TO THE EDITOR: Enoka and Duchateau (2) correctly call for caution when interpreting voluntary surface electromyography (sEMG) in terms of neural drive. If voluntary sEMG signals recorded during nonfatiguing isometric contractions depend on the number of motor units recruited, their firing rate, and their size (5), modeling found no direct association between neural drive and voluntary sEMG ampl...

We present a methodology to predict the presence of myopathy (muscle disease) from intramuscular electromyography (EMG) signals. By evaluating the shape and frequency of electrical action potentials produced by muscular fibers and captured in EMG measurements, a physician can often detect both the presence and the severity of such disorders. However, EMG measurements can vary significantly acro...

The macro electromyography method was developed in the 1980s. Since then, technical modifications have been made, and a number of conditions have been explored. This study is a methodological introduction and an update of findings in some nerve–muscle disorders. The spike component of a motor unit potential (MUP) recorded by a concentric or monopolar needle electromyography (EMG) electrode is g...

The purpose of the study was to quantify the effect of motor-unit synchronization on the spike-triggered average forces of a population of motor units. Muscle force was simulated by defining mechanical and activation characteristics of the motor units, specifying motor neuron discharge times, and imposing various levels of motor-unit synchronization. The model comprised 120 motor units. Simulat...

The dependence of transmitter release and synaptic effectiveness on the size of a neuron's peripheral field was studied using neuromuscular junctions in sartorius muscles of adult frogs (Rana pipiens). The size of the peripheral field (motor unit size) was reduced by crushing the sartorius nerve and surgically removing half of the muscle fibers. Synapses thus formed were compared with those for...

Quantification in clinical, diagnostic electromyography (EMG) currently includes motor unit action potential (MUAP) analysis and interference pattern analysis. Early efforts to examine the frequency/power spectra of the interference pattern showed modest value but the technique was not developed further. This paper re-examines spectral analysis, extending it into the time-varying domain, which ...

The purpose of the study was to determine the effect of motor-unit synchronization on the surface electromyogram (EMG) and isometric force using a computer model of muscle contraction. The EMG and force were simulated by generating muscle fiber action potentials, defining motor-unit mechanical characteristics and territories, estimating motor-unit action potentials, specifying motor-unit discha...

Introduction Electromyography (EMG) is a useful and objective tool to obtain information about the muscle activity(1). A muscle consists of muscle fibres. The ends of the efferent nerves are connected to the muscle fibres through motor units. Every single motor unit serves several muscle fibres. An electrical impulse, traveling through the nerves and motor units, cause a depolarisation (contrac...

Electromyographic (EMG) signals were recorded using intramuscular electrodes at six different sites in the brachioradialis muscles during voluntary isometric contractions in four subjects. The potential waveforms and discharge patterns of up to 12 simultaneously active motor units were identified from each signal using computer-aided decomposition. Out of a total of 301 motor unit potentials id...