**3. Kinesiological electromyography**

The numerous applications of EMG include the diagnosis of neuromuscular disease or trauma in clinical practice, rehabilitation and the study of kinesiological muscle function in specific activities [2].

In one study [13] the EMG behavior of some of the major muscles of mastication was compared while subjects chewed different materials (two brands of chewing gum, cotton and parafilm) in order to identify the best material based on performance during bilateral chewing.

The EMG signal serves as an indicator of the initiation of muscle activity and can provide the firing sequence of one or more muscles involved in a specific task [12]. Information from the EMG signal is used to indicate the strength contributed by individual muscles and muscle groups.

In EMG, potentials are produced as a direct result of voluntary effort [18].

The electrodes used in EMG convert the electrical signal resulting from muscle depolarization into an electrical potential that can be amplified, and the difference in electrical potential can be processed. The potential amplitude depends on the difference in potential between the electrodes, such that the greater the potential difference, the greater the amplitude of the electrical potential or voltage [24].

The instrumentation used during the collection of EMG signals includes electrodes, amplifiers, filters, registers, decoders and sound equipment [27]. The choice of the electrode will depend on the muscle being studied.

The factors that influence the EMG signal can be divided into three categories: causes, determinants and intermediate factors [14].

Causative factors have an effect on the basic or elementary signal and are divided into extrinsic and intrinsic factors. Among the extrinsic factors are electrode configuration, the distance between the electrodes, the location of the electrodes over the motor point and the myotendonous junction, the location of the electrodes in relationship to the lateral border of the muscle and the orientation of the electrode in relation to muscle fibers. Intrinsic factors are the physiological, anatomical and biochemical characteristics of the muscle, such as the number of active motor units at the time a particular contraction occurs, the muscle fiber type, blood flow in the muscle, the fiber diameter, depth and location of the active fibers of the muscles in relation to the detection electrodes, the amount of tissue between the electrode and the muscle surface, as well as other factors such as the length of the depolarization zone and the ion flux across the membrane.

Computational Intelligence in Electromyography Analysis – 394 A Perspective on Current Applications and Future Challenges

different areas of study for different research purposes.

to foster appropriate analysis methods for signal data.

**3. Kinesiological electromyography** 

EMG [3,12, 15, 28] .

specific activities [2].

muscle groups.

been discovered as developments in processing and instrumentation have been applied to

However, the purpose of this study is to present and discuss the use of sEMG as a quantification tool for studying motor and functional rehabilitation and neurophysiological

Many authors have used different procedures to analyze EMG signals, which impedes both the comparison and reproducibility of results obtained in laboratory experiments, although their experiments have been described in internationally recognized scientific journals.

Thus, although there is diversity in the procedures for both applying EMG and analyzing the signals, this technique for investigating myoelectrical activity can be used in many

It is important, therefore, to demonstrate some of the applications of EMG as a research tool as well as different methods of analyzing EMG signals to facilitate the design of future and

The numerous applications of EMG include the diagnosis of neuromuscular disease or trauma in clinical practice, rehabilitation and the study of kinesiological muscle function in

In one study [13] the EMG behavior of some of the major muscles of mastication was compared while subjects chewed different materials (two brands of chewing gum, cotton and parafilm) in order to identify the best material based on performance during bilateral chewing. The EMG signal serves as an indicator of the initiation of muscle activity and can provide the firing sequence of one or more muscles involved in a specific task [12]. Information from the EMG signal is used to indicate the strength contributed by individual muscles and

The electrodes used in EMG convert the electrical signal resulting from muscle depolarization into an electrical potential that can be amplified, and the difference in electrical potential can be processed. The potential amplitude depends on the difference in potential between the electrodes, such that the greater the potential difference, the greater

The instrumentation used during the collection of EMG signals includes electrodes, amplifiers, filters, registers, decoders and sound equipment [27]. The choice of the electrode

The factors that influence the EMG signal can be divided into three categories: causes,

In EMG, potentials are produced as a direct result of voluntary effort [18].

the amplitude of the electrical potential or voltage [24].

will depend on the muscle being studied.

determinants and intermediate factors [14].

abnormalities in the nervous system in comparison with peripheral stimuli.

The intermediate factors are the physical and physiological phenomena that are influenced by one or more causative factors and, in turn, influence the determinants. Among this type are the detection electrode volume, the overlap of the action potential in the EMG signal, "cross-talk" with neighboring muscles, the conduction velocity of the action potential and the effect of spatial filtering. Since the determinant factors have a direct effect on the EMG signal and include the number of active motor units, the mechanical interaction between muscle fibers, the firing rate and the number of motor units detected, the amplitude, duration and shape of action potentials of motor units, as well as the recruitment and the stability of these units.

Soderberg and Cook described the limitations, collection methods and interpretation of electrical activity. Regarding the type of electrode, they believe that the sEMG can be used to analyze superficial muscles without causing discomfort to the volunteer [25].

The normalization procedure is usually considered necessary for recording, quantifying and comparing the EMG data obtained from different individuals or the same individual on different days [27].

Concern about the establishment of common standards for the collection, recording, analysis and interpretation of EMG signals has been expressed by a number of authors [12,27,28,], and more recently a practical guide for standardizing procedures to be used in EMG studies has been presented [1]. Thus, there is a tendency toward consensus among researchers on the use of appropriate instrumentation for collecting, recording and processing EMG signals.

Several studies [3, 5, 16, 27] have described the need to normalize the EMG signal amplitude when trying to make comparisons between different muscles, subjects, materials and days. This is due to the great variability observed in EMG tracings obtained from both different individuals and different muscles.

The EMG signal can be rectified by mathematical processing or by the root mean square (RMS) of squared instantaneous values . This signal can be passed through a low-pass filter for a presentation wrap the curve. Signal processing can then be carried out in accordance with the specific aim of the work [2]. In general, it is necessary to normalize the EMG signal in order to minimize the differences between individuals [16], when not comparing pre-and post-treatment.
