**2.1 Kinematics**

Kinematics is the study of motion without involving the factor that causes that motion. The whole kinematics theory and analysis will evolve around three basic variables of mechanics, which are as follows:


## **2.2 Kinetics**

Kinetics is the study of motion, and the elements causes that motion, that is, force and torque. The kinetics as evident from the name kinetics will discuss the mechanics of the human body that are under motion, and the three basic variables that cause or influence the motion are as follows:

1.Force

2.Torque

3.Mass

## **2.3 Anthropometry**

Anthropometery is a combination of two Greek words anthropos, which means "Human" and metron, which means "Measure." Therefore, the literal meaning of the anthropometry is the measurement of the human individual. When discussing the mechanics of the human body, the discussion and understanding of the anthropometry become essential, due to the fact that the mechanics cannot be complete without the measurement of the subject. The basic parameters under consideration when discussing the anthropometry are *Height, Weight, Size* and *Esthetics* of organs, limbs, and other body parts. A number of

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*Muscle Mechanics and Electromyography DOI: http://dx.doi.org/10.5772/intechopen.93282*

**3. Muscle mechanics**

**3.1 Muscular system**

ize the anthropometry data, such as [1–3].

up almost 40% of the whole body mass.

**4. Electromyography**

same muscle fiber.

**5. EMG signal**

(MU). The MU consists of an

The signal from the

decaying of the signal amplitude.

studies were carried out for the collection and compiling a database to standard-

Contrary to the bones, which provide the structural strength and stability to the human body, muscles are responsible to hold the bones with the possible movement of each joint with the application of forces by contracting themselves. Muscles are not simply the force generators in the body; the force developed in the muscle depends on the level of neural excitation at the central nervous system (CNS) with the speed and length at which the muscle contracts. Almost all the muscles are arranged in pairs as agonistic and antagonistic muscles, and these pairs work against each other, as one muscle pull then the other muscle relaxes and stretched in response. There are almost 320 muscle pairs that exist in a human body which make

Electromyography is the study of electromyograph (EMG). EMG is the recording of the electrical activity of the muscle. This electrical activity is produced due to the ionic movement in the muscle in response of the conducting signal from the motor unit of a neuron. This motor unit (MU) acquires single or multiple muscle fibers to perform the actuation of the muscle; this selection of the muscle fiber is random and it is not necessary that the previously acquired MU will acquire the

Electromyogram (EMG) is the electrical activity produced by a contracting muscle. EMG signal is extensively used in the field of rehabilitation, biomechanics, orthopedics, ergonomic product design, and prostheses. Due to the fact that EMG allows directly looking into the muscle and measuring the muscular performance, it also helps in decision-making both before and after surgery. The basic functional element that is responsible for producing the EMG signal is called the motor unit

and extends its axon from the spinal cord to the skeletal muscle fiber (as shown in the **Figure 2**), where it innervates and forms a junction, usually called motor end-plates.

that travels in either direction from the junction and creates a potential difference. This difference is measured by the electrodes. The muscle fibers connected to a single neuron react together and hence termed as motor unit. The signal generates by the MU is called motor unit action potential (MUP). The resulting EMG signal is the sum of all activated MUs during the contraction of that muscle. When the signal is acquired using surface electrodes, the signal has to travel through the remaining tissues before reaching the electrodes. This traveling of the signal results in the



a

a

studies were carried out for the collection and compiling a database to standardize the anthropometry data, such as [1–3].
