Static Postural Stability on Narrow Platforms to Prevent Occupational Stepladder Falls

Abstract

Falls from heights are the most common causes of occupational fatal accidents in many countries; using agents, such as stepladders or scaffolds, is one of the main causal factor. This study aims to evaluate the postural stability of static standing on narrow platforms. Eleven male participants stood on five platforms that had anterior/posterior widths ranging from 6 to 25 cm and maintained their position for 50 s. The coordinates and velocities of center of mass (CoM) and center of pressure (CoP) were calculated from kinematic data of human body and foot reaction forces. The results showed that the relative position of CoP to the platform width and the translational velocity non-linearly increased with shortened platform width and more significantly changed than the relative position of CoM, while there was no significant difference between the 15-cm and 25-cm platforms. The regression lines of the relative position and the velocity of CoP were approximated as a function of the inverse of the platform width or the square, respectively. Shortened platforms make the postural balance of static standing non-linearly unstable, whereas platforms that are 15 cm or wider stabilize the postural perturbation comparable to that achieved on the ground. Therefore, the equipment with a platform or rungs at least 15 cm or wider should be recommended for tasks at elevated places.