[Multidimensional analysis of reactive forces of the foot during normal walking]

The authors present the analysis of the three components of ground reaction forces on both left and right feet on 50 subjects. Fourier analysis shows that a 25-Hz sampling is sufficient to fully characterize the normal gait. The approach used in order to study the data tables built for each component consisted in principal component factor analysis. This multivariate method, which looses the least possible information in relation to raw data, has indicated a high variability between subjects. Concerning the intrasubject variability, great asymmetry occurred between the forward and back forces. With respect to the relationship, the three components, the medial-lateral force was very independent of the two others. Particular classes of normal gait have been proposed.