Qin Jin, Lin Jia-Hua, Buchholz Bryan, Xu Xu
a Department of Work Environment , University of Massachusetts , Lowell , MA 01854 , USA.
Ergonomics. 2014;57(8):1201-12. doi: 10.1080/00140139.2014.914576. Epub 2014 May 6.
Age may modify the association between occupational physical demand and muscle loading, and ultimately increase the risk of musculoskeletal disorders. The goal of this study was to investigate age-related differences in shoulder muscle fatigue development during a repetitive manual task. Twenty participants in two age groups completed an 80-minute simulated low-intensity assembly task. Electromyographic (EMG) manifestation of muscle fatigue was observed in the upper trapezius, deltoid and infraspinatus muscles in both age groups, and coincided with an increase in the subjective ratings of perceived exertions. Compared with the younger group, older group showed a more monotonic decrease in EMG power frequency in the upper trapezius and deltoid muscles. However, the age-related difference in EMG amplitude was less consistent. Relative rest time of the upper trapezius muscle in the older group was less than the young group throughout the task. The observed patterns of EMG measures suggest that older participants may have disadvantages in fatigue resistance in the upper trapezius and posterior deltoid muscles during the simulated repetitive manual task.
年龄可能会改变职业体力需求与肌肉负荷之间的关联，并最终增加肌肉骨骼疾病的风险。本研究的目的是调查在重复性手工任务期间，肩部肌肉疲劳发展中与年龄相关的差异。两个年龄组的20名参与者完成了一项80分钟的模拟低强度装配任务。在两个年龄组的斜方肌上部、三角肌和冈下肌中均观察到了肌肉疲劳的肌电图（EMG）表现，且与主观用力感觉评分的增加相一致。与较年轻组相比，较年长组的斜方肌上部和三角肌的肌电功率频率呈更单调的下降。然而，肌电幅度的年龄相关差异不太一致。在整个任务过程中，较年长组斜方肌上部的相对休息时间少于较年轻组。观察到的肌电测量模式表明，在模拟重复性手工任务期间，年长参与者的斜方肌上部和三角肌后束在抗疲劳方面可能存在劣势。
