INTRODUCTION

The number one work-related occupational hazards in the United States are back injuries (1). It is estimated that 100 million days of work are lost annually due to back injuries (1). Back injuries create a total annual cost of between $30 billion and $60 billion (1). Improper lifting techniques are the primary cause of these lower back injuries. There are two different types of lifts. The first of which is the "stoop lift" where a worker bends at the hip, reaches down to grab an object, then rises, putting most of the load from the lift on the back. It is believed that this type of lift may cause unnecessary strain on the lower back of a lifter. The second type of lift, the "squat lift", is where a lifter would squat down to the level of an object, by bending the knees, then grab the object and rise, putting most of the strain on the legs. By putting the strain of the lift on the legs, the lower back is, in a sense, protected from injury. Many workers that do a lot of heavy lifting during the course of a work day are trained to use the squat lift, rather than the stoop lift. Unfortunately, lifters that are in this situation often become fatigued and revert to the stoop lift. The question is, is the squat lift less strenuous on the lower back then the stoop lift?

The purpose of this experiment is to determine whether the squat lift is, in fact, less stressful to the lower back than the stoop lift. This will be determined by examining the moment arms, velocities, and positions of each lift. Each lift will be examined by varying the distance of the object from the lifter. The weight of the object will remain constant.