The influence of the mechanical characteristics of certain insole materials in the generation and transmission of heel strike impacts while walking was studied. Three insole materials were selected according to their mechanical characteristics under heel strike impacts. The selection of materials has made it possible to distinguish the effect of rigidity and loss tangent in the transmission of heel strike impacts. A lower rigidity and a high loss tangent have been shown to reduce the transmission of impacts to the tibia. A low rigidity was seen to significantly increase the transmission of impacts from tibia to forehead.

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The great diversity of prosthetic mechanisms available nowadays leads to the question of which type of artificial foot would be the most advisable for a particular person. To answer correctly, it is necessary to establish, in an objective way, the performance of each type of prosthetic mechanism. This knowledge is obtained by means of the study of the subject-prosthesis interaction, both in static and dynamic conditions. This paper, based on the analysis of 8 transtibial (TT) amputees, presents a quantitative method for the study of human gait which allows the determination of the influence of four different prosthetic ankle-foot mechanisms (SACH, Single-axis, Greissinger and Dynamic) on gait. To do this, 1341 gait trials at different cadences were analysed (383 with normal subjects and 958 with amputees, using the four prosthetic feet under study). From all the variables available for study only those which offered interpretable clinical information were chosen for analysis. A total of 18 variables (kinetic, kinematic and time-related) were selected. A covariance analysis (ANOVA) of these variables was made, which showed that the factors influencing TT amputee gait were, in order of importance, cadence and leg studied (sound or prosthetic), inter-individual variability and, finally, the prosthetic mechanism used. When looking at the performance during gait of the 4 prosthetic mechanisms studied it can be observed that there are similarities in the kinetic study between SACH and Dynamic feet on one hand and Single-axis and Greissinger feet on the other. These results seem to support the classification criteria of articulated and non-articulated prosthetic mechanisms.

A new methodology of biomechanical analysis of materials for shoe inserts is presented. This methodology is based on the determination of the loads applied to the materials in real situations and its simulation by means of a dynamic testing machine. Both the rigidity and the energy-absorbing characteristics of the materials are investigated as a function of frequency. This methodology is applied to the study of several commercially available viscoelastic materials intended for shoe inserts in the treatment and prevention of degenerative joint diseases. The influence of thickness is investigated as well as the frequency-dependent behavior of the materials studied. Significant differences between materials and different behavior as a function of thickness and frequency were found. Poron materials were found to have the lowest rigidity, good for adequate pressure distribution, while Noene showed the highest energy absorption. A careful selection of the thickness of Sorbothane was found to be necessary for avoiding flattening of the material.

In this paper the changes produced in the kinematics of the foot during running when the upper vamp design of the shoes is modified are studied. Ten marathon runners who presented overpronation were selected, and five prototypes of running shoes, incorporating several rearfoot control features, were specially designed for the study. The rear plane of the lower leg was filmed at high speed during treadmill running while subjects wore the prototypes. Variables referring to maximum angles of rearfoot eversion and torsion were found to be more sensitive to changes introduced in the sport shoes than variables corresponding to ranges of motion. Statistically significant differences were found between prototypes during the support phase in rearfoot motion and torsion. In general the prototypes that showed an increase in rearfoot control also showed a decrease in torsion.