Fig 1.
(a) The multi-segment foot model consisted of a shank, rearfoot, forefoot, and toes.
The model includes three essential parts related to human motion: ankle, arch, and metatarsophalangeal joint, considering the PA’s tension force. (b) The free-body-diagrams of the foot during the heel contact phase, plantar contact phase, and push-off phase.
Fig 2.
(a) The layout of the experimental site with a 10-infrared camera motion capture system and two force plates.
(b) The location of the six markers at one foot and the definition of arch height. (c) The definition of MTPJ angle.
Fig 3.
(a) The changes in the height of markers at the posterior calcaneus and first metatarsal head (mean of ten subjects) and the subdivision of the stance phase.
(b) The change in arch height during the stance phase (mean±standard deviation). (c) The force at the arch during the stance phase (mean±standard deviation). (d) The variation of the foot arch stiffness across the stance phase (mean±standard deviation).
Fig 4.
An example of the load on the foot arch versus the downward displacement of the foot arch of a subject, and the fitted slopes during early heel contact, plantar contact, and late propulsion.
Table 1.
Details of subjects’ foot and the fitted average stiffness during early heel contact, plantar contact, and late propulsion.
Table 2.
Comparison of the trend and range of dynamic stiffness variation calculated by the model proposed in this study with those from previous studies and the coefficient of determination (R²) between the force-displacement (or moment-angle) curves.
Table 3.
Comparison between the proposed foot model and previous models for the human foot arch.