When you hear the words ‘physical therapy’, you often think of exercising, rehabilitation, massages and stuff along those lines.
But physical therapists also use electrotherapy to help their patients in different ways. One of the most commonly used electrotherapy devices is the TENS machine.
In this article, we’ll talk about what TENS therapy is and why it’s used in physical therapy. We’ll also answer some frequently asked questions about TENS.
What Is a TENS Machine?
A transcutaneous electrical nerve stimulation machine – or TENS machine for short – is a device that healthcare professionals use for various reasons. It’s a form of therapeutic electrotherapy and is widely used in physical therapy clinics.
The TENS machine is as small as your cell phone. You can carry it in a case and use it at your home as well as at the clinic. It comes with a couple of electrode wires and square 2×2 electrodes.
You connect one end of the wires to the machine and the other end to the electrodes. Then, you place the electrodes on the skin around the painful or injured area and set the frequency, intensity and type of electrical impulses.
There’s also an option to adjust the time and the machine stops on its own when the time runs out.
When you have the TENS attached to your skin, you only feel tingling, buzzing or twitching but ideally no pain.
Why Do Physiotherapists Use TENS Machine?
Here are some indications for which your physiotherapist might use TENS therapy:
1. For Pain Management
A TENS unit helps reduce acute and chronic pain. That’s one of its primary indications.
Your physical therapist might apply TENS to manage your postoperative pain, sciatica pain, low back pain, acute or chronic pain, arthritic pain, fibromyalgia, and neuropathic pain.
TENS therapy can reduce pain through two mechanisms – by reducing the painful stimulations being carried from the injured area to the brain and by increasing the level of natural opioids or endorphins.
By selectively activating certain nerve fibers in the skin using high-frequency (90-130Hz) stimulation, TENS causes the pain gates to close.
On the other hand, when you set a lower frequency (2-5Hz) in the TENS machine, you can increase the endorphin levels and decrease the levels of the neurotransmitters that increase painful sensations. (Reference)
These days, the burst mode of TENS is most often used for pain management in physical therapy. It shifts between low and high-frequency electrical stimulation and so you can benefit from both mechanisms of reducing pain.
2. To Repair Nerve Damage
A transcutaneous electrical nerve stimulation unit can help regenerate nerves and increase the nerve’s regeneration capacity. Recent animal studies have shown that TENS increases the axon’s (the main thread of a nerve) quality and diameter.
The studies on rats have shown significant positive results for facial nerve regeneration, nerve damage after crush injuries and sciatic nerve damage.
Physiotherapists use TENS therapy to treat pain and nerve damage due to diabetes-related neuropathy.
3. For Wound Healing
TENS therapy helps with wound healing. This includes superficial wounds on the skin and deep injuries involving the muscles.
The current theory for this effect is that the electrical stimulation from the TENS machines causes the body to release substance P and calcitonin gene-related peptides – both of these help repair wounds quicker. (Reference)
Electrical current from the TENS machine also produces vasodilation (widening of the blood vessels to increase blood supply to the area) which brings more nutrients to the injured area and helps the healing process.
4. For Tendon Repair
Although the evidence for tendon repair with TENS is lacking, some physiotherapists use it for this purpose. It’s often used for repairing rotator cuff and Achilles tendon injuries.
Animal studies have shown promising results for repairing degenerated and injured tendons with TENS. These suggest that low-frequency electrical stimulation increases the quality of collagen.
5. To Reduce Inflammation
TENS therapy can be effective in treating inflammation in tendinitis, bursitis, osteoarthritis, and after total knee replacement surgery. (Reference)
That’s because using electrical stimulation reduces the levels of proinflammatory cytokines (small proteins in the blood that regulate the immune system and cause inflammation) in the blood. (Reference)
The TENS unit also helps to reduce joint stiffness along with inflammation.
6. For Pinched Nerves
Although TENS therapy doesn’t directly work on a pinched nerve, it can certainly help relieve its symptoms.
People experience neck pain due to trapped nerves in the cervical spine or have pain in the legs due to trapped nerves in the low back.
TENS applied on the path of the nerve can decrease pain and tingling and improve muscle function in some patients.
In most cases, you feel the pain of trapped nerves at a different location from where the nerve is actually pinched.
Since the level of pain and effects caused by pinched nerves vary a lot between patients, your physical therapist is the best person to decide if Transcutaneous Electrical Nerve Stimulation is the way to go to treat your nerve pain.
Similarly, you can use TENS therapy to deal with the pain and muscle spasms caused by a herniated disk in the lower back or neck. But, remember, TENS can’t treat the herniated disk itself.
Common Questions About the Use of TENS in Physical Therapy
Patients are sometimes skeptical about how electrical current can fix their pain, inflammation and nerve damage. They also have questions about how the TENS machine works and how they can operate it on their own at home.
Here are answers to some frequently asked questions about the use of TENS in physiotherapy:
How Long Should You Use a TENS Unit at a Time?
You should only apply the TENS unit for 30 minutes at a time. If the recommendation is to apply the therapy for longer, then you need to give your skin a break for at least 20 minutes before reapplying the electrodes to the same location.
However, you can apply TENS somewhere else on your body during that 20 minutes break.
You should stop the machine if it causes pain, excessive painful muscle twitching or skin irritation. Also, don’t apply it while you’re sleeping, driving or underwater.
How Long Does TENS Pain Relief Last?
The pain relief you experience after TENS therapy varies from person to person. Low-frequency TENS – the one that releases endorphins – can cause pain relief for up to 24 hours or longer. (Reference)
Other times, the therapy only provides pain relief for a couple of hours so you have to apply it a few times a day.
What Is the Difference Between TENS and EMS?
TENS and Electrical Muscle Stimulation (EMS) devices are both used in physical therapy for providing electrical current to patients. These differ in their uses, intensity, and frequency of the current.
TENS is used for pain, inflammation, nerve damage and the other reasons we’ve covered above. EMS is used only for stimulating the muscles that are too weak or injured to work on their own.
EMS therapy is also used to strengthen the muscles in athletes after surgery when they can’t lift too much weight or move the muscles in certain ranges.
This device has a big role in physical rehabilitation clinics for treating patients who are recovering from stroke and spinal cord injuries. (Reference)
The devices for TENS and EMS look quite similar. These days, you’ll find both options in the same device since you need the same type of wires and electrodes for both therapies.
Can You Use the TENS Machine While Sleeping?
No, you shouldn’t use the TENS machine while sleeping. That’s because the intensity of the current might be too high and you won’t know it.
If there is any wire damage, it could harm you or cause sparks which can be dangerous. You need to be aware of how your body is responding to the current while the electrodes are attached to your body and you can’t do that while sleeping.
What Are the Advantages and Disadvantages of TENS Therapy?
Transcutaneous electrical nerve stimulation can produce excellent results for many patients. However, it can also have some side effects that you should be aware of.
Advantages of TENS Therapy:
- It’s non-invasive
- Generally safe
- Can be used at home by yourself after learning about the correct procedure
- Small, portable, and easy to carry around.
Side Effects of TENS Therapy
- Patients become too dependent on it and want to continue using it even when they don’t need it.
- You can experience burns if TENS is applied for too long
- Electrodes can cause skin irritation
How Many Times a Day Can You Use TENS?
The frequency of TENS application varies from case to case. You can safely apply the machine multiple times a day as long as you don’t keep it on for more than 30 minutes at a time.
For patients dealing with nerve pain or pain due to inflammation, using the TENS unit four or six times a day is usual. For others, applying it twice or thrice a week is enough.
The Takeaway
Electrotherapy is common in physical therapy clinics. It’s a passive form of treatment – meaning that patients don’t have to actively do any activity while the machine is applied.
Since TENS therapy has shown some excellent results in human and animal studies, it’s becoming even more popular now.
Feel free to contact us if you have any more questions about if, when and how you should use the TENS machine.
Disclaimer: This article is for informative purposes only. We provide well-researched and authentic information. Do not consider this personalized health advice. Please contact a licensed healthcare professional for medical issues and health concerns.