Table 3.

Summary of TENS devices classifications.

Conventional TENS	Activation of large diameter non-noxious afferents Surface electrodes	Low-intensity stimulation/high-frequency (between 10 and 200 pulses per second)
Acupuncture-like TENS	Activate small diameter motor fibres, producing muscle twitches. Needle or surface electrodes.	High-intensity stimulation/low-frequency (less than 10pps, usually 2–4 pulse per second)
Intense TENS	Activate small diameter noxious afferents. Eliciting peripheral nerve blockade and extra-segmental analgesia Surface electrodes	High-intensity stimulation/high-frequency (up to 200 pulse per second)