Fall Prevention Analysis during a Fall Stimulus Using the Differential Velocity of a Split Belt Treadmill

Amid trends toward population aging in many developed countries, 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 previous studies have analyzed the movements produced by artificially generated slip and fall stimuli, but few have investigated these stimuli directly. 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, with which a speed difference between the belts could be applied to produce a slipping motion. In two male participants, we induced 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. The results indicated that the transition of the floor reaction force during a fall stimulus correlates with the location of the center of mass and the risk of fall. In future, we plan to test larger samples of young, healthy participants, and to examine at-risk elderly participants.