A material testing method to evaluate various running shoe design for foot-strike impact is developed. The foot-strike impact is one of the major culprit of the running related injuries and many efforts were done by various sectors to minimize this adverse effect. Still there is no sensible way of evaluating the shoe designs with respect to this foot-strike impact in running.
Two simple mechanisms made of four bar linkages are developed in this study such that the foot-strike dynamics may be simulated and the impact forces from the ground can be measured simultaneously using a force platform. The lower extremity and foot motion during impact is filmed by a 16mm high speed movie camera. Several points on the rear half of the shoe and points near the trochanter major and the lateral epicondyle, which are presumed moving as a solid rigid body, are digitized to provide the linear- and angular-positions and velocities during impact. With these observed kinematics, the foot-strike dynamics simulator and the thigh motion simulator made of four-bar linkage motion generator are developed with some problems, and a slider type foot-strike simulator is evolved. This third version is realistic and several running shoes are tested and graded.
The simulator makes the artificial foot with running shoe on it to follow foot-strike motion. The simulator also invokes the relevant mass-spring-damper system which is modelled after McMahon's.
The motion of the model is drived by the gravity force and the drop height can be adjusted to get the proper magnitude of velocities and ground impact forces. The generated motion along with the ground reaction forces are monitored by the same procedures aforementioned.
