8 Channel Ten's Machine

Research trials that have studied the use of TENS machines have provided conflicting results as to how well they work, and how much pain relief they give. Some conclude that they are not effective. Others conclude that they seem to help some people. Further research is needed to clarify their role and effect.

However, TENS machines seem to be popular for various painful conditions. Their popularity would imply that they may well have some effect to reduce pain. However, the amount that the pain is eased is likely to vary from person to person with the same condition.

How do TENS machines work?

Transcutaneous means 'through the skin'. TENS machines deliver small electrical pulses to the body via electrodes placed on the skin. TENS machines are thought to affect the way pain signals are sent to the brain. Pain signals reach the brain via nerves and the spinal cord. If pain signals can be blocked then the brain will receive fewer signals from the source of the pain. We may then feel less pain.

TENS machines are thought to work in two ways:

• When the machine is set on a high pulse rate (90-130 Hz) it is thought to trigger the 'pain gate' to close. The 'pain gate' is a theory that says that when certain non pain-carrying nerves are stimulated then these can can interfere with ('close') signals from nerves that transmit pain. The TENS machine is thought to stimulate certain non pain-carrying nerves. This may then interfere or block pain messages sent to the brain. This is the normal method of use.
• When the machine is set on a low pulse rate (2-5 Hz) it stimulates the body to make its own pain easing chemicals called endorphins. These act a bit like morphine to block pain signals.