How does a TENS unit work?

Chances are you’ve heard of a tens unit before. It’s what looks super high-tech in PT clinics with electrodes, wires, and fancy equipment. Are you familiar with how it works in giving you pain relief?

How does a TENS unit work?

How to Use It

There are some different ways to use TENS for pain relief, but we’re going to cover conventional TENS. In conventional TENS, the goal is to stimulate sensory nerves – the nerves in our bodies that send information to our brains when we feel something in our environment – to eliminate pain after an injury. In this case, these are the nerves responsible for experiencing “normal” sensations – not painful sensations.

Pain Gate Theory

The Pain Gate Theory helps explain why stimulating these sensory nerves actually works to block the perception of pain in a patient undergoing conventional TENS. When we feel something, information is sent along sensory nerves to the spinal cord and eventually the brain. Then the brain processes that information and makes us actually feel it. But in the spinal cord, there’s a region responsible for gathering information and sending it to the brain to signal you to feel pain.

This region can be referred to as the “gate” that can either be opened or closed to allow pain to get through or not. If the gate is open, you’ll feel pain; if it’s closed, no pain will be felt and you’ll simply feel normal touch, pressure, or vibration. Non-painful sensory information travels along nerves that work to effectively close that gate to pain. These nerves working to shut down pain are the ones we stimulate with conventional TENS. So basically, by simply stimulating those nerves that make you feel the tingly ants crawling on your skin during TENS, your body is working to shut pain off and give you some relief!


TENS is just one of many tools we use at Symmetry Physical Therapy in Downtown Miami to help you become pain-free. We’ll do whatever it takes to create the best plan of care possible for you and what you are experiencing. Getting back your health, ability to be pain-free, and ability to do the activities you love are our focus.

Ready to get started on physical therapy? Book a session with us in clinic or virtually!

Not ready for physical therapy? Check us out on Youtube for extra exercises and how to use a tens unit. 

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