TENS electrodes primarily stimulate which type of nerve fibers?

Transcutaneous Electrical Nerve Stimulation (TENS) primarily stimulates large diameter nerve fibers. These large diameter fibers, often referred to as A-alpha and A-beta fibers, are responsible for conducting sensations of touch and pressure. When TENS electrodes are applied, they deliver electrical impulses that stimulate these fibers, which can help to inhibit the transmission of pain signals through a mechanism known as the gate control theory of pain.

The stimulation of large diameter fibers is effective in reducing pain perception by "closing the gate" to pain signals that travel through smaller diameter fibers, such as A-delta and C fibers, which are primarily responsible for transmitting pain and temperature sensations. By activating the larger fibers, TENS can help modulate and interrupt the pain experience, providing relief for patients dealing with various types of pain conditions.

In contrast, small diameter fibers are traditionally associated with the transmission of pain, and while TENS can have some effect on them, the primary goal of TENS is to target large diameter fibers to achieve pain relief efficiently.