Transcutaneous electrical nerve stimulation (TENS) is a physical therapy system using low-level electrical pulses to the nerves just beneath the skin. The electrical stimulation helps mask pain signals to the brain from deeper tissue nerve centers.
Once reserved only for medical professionals, TENS machines, more commonly referred to as TENS units, are now available to the general public.
There is a wide variety of models to choose from. The most common portable TENS units have a controller device similar in appearance to a smartphone. Most units also come with between two to five electrode patches that attach to the skin to transmit the electrical impulses.
Used in almost all physical therapy settings, TENS units have far-reaching benefits, especially for pain relief.
Joint pain relief
A joint that gets injured through a traumatic event, such as a vehicle accident, will protect itself by tightening the muscles and tendons in and around the joint.
The problem is that the attached limb is unable to move freely as it was designed to do. The severe pain sometimes created by the condition can delay physical therapy designed to increase range of motion.
The idea is to use TENS therapy right at the joint, alleviating pain so physical therapy can start. The patient experiences better outcomes because there is less focus on pain and more attention paid to the goals of the therapy.
When using a TENS unit for joint pain, special consideration should be given to the placement of the electrodes.
For example, when treating the knee, it is advisable to use four electrodes instead of two. Also, a criss crossing pattern ensures that the electrical stimulation will reach all facets of the joint.
When treating a smaller joint such as the elbow, two electrodes placed in tandem is sufficient to have the desired effect.
Back pain relief
Millions of adults suffer from lower back pain. It is the second-highest cause of disability behind arthritis. TENS therapy has been shown to be effective in treating low back pain.
TENS units are now just as much a part of the athlete's equipment as cleats and helmets. They are proven useful for treating everything from muscle pulls to dislocated joints.
For muscle pain, it is best to use a higher setting to affect the deeper tissue areas.
Older adults see the benefit too. Arthritis is the number one cause of disability in the US.
For arthritis, a lower setting is used to provide a gentler, longer-lasting effect.
Some people should not use a tens unit
There are certain circumstances where a TENS unit may cause more harm than good.
Pregnant women. There is no scientific evidence for or against a pregnant woman using a TENS unit. And that's the problem. Until scientists can decide, it is best to stay away until there are more studies.
People who wear pacemakers. Again, very few studies conclude that heart patients who wear a pacemaker are safe using a TENS unit. Most doctors conclude that electrical stimulation could destroy the pacemaker. The best thing right now is to forego their use until there is more data available.
Those with epilepsy. Can the electrical current cause an epileptic seizure? It is unclear. So until there is more research, those with epilepsy should not use a TENS unit.
Lymphedema patients. TENS units can temporarily disrupt the circulatory system and cause fluid retention. For this reason, people with lymphedema should never use a TENS unit.
The bottom line
As long as there are no major medical complications, most people suffering from pain can benefit from a TENS unit.