The goal of the present work is to show how relative movements between (i) forefoot and rearfoot, and between (ii) rearfoot and lower leg can be measured and described during activities such as walking and running. For that purpose a 2-segment foot model is proposed (forefoot and rearfoot) composing of 9 markers to capture the foot movements. The results show considerable improvements
of the 2-segment model compared to previous 1-segment models.
This new model is particularly suited to demonstrate movement coupling between the rearfoot and the lower leg. Furthermore, the results with the new model show a remarkable plantarflexion between forefoot and rearfoot during take-off in walking and running.
This movement can be considered as a deformation which
reduces the leverage in comparison to an ideally rigid foot. This work constitutes a basis for improved three-dimensional description of the kinematics of the lower extremities during walking and running.