The medial longitudinal arch (MLA) is an important structure of the human foot, providing support and load transformation for standing, walking and other complex movements in daily life. Research has focused on understanding the structure and functionality of the arch, attempting to comprehend the biomechanics behind injury patterns, in order to benefit surgical techniques, physical therapies, and sports performance.

Past studies emphasized that both arch height and arch flexibility were regarded as important aspects when evaluating the arch area. However, in contrast to the various types of metrics evaluating arch height, techniques used for evaluating arch flexibility were limited. Only one metric was widely used which compared the difference in midfoot height between sitting...[ Read more ]

The medial longitudinal arch (MLA) is an important structure of the human foot, providing support and load transformation for standing, walking and other complex movements in daily life. Research has focused on understanding the structure and functionality of the arch, attempting to comprehend the biomechanics behind injury patterns, in order to benefit surgical techniques, physical therapies, and sports performance.

Past studies emphasized that both arch height and arch flexibility were regarded as important aspects when evaluating the arch area. However, in contrast to the various types of metrics evaluating arch height, techniques used for evaluating arch flexibility were limited. Only one metric was widely used which compared the difference in midfoot height between sitting and standing postures.

Inspired by the arch-supporting mechanism used by foot orthotics as well as the techniques to test the soft tissue compression at the plantar area, the idea of evaluating arch flexibility through loading the arch was developed and tested. Thirty participants volunteered to take part in an experiment by standing on a rigid testing platform and having their right arch raised by a customized and adjustable plastic piece. During this time, data on the contact force and the arch deformation were collected by force and displacement sensors.

It was established that midfoot height change in the plantar arch loading area directly correlated with and was lower than the midfoot height difference between sitting and standing. In addition, it was noted that the lower arches showed larger midfoot height change, larger load, and larger stiffness in plantar arch loading.

The findings of this study would benefit the understanding of arch structure and functionality and provide reference for the application of an arch-supporting mechanism such as the design of foot orthotics.