Change in Electromyographic Activity of Wrist Extensor by Cylindrical Brace

Purpose

To verify the effect of a newly-developed cylindrical type forearm brace, which was designed to give focal counterforce perpendicularly on the muscle belly of the wrist extensor.

Materials and Methods

The dominant hands of 24 (12 males, 12 females) healthy subjects were tested. Two types of forearm braces (focal cylindrical type and broad pneumatic type) were examined. The braces were applied at the extensor carpi radialis brevis, 5 to 7 cm distal to the lateral epicondyle. Two surface electrodes were attached to the proximal and distal parts of the brace. By quantitative electromyography, the mean amplitudes of voluntary extensor carpi radialis brevis contraction before and after applying each brace were recorded and analyzed.

Results

The mean amplitudes of the focal cylindrical brace and broad pneumatic brace were reduced significantly compared to no brace (p<0.05), with a larger reduction for the cylindrical brace than the pneumatic brace (p<0.05). There was no significant difference between the proximal and distal mean amplitudes with each brace.

Conclusion

A cylindrical type brace decreased electromyographic activity in the wrist extensor more effectively than did the pneumatic type brace.     

Nerve stimulator for regional anaesthesia procedures with automatic interactive closed-loop control

Abstract

Peripheral nerve stimulators have widespread among anaesthesiologists and remain a popular technique. However, in commercial devices, the user has to manually adjust stimulus intensity. Thus, the aim of this study is to propose a method that allows automating the current intensity control. An earlier nerve stimulator prototype was modified to add an accelerometer and an sEMG module. The choice of these two sensors is aimed at the possibility of observing the mechanical and electrical responses of the muscle contraction evoked by the stimulation. The tests were performed in two steps. The first step was to observe how the sensors behave during stimulation and muscle contraction. The second step was to implement a control algorithm and to validate the automation technique. Comparing the two methods, no significant differences were found on procedure time (manual: 12.5?±?2.3; automatic: 11.6?±?1.9; ρ?=0.380) and blockade latency time (manual: 11.6?±?1.1; automatic: 11.9?±?1.2; ρ?=0.524). Comparing needle-nerve distance in manual or automatic mode, no significant differences were found for 1.0?mA, 0.8?mA, 0.5?mA and 0.3?mA. We conclude that the technique for automating the current intensity update, using accelerometer and/or electromyography, is satisfactory. Furthermore, we conclude that the use of the accelerometer alone is sufficient for detection of muscle contraction.     

Chronic fatigue syndrome: Abnormally fast muscle fiber conduction in the membranes of motor units at low static force load

ObjectiveChronic fatigue syndrome (CFS) and fibromyalgia (FM) are disorders of unknown etiology and unclear pathophysiology, with overlapping symptoms of – especially muscular –fatigue and pain. Studies have shown increased muscle fiber conduction velocity (CV) in the non-painful muscles of FM patients. We investigated whether CFS patients also show CV abnormalities.MethodsFemales with CFS (n = 25), with FM (n = 22), and healthy controls (n = 21) underwent surface electromyography of the biceps brachii, loaded up to 20% of maximum strength, during short static contractions. The mean CV and motor unit potential (MUP) velocities with their statistical distribution were measured.ResultsThe CV changes with force differed between CFS-group and both FM-group and controls (P = 0.01). The CV of the CFS-group increased excessively with force (P < 0.001), whereas that of the controls increased only slightly and non-significantly, and that of the FM-group did not increase at all. In the CFS-group, the number of MUPs conveying very high conduction velocities increased abundantly with force and the MUPs narrowed.ConclusionOur results suggest disturbed muscle membrane function in CFS patients, in their motor units involved in low force generation. Central neural deregulation may contribute to this disturbance.SignificanceThese findings help to detangle the underlying mechanisms of CFS.     

基于经验模态分解-小波包变换的表面肌电信号手势识别

为了提高表面肌电信号（sEMG）手部运动识别的正确率,比较常规的sEMG预处理和特征提取方法,提出一种基于经验模态分解（EMD）和小波包变换（WPT）的sEMG手势识别模型。首先,使用EMD方法将sEMG进行平稳化,得到一系列的固有模态函数。其次,求取各个固有模态函数与原始信号的相关性,选取相关性较高的前4个分量作为有效分量。然后,采用Db3小波函数进行WPT,提取小波包系数中的平均能量、平均绝对值、最大值、均方根和方差等特征。分别采用线性判别分析和支持向量机对12种手部运动进行模式识别。结果表明基于EMD和WPT的sEMG手势识别正确率比直接提取小波包系数中的特征识别正确率高。     

指屈肌主动不足条件下屈指运动时神经肌肉的调控

目的 观察健康人指屈肌主动不足条件下进行屈指运动时,大脑对肌肉的调控特点。方法 2019年3月,招募健康女性大学生12例,在腕关节中立位和最大屈曲条件下测量右手最大静握力,完成50%最大随意等长收缩屈指运动15次(动力性收缩)。同步采集表面肌电图(sEMG)和脑电图,记录sEMG平均振幅和平均功率频率,以及皮质-肌肉相干性(CMC)。结果 腕最大屈曲时握力显著低于腕中立位时(t = 5.757, P < 0.001),指屈肌肌电平均功率频率降低(t = -2.152, P = 0.043)。动力性收缩时,指伸肌肌电平均振幅明显低于指屈肌(t > 2.964, P < 0.01);腕最大屈曲条件下指屈肌平均振幅显著提高(t = 4.135, P < 0.001),CMC升高(t > 2.203, P < 0.05)。结论 腕极限屈曲可诱导指屈肌主动不足;在指屈肌主动不足条件下进行屈指运动时,脑相关皮质区活动增强,可能为脑的代偿机制。     

基于表面肌电图的人体运动意图识别研究进展

分析基于表面肌电图人体运动意图识别的研究方法和识别效果。     

微电子肌电桥技术对颈脊髓损伤患者桡侧腕长伸肌运动功能康复的效果

观察微电子肌电桥(EMGB)技术对C₅完全性脊髓损伤患者桡侧腕长伸肌运动功能的康复疗效。     

不同干预方式对斜方肌在运动中激活模式的影响

目的 分析正常人斜方肌的激活特征,观察不同干预方式对斜方肌异常者激活模式恢复的作用。方法 2017年9月至10月,互联网招募肩关节正常人(正常组,n = 20)和肩关节不适者(观察组,n = 20),在无干预、上斜方肌(UT)静力牵拉、下斜方肌(LT)等长收缩和组合干预后,均完成直臂侧上举、坐姿划船和反向飞鸟动作。测试记录肌电信号的均方根值(RMS),计算最大自主收缩肌电百分比(MVE%),观察激活比例和激活时间。结果 无干预时,与对照组比较,观察组UT MVE%增加(P < 0.05),激活时间提前(P < 0.05);中斜方肌(MT)和LT MVE%降低(P < 0.05),激活时间延迟(P < 0.05);UT/LT和UT/MT增加(P < 0.05)。UT静力牵拉、LT等长收缩和组合训练后,两组不同肌肉MVE%、激活时间、激活比例在不同动作下均有不同程度改变(P < 0.05)。结论 斜方肌三束在不同动作中,激活程度与激活时间不同;在运动开始前进行UT静力牵拉和LT等长收缩可以改善肩关节不适者的斜方肌在运动中的激活模式,有利于肩关节发挥正常功能。