EFFECT OF LOAD ASYMMETRY ON INTERNAL LOADING OF TRUNK

在工业中，不对称地搬运和提升物体是规则 而不是例外。这种情况是危险的， 肌肉骨骼系统由于增加共激活的 肌肉组织和脊柱上的力量增加。 本研究的目的是量化十个躯干肌肉的活动 通过在最大和次最大期间使用表面肌电图（EMG）， 在单纯和联合负荷条件下的等长用力 后备箱 组合载荷定义为 矢状面和横断面。 这些平面的选择基于 他们在工业工作和腰部受伤中的患病率。 为了计算内部负荷的影响，肌肉参数为 根据每个个体参与者的CT扫描图像计算， 使用EMG驱动模型来估计个体肌肉力。 的 在建议的条件下计算压缩力和剪切力。 平面运动（纯运动）和联合运动对 躯干肌募集和压缩力和剪切力的模式 将被比较。 本研究的主要假设是： 1)躯干肌的肌电活动峰值在运动过程中会更高， 最大联合用力比单纯最大用力时更大。 2)10块躯干肌的均方根-肌电均值会发生变化 明显地，与净合成力矩的方向有关， 后备箱 3)压缩力和剪切力将显著改变， 合力矩的方向。 本研究将提供一个更好的理解的影响， 不对称提升对机械和神经肌肉性能以及 背部受伤的风险。

In industry, carrying and lifting objects asymmetrically is the rule rather than the exception. This situation is hazardous to the musculoskeletal system due to an increase in coactivation of the musculature and an increase of the forces on the spine. The aim of this study is to quantify the activities of ten trunk muscles by using the surface electromyography (EMG) during maximal and submaximal isometric exertion under pure and combined loading conditions of the trunk. Combined loading is defined as the vectorial sum of moments in the sagittal and transverse planes. These planes are selected based on their prevalence in industrial tasks and low back injuries. To calculate the effect of internal loading, the muscle parameters are calculated from CT-scan images of each individual participant and individual muscle forces are estimated using an EMG-driven model. The compression and shear forces are calculated under suggested conditions. The effects of planar exertion (pure exertion) and combined exertion on the patterns of trunk muscle recruitment and compression and shear forces will be compared. The primary hypotheses of this study are: 1) The peak EMG activity of trunk muscles will be higher during the maximal combined exertion than during pure maximal exertion. 2) The mean of RMS-EMG of the ten selected trunk muscles will change significantly with the orientation of the net resultant moments of the trunk. 3) The compression and shear forces will be changed significantly by the orientation of the resultant moment. The present study will provide a better understanding of the effect of asymmetrical lifting on mechanical and neuromuscular performance and on the risk of injury to the back.