Lower extremity bone stress injuries (BSI) (i.e. pelvis, femur, tibia) are common in distance running athletes relative to other sports. PURPOSE: To (1) characterize bone mineral density (BMD), body composition (BComp, DXA), and anthropometric parameters in D1A collegiate runners presenting with and without BSIs during a collegiate season and (2) develop BMD prediction models with an accompanying mobile application for novel noninvasive field prediction of BMD and BSI risk. METHODS: Distance runners (n = 79; 42♂, 37♀) from a single university track and field team were retrospectively enrolled into study. The runners completed a DXA scan during fall screening (August-November). Three months after scanning, medical records were reviewed for the occurrence of BSI confirmed by a licensed physician. A t-test was used to compare BMD (total and regional [spine, pelvis, and legs]), BComp (% body fat, fat mass, and lean mass), and anthropometric measurements (shoulder width and leg, arm, and trunk length) between runners with versus without BSI (included subgroup analysis by sex). Multiple linear regression with stepwise removal was used to determine variables most predictive of BMD. Xcode (Apple Inc.) was used to develop the mobile application based on the derived BMD prediction models utilizing lower-bound 95% confidence intervals for runner-specific BMD norms as risk cutoffs. RESULTS: Eighteen runners (22.8%; 11♀, 7♂) sustained a lower limb BSI. Compared to the noninjured group (NoBSI), injured runners (BSI) had lower total BMD (NoBSI: 1.24 0.02, BSI: 1.15 0.04, p<0.001) and regional BMD (spine -11%, legs -9%, pelvis -10%, p<0.001). Injured athletes were observed to have shorter leg length (NoBSI: 95.6 1.4cm, BSI: 91.9 2.6cm, p=0.015) and arm length (NoBSI: 56.1 0.8, BSI: 53.8 1.5, p=0.006). Injured males had lower fat mass (NoBSI: 7.7 0.5kg, BSI: 6.4 0.7cm, p=0.041) and injured females had lower leg lean mass (NoBSI: 14.7 0.6kg, BSI: 13.5 0.7kg, p=0.035). BComp and anthropometric measures were predictive of bone mass (p<0.05, R2 =0.61; SE= ±0.27kg) and BMD (Total: p<0.05, R2 =0.77; SE= ±0.05g/cm2). BONE MASS, kg = (0.046 x Ageyears) +(0.024 x Weightkg) +(0.014 x %BodyFat) +(-0.017 x Arm Lengthcm) +(0.017 x Shoulder Widthcm) +(-0.009 x Trunk Lengthcm) +(0.037 x Leg Lengthcm) -2.867] | BMD, g cm2 =(-0.011 x %BodyFat) + (0.016 x Fat Mass kg) + (0.203 x Bone Masskg) +(-0.003 x Leg Lengthcm) +1.023. The mobile application was able to successfully run the developed prediction models for BMD assessment. CONCLUSION: Collegiate distance runners with shorter limb lengths, reduced fat mass(♂), reduced leg lean mass(♀), and lower BMD are at an increased risk for a lower extremity BSI. BComp and anthropometric measures are predictive of BMD in this population and may be utilized with the mobile application developed here as a screening tool to identify potentially “at-risk” runners.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.