Action Principles; Muscular Electrostimulation - Globus GENESY 1500 User Manual

ACTION PRINCIPLES

Muscular electrostimulation

Electrostimulation is a technique which, by means of electric pulses acting on the
muscle motor points (motoneurons), causes muscular contractions similar to
voluntary contractions.
Each side of the human body approximately includes 200 muscles (about 400
muscles overall) most of which are striated or voluntary.
The physiology of muscular contraction
The skeletal muscle performs its functions through the contraction mechanism.
When a person decides to make a movement, the motor center of the brain sends
an electric signal to the contracting muscle.
When the electric signal reaches the muscle, the motor plaque of the muscle
surface produces the depolarization of the muscle membrane and the release of
CA++ ions inside it. The Ca++ ions, interacting with the actin and myosin molecules,
activate the contraction mechanism which leads to the shortening of the muscle.
The amount of energy needed for the contraction is provided by the adenosine
triphosphate (ATP) and is supported by an energy recharging system based on
aerobic and anaerobic energy mechanisms which use carbohydrates and fats. In
other words, electric stimulation is not a direct source of energy but it works as a tool
that causes a muscular contraction.
The same type of mechanism is activated when the muscular contraction is
produced by the EMS; they have the same function of a pulse naturally transmitted
by the motor nervous system. When the contraction is over, the muscle relaxes and
returns to its original state.
Isotonic and isometric contraction
An isotonic contraction occurs when, during a movement, the interested muscles
exceed the external resistance by shortening, thus provoking a constant state of
tension in the ends of the tendons. When the external resistance impedes its
movement, the muscular contraction, instead of provoking a shortening effect,
causes an increase in the tension at the extremes; this is an isometric contraction. In
the case of electrostimulation, an isometric stimulation is normally used because it
permits a more powerful and efficient contraction.
The distribution of different types of fibers in the muscle
The relation between the two main categories (type I and type II) can vary
noticeably.
There are muscular groups that are typically made up of type I fibers, like the soleus,
and muscles which are made up of only type II fibers, like the orbicular muscle, but
the majority of the human body muscles are composed of a combination of the
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