In order to understand the movement ecology of species, preprocessing is considered a fundamental step to in treating any signal contaminated with noise. Thus it is performed on data to remove undesirable characteristics that were introduced during acquisition. A modified filtering model of gait vertical ground reaction force signals is highlighted in this work in the light of the commonly applied fixed filters on the signals from various sources. This common practice is pointed out to harm the signal's content. The alternative technique is based on Empirical Mode Decomposition.