Rotation of load during the prelift period.

Abstract

Lifting is a major source of back injuries because of the mechanical effects on the spinal structures. A number of methods are known by which a lifter can reduce the load on the spine during lifting. This study explores an additional method: rotation of the load before it is actually lifted off the ground. The hypothesis tested is that when a lifter lifts a box, he or she rotates it before it leaves the floor. By the use of an optoelectronic system to study weight box rotation, it was established that rotation occurs in every lift before the actual lift occurs. Rotation time increased with increasing load, indicating that the rotation technique is more important when load reduction is most critical.