Influences of age and light touch on the preparation for protective stepping reactions

Abstract

Objective: The present study examined the effect of light touch on the preparation for fall-induced protective stepping in elderly and young individuals. Material and Method: The subjects were perturbed with forward pull with no-touch and light touch conditions. Anticipatory periods, lift-off onset, center of pressure displacement and velocity were measured and analyzed. Results: The authors observed a stabilizing effect during with light touch in pre-perturbation periods. During the perturbation, the elderly took steps earlier than did the young individuals by reducing anticipatory periods; however, their anterior stability limit was similar to that of the youth, indicating that the step was pre-selected. In the youth, a delay in anticipatory onset and shorter periods were observed with light touch, resulting from a limitation in lateral limb loading. Additionally, the stabilizing effect in the pre-perturbation period did not influence stabilization of preparatory period before stepping. In the elderly, shorter anticipatory periods and lower stability limits were also shown in light touch conditions. The authors concluded that the elderly were more concerned with a postural task than with light touch. Conclusion: Protective stepping is reflected in the state of balance stability and involves a pre-selection process. Light touch enhances postural stability in stance and impacts the stepping.