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Assuming that walking is a "safe" activity for a hip prosthetic patient, controlled alpine skiing and cross-country skiing appear relatively safe with respect to the magnitude of loading. However, the skiing activities showed considerably higher mediolateral and anterior-posterior forces than walking. Mechanical testing of prosthetic devices with loading conditions specific to these activities is needed to assess the effect of these force components on hip prostheses and to allow interpretation with respect to potential effects of skiing for a hip prosthetic patient.

The purposes of this study were: 1) to compare the impact forces in running using running shoes with conventional insoles to the impact forces using running shoes with four different viscoelastic insoles, 2) to discuss possible effects of the viscoelastic insoles on lower leg kinematics, and 3) to explain the force and kinematic results using a mechanical model. Kinetic and kinematic data were collected for 14 subjects running heel-toe at an average speed of 4 m/s. The results showed that the four tested viscoelastic insoles did not differ in variables describing the vertical impact forces (vertical force peak, time of occurrence of vertical force peak, maximum vertical loading rate) compared to the conventional insoles furnished in running shoes. Furthermore, the viscoelastic insoles did not influence kinematic variables of the lower extremities in a systematic way.