Wearable passive (ie, spring powered) shoulder exoskeletons could reduce muscle output during motor tasks to help prevent or treat shoulder musculoskeletal disorders. However, most wearable passive shoulder exoskeletons have been designed and evaluated for static tasks, so it is unclear how they affect muscle output during dynamic tasks. The authors used a musculoskeletal model and Computed Muscle Control optimization to estimate muscle output with and without a wearable passive shoulder exoskeleton during 2 simulated dynamic tasks: abduction and upward reach. To an existing upper extremity musculoskeletal model, the authors added an exoskeleton model with 3-dimensional representations of the exoskeleton components, including a spring, cam wheel, force-transmitting shoulder cable, and wrapping surfaces that permitted the shoulder cable to wrap over the shoulder. The exoskeleton reduced net muscle-generated moments in positive shoulder elevation by 28% and 62% during the abduction and upward reach, respectively. However, muscle outputs (joint moments and muscle effort) were higher with the exoskeleton than without at some points of the movement. Muscle output was higher with the exoskeleton because the exoskeleton moment opposed the muscle-generated moment in some postures. The results of this study highlight the importance of evaluating muscle output for passive exoskeletons designed to support dynamic movements to ensure that the exoskeletons assist, rather than impede, movement.

中文翻译：

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机械被动、可穿戴肩部外骨骼对动态上肢运动期间肌肉输出的影响：计算模拟研究。

可穿戴被动（即弹簧驱动）肩部外骨骼可以减少运动任务期间的肌肉输出，以帮助预防或治疗肩部肌肉骨骼疾病。然而，大多数可穿戴被动肩部外骨骼都是针对静态任务进行设计和评估的，因此尚不清楚它们在动态任务期间如何影响肌肉输出。作者使用肌肉骨骼模型和计算肌肉控制优化来估计 2 个模拟动态任务（外展和向上伸展）期间使用和不使用可穿戴被动肩部外骨骼的肌肉输出。作者在现有的上肢肌肉骨骼模型中添加了一个外骨骼模型，该模型具有外骨骼组件的 3 维表示，包括弹簧、凸轮、传力肩缆和允许肩缆缠绕在肩膀上的缠绕表面。在外展和向上伸展过程中，外骨骼将肩部正抬高过程中肌肉产生的净力矩分别减少了 28% 和 62%。然而，在运动的某些点上，使用外骨骼的肌肉输出（关节力矩和肌肉力量）比不使用外骨骼时更高。外骨骼的肌肉输出更高，因为在某些姿势下外骨骼力矩与肌肉产生的力矩相反。这项研究的结果强调了评估用于支持动态运动的被动外骨骼的肌肉输出的重要性，以确保外骨骼帮助而不是阻碍运动。