Transcutaneous electrical nerve stimulation (TENS) is used to treat muscle pain and stress associated with TMJ. Although there are some people who should not use TENS, overall the unit is a very safe way to treat pain associated with muscle tension or stress.
The amount of electric energy delivered via a TENS unit is very small compared to more dangerous currents such as a household electric current.
Voltage, Amps, and Your TENS Unit
TENS units create an electric current that goes through your muscles to stimulate muscle activity. TENS units often have modes that allow them to create a current that ranges from 0-350 volts (V).
This may sound like a lot if you know that the average household current runs at 120 V. However, there’s no real concern because the number of volts does not determine the risk of exposure to an electric current.
An electric current is caused by the movement of electrons, which are part of every atom. Voltage is a measure of the electric potential that is established. Think of the electric potential as a hill that electrons roll down to get from one part of the circuit to another. The higher the voltage, the steeper and longer the slope, so the more energy the electrons will have when they get to the bottom.
However, the number of volts doesn’t determine the number of electrons that actually roll down the hill. The number of electrons is related to a different measurement of electricity, called the amps (A). Amps are a measure of how much energy flows through a current in a given period of time. The amps in a TENS unit can typically only reach up to 700 mA, or 0.7 A. By comparison, the current reaching your house from outside may be as much as 200 A, and most circuit breakers in your house will trip at 15-20 A. This means that even at the highest setting of a TENS you’re receiving ? or less of the energy you would be exposed to from a household current before the breaker tripped.
And you’ll be exposed to it for less time. It takes a breaker at least 1 cycle of alternating current to trip at its rated current. For a TENS machine at a high-voltage setting, the pulses last about 100 ?S (microseconds, or millionths of a second). Since electric current alternates at 60 cycles per second (Hz), you would be exposed to the current for 1/60 of a second, or a little less than 17,000 ?S. So, although TENS can be dangerous if misused, you can see that the amount of current you’re exposed to is much less than what’s in a house current, giving you plenty of time to adjust the current yourself or signal us to adjust it for you before you suffer any injury.
Who Shouldn’t Use TENS
There are some people who are not good candidates for TENS, however. This includes people who:
- Use a pacemaker
- Have a bleeding disorder
- Experience epileptic seizures
- Are pregnant