What is a TENS Unit and How Can it Relieve Pain?

TENS Unit and How Can it Relieve PainA TENS unit – Transcutaneous Electrical Nerve Stimulation Unit is a battery-operated device that is used to relieve different types of pain.

The device has leads connected to sticky pads termed as electrodes.

When the electrodes of the device are applied on the area of pain, a current of electrical impulses is created which causes stimulation of muscles and nerves thereby reducing the pain.

How does a TENS Unit work?

When the device is used as directed, the TENS Unit machine is a non-invasive, safe and drug-free technique of pain management.

So how can a TENS Unit Relieve Pain? It works by delivering electrical current across the skin and along the nerve strands. These electrical impulses travel through the electrodes and into the skin stimulating specific nerve pathways to create a buzzing or massaging sensation, that alleviates the perception of pain.

To be more precise, the machine helps in blocking and supressing pain signals to the spinal cord and brain.

What does a TENS machine do to alleviate, relieve, or eliminate pain? As a form of electrotherapy, TENS Unit device is designed to reduce pain in the human body. There are 2 main theories to give an account of how a TENS unit device works to relieve pain.

The Gate Control Theory

As per this theory, the spinal cord consists of a neural mechanism that serves as nerve “gates”, preventing the flow of pain signals or allowing them to travel from the periphery to the central nervous system.

Whether the nerve gate is open, blocked or partially blocked depends on the type of signal it receives from the central nervous system to change the perception of pain in the user’s body. This spinal cord “gate” functions by differentiating between the types of nerve fibres that carry pain messages. Small nerve fibres allow the pain signals to pass through while the signals that travel via large nerve fibres are prevented from travelling to the brain.

Gate control theory is often used to describe the chronic or phantom pain. Rubbing the painful area when we get hurt is a perfect example of the gate control theory in action. The sensation caused by rubbing the painful area (touch) creates a signal that temporarily blocks the pain messages travelling from the effected are (injury area) to the brain, making you feel better.

The Endorphin Release
The TENS Unit device alleviates pain by releasing chemicals that serve as natural pain relievers in the body – endorphins and enkephalins (powerful peptide or polypeptide analgesics. The electrical impulses produced by TENS Unit machine produces these pain-relieving chemicals that interact with the brain receptors and alleviate your perception of pain.
The analgesic activity of these chemicals inhibits the pain fibres in the nerve cells. Endorphins and enkephalins are also known to trigger positive feelings of ecstasy, pleasure, elation, and reduced pain in the body, similar to that of morphine.

Scientific theory for working for TENS Unit Machine

Scientific theory suggests that TENS Unit electrotherapy works in several ways-

  •  The gentle electrical stimulation travels through the skin to nearby nerves to prevent the pain signals from ever reaching the central nervous system from the source of the pain.
  • The gentle electrical current increases the release of chemicals like endorphins (natural pain killers) that serves as a natural analgesic in the body.
  • Blood circulation also improves due to the electrical impulses. As a result, there is repeated contracting and relaxing of the muscles and reduction in any pain in the body.


TENS Unit device is a safe, non-drug and non-invasive choice for relieving pain. The TENS machines have an adjustment for the frequency (low/high), and also for intensity of the electrical current. It is advisable to begin on a low adjustment and gradually increase it.

The electrical stimulation creates a tingling sensation that should feel strong but at the same time should be comfortable and not hurt.

High-frequency TENS machine is the best for stopping pain signals, while low-frequency TENS machine is more effective for triggering release of natural pain-relieving chemicals called endorphins in the body.

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