Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Ergonomics. 2010 Jan;53(1):83-91. doi: 10.1080/00140130903323232.
Overhead work has established links to upper extremity discomfort and disorders. As many jobs incorporate working overhead, this study aimed to identify working conditions requiring relatively lower muscular shoulder load. Eleven upper extremity muscles were monitored with electromyography during laboratory simulations of overhead work tasks. Tasks were defined with three criteria: work configuration (fixed, stature-specific); target angle (-15 degrees , 0 degrees , 15 degrees , 30 degrees from vertical); direction of applied hand force (pulling backwards, pushing forwards, downwards, sideways, upwards). Normalised electromyographic activity was greater for fixed configurations, particularly when pulling in a backward direction (total activity = 108.3% maximum voluntary exertion (MVE)) compared to pushing down or forward (total activity ranging from 10.5 to 17.3%MVE). Further, pulling backwards at angles of -15 degrees and 0 degrees showed the highest muscular demand (p < 0.05). These results suggest that, if possible, positioning overhead work in front of the body with exertions directed forwards will result in the lowest upper extremity muscle demand. STATEMENT OF RELEVANCE: Overhead work pervades occupational settings and is associated with risk of upper extremity musculoskeletal disorders. The muscular intensity associated with performing overhead work was assessed in several combinations of work placement and hand force direction. These findings should have utility for designing overhead work tasks that reduce muscular exposure.
overhead 工作与上肢不适和疾病有关。由于许多工作都涉及到 overhead 工作，因此本研究旨在确定需要相对较低肩部肌肉负荷的工作条件。在 overhead 工作任务的实验室模拟中，通过肌电图监测了 11 块上肢肌肉。任务通过三个标准定义：工作配置（固定，特定身高）；目标角度（-15 度，0 度，15 度，30 度垂直）；施加手部力的方向（向后拉，向前推，向下，向侧面，向上）。固定配置的肌电图活动归一化值更高，特别是在向后拉时（总活动= 108.3％最大自主用力（MVE））与向下或向前推相比（总活动范围为 10.5 至 17.3％MVE）。此外，在-15 度和 0 度的向后拉角度下，肌肉需求最高（p <0.05）。这些结果表明，如果可能的话，将 overhead 工作置于身体前方，并使力指向前方，将导致上肢肌肉的需求最低。相关性陈述： overhead 工作在职业环境中普遍存在，并且与上肢肌肉骨骼疾病的风险相关。评估了几种工作位置和手部力方向组合下进行 overhead 工作的肌肉强度。这些发现对于设计减少肌肉暴露的 overhead 工作任务应该具有实用价值。
