Department of Kinesiology and Physical Education, McGill University, 475 Pine Avenue West, Montreal, QC, H2W 1S4, Canada.
Exp Brain Res. 2012 Feb;216(4):553-64. doi: 10.1007/s00221-011-2959-6. Epub 2011 Nov 29.
Neck/shoulder pain has previously been linked to repetitive work and muscle fatigue. We have shown that asymptomatic people performing repetitive upper limb tasks display signs of shoulder fatigue and of whole-body compensatory strategies. However, the role played by the proprioceptive system in the production of these compensatory strategies has not been studied. A group of asymptomatic adults (n = 18) performed a repetitive pointing task at shoulder height to fatigue. Before and after fatigue, they performed two position sense tasks, eyes closed: a single-joint task where they abducted their shoulder to the perceived horizontal and a multi-joint task, where they stood and placed their finger at the perceived location of a target in front of them at shoulder height. After fatigue, subjects made larger shoulder errors by raising their elbow higher above the horizontal (~ +1.3 cm) than before fatigue; however, their finger position accuracy was not changed, despite all subjects performing the movement in less time (~ -0.18 s) while fatigued. There were no gender differences in shoulder or finger position accuracy before or after fatigue; however, there were gender differences in the perceived finger-target location and in the temporal characteristics of the finger movement toward the target. Results suggest that healthy individuals are able to develop strategies to compensate for fatigue-induced deficits at one joint to maintain the endpoint accuracy of a multi-joint task constant. Gender differences in movement strategies and perception of endpoint location may play parts in the previously reported gender differences in work-related neck/shoulder symptoms.
先前的研究表明，颈部/肩部疼痛与重复性工作和肌肉疲劳有关。我们已经证明，进行重复性上肢任务的无症状人群会表现出肩部疲劳和全身代偿策略的迹象。然而，本体感觉系统在产生这些代偿策略中的作用尚未得到研究。一组无症状成年人（n=18）在肩高处进行重复性的上肢指向任务以达到疲劳状态。在疲劳之前和之后，他们进行了两项位置感知任务，闭眼：一项是单关节任务，他们将肩部外展到感知的水平位置；另一项是多关节任务，他们站立并将手指放在感知到的目标位置在他们面前的肩高处。疲劳后，与疲劳前相比，受试者将肘部抬得更高，超过水平位置（+1.3cm），从而导致肩部误差更大；然而，他们的手指位置准确性并没有改变，尽管所有受试者在疲劳时以更短的时间（-0.18s）完成了运动。在疲劳前后，肩部或手指位置准确性没有性别差异；然而，在感知手指-目标位置和手指向目标移动的时间特征方面存在性别差异。结果表明，健康个体能够发展策略来补偿一个关节的疲劳引起的缺陷，以保持多关节任务的末端准确性不变。运动策略和末端位置感知方面的性别差异可能在先前报告的与工作相关的颈部/肩部症状的性别差异中发挥作用。
