Ergonomic Analysis of Mobile Cart–Assisted Stocking Activities Using Electromyography

Workers in grocery stores are exposed to numerous musculoskeletal risks that can be reduced using assistive devices while performing stocking tasks. A regional grocery store has recently deployed a mobile cart without comprehension of its ergonomic impact on workers, which this paper investigates using normalized electromyography data (%MVC). This paper studies not only ergonomic impact based on %MVC values, but also work performance represented by a muscle force metric (MFM). The results from this study showed highest muscle groups in %MVC and MFM were the erector spinae and triceps. Interestingly, muscle activations on erector spinae were reduced when mobile cart is used. %MVC and MFM distribution for value-addedand non-value-added subtasks were slightly different, with larger differences observed for non-value-added tasks. Video recordings revealed higher work performance when mobile cart is used. In future research, the number of participants will be increased to further validate the results from this study.