INTRODUCTION

Low back pain is a common problem in the United States and is a major cause of morbidity, disability, limitation of activity, and economic loss. Studies have shown that 60 to 90% of people are affected at some time during their lives (Kelsey and Golden, 1988). Approximately one-half of all compensable back pain incidents are associated with manual lifting tasks (Snook, 1988). This has resulted in a major effort in industry to identify safe lifting techniques. This study will analyze two biomechanical motions and compare the torques acting upon the lower back and hip joints in both cases.

The first motion will involve lifting a load from the ground when bending from the knees ("squat lift"). The second motion will require lifting the same load when bending only at the hip ("back lift"). We hypothesize that the squat lift reduces the amount of torque acting upon the lumbar vertebrae compared to the back lift. We will use digital video analysis to identify differences in joint angles and body segment position to discuss angular and linear kinematics.