Dolan P, Kingma I, De Looze M P, van Dieen J H, Toussaint H M, Baten C T, Adams M A
Department of Anatomy, University of Bristol, Southwell Street, BS2 8EJ, Bristol, UK.
Clin Biomech (Bristol). 2001;16 Suppl 1:S17-24. doi: 10.1016/s0268-0033(00)00097-8.
To compare two methods of calibrating the erector spinae electromyographic signal against moment generation in order to predict extensor moments during asymmetric lifting tasks, and to compare the predicted moments with those obtained using a linked-segment model.
Eight men lifted loads of 6.7 and 15.7 kg at two speeds, in varying amounts of trunk rotation. For each lift, the following were recorded at 60 Hz; the rectified and averaged surface electromyographic signal, bilaterally at T10 and L3, lumbar curvature using the 3-Space Isotrak, movement of body segments using a 4-camera Vicon system, and ground reaction forces using a Kistler force-plate. Electromyographic (EMG) and Isotrak data were used to calculate lumbosacral extensor moments using the electromyographic model, whereas movement analysis data and ground reaction forces were used to estimate net moments using the linked-segment model. For the electromyographic technique, predictions of extensor moment were based on two different sets of EMG-extensor moment calibrations: one performed in pure sagittal flexion and the other in flexion combined with 45 degrees of trunk rotation.
Extensor moments predicted by the electromyographic technique increased significantly with load and speed of lifting but were not influenced by the method of calibration. These moments were 7-40%greater than the net moments obtained with the linked-segment model, the difference increasing with load and speed.
The calibration method does not influence extensor moments predicted by the electromyographic technique in asymmetric lifting, suggesting that simple, sagittal-plane calibrations are adequate for this purpose. Differences in predicted moments between the electromyographic technique and linked-segment model may be partly due to different anthropometric assumptions and different amounts of smoothing and filtering in the two models, and partly due to antagonistic muscle forces, the effects of which cannot be measured by linked-segment models. RelevanceAsymmetric lifting is a significant risk factor for occupationally-related low back pain. Improved techniques for measuring spinal loading during such complex lifting tasks may help to identify work practices which place the spine at risk of injury.
比较两种将竖脊肌肌电信号与力矩产生进行校准的方法，以便预测不对称举重任务期间的伸肌力矩，并将预测力矩与使用链接节段模型获得的力矩进行比较。
八名男性以两种速度提起6.7千克和15.7千克的重物，躯干旋转量各不相同。对于每次举重，以60赫兹记录以下数据；在T10和L3双侧的整流和平均表面肌电信号、使用3-Space Isotrak的腰椎曲率、使用4台摄像机的Vicon系统记录身体节段的运动，以及使用Kistler测力板记录地面反作用力。肌电（EMG）和Isotrak数据用于使用肌电模型计算腰骶伸肌力矩，而运动分析数据和地面反作用力用于使用链接节段模型估计净力矩。对于肌电技术，伸肌力矩的预测基于两组不同的EMG-伸肌力矩校准：一组在纯矢状面屈曲中进行，另一组在屈曲并结合45度躯干旋转中进行。
肌电技术预测的伸肌力矩随着举重的负荷和速度显著增加，但不受校准方法的影响。这些力矩比使用链接节段模型获得的净力矩大7%-40%，差异随着负荷和速度增加。
校准方法不影响肌电技术在不对称举重中预测的伸肌力矩，表明简单的矢状面校准足以实现此目的。肌电技术和链接节段模型之间预测力矩的差异可能部分归因于两种模型中不同的人体测量学假设以及不同程度的平滑和滤波，部分归因于拮抗肌力量，而链接节段模型无法测量其影响。相关性不对称举重是职业性下背痛的一个重要风险因素。在这种复杂的举重任务中，改进测量脊柱负荷的技术可能有助于识别使脊柱有受伤风险的工作方式。
