The relations of motor abundance during gait with fall risk in older adults

Abstract

Our body has more elements such as joints and muscles than needed to perform any activities of daily living, including gait. As an approach to the problem of motor redundancy, the principle of abundance was suggested. The principle views the apparently redundant design of the body as a useful and crucial mechanism stabilizing different performance variables in a task-specific way. There are many papers based on this idea using the framework of the uncontrolled manifold (UCM) hypothesis. The UCM hypothesis assumes that the central nervous system acts in an abundant space of elemental variables and organizes in that space a subspace corresponding to a stable value of a performance variable. The UCM method has been developed for various actions, including multi-joint reaching, standing, and gait, and used for different subjects (e.g., younger adults, older adults, patients with neurological impairment). Using the method, we explored if segment configurations contributing to the stability of swing foot and center of mass are related to falling risk in older adults. With this paper, we introduce our previous studies as well as the basic concept of motor redundancy and the principle of abundance.