The Adequacy of NIOSH Equation to to Determine the Rate of Stresses Exerted on the Back Based on Compressive Force Estimation

Background: Manual handling may cause workers to deal with various risk factors. Workers performing such tasks repeatedly for a long time are more prone to bodily injuries and physical problems such as back pain. Objectives: The current study aimed to assess the compressive loads estimation and analysis of forces exerted on the workers’ back in manual load lifting tasks using the national institute for occupational safety and health (NIOSH) equation and compare them with the recommended weight limit (RWL). Methods: It was a cross-sectional study in a laboratory setting on 15 healthy male workers in 2015. The participants were required to randomly perform 25 tasks with four iterations. The lifting index (LI) was calculated by NIOSH equation in simple tasks and compressive loads on the low back (L4/L5) for each task were calculated using the 3DSSPP. Data were analyzed using SPSS version 16. Results: The results showed that the highest compressive force exerted on the back was equal to 4002 N and the lowest force 1425 N. Moreover, 76% of the tasks were reported to have the highest compressive force greater than the recommended limit; 72% of the tasks had an LI 1 - 3 and 28% of them had an LI less than 1. There was a weak direct correlation between compressive force and RWL. Conclusions: The NIOSH equation and compressive force estimation function were partially similar to identify high-risk tasks, however, by the compressive force estimation, biomechanical analysis of tasks can be done better since it is quantitative and can determine the exact amount of forces exerted on the back.