In the research of running shoes, excessive pronation is often related to various running injuries. Anatomically, pronation is a movement that occurs in more than one joint. Previous investigations that evaluated the pronation in running studied the movements of the lower leg and the rearfoot only. However, pronation could also be influenced by the movement of the forefoot and therefore depend on the torsional stiffness of the foot and of the shoe sole. This study investigated the relationship between the torsion and the pronation in running with a rearfoot touchdown and with a forefoot touchdown. The results show that, compared to running barefoot, running with a shoe decreases torsion and thereby increases pronation significantly (p < 0.01) for the forefoot and rearfoot touchdown conditions. Thus the reduction of torsional movement due to stiff shoe soles could well be a reason for running injuries caused by excessive pronation. It is concluded that modern running shoes could be designed to allow a certain torsional movement of the foot.
Alex Stacoff, Xaver Kaelin, and Edgar Stuessi are with the Biomechanics Laboratory of the Swiss Federal Institute of Technology (ETH), 8092 Zuerich, Switzerland. Bernhard Segesser is with the Praxisklinik Rennbahn, St. Jakobsstrasse 106,4132 Muttenz/Basel, Switzerland.