Fall stimulation method based on differential velocity of split belt treadmill

Amid trends toward population aging in developed nations, the number of people requiring nursing care has increased markedly. Slips and falls during ordinary daily activities are a common cause of bone fracture and muscle injury. Several studies have analyzed the movements produced by artificially generated slip and fall stimuli, but few have investigated these stimuli per se. We analyzed lower limb motion following a slip and fall stimulus produced using a pulled free-walking system. This consisted of a controllable split-belt treadmill, wherein a speed difference between the belts could be applied to produce a slipping motion. In two male participants, we established the slip motion by immediately applying acceleration in the sagittal plane direction of the right leg upon contact with the treadmill. Each participant demonstrated a unique recovery method from falling. Additionally, we found that increased stimulation led to faster right foot motion during recovery or a stronger floor reaction force if recovery failed. In the future, we intend to test larger samples of young, healthy participants, and further extend it to the at-risk elderly population. In so doing, we will be able to develop a possible indicator for fall risk by analyzing limb motion when a slip and fall stimulus is applied.