Samadi S, Arjmand N
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
Med Eng Phys. 2018 Jun 23. doi: 10.1016/j.medengphy.2018.04.019.
Traditional electromyography-assisted optimization (TEMG) models are commonly employed to compute trunk muscle forces and spinal loads for the design of clinical/treatment and ergonomics/prevention programs. These models calculate muscle forces solely based on moment equilibrium requirements at spinal joints. Due to simplifications/assumptions in the measurement/processing of surface EMG activities and in the presumed muscle EMG-force relationship, these models fail to satisfy stability requirements. Hence, the present study aimed to develop a novel stability-based EMG-assisted optimization (SEMG) method applied to a musculoskeletal spine model in which trunk muscle forces were estimated by enforcing equilibrium conditions constrained to stability requirements. That is, second-order partial derivatives of the potential energy of the musculoskeletal model with respect to its generalized coordinates were enforced to be positive semi-definite. Fifteen static tasks in upright and flexed postures with and without a hand load at different heights were simulated. The SEMG model predicted different muscle recruitments/forces (generally larger global and local muscle forces) and spinal loads (slightly larger) compared to the TEMG model. Such task-specific differences were dependant on the assumed magnitude of the muscle stiffness coefficient in the SEMG model. The SEMG model-predicted and measured L4-L5 intradiscal pressures were in satisfactory agreement during simulated activities.
传统肌电图辅助优化（TEMG）模型通常用于计算躯干肌肉力量和脊柱负荷，以设计临床/治疗以及人体工程学/预防方案。这些模型仅基于脊柱关节处的力矩平衡要求来计算肌肉力量。由于在表面肌电活动的测量/处理以及假定的肌肉肌电-力关系中存在简化/假设，这些模型无法满足稳定性要求。因此，本研究旨在开发一种新的基于稳定性的肌电图辅助优化（SEMG）方法，应用于肌肉骨骼脊柱模型，其中通过强制满足受稳定性要求约束的平衡条件来估计躯干肌肉力量。也就是说，将肌肉骨骼模型的势能相对于其广义坐标的二阶偏导数强制为正半定。模拟了在不同高度有和没有手部负载的直立和弯曲姿势下的15项静态任务。与TEMG模型相比，SEMG模型预测了不同的肌肉募集/力量（通常更大的全局和局部肌肉力量）和脊柱负荷（略大）。这种特定任务的差异取决于SEMG模型中假定的肌肉刚度系数大小。在模拟活动期间，SEMG模型预测的和测量的L4-L5椎间盘内压力具有令人满意的一致性。
