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.

Impact mechanics of the human heel pad were studied using a ballistic pendulum. Young and elderly men and women took part in the experiment. Twelve parameters were used to describe heel pad properties. Analysis of variance was conducted to assess the influence of age, gender, and obesity. Heel pad properties were correlated with impact force and time to peak force in order to study impact mechanics. Maximal stiffness, peak displacement, and energy absorption were established so as to sufficiently describe impact properties of the heel pad. Age, gender, and obesity introduced significant differences in heel pad properties. Peak displacement and time to peak force increased in the elderly. Women presented a shorter time to peak force together with lower peak displacement, energy absorption, and lower maximal stiffness than men. Obese elderly showed lower impact forces, longer time to peak, and greater peak displacement than non-obese and younger participants. In addition, energy absorption was greater and maximal stiffness was lower for obese than for non-obese participants.

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.

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