Hand Placement and Risk Assessment by the LMM Model

Previous studies have shown a variety of hand placement locations employed by workers performing manual lifting tasks in industry. In this study, participants used four different hand placement locations to lift a box of variable weight and starting height. As they performed these lifts, the motions of their torso were captured using the lumbar motion monitor and these trunk kinematics were then input into the LMM low back injury risk assessment model. The results showed significant effects of all three independent variables with asymmetric hand placement locations generating the highest level of risk: 20% in the symmetric, 5kg condition as compared to a high of nearly 40% under the asymmetric, 10kg condition. These results indicate that hand placement is a relevant variable to consider when designing manual materials handling tasks.