Interferential current therapy uses two carrier frequencies that intersect. The beat frequency falls in which range to modulate pain?

• A. 1-150 Hz range
• B. 60-100 Hz range
• C. 0-1 Hz range
• D. 150-300 Hz range

Answer: (A)

Interferential current therapy creates a low-frequency beat by the interference of two carrier signals that are close in frequency. The beat frequency is simply the difference between those two carriers, and this low-frequency modulation is what interacts with nerve fibers to relieve pain. To achieve analgesia without causing strong muscle contractions, this beat frequency is kept in a low range, typically about 1 to 150 Hz. Clinically, many practitioners use around 80–100 Hz for acute pain. Frequencies much lower (0–1 Hz) or much higher (150–300 Hz) don’t provide the same effective pain modulation through the nerve fibers.