Relative energy deficiency in sport (REDs) in elite adult team ball sport athletes: a systematic review

Objectives: To investigate the prevalence of Relative Energy Deficiency in Sport (REDs) in elite adult team ball sport athletes and critically evaluate the methods used to assess prevalence. Design: Systematic review. Methods: Six databases were searched in October 2024 for original articles published in English from 2005 onwards. Eligible studies measured prevalence of REDs, low energy availability (LEA), or the Triad in elite team ball sport athletes aged ≥ 18 years. Results: Fourteen studies met the eligibility criteria (n = 2 case; n = 2 longitudinal; n = 10 cross-sectional), including 265 athletes representing 12 team ball sports. The 12 included cross-sectional and longitudinal studies used six different methods to identify REDs/LEA prevalence as 0–80 %. Seven studies used energy availability calculations, identifying clinical LEA (< 30 kcal·kg FFM^–1·day^–1) in 26.3–63.6 % of athletes. The LEA in Females Questionnaire identified LEA in 29.6–80.0 % of participants across 4 studies. Two studies evaluated REDs via blood/salivary markers, with low total-testosterone in 0–36.4 % of participants. One study found 50 % with low free-testosterone, 9.1 % with low free-T3, and 13.6 % with elevated LDL cholesterol. The REDs Specific Screening Tool identified 33.3 % of athletes in one study at medium risk of REDs. The Exercise Dependence Scale and Eating Disorder Examination Questionnaire were distributed in combination in one study, finding prevalence of REDs in 4.3 % and 25.5 % of participants, respectively. Conclusions: REDs appears ubiquitous in elite team ball sports, but research remains limited. A criterion approach for evaluating REDs/LEA prevalence is needed for accurate, reliable, and consistent reporting and cross-study comparisons.