Soccer Players Demonstrate Greater Lower-extremity Bone Shaft Size And Strength Compared To Cross-country Runners

Female cross-country runners have a high rate of bone stress injuries (BSIs). Enhancing bone size and strength during youth may represent a means of prevention. We previously found cross-country runners with a history of participating in multidirectional sports had improved bone size and strength at the second metatarsal (2nd MT) and fibular shafts, but not the tibial shaft - the most common site for BSI. It is possible that greater and more prolonged exposure to multidirectional loading may confer measurable benefits at the tibial shaft. PURPOSE: Explore differences in bone shaft properties between collegiate-level cross-country runners and soccer players. METHODS: 16 cross-country runners (RUN) and 16 soccer players (SOC) had scans of the 2nd MT, tibial, fibula, and radial diaphysis using a Scanco high-resolution peripheral quantitative computed tomography (HRpQCT) scanner. Dual-energy x-ray absorptiometry was used to collect whole-body lean and fat mass and whole-body, lumbar spine, and hip bone density. Univariate general linear model analyses compared HRpQCT outcomes between groups at the tibia, fibula, and 2nd MT, with outcomes at the radius included as a covariate. RESULTS: The tibial shaft in SOC had greater total area (7.5%), cortical area (9.4%), minimum second moment of inertia [IMIN] (29.4%), and failure load (8.2%). At the fibular shaft, SOC had greater maximum moment of inertia (25.5%), polar moment of inertia (25.8%), and failure load (9.3%), while RUN had higher cortical volumetric bone density (1.9%). The 2nd MT shaft in SOC had greater cortical volumetric bone density (1.7%), total area (10.1%), cortical area (14.7%), cortical thickness (12%), maximum moment of inertia (21.2%), and polar moment of inertia (23.6%). SOC had greater fat mass (14.49%), whole-body aBMD (9.8%), lumbar aBMD (17%), and total hip aBMD (29.2%). CONCLUSION: SOC had greater size and strength at the 2nd MT, tibia, and fibula compared to RUN, independent of any differences at the radius. Notably, SOC had greater cross-sectional strength at the tibial shaft in the direction of least bending resistance (IMIN). The increased IMIN at the tibia in SOC may represent a dose dependent effect as this was not seen in the previous study comparing cross-country runners who had a shorter history of participating in multidirectional sports.