Describing force-patterns: a method for an analytic classification using the example of sledge jumps

To recognise and classify movement patterns correctly can be a difficult task. Nevertheless, movement analysts are working on it on a daily basis. Therefore, we have developed and evaluated a method to do the classification by using contact forces during hopping in a sledge system. Here, experiments showed that reaction-forces of different subjects on a sliding sledge could be divided into four major types. These types are symmetric single-modal (type I), positive mono-modal (type II), negative mono-modal (type III), and multi-modal associated with plateau formation (type IV). Up until now, an exact determination of these types was not possible. However, the new method helps to approximate those four types with well established mathematical functions. With this approach, the measured reaction-force will be reproduced by particular coefficients. Subsequently, the coefficients are subjected to a discriminant-analysis. The result is a three-dimensional function-coefficient, which allows the classification of the actual force-pattern on the one of the four types.