Quantitative Investigation of Torsional Loading of the Tibia during Quick Change of Running Direction

Abstract

No quantitative information has been reported about tibial loading during quick changes of direction (cutting) during locomotion. The purpose of the present study was to reveal quantitatively the characteristics of tibial torsional loading during zigzag running (ZR) using open-step quick cuts in comparison with straightforward running (SR). Seven adult male subjects were asked to perform SR and ZR at their maximum effort. Ground reaction force (GRF) and 3D motion data were synchronized and sampled during the course of each trial. For tibial loading analysis, net axial moments acting at both (distal and proximal) ends of the tibia were calculated using inverse dynamics. These axial moments were determined as tibial torsional moment based on the assumption that these moments matched well with each other during the stance phase of running (quasi equilibrium assumption). In the present results, the principal direction of the torsional moments seen in the ZR (external/internal rotational loading of the proximal/distal tibia) was opposite to the direction seen in the SR. The mean peak moment as well as angular impulse for the ZR was significantly larger than for the SR (28.8±8.5Nm vs 16.0±8.1Nm, P<0.05; 4.48±1.71Nms vs 1.34±0.69Nms, P<0.01). These results suggested that tibiae tend to be continuously loaded in greater torsion in the opposite direction during the stance phase of open-step cutting compared to straightforward running. Peak moments obtained from individual ZR trials could be successfully regressed with 1) the free moment of ground reaction, 2) shank transversal rotation, and 3) shank sideward tilt (R=0.838, P<0.001). The modifications of these factors would be effective for the reduction of tibial torsional loading during open-step cutting maneuvers.