Effects of vibration therapy on neuromuscular efficiency & features of the EMG signal based on endurance test

BackgroundVibration Therapy (VT) stimulate the muscle spindles, which in turn enhances its afferent activities.ObjectiveThe present study was designed to investigate the effect of VT at 23 and 35 Hz on muscle performance. The EMG features (six time-domain (TD) and four frequency-domain (FD)) and a new formula for computing neuromuscular performance were used as dependent variables to evaluate the effect of VT.MethodThe EMG recording was performed at 50% MVC during grip endurance test before and after VT. The EMG features were extracted out of raw EMG signals acquired from four forearm muscles, viz., flexor digitorum superficialis (FDS); flexor carpi ulnaris (FCU); extensor carpi radialis brevis (ECRB); and extensor carpi ulnaris (ECU) in supine position. Fatigue assessments were evaluated based on the pattern of TD and FD features.ResultsStatistical analysis showed a significant difference in the effect of vibration exposure frequency on IEMG (p < 0.001), MAV (p = 0.041), SSI (p = 0.032), and WL (p < 0.001) of FCU muscle. In addition, the greatest increase in neuromuscular efficiency (NME) was observed in the performance of ECRB after 35 Hz of VT and ECU muscles after 23 Hz of VT.ConclusionsThe features of EMG signals could be used for fatigue analysis. However, the slope based on the median frequency regression line may be the best feature for fatigue assessment.     

Motor control after spinal cord injury: Assessment using surface EMG

The brain motor control assessment (BMCA) protocol is a comprehensive multichannel surface EMG recording used to characterize motor control features in persons with upper motor neuron dysfunction. Key information is contained in the overall temporal pattern of motor unit activity, observed in the EMG (RMS) envelope. In paralysis, a rudimentary form of suprasegmental control of tonic and phasic reflexes can be demonstrated. EMG patterns evoked by voluntary and passive maneuvers and by volitional modulation of reflex responses reveal features of motor control not apparent in the clinical examination. Such subclinical findings may explain paradoxically different responses in apparently similar SCI subjects, and may be used to monitor spontaneous or induced changes. The recording protocol, examples of EMG patterns, and their prevalence in 40 spinal cord injured (SCI) subjects are presented, and compared with 5 healthy subjects. © 1996 John Wiley & Sons, Inc.     

握物受扰平衡恢复时上肢运动控制机理的实验研究

目的研究人手在握物受扰后的恢复过程以及整个过程中视觉对于神经肌肉控制系统的影响。方法在人手握物状态下,对所握物体施加干扰,记录上臂在恢复过程中的运动信号和肌电信号,对相关的运动和肌电信号参数进行分析,分别在有无视觉的两种情况下进行实验,对比实验结果。结果恢复平衡主要通过肢体的移动和肌肉的收缩完成。在无视觉的情况下恢复平衡反应时间有延迟,运动幅度加大。结论握物受扰后主要依靠上肢腕和肘关节运动和前臂的腕屈肌活动恢复平衡和抓紧状态。自身的感觉反馈是控制的主要信息源,视觉对于人体上肢恢复平衡有加快响应和减小运动幅度的作用。     

The motor unit and quantitative electromyography

Electromyography (EMG) assesses the anatomic motor unit (A-MU), but knowledge of its anatomy, physiology, and changes with pathology is limited. The electrophysiological motor unit (E-MU) and its motor unit potential (E-MUP) represents a fraction of the A-MU. Routine EMG assesses a limited number of E-MUP waveform characteristics (metrics) and their magnitudes qualitatively scaled in a nonlinear manner. Another approach is quantitative EMG (QEMG), whereby 20⁺ E-MUPs are extracted and both basic and derived metrics obtained and values expressed quantitatively. In diseased muscle, many E-MUP metrics may be normal, which complicates diagnostic interpretation. In QEMG, E-MUP metrics can be clustered and statistical analyses performed to assign probabilities that E-MUPs (and the muscle) are normal, neuropathic, or myopathic. In this article we review what is known about the A-MU, the restricted E-MU, E-MUP metrics, and what QEMG offers currently and in the future.     

Recovery of locomotion after chronic spinalization in the adult cat

Cats were spinalized (T13) as adults and were trained to walk with the hindlimbs on a treadmill. After 3 weeks to 3 months and up to 1 year depending on the animal, all were capable of walking on the plantar surface of the feet and support the weight of the hindquarters. Interactive training appeared to accelerate the recovery of locomotion and maintain smooth locomotor movements. Despite the obvious loss of voluntary control and equilibrium which the experimenter partially compensated for by maintaining the thorax and/or the tail, the cats could walk with a regular rhythm and a well-coordinated hindlimb alternation at speeds of 0.1-1.2 m/s. Cycle duration as well as stance and swing duration resembled those of normal cats at comparable speeds. The range of angular motion was also similar to that observed in intact cats as was the coupling between different joints. The EMG activity of the hindlimb and lumbar axial muscles also retained the characteristics observed in the intact animal. Some deficits such as a dragging of the foot in early swing and diminution of the angular excursion in the knee were seen at later stages. Thus, the adult spinal cat preparation is considered as a useful model to study the influence of different types of training and of different drugs or other treatments in the process of locomotor recovery after injury to the spinal cord.