Sparto P J, Parnianpour M, Marras W S, Granata K P, Reinsel T E, Simon S
Biomedical Engineering Center, Ohio State University, Columbus, USA.
Spine (Phila Pa 1976). 1998 Feb 15;23(4):423-9. doi: 10.1097/00007632-199802150-00003.
An experimental study of fatiguing isometric trunk extension was conducted to investigate the spinal loading estimated from an electromyogram-assisted biomechanical model.
To evaluate the sensitivity of the model outputs to two crucial assumptions: electromyogram-force relationship and method of gain estimation.
In the proposed electromyogram-assisted models of the trunk, the nature of the electromyogram-force relationship and the wide variation in reported muscle gains can result in a wide variation in estimates of spinal loading. Given the absence of any gold standard for validation of muscle forces, the delineation of confidence intervals for the estimated loads has become critical.
Ten subjects performed a fatiguing isometric trunk extension while the net muscular torque output and trunk muscular activity were measured. An electromyogram-assisted model was used to estimate the torque output and spinal loading. Linear and nonlinear erector spinae electromyogram-force relationships and three methods for gain estimation were investigated: constant gain determined from an initial maximum extension exertion, constant gain based on the fatiguing exertion, and a time-varying gain from the fatigue test.
The predicted torque was not sensitive to the electromyogram-force relationship; the nonlinear model produced 10% lower estimates of peak spinal compression force and 14% higher estimates of peak anterior shear force. The gain determined from an initial calibration exertion underestimated the external torque and underpredicted the peak compression force by 20%, compared with gains calculated in the fatigue test.
The nature of the electromyogram-force relationship and of the method for estimating the gain significantly affect the outcomes of an electromyogram-assisted model of spinal loading.
进行了一项关于疲劳性等长躯干伸展的实验研究，以调查从肌电图辅助生物力学模型估计的脊柱负荷。
评估模型输出对两个关键假设的敏感性：肌电图-力关系和增益估计方法。
在提出的躯干肌电图辅助模型中，肌电图-力关系的性质以及报告的肌肉增益的广泛变化可能导致脊柱负荷估计的广泛差异。鉴于缺乏验证肌肉力量的任何金标准，估计负荷的置信区间的划定变得至关重要。
10名受试者进行了疲劳性等长躯干伸展，同时测量净肌肉扭矩输出和躯干肌肉活动。使用肌电图辅助模型估计扭矩输出和脊柱负荷。研究了线性和非线性竖脊肌肌电图-力关系以及三种增益估计方法：从初始最大伸展用力确定的恒定增益、基于疲劳用力的恒定增益以及来自疲劳测试的时变增益。
预测扭矩对肌电图-力关系不敏感；非线性模型对脊柱峰值压缩力的估计低10%，对峰值前剪切力的估计高14%。与在疲劳测试中计算的增益相比，从初始校准用力确定的增益低估了外部扭矩，并且对峰值压缩力的预测低20%。
肌电图-力关系的性质和增益估计方法显著影响肌电图辅助脊柱负荷模型的结果。
