Sport-Specific Impact Loading is Associated with Bone Mineral Density in Athletes: Implications for Relative Energy Deficiency in Sport (REDs) Assessment

Both sport-specific impact loading and Relative Energy Deficiency in Sport (REDs) are known to impact bone mineral density and bone stress injuries in athletes; however, the interactive effects are still emerging.

The primary aim was to investigate the effects of sport-specific impact loading on bone mineral density and bone stress injuries and the influence this has on the International Olympic Committee’s REDs Clinical Assessment Tool-Version 2 severity/risk assessment.

Female (n = 143) and male (n = 70) athletes (performance tier 3–5) from 13 different sports were cross-sectionally assessed with the Clinical Assessment Tool-Version 2 (questionnaire, blood, dual-energy X-ray absorptiometry-derived bone mineral density assessment), and prospectively assessed for new bone stress injuries, and compared across low-, medium-, and high-impact loading sports.

Spine and femoral neck Z-scores were significantly lower in low- and medium-impact versus high-impact sports (p < 0.01). The highest femoral neck Z-scores were in the high-impact group, with nearly all other low- and medium-impact groups being significantly (p < 0.016) lower regardless of REDs traffic-light status. The adjusted odds of future bone stress injuries were approximately three-fold higher in athletes with a recent bone stress injury (previous 2 years only; p = 0.16). Athletes in low-, medium- and high-impact sports with zero to low-risk REDs (green + yellow traffic-light) had femoral neck Z-scores of 0.4 ± 0.9, 0.5 ± 0.9 and 1.4 ± 1.0, respectively (p < 0.01).

Sport-specific impact loading significantly influences bone mineral density independent of REDs risk/severity status. These findings indicate that practitioners should interpret bone mineral density results in the context of an athlete’s specific sport background rather than relying solely on general population norms, enabling more accurate REDs risk assessment and targeted injury-prevention strategies.