Gentle pulses: the higher the frequency, the lower the resistance
Another factor is vital before the electrical signal penetrates the muscles and nerves to take effect – the current must overcome the galvanic and capacitive resistance of the skin. For what we call a low-frequency current up to 1,000 Hz, or LF for short, the capacitive resistance of skin is a high barrier – this means that the current penetrates less deeply. For medium-frequency alternating currents, i.e. a frequency of 1,000 Hz or higher, skin resistance is not a problem. This is due to the following principle: the higher the frequency, the lower the resistance. Medium-frequency current, or MF for short, therefore penetrates deeper and affects a wider area.
This is known as the ‘volume effect’ and it enables optimal activation of the superficial muscle layers as well as the deeper muscle fibres. Furthermore, owing to the minimal capacitive skin resistance, users perceive the MF current as extremely pleasant. This therefore enables higher pulse strengths, producing more intense effects through stronger muscle contractions.