REDUCTION OF SPINAL LOADING THROUGH THE USE OF HANDLES

A study was performed to investigate how different types of handle cou pling affect the loading on the spine. Ten male grocery item selectors performed a laboratory simulation of a warehouse palletizing task. Pa rticipants transferred the cases from a pallet in a storage bin to the destination pallet. The trunk motions and muscle activities were moni tored by a Lumbar Motion Monitor (LMM) and electromyographic electrode s, respectively, and used as input to an EMG-assisted biomechanical mo del. The results of the study revealed that the presence of handles re duced the complex loads on the spine. This was particuarly true when l ifting to the lowest positions of the pallet, where the highest forces occurred. It was determined that the maximum spinal compression force s were reduced by an average of 6.8% when handles were added to the ca ses. The presence of handles affected the moments imposed on the trunk in the lower regions on the pallet, indicating a difference in liftin g style and/or more sagittal flexion. The results of this study sugges t that the multiplier for handle coupling in the 1991 NIOSH Revised Li fting Equation was appropriate for higher lifts (at 133.8 cm), but nee ds to be more protective for 'poor' coupling conditions with lower ver tical heights, which are the most common in industry. Based on these r esults, it is recommended that handles be designed into the cases that are commonly lifted from low levels in warehousing and other manual m aterials handling situations.