Zoras, Vanessa2025-01-022025-01-022024https://hdl.handle.net/1828/20903Background: Relative Energy Deficiency in Sport (REDs) negatively affects athlete health and performance. Although the International Olympic Committee (IOC) recommends a validated REDs clinical assessment tool (REDs CAT2) for use by physicians, no evidence-informed tool exists to facilitate its implementation. Objective: This study aims to co-design a severity/risk outcome report with end users and evaluate its effect on athlete REDs-related knowledge, attitudes, and motivations (KAM) compared to a control report. Methods: A prototype of a REDs CAT2 report was developed through discussions with REDs experts (n=10), an environmental scan, and the integration of theory (Phase 1). The report underwent iterative testing with athletes (n=15, Phase 2) and questionnaire-based usability and acceptability (U&A) assessments and verbal feedback were used to determine design modifications. A two-arm randomized controlled pilot study (Phase 3) was conducted to test the hypothesis that REDs-related KAM scores would be higher in athletes who used the refined REDs CAT2 report (n=47), compared those who used the control report (n=37). Results: Five report revisions based on four user testing sessions resulted in mean U&A scores exceeding 90%. Post-intervention assessments showed significantly higher U&A and REDs-related KAM scores in the experimental group (U&A = 66.7 ± 5.0; K = 10.5 ± 1.2; AM = 75.3 ± 5.1) compared to the control group (U&A = 60.3 ± 10.5; K = 9.5 ± 2.1; AM = 71.3 ± 6.6), after controlling for pre-intervention KAM scores. Conclusions: The report developed through this study offers a practical and cost-effective tool to facilitate the implementation of IOC policy recommendations and the REDs CAT2.enAvailable to the World Wide WebRelative Energy Deficiency in Sport (REDs)Athlete HealthBehavioural TheoryImplementation ToolsUsability and AcceptabilityThesis