Shear cushions reduce the impact loading rate during walking and running

Abstract

In addition to vertical ground reaction force (GRF), anterior–posterior GRF with a greater external moment arm may be another repetitive impact force that contributes to overuse running injuries. In this study, a shear cushion device was placed between the sole of a shoe and the ground to reduce not only the vertical loading, but also the anterior–posterior loading while walking and running. For this study, 15 healthy male runners classified as heel strikers (height: 173.2 ± 4.7 cm, mass: 68.5 ± 5.6 kg) were recruited. Participants were required to walk (2.5 m/s), jog (3.5 m/s), and run (4.2 m/s) while wearing shoes with three different sole groove designs (conventional, straight groove, and 45° groove). Both the straight and 45° groove soles provided significant shear shift during walking, jogging, and running, as well as delayed the time to first peak anterior–posterior GRF during walking. The straight groove sole reduced the vertical loading rate during jogging (p = 0.010) and running (p = 0.010), and delayed the time to first peak vertical GRF in all gait conditions. These findings suggest that the vertical loading rate and the time to the first peak anterior–posterior GRF can be changed by the sole groove design under various gait conditions.

Keywords::

• Ground reaction force
• shoe grooves
• soles

Acknowledgements

This study was funded by “Aim for the Top University Project” of the National Taiwan Normal University and the Ministry of Education, Taiwan, R.O.C. The authors would also like to express their sincere gratitude to the support from Nike Sport Research Lab.