Explanation of TENS units treatment modes

There are many TENS units available, and though the more popular are the TENS 7000 and the TENS 3000, everyone has its favorite, whether it is the TENS AA digital unit, the Ultima 3T, or the InTENSity Twin Stim. There are also many TENS treatment modes; some common to all devices, and others more exclusive to a specific machine. Here we will attempt to review some of the most used.

Conventional TENS is a high frequency (80 to 125 pulses per second), short pulse width (50 to 125 microseconds), low amplitude mode that relieves pain through the gate theory of pain, although it can also activate opioid receptors in the body, triggering the release of endorphins. Conventional TENS provides quick relief for chronic and acute pain with a level of stimulation often deemed comfortable. The downside is that the effect doesn’t usually last too long, and nerve accommodation is common too, forcing users to increase amplitude or pulse duration.

Low-frequency TENS is also known as acupuncture-like TENS; its effects are medium lasting but patients may experience uncomfortable muscle contraction provoked by a long pulse duration of 200 to 500 microseconds. Other parameters include low frequency (1 to 5 pps), and medium-high amplitude. Low-frequency TENS is slow acting, but nerve accommodation is uncommon, and pain relief is achieved through the endogenous opiates and B-endorphin release.

Brief intense TENS employs high ranges of frequency (between 110 and 200 pps) and pulse width (200 to 500 microseconds), for a quick onset of pain relief that may last for up to 6 hours. Conversely, the user may encounter muscle contraction, discomfort and fatigue, especially after prolonged application at higher intensities. Otherwise, patients usually tolerate well, though it may not be as effective for chronic pain.

Burst mode TENS emits 70 to 100 pulses per second in individual bursts ranging from 1 to 5 every second, accompanied by 200 to 500 microsecond pulse duration. Even though the amplitude is strong enough to produce intermittent muscle contractions that could be uncomfortable for the patient, most users find it more comfortable than low-frequency TENS. It’s used almost exclusively for chronic pain.

Modulated TENS cycles through amplitude, pulse width or frequency in order to prevent accommodation. This mode is more often than not considered comfortable, fast acting, and effective for both chronic and acute pain. However, its effects may be short-lasting. 

Related Read: How to set a TENS unit?