The Electromyogram: Modeling and Analysis

Abstract

The electromyogram (EMG) represents the electrical activity of skeletal muscle during voluntary activity. The recorded signal depends upon the anatomy of the muscle and the recording electrode arrangement as well as the physiological activity. It is important to understand the effect of the recording arrangement in order to discount the peculiarities of the recording setup during analysis. The difference between needle EMG and surface EMG can be explained on the basis of the recording geometry. Different analytical techniques focus on the anatomical structure (e.g., distribution of the neuromuscular junction, size and distribution of motor units, etc.) or on the physiological behavior (e.g., degree of activation, neuronal firing patterns, the fiber conduction velocity, muscle fatigue, etc.). A combination of exact geometric information (of the recording electrode placement), action potential characteristics and statistical descriptions of the muscle architecture can be used to develop a model of the EMG. Commonly used phrases like electrode “filter function”, “end-plate region” are incorporated formally in this model.

… for the success of any physical investigation depends on the judicious selection of what is to be observed as of primary importance, combined with a voluntary abstraction of the mind from those features which, however attractive they appear, we are not yet sufficiently advanced in science to investigate with profit.

–James Clerk Maxwell