EMS = Electrical Muscle Stimulation

The principle behind this is to stimulate and strengthen the muscles with the help of electrical impulses. With EMS it is possible to train the entire skeletal muscles in a simple and safe way. The effectiveness and safety of EMS training has already been scientifically proven in various studies. [1]

Electrical muscle stimulation is based on a principle inherent in the body

When our sensory organs such as eyes, ears, nose and skin receive stimuli from the environment - i.e. we see something, hear a noise or feel the rain on our skin - this information is passed on to the brain, processed there and the corresponding body reactions are triggered. For example, the brain tells the muscles to tense up. The brain communicates with the muscles and organs using electrical signals. This means: Everything we see, smell, taste, feel, every thought and every movement is the result of electricity. Electrical signals are nothing foreign to our body.

Electricity is not the same as electricity

Two different forms of current are used in EMS training: purely low-frequency or “modulated” medium-frequency current. But what effects can be achieved with what impulses? In addition to the duration and width of the pulse, the decisive factor for the effectiveness of the current is also the frequency, i.e. the number of electrical pulses per second. Depending on the frequency, different types of muscle fibers are addressed.

As can be clearly seen above, the C1 (yellow) pulse sequence is a modulated center frequency. Shown below in C2 (green) is the same pulse sequence with a low-frequency stimulation current. From the top (100ms) to the bottom (2ms) screenshot, the oscilloscope zooms into the same pulse sequence. This clearly shows how much more. Current of the modulated medium frequency enters the body in the same amount of time compared to the low frequency. The pauses between the impulses make the big difference! While C1 (yellow) constantly generates a current flow to activate the muscle, C2 (green) reaches the muscles at intervals, through short pulses and without modulation. Even if you use C2 (green) to briefly advance into areas of the medium frequency using impulse bursts, this has nothing to do with a truly modulated medium frequency because these short impulse impulses cannot cause any adjustments in the muscles.

Red and white muscle fibers

Skeletal muscles are composed of different types of muscle fibers. It consists of the red, slowly tiring type I muscle fibers, which work less intensively but more persistently, and the white type II muscle fibers, which can develop a lot of force for a short period of time but tire more quickly than the red ones.

The red muscle fibers work almost constantly: thanks to their help we can carry out everyday movements and postures such as sitting, standing or walking. The white muscle fibers are thicker and have more pronounced growth potential than the red ones. Strength training cannot increase the amount of white muscle fibers, but their diameter increases, which means muscle mass increases.

Which muscle fibers react to which frequencies?

Since the red and white muscle fibers fulfill different functions and have different properties, they also respond differently to different current frequencies.
Transferred to the impulse this means:

• Up to approx. 40 Hz, mainly the low-fatigue, red type I fibers react
• At frequencies between approx. 50 to 100 Hz, the quickly tiring, white type II muscle fibers are primarily stimulated
• Between 20 and 30 Hz, type I and type IIa muscle fibers are addressed in combination
• With pulses between 2-15 Hz, the body releases additional hormones that counteract pain and at the same time lighten the mood

The higher the frequency, the lower the resistance

Before the electrical signal reaches the muscles and nerves, the current must first overcome the galvanic and capacitive resistance of the skin. The principle applies: the higher the frequency, the lower the resistance.

For low frequency (LF) up to 1,000 Hz, the capacitive resistance of the skin presents a high barrier – thus, the current penetrates less deeply. [2] Therefore, the pure LF impulse is sometimes perceived by users as "prickly".

For the medium frequency (MF) starting from 1,000 Hz, the skin resistance is not a problem. Due to the minimal capacitive skin resistance, the medium-frequency current penetrates deeper. [3] Therefore, the MF current is also perceived as more pleasant by users. This, in turn, allows for higher impulse strengths, which induce more intense effects through stronger muscle contractions.

Another difference

With low frequency, the contraction of the muscle fibers is triggered exclusively via the nerve, while the medium frequency current addresses the muscle cell directly. In addition: In contrast to pure low frequency, the medium frequency has a depth and volume effect, which means that the electrical impulses penetrate deeper and have a broader effect.

Low frequency vs. medium frequency – it’s the mix that counts

The combination of medium frequency and low frequency achieves optimal training results: the medium frequency acts as a so-called “carrier signal”. This means that the impulse penetrates deeper and has a broader effect. At the same time, the low-frequency current leads to an intensive contraction of the muscle cells.

The modulated center frequency

So that the effects of the medium frequency and those of the low frequency can develop their optimal effect together, the medium-frequency current is changed, i.e. “modulated,” using various methods. The modulation achieves an ideal penetration depth of the electrical impulses and specifically promotes cell activity and cell metabolism. Not only muscle cells, but also skin cells, fat cells and connective tissue are reached, activated and stimulated for metabolism.

Last but not least

With modulated medium frequency, both intermuscular coordination (the interaction of agonists and antagonists) and intramuscular coordination (the interaction of nerves and muscle fibers within a muscle) can be particularly effectively improved.

[1] See Wolfgang Kemmler, Anja Weissenfels, Sebastian Willert, Mahdieh Shojaa, Simon von Stengel, Andre Filipovic, Heinz Kleinöder, Joshua Berger, and Michael Fröhlich in Efficacy and Safety of Low Frequency Whole-Body Electromyostimulation (WB-EMS) to Improve Health- Related Outcomes in Non-athletic Adults. A Systematic Review, at https://pubmed.ncbi.nlm.nih.gov/29875684 (accessed on July 1, 2020)

[2] See Vogelmann, Tim: Electromyographic muscle stimulation/muscle activation (EMS/EMA) in competitive/leisure sports: training effects compared to conventional training. Hamburg, Diplomca Verlag GmbH 2013, page 27

[3] See Vogelmann, Tim: Electromyographic muscle stimulation/muscle activation (EMS/EMA) in competitive/leisure sports: training effects compared to conventional training. Hamburg, Diplomca Verlag GmbH 2013, page 28