Effects of Medial and Lateral Motion of the Foot during a Forward Slip on the Loss and Recovery of Balance

Falls, especially those caused by slips, are a major health concern. Past research has\ud examined the mechanisms of preventing a fall from a forward slip; however, the effects of a\ud mediolateral component to the slip have not been thoroughly analyzed. The purpose of this study\ud was to examine how medial or lateral motion of the foot during a forward slip while walking\ud affects the loss and recovery of balance.\ud A perturbation platform was used to cause 15 young, healthy adults to slip 13 cm while\ud walking. Participants slipped four times across 30 trials, with the final three slips analyzed. Each\ud participant slipped once in the forward, forward-and-lateral, and forward-and-medial directions\ud during their final three slips. All participants were classified as having recovered from the slips.\ud Twenty-five variables, extracted from the recorded motion capture data, were analyzed.\ud The position and velocity of the participants’ center of mass at the end of the slip and at\ud touchdown of the first recovery step differed between slip directions. During a lateral slip,\ud participants lost their balance medially and, during a medial slip, they lost their balance laterally.\ud This caused variations in stepping patterns used in reacting to the different types of balance loss.\ud Participants responded to lateral slips with a significantly shorter, wider, and quicker step\ud whereas, for medial slips, they tended to take a large step across their midline. Adding a\ud mediolateral component to a forward slip was found to not only change the resulting loss of\ud balance, but also change the reaction to the slip