Effects Of Foot Rotation On Knee Joint Reaction Forces During Running

Abstract

PURPOSE: The purpose of this study was to examine the effects of internal and external foot rotation on knee joint reaction forces during running. METHODS: Motion capture and force data were recorded on nineteen healthy adult runners (22.3±4.0 years, 67.99±10.27 kg, and 1.77±0.10 m) running at 3.5 m/s with normal and maximal comfortable external (EXT) and internal (INT) foot rotation. Musculoskeletal simulations were performed using the Rajagopal 2015 model and OpenSim (SimTK). All data were low pass filtered at 10 Hz and normalized to a full stride (stance: 0-36% & swing: 37-100% stride). Models were scaled to each subject’s anthropometric parameters. Inverse dynamics were derived by combining inverse kinematics and force data. Muscle excitations were derived using Static Optimization, including muscle physiology parameters. Joint Reaction Forces were obtained by combining inverse kinematics, force data, and muscle excitations. Within-subjects ANOVAs via Statistical Parametric Mapping were used to determine differences in resultant knee joint reaction force waveforms. RESULTS: The EXT condition decreased early stance (0-2% stride) and late swing (92-100% stride) phase forces, but increased forces during early swing (44-46%) phase compared to normal. The INT condition reduced forces during very late swing phase (92-94% stride). The EXT reduced forces during early stance (0-1% stride) and late swing (97-100% stride) compared to INT. CONCLUSIONS: Despite the known success of altered foot rotation on reducing external knee abduction moments during walking and running, knee forces were only reduced during low-loading portions of running strides. Thus, it appears altered foot rotations does not improve knee loading during running.