Investigation of 3D dynamic and quasistatic models for spinal moments during combined manual material handling tasks

• Published in: Applied ergonomics 2021-02, Vol.91, p.103305-103305, Article 103305
• Main Authors: Harari, Yaar, Bechar, Avital, Asci, Simone, Riemer, Raziel
• Format: Article
• Language: English
• Subjects: Biomechanical model; Digital human modeling; Ergonomics; L5/S1 moments
• ISSN: 0003-6870; 1872-9126
• DOI: 10.1016/j.apergo.2020.103305

Digital human modeling software uses biomechanical models to compute workers' risk of injury during industrial work processes. In many cases, the biomechanics are calculated using quasistatic models, which neglect the body's dynamics and therefore might be erroneous. This study investigated the differential effect of using a dynamic vs. a quasistatic model on spinal loading during combined manual material handling tasks that are prevalent in industry. An experiment was conducted involving nine male and nine female participants performing a total of 3402 cycles of a box-conveying task (removing, carrying and depositing) for different box masses and shelf heights. Using motion capture data, the peak and cumulative moments acting on the L5/S1 joint were calculated using 3D dynamic and quasistatic models. This revealed that neglecting the dynamic movements (i.e., using a quasistatic model) results in an on average underestimation of 19.7% in the peak spinal moment and 3.6% in the cumulative moment that in some cases exceeds the maximal limit for the compression forces acting on the lower back. •Many ergonomic tools and digital human modeling software use static biomechanical models.•We investigated the differences between static and dynamic models on spinal moments.•In a lab experiment 18 participants performed 3402 manual material handling tasks.•We used motion capture technology and calculated peak and cumulative L5/S1 moments.•Using a static model resulted in underestimation of 19.7% and 3.7% in peak and cumulative moments respectively.