  There has been a controversy as to whether or not the non-pathological flat
foot and high-arched foot have an effect on human walking activities. The 3D
foot scanning system was employed to obtain static footprints from subjects
adopting a half-weight-bearing stance. Based upon their footprints, the
subjects were divided into two groups: the flat-footed and the high-arched. The
plantar pressure measurement system was used to measure and record the
subjects' successive natural gaits. Two indices were proposed: distribution of
vertical ground reaction force (VGRF) of plantar and the rate of the footprint
areas. Using these two indices to compare the natural gaits of the two subject
groups, we found that (1) in stance phase, there is a significant difference
(p<0.01) in the distributions of VGRF of plantar; (2) in a stride cycle, there
is also a significant difference (p<0.01) in the rates of the footprint areas.
Our analysis suggests that when walking, the VGRF of the plantar brings greater
muscle tension to the flat-footed while a smaller rate of the footprint areas
brings greater stability to the high-arched.
