Effects of transfer distance on spine kinematics for de-palletizing tasks.

One approach to reducing lateral bending and twisting in manual lifting tasks is to separate the lift's origin and destination, thereby encouraging lifters to step and turn their entire bodies. The objective of the current study was to determine how the degree to which one laterally bends and twists changes with transfer distance and initial lift height. Eighteen males lifted 10.9kg boxes from a conveyor 0.5m, 0.9m, and 1.3m above the floor and placed the boxes on a conveyor .50, .75, 1.00, 1.25, 1.50, or 1.75m away at a height of .9m. During picking, lateral bending and trunk extension velocities increased with increasing transfer distances. When placing the box, the degree of twisting decreased with increased transfer distance. In sum, when attempting to control the twisting and lateral bending during de-palletizing, the lift origin and destination should be separated by between 1 and 1.25 meters.