The Spring-Mass Model and Ground Reaction Force Vector of Running Modelling is used in science in an attempt to make an activity easier to understand, define, quantify, visualize, or simulate by referencing it to existing and usually commonly accepted knowledge. For human running, the preferred model within the international biomechanics community for the past quarter-century is the Spring-Mass Model (Blickhan R: The spring-model for running and hopping. J Biomech, 22(11/12):1217-1227, 1989). In