Assessment of an EMG-based method for continuous estimates of low back compression during asymmetrical occupational tasks
Assessment of an EMG-based method for continuous estimates of low back compression during asymmetrical occupational tasks
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DOI：
10.1080/001401399185342
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发表时间：
1999-06-01
期刊：
影响因子：
2.4
通讯作者：
McGill, SM
中科院分区：
文献类型：
--
作者：
Mientjes, MIV;Norman, RW;McGill, SM
诸如峰值和累积力矩以及脊柱压缩力等变量已被证明是职业性腰痛的危险因素。在长时间的、动态的、不对称的任务中，使用生物力学模型来估计这些力是复杂而耗时的。在矢状面提升和复杂的不对称工作期间，需要一种简单的技术来连续测量这些变量，以测量脊柱负荷的分布。本研究的目的是确定直立者脊柱肌电图与脊柱压缩力的线性归一化，即压缩归一化肌电图（CNEMG），是否可以用于估计模拟不对称职业任务时脊柱负荷。使用归一化肌电图获得的脊柱压缩力估计以振幅概率分布函数的形式呈现，并与三维生物力学模型的估计进行比较。显示工人超过特定水平的脊柱负荷（如NIOSH的压缩动作极限）的时间百分比。五名男性执行模拟的职业任务。CNEMG估计，在特定水平的脊柱压缩力下，三种任务组合的暴露时间平均在生物力学模型计算时间的6.5%以内。然而，如果任务组合以轴向扭转力矩为主导，则差异平均为13.4%。在特定概率下，脊柱压缩幅度的差异平均为14.9%，而当轴向躯干扭曲占主导地位时，差异为30.7%。综上所述，当任务组合以矢状面伸肌力矩为主要特征时，CNEMG可以估计特定水平脊柱压缩力的概率。在特定概率下的脊柱压缩估计，以及在由轴向扭转力矩主导的任务组合中获得的估计，都很差。
Variables, such as peak and accumulated moments and spine compression forces, have been shown to be risk factors for occupational low back pain. Estimates of these forces during prolonged, dynamic, asymmetric tasks using biomechanical models is complex and time-consuming. A simple technique for continuous measurement of these variables over a prolonged period is needed to measure the distribution of spinal loading during both sagittal plane lifts and complex asymmetrical jobs. The aim of this study was to determine whether a linear normalization of erector spinae EMG to spine compression force, called compression normalized EMG (CNEMG), could be used to estimate spinal loading for simulations of asymmetrical occupational tasks. The estimates of spine compression force obtained using the normalized EMG are presented in the form of an amplitude probability distribution function and are compared with estimates of a three-dimensional biomechanical model. The per cent time a worker spends above particular levels of spinal loading of interest, such as the NIOSH action limit for compression, are displayed. Five males performed simulated occupational tasks. The exposure time at a specific level of spine compression force for a combination of three tasks, estimated by CNEMG, was, on average, within 6.5% of the time calculated by the biomechanical model. However, if the task combination was dominated by an axial twisting moment, then the difference was, on average, 13.4%. The difference in magnitude of spine compression at a specific probability was, on average, 14.9% and when axial trunk twist dominated, 30.7%. It is concluded that CNEMG can estimate probability at a specific level of spine compression force when the task combination is characterized by a predominant extensor moment in the sagittal plane. Estimates of spine compression at a specific probability, and estimates obtained during task combinations dominated by an axial twisting moment, are poor.