Localized Musculoskeletal Density, Quality, And Morphology In Division I Track And Field And Cross-Country Athletes

Track and field and Cross-Country (TFXC) athletes chronically load the shank and report a high incidence of bone stress injuries; however, little data exist describing the connection between regional bone and muscle properties in this population. PURPOSE: To compare site-specific bone indices using Dual-energy X-ray Absorptiometry (DXA) and muscle characteristics using diagnostic ultrasonography between NCAA Division I TFXC athletes and matched controls. METHODS: Thirty TFXC athletes (female n = 21, male n = 9) were matched with age (±2 yrs), weight (±5 kg), and sex controls who were physically active ≥3 d/wk. All participants provided voluntary informed consent, injury logs, and completed a total body DXA scan with shank region of interests (tibial plateau to distal foot) allowing for regional assessments of bone and lean mass measures. Real-time brightness mode ultrasonography assessed muscle cross-sectional area (CSA), muscle thickness (MT), subcutaneous fat-corrected muscle echo intensity (mEI), and muscle quality (MT/mEI) of the medial and lateral gastrocnemius and tibialis anterior muscles of each leg. Initially independent t-tests were used to compare group differences, subsequent univariate analyses with controlling for shank lean mass was also conducted. Cohen’s d effect sizes were calculated and α = 0.050. RESULTS: Over 40% of athletes reported one or more shank bone stress injuries compared to less than 15% of controls (p = 0.009). Athletes’ bilateral bone indices, corrected mEI, and muscle quality were superior before and after statistical correction compared to controls (all p ≤ 0.001; d = 0.61-1.05). MT and CSA did not differ between groups (all p ≥ 0.168; d = 0.00-0.35). CONCLUSION: These data suggest local muscle quality, but not morphology, is strongly associated to superior local bone measures and support the further use of DXA and ultrasound for injury risk and musculoskeletal health assessment in this athletic cohort. No funding to disclose.