Scientific Details on Electromyostimulation - EMS

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Electrostimulation for sport training is very different from other forms of electrostimulation, such as TENS, or those utilized by medical practitioners in rehabilitation settings. It focuses on the development of 

  • force,
  • endurance,
faster recovery from sport performance and muscle soreness of skeletal muscles used in various sports.

Muscles contract in the following way: when a person decides to  move a muscle, the brain sends an electric impulse, called action potential, to the muscle needed for the movement. The electrical signal is transmitted as a change of potential (voltage), an electrical impulse that traverses the motor nerve to the muscle to be stimulated. After receiving the impulse, calcium ions are freed from neural stores, which in turn cause two components of muscular fibers, actin and myosin, to approach each other. This results in the shortening of certain areas of the fiber, leading to muscular contraction. The energy needed for contraction is supplied by sugars and fats stored in the body. In other words, electrical stimulation is not a direct energy resource but it works as a trigger of this energy, which results in a muscular contraction. The same type of mechanism is activated when muscular contraction is produced by an electro-muscle-stimulator (EMS). EMS assumes the same role as a natural impulse transmitted by the nervous system.

Voluntary muscles are composed of muscle fibers that can be subdivided in two types: type I and type II. Type I fibers are slower moving fibers, and are called slow-twitch fiber; Type II fibers are faster moving fibers, and are called fast-twitch fibers. Type I and Type II fibers utilize different mechanisms, of energy conversion, and are stimulated at different frequencies. The proportions of the two main types of muscle fibers (types I and II) vary significantly from muscle to muscle. Some muscle groups contain predominantly type I fibers, such as the soleus muscle, while others have only type II fibers, e.g. orbicular muscles. However, most muscles contain a sizable portion of both types of fibers.

Another parameter that greatly affects the contraction of the muscle is the duration of the impulse necessary to trigger a proper reaction, called Chronaxie (this duration is typically measured in millionths of a second). Different muscle groups are better stimulated using different chronaxie. That's why you have to employ different programs to benefit most from EMS training: different sports and different muscles require particular combination of frequency and chronaxie.

Alternate Names

NMES: Neuro Muscular Electro Stimulation
EMS: Electro Muscle Stimulation