National Institute of Occupational Health, Oslo, Norway.
J Electromyogr Kinesiol. 2013 Jun;23(3):540-7. doi: 10.1016/j.jelekin.2012.12.004. Epub 2013 Jan 31.
The purpose of this paper was to compare the effects of different data reduction procedures on the values of variables characterizing the time pattern of trapezius muscle activity during full work shifts. Surface electromyography (EMG) of the right and left upper trapezius muscles were obtained from 40 young subjects in different occupations, mainly electricians, hairdressers and students. The target EMG variables were gap frequency, muscle rest, and the number and duration of episodes with sustained muscle activity (from 0.13s to 30min as minimum duration). These variables were derived from the EMG recordings using different Root Mean Square (RMS) windows (from 0.13 to 6.38s), and discrimination levels between "activity" and "rest" (0.5%, 1% and 2% of maximal EMG). The results give basis for practical suggestions for EMG analyses of full work shifts. For most variables, a discrimination level of 0.5% EMGmax showed to be preferable. The time proportion of muscle rest and sustained muscle activity should, in general, be preferred over the corresponding frequency measures. Sustained muscle activity should be calculated using a RMS window between 1 and 3s, and preferably be stated in terms of variables describing time proportions of activity. Uninterrupted activity episodes longer than 10min proved not to be a useful variable due to limited occurrence in many work shifts.
本文旨在比较不同数据缩减程序对描述斜方肌活动时间模式的变量值的影响，这些变量值来自不同职业的 40 名年轻受试者，主要是电工、理发师和学生。目标肌电图变量包括间隙频率、肌肉休息以及持续肌肉活动的发作次数和持续时间（最短持续时间为 0.13s 至 30min）。这些变量是通过使用不同均方根 (RMS) 窗口（0.13 至 6.38s）和“活动”和“休息”之间的区分水平（最大肌电图的 0.5%、1%和 2%）从肌电图记录中得出的。结果为整个工作班次的肌电图分析提供了实用建议的基础。对于大多数变量，0.5%EMGmax 的区分水平显示更可取。肌肉休息和持续肌肉活动的时间比例通常应优先于相应的频率测量。应使用 1 至 3s 的 RMS 窗口计算持续肌肉活动，并最好以描述活动时间比例的变量表示。由于在许多工作班次中发生的频率有限，持续 10 分钟以上的不间断活动发作并不是一个有用的变量。
