ELECTRO MUSCLE STIMULATION L’electrostimulation is a technique that, through the use of electrical impulses acting on the motor points of the muscles (motor neuron), It causes a muscle contraction similar to the voluntary one. Most of the human body muscles belong to the category of striated or voluntary muscles, with about 200 muscles to each side of the body (400 about total).
Physiology of muscle contraction
Skeletal muscle exercises its functions through the contraction mechanism. When a person decides to make a move, the motor center of the brain generates a SignalElectric ale that is sent to the muscle to contract. When the electrical impulse reaches, the endplate on the muscle surface produces the depolarization of the muscle membrane and subsequent release of Ca ++ ions in its interior. The Ca ++ ions, interactsndo with the molecules of actin and myosin trigger the contraction of the mechanism that leads to the shortening muscle. The request for the contraction energy is supplied by ATP and supported by a recharging system dell'energia based on energy aerobicici and anaerobic mechanisms that use carbohydrates and fats. In other words, electrical stimulation is not a direct source of energy but it works as a tool that triggers muscle contraction. The same type of mechanism is activated when the muscle contraction is produced by EMS; they then assume the same role as a natural impulse transmitted by the motor nervous system. At the end of the contraction the muscle relaxes and returns to its original state.
Isotonic and isometric contraction
The isotonic contraction It occurs when, within motor action, the affected muscles win the external resistor shortening and thereby determining a state of constant tension to the tendon leaders. When, inv
eca, the external resistor prevents movement, the contraction of the muscles instead of producing accorciamento determine an increase in the voltage at its ends: this condition is called isometric contraction. In the case of electrostimulation It is normally used in a stimulation condition isometric because it allows to achieve a more powerful and more effective contraction.
The distribution in the muscle of different types of fibers
The relationship between the two main categories (The type I and type) It can vary significantly. There are muscle groups that are typically made from type I fibers, as the soleus, and muscles that have only type II fibers as the orbicularis muscle, but in most cases we have a presence of different types of fibers. Studies on the distribution of the fibers in the muscle have highlighted the close relationship between the motor neuron (tonico the phasic) and the functional characteristics of the fibers innervated by it and have demonstrated as a specific motor activity (sports and in particular) can determine a functional adaptation of the fibers and a modification of the metabolic characteristics of the same.
| Type of Motor Unit | Type of contraction | contraction frequencies |
| Tonica ST | The slow decline | 0 – 50 Hz |
| Fasica FT | II fast twitch | 50 – 70 Hz |
| Fasica FTb | fast twitch II b | 80 – 120 Hz |
Electrical stimulation, with the ability to stimulate with specific frequencies, It allows you to specifically train the fibers involved in the gesture that you want to train (fibers for rapid gestures explosives and fiber glass for actions long) or transform the metabolism and the characteristics of the intermediate fibers in order to make them more suitable to express the desired action.