Individuals can coordinate small kinematic changes at several degrees of freedom simultaneously in the presence of fatigue, leaving it unclear how overall biomechanical demands at each joint are altered. The purpose of this study was to evaluate trade-offs in joint moments between the trunk, shoulder, and elbow during repetitive upper extremity work. Participants performed four simulated workplace tasks cyclically until meeting fatigue termination criteria. Emergent fatigue-induced adaptations to repetitive work resulted in task-dependent trade-offs in joint moments. In general, reduced shoulder moments were compensated for by increased elbow and trunk joint moment contributions. Although mean joint moment changes were modest (range: 1-3 Nm) across participants, a wide distribution of responses was observed, with standard deviations exceeding 10 Nm. Re-distributing biomechanical demands across joints may alleviate constant tissue loads and facilitate continued task performance with fatigue but may be at the expense of increasing demands at adjacent joints.

中文翻译：

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在重复工作期间，整个上肢和躯干的共同力矩折衷。

在存在疲劳的情况下，个人可以同时在几个自由度上协调小运动学变化，尚不清楚每个关节的总体生物力学要求如何改变。这项研究的目的是评估在重复上肢锻炼过程中躯干，肩膀和肘部之间的关节弯矩的取舍。参与者周期性地执行四个模拟工作场所任务，直到达到疲劳终止标准。疲劳引起的对重复性工作的新适应导致了在共同时刻中取决于任务的权衡。通常，减少的肩部力矩可以通过增加肘部和躯干关节力矩来弥补。尽管参与者的平均关节力矩变化不大（范围：1-3 Nm），但观察到的响应分布广泛，标准偏差超过10 Nm。在关节之间重新分配生物力学需求可以减轻恒定的组织负荷并促进疲劳持续的工作表现，但可能以增加相邻关节的需求为代价。