Everything You Need To Know about TENS Units.
TENS, or Transcutaneous Electrical Nerve Stimulation, can be a confusing concept for some. This article will clear up what the device is, how it works, and go over certain things like pulse width and rate.

Everything You Will Ever Need To Know about Transcutaneous Electrical Nerve Stimulation Units

By Clark on March 25th, 2014

Transcutaneous Electrical Nerve Stimulation might sound like a mouthful, but the actual technology used isn't too complex or hard to understand. A TENS unit is simply a device that sends therapeutic electrical pulses/signals through electrodes that are attached to the skin. Many find this useful for relieving different kinds of chronic or acute pain - arthritic pain, joint pain, muscle soreness, strain, etc. Machines like the American Imex Biotens 2 Unit allow the user to modulate different pulse widths, rates, and frequencies, in turn helping them find a comfortable and therapeutic level of relief through electrical signals. Contrary to what some may believe, this is not at all painful, as the signals are slowly ramped up from a low level to keep the therapy comfortable.

Persons that have difficulty taking medicine, or just don't want to use various pharmaceuticals prescribed by their doctor may find it a good idea to invest in a TENS unit. Transcutaneous Electrical Nerve Stimulation is a fantastic way to relieve pain without drugs or surgery, and may be worth a try if you suffer from chronic or acute pain and are seeking relief. Though the therapy will not likely cure you completely, it can and does relieve pain for many people across the world. It's totally safe and approved by the FDA for usage in the united states. Your doctor may have even already recommended you a TENS unit!

Is TENS Therapy Safe?

Yes! TENS therapy is much safer than opiate based pharmaceuticals or other drugs for relieving pain. TENS therapy is non-addictive, since it isn't a chemical taken internally. You can't overdose on TENS therapy or have withdrawals (something very possible with many prescribed drugs - even some over the counter ones) as it's an entirely physical form of pain relief. The electrodes applied to the skin are more akin to a very unique type of massage, and when used correctly this is a highly therapeutic and safe method of pain relief.

As mentioned above, all of our TENS units have been approved for use in the United States by the Food and Drug Administration. This gives merit to the safety of such devices. Being reviewed and approved by a government organization involves a lot of testing and studies to show that something is safe. The fact that a device is actually proved is an even bigger indicator of safety.

How Does TENS Work?

Many studies have been conducted to find out how a TENS unit actually helps relieve pain. The main theory is that the electrical impulses disturb, interrupt, or override the nerve signals that are delivering pain messages to the brain. This in turn eliminates the actual sensation of pain because the signals are not sent to the brain. Rather than blocking or deadening the signals like certain pain medications, TENS units actually prevent the signals from even being transmitted in the first place, thus pain isn't felt as the brain isn't receiving anything telling it to feel pain.

Another theory on TENS is that it increases endorphin production at pain sites, thus acting more like a painkiller without the ingestion aspect. Doctors and scientists have also suggested that the device may increase blood flow in areas of pain. The actual mechanism of a TENS unit isn't entirely clear, but it is agreed upon by researchers that the therapy works. Many doctors across the world prescribe TENS therapy based on the many studies and research done proving such devices do in fact relieve pain in an effective manner.

What Does a TENS unit feel like?

Some liken the feeling of an electrode impulse to pins and needles, a tingling, or other similar sensations. It's not at all uncomfortable, and many say the feeling is therapeutic, and much better than the chronic pain they're experiencing. Depending on the intensity that the TENS device is set to, the feeling may change. It's important to adjust the TENS unit from a low setting in order to make sure that you're delivering a comfortable intensity, as higher intensities may be perceived as discomfort.

Some people use Transcutaneous Electrical Nerve Stimulation to induce involuntary muscle contractions. Though this isn't the main design for TENS units, it is a possibility, especially at higher intensity levels. Again, just be sure to set the unit to a level that is comfortable for you.

What Is a Signal? What is Pulse Width? What are all these terms?

Signal Basics

TENS units allow the user to modulate electrical pulses sent to the electrodes. Often times, the user can modulate the pulse rate and width, and cycle between modes like burst, modulation, or conventional. Most TENS units have dual, isolated, biphasic, asymmetrical channels. This simply means that each channel (electrode) can be adjusted individually. If you look at the image below you will see what a simple monophasic signal looks like, and what biphasic asymmetrical signals look like. The best way to think of it is that the shapes above the line are the pulses being sent to electrode A, and the pulses below the line are manipulating electrode B. Both shapes above and below the line can be adjusted according to how the user wants , and are adjustable independent of one another (biphasic, asymmetrical).

Pulse Width and Rate

Adjusting the actual 'shape' of the signal with the knobs on your tens unit is actually adjusting the pulse rate and width. Pulse rate is best thought of as how fast each signal is being sent. Be it one every second, two every second, etc. Pulse width is best thought of as how drawn out each shape is going to be in our graph - a signal with a long pulse width is going to feel like it's sweeping from low to high, very slowly. This will happen as frequently as the pulse rate is set. A signal with a short pulse width is going to look sharper on the graph, and the signal will ramp up and down quickly. See the graph below for a graphical explanation.


In addition to allowing you do adjust how quickly the pulses are being sent, and how drawn out the signal is, a good TENS unit will allow you to modulate the amplitude, or intensity, of the signal. A low amplitude will send less current than a higher amplitude. A very high amplitude will feel more 'intense' than a lower one. See the graph above again for intensity (mA is for how many milliamps are being sent to the electrode - this is your intensity adjustment)

Where to Apply Electrodes
TENS applies an electrical signal across two electrodes placed at points of pain. Often this is the back, but can be applied anywhere you might be having pain, including the knees, shoulders, upper back, thighs, legs, and so on. Anywhere you have muscle or joint pain, electrodes can be applied. The idea is to apply the electrodes across the muscles that are hurting. In the lower back, for example, you might place the two electrodes on either side of the spine. In the forearm, you might place one close to the elbow, and another halfway down the wrist. Placing the electrodes for the best use out of your TENS unit is going to take some experimentation, but here is an image with some common placements that may help you during your experimentation. If you need replacement electrodes, check out our replacement electrodes from American Imex

How Long Can I Use My Tens Unit?

TENS units are great for managing chronic forms of pain because they can be used for long periods of time without any side effects. Reports from TENS therapy users online have been found where they use TENS therapy for up to 22 hours a day with high quality electrodes. This isn't recommended, obviously, but the TENS units can be used for a long period of time. Many people find that using a transcutaneous electrical nerve stimulation device is a better alternative to pharmaceutical pain relievers, as there are no risks for addiction or withdrawal with TENS. In addition, many find that after removing the electrodes, the therapy continues to work for some time after, up to a few hours in some cases.

As always, with any pain treatment regimen, you should consult with your doctor before using a TENS device. Though TENS therapy is harmless, certain people should not use TENS units, such as people that are nursing or pregnant, persons with epilepsy, and persons that have a pacemaker installed. You also should not use these devices directly on open wounds or broken skin (though some manufacturers state it's safe to place electrodes around open wounds). Wondering where to buy a tens unit? Click here.