Biomechanical demand analysis of older passengers in a standing position during bus transport

Abstract

Abstract Bus driving maneuvers are likely to trigger perturbation forces that may cause postural instability in standing passengers and cause tumble. These noncollision incidents are considered a major cause of injuries and may induce passenger discomfort in public transport. Therefore, we analyzed the effects of acceleration and deceleration forces on older passengers in an upright standing position in everyday bus transport situations. We recorded ground reaction and handgrip forces, electromyographic data of the leg muscles, and the acceleration pattern of 8 elderly participants (68.1±5.2 years). The participants were exposed to acceleration and deceleration maneuvers while standing upright in three different positions: in the direction of travel (IT), against the direction of travel (AT), and sideways to the direction of travel (ST). The acceleration pattern of the bus was similar to everyday driving situations (starting and stopping in traffic). Ground reaction forces were higher in free-standing positions, as expected, with peak forces of 135% (ST) to 165% (AT) of individual body weight, than in standing position by grasping a strap, with peak forces of 120% (all conditions). However, when participants grasped the strap, peak forces comprised 65% (ST) to 90% (AT) of individual maximal pulling power. A passenger may experience these forces numerous times during a typical bus transport. Electromyographic analysis revealed a correlation between jerk events and muscle activation and coactivation of antagonistic muscles. This study presents, for the first time, relevant information with regard to the biomechanical demands of older passengers standing upright in bus transportation. On this basis, conceptual solutions may be introduced to improve passenger safety and comfort. Further research studies exploring the relationship between acceleration forces and travel safety of the elderly should be conducted.