Objective

To highlight the working strategies used by expert manual handlers compared with novice manual handlers, based on recordings of shoulder and upper limb kinematics, electromyography (EMG), and estimated muscle forces during a lifting task.

Background

Novice workers involved in assembly, manual handling, and personal assistance tasks are at a higher risk of upper limb musculoskeletal disorders (MSDs). However, few studies have investigated the effect of expertise on upper limb exposure during workplace tasks.

Method

Sixteen experts in manual handling and sixteen novices were equipped with 10 electromyographic electrodes to record shoulder muscle activity during a manual handling task consisting of lifting a box (8 or 12 kg), instrumented with three six-axis force sensors, from hip to eye level. Three-dimensional trunk and upper limb kinematics, hand-to-box contact forces, and EMG were recorded. Then, joint contributions, activation levels, and muscle forces were calculated and compared between groups.

Results

Sternoclavicular–acromioclavicular joint contributions were higher in experts at the beginning of the movement, and in novices at the end, whereas the opposite was observed for the glenohumeral joint. EMG activation levels were 37% higher for novices but predicted muscle forces were higher in experts.

Conclusion

This study highlights significant differences between experts and novices in shoulder kinematics, EMG, and muscle forces; hence, providing effective work guidelines to ensure the development of a safe handling strategy is important.

Application

Shoulder kinematics, EMG, and muscle forces could be used as ergonomic tools to identify inappropriate techniques that could increase the prevalence of shoulder injuries.

中文翻译：

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提升任务期间专业知识对肩部和上肢运动学、肌电图和估计肌肉力量的影响

客观的

根据肩部和上肢运动学、肌电图 (EMG) 和举重任务期间估计的肌肉力量的记录，突出专家手动处理者与新手手动处理者相比使用的工作策略。

背景

参与组装、手动处理和个人协助任务的新手工人患上肢肌肉骨骼疾病 (MSD) 的风险更高。然而，很少有研究调查专业知识对工作场所任务期间上肢暴露的影响。

方法

16 名手动操作专家和 16 名新手配备了 10 个肌电电极，以记录手动操作任务期间肩部肌肉活动，该任务包括举起一个箱子（8 或 12 公斤），配备三个六轴力传感器，从臀部到眼睛水平. 记录了 3D 躯干和上肢运动学、手对盒接触力和 EMG。然后，计算并比较组间的关节贡献、激活水平和肌肉力量。

结果

在运动开始时，专家的胸锁-肩锁关节贡献较高，而在运动结束时，新手的贡献较高，而盂肱关节则相反。新手的 EMG 激活水平高出 37%，但专家预测的肌肉力量更高。

结论

这项研究强调了专家和新手在肩部运动学、肌电图和肌肉力量方面的显着差异；因此，提供有效的工作指南以确保制定安全处理策略非常重要。

应用

肩部运动学、肌电图和肌肉力量可用作人体工程学工具，以识别可能增加肩部受伤患病率的不适当技术。