The impact of asymmetrical loading on tibial characteristics and bone strength in high-impact athletes.

Background: Asymmetrical athletes produce movements where the external load is unequally distributed in the lower extremities e.g., cricket fast bowling. Loading magnitude is known to affect bone adaptation. It is not understood if tibial characteristics differ between legs when they are exposed to different magnitudes of external load, as happens in asymmetrical athletes. This study aimed to assess the association between external load and tibial characteristics and compare the effect that asymmetrical loading has between legs in asymmetrical athletes. Footballers were recruited as a comparator group.

Methods: Inertial measurement units (IMU) were placed at the 14% site of the anteromedial tibia to measure external load during habitual training. Whole body dual-energy X-ray absorptiometry (DXA) and tibial peripheral quantitative computed tomography (pQCT) scans were taken of the athlete within 2 weeks of the external load measurement.

Results: Asymmetrical athletes experienced 34% higher peak acceleration and 28% higher peak positive acceleration (PPA) in the front leg compared to the back leg and showed greater bone mineral content (BMC; 2%) and torsional tibial strength (7%) in the front leg. Positive correlations were shown between cumulative load in the front leg and tibial strength (r=0.638; P=0.035) in asymmetrical athletes.

Conclusions: Exposure to cumulative load showed higher tibial anteroposterior bone strength and transverse and torsional fracture resistance than the lesser loaded contralateral limb. The ability to monitor external load within the applied setting and how it impacts bone can help practitioners estimate the athletes' bone load throughout the season.