What is a TENS Unit?

Welcome to our article titled “What is a TENS unit?” Maybe you’re wondering what a TENS Unit does.  Well, turns out we were just as curious and we set out to find some answers.

After all, applying electricity to your body to relieve pain sounds… silly.

Tens Unit

Therabody Power 2.0 Tens Unit

TENS stands for Transcutaneous Electrical Nerve Stimulation

It’s kind of a mouthful but we can break it down in simpler:

  • Transcutaneous means ‘applied across the depth of the skin’
  • Electrical means using electricity
  • Nerves are specialized cells that help carry messages from one part of the body to another
  • Stimulation means to excite or overwhelm the senses (in this case, touch)

Now that we understand the definition, let’s get into how it affects the nervous system to ultimately relieve pain.

TENS is not backed by science and is still a theory

Many tests have been conducted to find the efficiency of TENS but to no avail.  It rests based on pure theory, one of them being the Gate Control Theory.

The Gate Control Theory says that non-painful inputs can essentially block out painful inputs.  That these sensations are ‘blocking’ – so to speak – the gate of pain.

For TENS units the assumption is that the electricity that runs through our skin is blocking the central nervous system from sending real pain messages from the muscles to the brain.

Gate Control Theory

It was once believed that pain perception was equivalent to the degree of damage done to the tissue.  It makes intuitive sense.  However, it turns out that it’s not that simple, according to the Gate Control theory.

Roland Melzack and Patrick Wall pioneered this theory and propose that there are two types of nerve fibers: small and large based on diameter.

The larger nerve fiber handles sensory activity like touch, pressure, and vibrations.  These influence what’s called an inhibitory interneuron, which can directly decrease the chance of pain being felt.  The theory is that the more active these larger nerve fibers are relative to small fibers, the less pain is felt.

You see where this is going.  The electricity produced from the TENS Unit is assumed to be the sensory activity that activates these larger nerve fibers which ultimately blocks pain.

Releasing Endorphins And Enkephalin

Studies have shown increases in endorphins and enkephalin with the use of low-frequency TENS.

Endorphins are hormones that are the body’s ‘natural pain killer.’  If you’ve ever heard of the runner’s high (i.e. the euphoric feeling after running) then you understand how endorphins make you feel.

Enkephalins are a little more complicated in that they are involved in regulating our body’s response to painful stimuli.  During a stress event, a subset of enkephalins called methionine(‘met’) is increased in activity in the hippocampus, helping to cope with the stress.  In short, they are natural analgesics.

Essentially, when electricity produces things that make you feel good and relaxed, it tends to offset the pain you feel.

Summary without scientific terms

Okay, maybe I spoke too much about the physiological aspects of the TENS.  Let me try to break it down simply without the use of scientific terms.  Just remember that it’s still a working theory.

Your body feels pain because it’s an alarm to let you know something is wrong.  Your brain ultimately decides what kind of alarm to ring using all the information it has.

The electricity produced from a TENS unit is supposed to interfere with that alarm system.  The brain is too busy to process the pain from your tissue and instead focuses on the tingly sensation spread throughout your body.

If you were a teacher, you would reprimand each student differently because they respond differently.  Well, the brain is similar in that it handles pain and stress differently.  So that’s why having a multitude of options on the TENS unit is often favorable to the consumer.

In the end, a TENS unit seems to be more of a pain distractor than a pain reliever.

For a complete review of TENS units click here.



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