Hulkenberg Alfred C, Strotmann Niko, Mokni Amine, Greulich Leon, Laurentius Thea, Cornelius Bollheimer L, Rutkove Seward, Freeborn Todd, Leonhardt Steffen
IEEE Trans Neural Syst Rehabil Eng. 2025;33:2659-2671. doi: 10.1109/TNSRE.2025.3581348.
To address muscle performance, a local Electrical Impedance Myography (EIM) framework is introduced that targets the quadriceps femoris muscle group, which is sensitive to age-related muscle loss. It can be used for force estimation during the seated leg extension exercise under isometric conditions, providing a novel tool for geriatric assessment and therapy tracking.
In this pilot study involving ten healthy male adults, a quasi-static comparison of the measured torque with either EIM signals, parameters calculated from the Debye- or Cole model, and characteristic frequency was performed. Motivated by electromyography, a baseline-removal and normalization to approximate muscle activity was implemented based on an exponential function. Finally, the muscle torque was estimated by multiplying the estimated muscle activity by the maximal voluntary torque.
Our data suggests systematic variations of EIM signals caused by holding a joint angle, pushing against a immobile lever, and changes due to applying repetitive contraction scenarios.
For frequencies below the intersection point of the Nyquist plots of the muscle at rest and under contraction ${f} \leq {f}_{x}$ , the resistance and reactance are sensitive to the effects of muscle activity, with a strong Pearson correlation of nearly ${0}.{9}$ with torque. During pushing and small extension angles, the averaged accuracy of the estimated torque is ${T} =\pm {200} \pm {5} \ {\text {Nm}}$ .
为了研究肌肉性能，引入了一种针对股四头肌群的局部电阻抗肌电图（EIM）框架，该肌群对与年龄相关的肌肉流失敏感。它可用于在等长条件下的坐姿腿伸展运动中进行力量估计，为老年评估和治疗跟踪提供了一种新工具。
在这项涉及十名健康成年男性的初步研究中，对测量的扭矩与EIM信号、从德拜或科尔模型计算出的参数以及特征频率进行了准静态比较。受肌电图启发，基于指数函数进行了基线去除和归一化以近似肌肉活动。最后，通过将估计的肌肉活动乘以最大自主扭矩来估计肌肉扭矩。
我们的数据表明，由于保持关节角度、推不动的杠杆以及应用重复收缩场景而导致的EIM信号的系统变化。
对于低于肌肉在休息和收缩状态下的奈奎斯特图交点频率$f \leq f_x$，电阻和电抗对肌肉活动的影响敏感，与扭矩的皮尔逊相关性强，接近0.9。在推和小伸展角度时，估计扭矩的平均精度为$T =\pm 200 \pm 5 \text{ Nm}$。
