What you always wanted to know about EMS
EMS stands for Electro-Myo-Stimulation - a neuronal stimulation of the muscles by external, electrical impulses. The natural activation of muscles, muscle contraction, is triggered by action potentials. These are transmitted as electrical signals via neurons from the spinal cord to the muscles. EMS uses these neurons to stimulate the muscle. The muscle thus experiences an electrically induced action potential, regardless of whether the impulse originally came from the brain or from an external electrode. The unit of neuron and associated muscle fibers is called the motor unit. EMS stimulates many of these motor units simultaneously.
The current from the external electrodes first hits the skin and subcutaneous fatty tissue before it reaches the muscles where it can stimulate the motor units. The skin acts as a capacitive resistor for the current. The amount of current that reaches the muscle depends on personal biological factors such as subcutaneous fat tissue. By adjusting the EMS signals, these factors can be adjusted and everyone can be trained according to their needs. With EMS only a small current strength in the milliampere range is used, which is not dangerous for humans.
Good connectivity between the electrodes and the body is necessary so that the electrodes can stimulate the muscles in a targeted manner. Only in this way can the current be transmitted as desired. In order to ensure conductivity between the electrodes and the body, our system uses the natural sweat of the user. The sweat contains many salts which have a good conductivity and thus ensure the connection. Sufficient sweating is given when the user is well hydrated and warmed up. External moistening of the skin with water, contact spray or electrode gel is not necessary.
To bridge the capacitive resistance that lies between the skin surface and muscle fibers, alternating current is used for EMS. In addition to voltage and current, this is characterized by its frequency. Classically, EMS signals consist of modulated frequencies between 40 and 150 Hz. The higher the frequencies, the lower the resistance of the skin and the deeper the signal penetrates into the body.
This has a particularly positive effect on the subjective perception of the trainee, as the stimulation is perceived as "more pleasant" and less "stabbing". The perception of a stimulation is generally divided into subliminal stimuli, i.e. stimuli where no feeling of current occurs, superliminal stimuli characterized by a strong feeling of current and the so-called "neutral" smouldering stimuli.
Due to the summation behaviour of action potentials, very slow muscle twitches up to muscle waves occur depending on the training person and the stimulation intensity/stimulation frequency.
Higher frequencies, which however are still below 1000 Hz, can hardly generate new action potentials, since between two activations of the motor unit there is always a short time in which a new activation is impossible. Frequencies around 2000 Hz are called medium frequencies and bridge the neuronal path by directly stimulating the muscle fibers. However, current research shows no advantages of this method over stimulation of the motor units, so both frequency bands can be called EMS.