Summary
Highlights
Interferential currents are classified based on their modulation. They can be modulated in amplitude (changing intensity without altering other patterns), in amplitude and frequency (varying both intensity and frequency, creating a sweep effect), with fixed frequency throughout the session, or grouped in trains or bursts (amplitude-modulated trains with pauses).
There are different generations of medium frequency systems. First-generation devices use a sinusoidal modulation with two circuits and employ the interferential technique. Second-generation devices also feature sinusoidal modulation but can use bipolar or tetrapolar techniques, with the interference occurring within the device or centrally in the tetrapolar setup. The positioning of electrodes can alter the interference zone. Third-generation devices allow for carrier frequency adjustment (2,000 to 10,000 Hz) with modulations between 200 and 500 Hz.
Interferential currents produce several physiological effects, including pain reduction (acting on the gate control theory), increased circulation, muscle relaxation, and prevention of accommodation due to their frequency spectrum and oscillation. They also normalize neuro-vegetative balance, improve circulation, decrease skin resistance, and stimulate thick afferent fibers. This specific device shown is a first-generation model, indicated by its repolarization technique and conventional sinusoidal interference.