Department of Industrial Engineering and Management, Ben-Gurion University of the Negev, Beer Sheva, Israel.
Institute of Agricultural Engineering, Agricultural Research Organization, Bet Dagan, Israel.
Ergonomics. 2021 May;64(5):613-624. doi: 10.1080/00140139.2020.1858184. Epub 2020 Dec 30.
Shoulder musculoskeletal disorders due to manual material handling tasks are common workplace injuries. Here we investigated the difference in shoulder biomechanics (moments and angles) between a single task of removing a box from a shelf (or depositing a box on a shelf) and the equivalent part of a combined task that consisted of removing, carrying and depositing boxes; that is, a single [] task was compared with the [] part of a combined task. We found that the peak and cumulative shoulder moments were larger during the single-task paradigm than during the equivalent part of the combined task by 26.3 and 25.5%, respectively. The two paradigms also differed in terms of shoulder angles. It is likely that the main contributors to this overestimation were differences between the single and combined tasks in terms of the lever arm (i.e. horizontal distance), the shoulder angle, and the task duration. We investigated shoulder moments during single and combined manual material handling tasks. Shoulder moments were found to be smaller during combined tasks. Practitioners should consider that analysing combined tasks using estimations based on single tasks could result in an overestimation of 26.3 and 25.5% in peak and cumulative shoulder moments, respectively. MSDs: musculoskeletal disorders; MMH: manual material handling; LMM: linear mixed model.
由于手动搬运任务导致的肩部肌肉骨骼疾病是常见的工作场所损伤。在这里，我们研究了从货架上取下（或存放）箱子的单一任务与由取出、搬运和存放箱子组成的等效组合任务的肩部生物力学（力矩和角度）之间的差异；也就是说，将单一任务与组合任务的等效部分进行了比较。我们发现，在单任务范式中，峰值和累积肩部力矩分别比组合任务的等效部分大 26.3%和 25.5%。这两种范式在肩部角度方面也存在差异。造成这种高估的主要原因可能是单任务和组合任务在杠杆臂（即水平距离）、肩部角度和任务持续时间方面存在差异。我们研究了单一和组合手动搬运任务中的肩部力矩。结果发现，在组合任务中肩部力矩较小。从业者应该意识到，使用基于单一任务的估算来分析组合任务可能会导致峰值和累积肩部力矩分别高估 26.3%和 25.5%。MSDs：肌肉骨骼疾病；MMH：手动搬运；LMM：线性混合模型。
