Chen Jing, Yang Lei
Medical and Life Science College, Jianghan University, Wuhan 430056, China.
Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi. 2006 Apr;24(4):198-200.
To evaluate the work load and related factors for asymmetric lifting tasks using surface electromyography (EMG).
Thirteen male volunteers lifted loads of 6 and 13 kg at two speeds, in varying angles of trunk rotation, from floor to knuckle height, performing 16 lifting tasks. During lifting, surface electromyography signals from the erector spinae, bilaterally at level of T10 and L3, was continually recorded. The work load and related factors for asymmetric lifting tasks were evaluated by comparing the average amplitude of EMG signals.
The EMG average amplitude when lifting the load of 13 kg (43.30% MVE) was significantly greater than that when lifting the load of 6 kg (37.70% MVE) (P < 0.01). The EMG average amplitude when lifting at the higher speed (41.80% MVE) was significantly greater than that at the lower speed (39.19% MVE) (P < 0.05). The EMG average amplitude was increased with the increase of the trunk rotation angle without significant difference (P > 0.05). At T10, the EMG average amplitude was greater on the right side than that on the left side (50.31% MVE and 25.88% MVE respectively) while at L3, it was on the contrary (45.60% MVE on the left and 40.22% MVE on the right respectively) (P < 0.01). Multiple stepwise regression analysis showed that the load of lifting was the factor contributing most to the EMG average amplitude followed by the lifting speed.
The risk factors related to work load for asymmetric lifting tasks are mainly the load and the speed of lifting. The EMG activity between the right and left side of erector spinae is different during such lifting.
使用表面肌电图（EMG）评估不对称举重任务的工作量及相关因素。
13名男性志愿者以两种速度、在不同的躯干旋转角度下，将6千克和13千克的重物从地面举至指关节高度，共进行16项举重任务。在举重过程中，持续记录双侧T10和L3水平竖脊肌的表面肌电图信号。通过比较肌电图信号的平均幅度来评估不对称举重任务的工作量及相关因素。
举起13千克重物时的肌电图平均幅度（43.30%最大随意收缩）显著大于举起6千克重物时的平均幅度（37.70%最大随意收缩）（P < 0.01）。以较高速度举起时的肌电图平均幅度（41.80%最大随意收缩）显著大于以较低速度举起时的平均幅度（39.19%最大随意收缩）（P < 0.05）。肌电图平均幅度随躯干旋转角度的增加而增大，但无显著差异（P > 0.05）。在T10水平，右侧的肌电图平均幅度大于左侧（分别为50.31%最大随意收缩和25.88%最大随意收缩），而在L3水平则相反（左侧为45.60%最大随意收缩，右侧为40.22%最大随意收缩）（P < 0.01）。多元逐步回归分析表明，举重负荷是对肌电图平均幅度影响最大的因素，其次是举重速度。
不对称举重任务中与工作量相关的危险因素主要是举重负荷和举重速度。在此类举重过程中，竖脊肌左右两侧的肌电活动不同。
