEAF-Q (Low Energy Availability in Females Questionnaire) score, and amenorrheic athletes were approximately 4.5 times more likely to have sustained a bone stress injury than eumenorrheic athletes.¹⁵

These physiological disruptions can directly impact performance.

Data from track and field athletes have shown that the likelihood of achieving a performance goal decreased sevenfold in those athletes who completed less than 80% of their planned training weeks in a year.¹⁷

Athletes with LEA indicators had slower race times, poorer finishing places, about twice the relative risk of any medical encounter during the event, nearly three times the risk of major medical encounters and higher odds of pre-race overuse injuries and illnesses, compared to athletes without LEA indicators.¹⁸

Problematic LEA is also associated with impaired hematological function, which can directly affect performance.

A study of elite female athletes estimating low energy availability using food/training logs and questionnaires found that amenorrheic athletes had approximately 8.0% lower hemoglobin mass than eumenorrheic athletes.¹⁹ Collectively, the negative REDs outcomes associated with LEA can profoundly influence both performance and longevity in sport.

NOTE: None of these symptoms on their own is a diagnosis of REDs!

A physician is required to make a diagnosis of REDs. The diagnostic process is based on a comprehensive history and physical examination, along with various tests (e.g., blood work, bone density assessment). Ideally, this process involves implementing the IOC REDs Clinical Assessment Tool-2 (CAT2)¹⁶ and requires the physician to consider various possible diagnoses that could be causing the athlete’s symptoms.

Implementing real change in REDs prevention requires a multifactorial approach to REDs, including:

Education

For athletes and staff on fueling, recovery and the risks of LEA.

Culture change

In sport to shift the focus from body shape/weight to performance, health and long-term athlete development.

Open communication

So athletes feel safe reporting symptoms without fear of judgment or losing their spot.

Screening and monitoring

When symptoms present, screening, physician evaluation and monitoring should be considered, along with collaboration with a multidisciplinary team.