Box Weight or Lift Rate: Which Factor Matters More during Lifting?

Previous research has shown that lift rate and box weight are known to influence the risk of developing a low back disorder. However, when a given amount of material must be transferred there is little guidance as to the best combination of weight and lift rate in order to have the lowest risk of developing a back injury. The current study investigated combinations of lift rate and box weight when moving a given amount of material with respect to the impact on spinal loading, perceived exertion, and perceived risk of injury. The results show that there is an interaction between lift rate and box weight. There was a trade-off in loading cumulative and peak loading for both compression and shear loads which was dependent upon the weight and lift rate. Perceived exertion was influenced more by box weight than lift rate. Based on all the loading results, it is recommended that workers should under one of the following conditions: 4 or 8 lpm for 9.1 kg weight boxes and 12 lpm for the 4.5 kg weight boxes.