Comparison of DXA and HR-pQCT Measures Among Female Runners at Risk for Relative Energy Deficiency in Sport (REDs): A Pilot Study

ObjectivesRelative Energy Deficiency in Sport (REDs) is a syndrome driven by problematic low energy availability, impairing physiological and/or psychological function. While REDs assessment typically utilizes dual energy X-ray absorptiometry (DXA) of areal bone mineral density (BMD), high-resolution peripheral quantitative computed tomography (HR-pQCT) offers additional insight into bone microarchitecture, geometry, and volumetric BMD. This study aimed to evaluate bone health among female runners at risk for REDs using DXA and HR-pQCT measures. MethodsFemale runners aged 18-30 years, training at least 5 hours/week, were recruited and underwent anthropometric measurements, VO2 max testing, clinical laboratories, DXA scans, and HR-pQCT imaging of the tibia. REDs risk was assessed using validated questionnaires, clinical laboratories, and physician interviews. Participants were categorized as no-risk (green) or at-risk (yellow/orange/red) for REDs. ResultsTwenty-one participants (age 26 {+/-} 3 years) completed the study. Six were classified as no-risk and fifteen as at-risk for REDs. Sub-clinically low BMD (z-score [≤]-1) was the most prevalent indicator in at-risk participants. The at-risk group reported significantly higher weekly mileage (>40 miles/week: 66.7% vs 33.3%, p=0.043) and lower maximum extensor strength on muscular endurance testing (p=0.015). While no other between-group differences reached statistical significance, 12 of 14 HR-pQCT values showed poorer outcomes in the at-risk group. ConclusionsDespite the small sample size, this pilot revealed consistent HR-pQCT trends suggesting potential links between REDs risk and compromised bone geometry, microarchitecture, and volumetric BMD. Integration of HR-pQCT with REDs screening may provide a more comprehensive characterization of bone health compared to DXA alone. SUMMARY BOXO_ST_ABSWhat is already known on this topicC_ST_ABSRelative Energy Deficiency in Sport (REDs) is a clinical syndrome driven by problematic low energy availability that negatively impacts bone density and increases risk for bone stress injury (BSI). What this study addsConsistent trends in HR-pQCT outcomes demonstrate possible patterns of compromised bone geometry, microarchitecture, and volumetric bone mineral density in athletes with elevated REDs risk. How this study might affect research, practice or policyOur findings suggest that integrating HR-pQCT imaging with REDs screening may provide a more comprehensive characterization of REDs-related bone health than DXA alone. Further research examining the relationship between REDs risk and detailed bone health measures, including geometry and microarchitecture, is warranted to better inform clinical practice and screening tools.