Dynamic analysis in javelin throwing considering javelin elasticity

The present paper presents a new sensor for measuring six components of force and two components of deflection applied to a javelin. Two types of javelin differing in stiffness were thrown by three javelin throwers. The force and the deflection applied to the Javelin during throwing were measured to analyze the throwing motion and the dynamic behavior of the javelin. The major results obtained were as follows; The force in the axial direction of the javelin falls or remains unchanged temporary just before the value reaches its peak during release. The torque around the axial direction of the javelin tends to fall to aminimum value and then reach a peak. The change of force in the lateral direction of the javelin is roughly dominated by that in one direction. The deflection of the javelin during throwing is not one-directional as reciprocation, but multidirectional. In order to consider the force applied to the javelin and the deflection of the javelin form the viewpoint of the thrower, it is necessary to consider the rotation around the axial direction of the javelin as well. The value of deflection of the javelin is affected by its stiffiness. However appears that the stiffness dose not affect the values and patterns of force and torque applied to the javelin.