Analysis of the slip-related falls and fall prevention with an intelligent shoe system

We studied a relationship between a zero moment point (ZMP) and a base of support (BOS) during slipping. ZMP is the point on the ground where no moment may be transmitted about the whole body center of mass (COM). When subjects could walk without slipping, ZMP was located within the BOS at a single support phase. When a fall after a forward slip was observed, the ZMP remained outside of the BOS edge. The maximum distance between the ZMP and the BOS edge (L
max
) was longer in the fall group than in the recovery group (p < 0.001). The maximum velocity of the slipping foot segment relative to the torso segment (vr max) had a positive correlation with L
max
. An intelligent shoe system, which can extend the shoe sole area (BOS) laterally, improved both static standing balance and dynamic standing balance. Thus, appropriate coefficient of sliding friction on the shoe sole and intelligent control of the shoe sole area would be of value in reducing the risk of falling, particularly for the people with movement disorders.