Assessment of the adecuacy of KIM-LHC method in assessing the risk level based on biomechanical loads for manual lifting tasks: A laboratory study

Manual Material handling includes activities in which pushing, pulling, lifting, lowering, carrying, and holding the load, the most common of which is lifting. This study aimed to evaluate the reliability of the KIM-LHC method to identify high-risk manual load lifting tasks.

This cross-sectional study was performed on healthy male workers with a history of manual material handling in a laboratory setting. The sample size was determined according to previous studies of 15 people. The participants were required to perform 25 tasks with four iterations randomly. An inclinometer device was used to determine the forward bending angle at the waist. Compression loads exerted on L5/S1 were estimated using 3DSSPP software using participants' postural and anthropometric information. Also, the tasks were evaluated using the KIM-LHC method, and their final scores and levels of MSD risks were determined. Data were analyzed using SPSS.20 software and the Chi-square test.

The results of compression load estimation for lifting tasks showed that 92% of the tasks had a low-risk level (less than 3400 N), and 8% of the tasks had a medium-risk level (3400 to 6800 N). While the results of the KIM-LHC method showed that 28% of tasks had a low-risk level, 64% had a medium level, and 8% had a high-risk level. 

The results of this study showed no correlation between the risk levels of the KIM-LHC method and the estimated compression load for some designed lifting tasks. Therefore, there is a possibility of error in estimating the risk level of some lifting tasks by the KIM-LHC method, and more biomechanical studies should be performed on kinetics and kinematics.