Determination of ground reaction force peaks from human footprint depths

The aim of the present study was to estimate ground reaction force (GRF) by means of a linear regression equation with input data from footprints. It can be used to provide further information on locomotion of extinct mammals and/or early humans, thus providing important knowledge about human bipedal locomotion evolution. Fossilized footprints contain information about gait dynamics, but their interpretation is difficult, as they are a combined result of foot anatomy, gait dynamics, and substrate properties. Several approaches are used for modeling and estimating data in biomechanics, simple modeling is useful when trying to understand complex events. Force measurements were performed using a force platform; at the same time a footprint was registered on a clay surface. From the measurements of length, width and depth of the footprint it was possible to estimate body height (BH), body mass (BM) and vertical GRF peaks during human walking. The main findings of the present study were two linear regression equations for estimation of GRF peaks from footprint depths (R 2 =0.81, p<0.001; R 2 =0.56, p<0.001). This study accomplishes a first step to a fully understanding of how to estimate GRF from footprint data, and have further application to locomotion evaluations from fossilized footprints.