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What is a TENS unit, and will it help me?
[+surprising new research about calorie burn]

A transcutaneous electrical nerve stimulation (TENS) unit is a device that some people use for pain relief.

Medically reviewed on April 21st, 2021 by Dr. Louis Crowe, M.D.

  1. Pain Relief Uses
  2. TENS Benefits
  3. Side effects of TENS
  4. Cautions
  5. Does a TENS unit relieve pain?
  6. How long does pain relief last?
  7. A different kind of electrical nerve stimulation
  8. BionicGym is not your typical TENS unit
  9. A role in weight control
  10. BionicGym safety information
  11. Takeaway



A TENS unit delivers small electrical impulses to your nerves via electrode pads on your skin.

These electrical impulses can reduce the level of pain you feel. There are two theories as to why this works. One is that the small electric currents block the transmission of pain signals in your nerves. The other is that stimulating the nerves causes your body to release endorphins, nature’s own pain relieving chemicals. 

BionicGym uses similar technology as a typical TENS unit. We’ll discuss below what’s the same and how it’s different. For example, BionicGym provides vigorous exercise.

If you read more, you’ll also learn about the uses of a TENS machine, benefits, and risks.

Pain Relief Uses:

TENS units are often prescribed by doctors to reduce pain resulting from the following conditions:

  • osteoarthritis
  • endometriosis
  • fibromyalgia
  • arthritis
  • sports injuries such as tendonitis
  • multiple sclerosis
  • bursitis
  • peripheral artery disease
  • diabetic neuropathy
  • spinal cord injury

A TENS unit may also help treat the following symptoms:

  • low back pain
  • period pain
  • postoperative pain
  • labour pain
  • chronic pelvic pain
  • neck and back pain
  • postoperative pain
  • joint pain

They are also non-prescription in many countries. Please read the leaflet before using. 

A battery-powered TENS unit is usually no larger than an iPhone. It comes with a controller, electrode pads, and wires that connect the electrodes to the unit. 

The electrodes are placed on your body along nerve pathways that connect to painful areas. The unit then delivers pulses of electrical current to your nerves. 

A TENS unit puts you in control of your level of pain relief. You do this by changing the intensity, frequency, and duration of the electrical signals stimulating your nerves.

TENS Benefits:

TENS can be highly effective in treating pain. It is non-invasive. It may allow some people to reduce their intake of prescription pain medications after consulting with their doctors. 

TENS units are small and portable. This makes pain relief convenient and available both at home or away.

Side effects of TENS:

Most people don’t experience any undesirable side effects when using a TENS unit. Its use is considered generally safe.

Some people may find that the prickling or tingling sensations they feel when using a TENS unit are uncomfortable. Others may be allergic or have a reaction to the adhesive used on the electrode pads and develop signs of skin irritation such as redness or rash.


TENS could be hazardous in the following cases:

  • Pregnancy: The effect of TENS therapy on fetuses is unknown, so pregnant women should not use it for pain relief.
  • Heart conditions.
  • Having a pacemaker, infusion pump, defibrillator, or other similar devices.
  • Epilepsy.

TENS electrodes should not be placed over the eyes or front of the neck, as serious injury could result.

It’s important that you consult with your doctor before starting TENS treatment.

Does a TENS unit relieve pain?

TENS can work very well for many people. 

However, the scientific evidence for pain relief with a TENS unit is mixed. Some studies have shown that TENS may provide effective pain relief. Others have shown that TENS therapy was no better than a placebo.

The effectiveness of TENS for pain relief depends both on how it’s used as well as the condition for which pain relief is sought. Researchers don’t yet know if TENS is a reliable treatment for pain. However, it does pose a relatively low risk for many people.

How long does pain relief last?

The level of pain relief can vary.

For some people, a TENS unit can provide pain relief for over 24 hours. For others, the pain comes back as soon as they turn off the device. Repeated TENS sessions can increase the amount of pain relief, but they can also lead to a person building up a tolerance to the treatments.

Increasing the intensity of the electrical stimulation can overcome the tolerance-building effects of frequent treatments for relieving pain.

A different kind of electrical nerve stimulation

BionicGym Intro & DEMO from BionicGym on Vimeo.


Over the past 20 years, a small group of dedicated researchers has found that a technology related to TENS can be used for more than just pain relief. This related technology is called Electrical Muscle Stimulation (EMS) or neuromuscular electrical stimulation (NMES). When it’s applied in a special way, it can create real, calorie burning exercise.

This way of using EMS works by mimicking shivering. That’s “nature’s hack” for generating heat. And generating heat means you’re burning calories.

Using this form of electrical muscle stimulation can also lead to raised heart rate, breathlessness, and sweating during training sessions.

A strange but true feature of this form of exercise is that it targets sugar-hungry “fast twitch” muscle fibres first. That makes it soak up blood sugar like a sponge soaks up water. Some people say that they are able to lose stubborn weight with this form of electrical muscle stimulation because it gives them the daily exercise they need.

BionicGym is the only electrical stimulator that is capable of producing a significant calorie burning training effect using the “shivering hack.” 

BionicGym is not your typical TENS unit

A TENS unit stimulates sensory nerves for pain relief. BionicGym stimulates the motor nerves that control your muscles.

BionicGym uses the “shivering hack” to make you burn calories without loading up your joints. It is lightweight and portable. It allows you to exercise nearly anywhere you choose. You can even train for a marathon from your couch, which sounds too good to be true. It’s been done.

Unlike other electrical muscle stimulators, BionicGym has been shown in studies to raise a key marker of aerobic fitness, VO2 Max. It is also capable of raising heart rate for extended periods of time.

If you choose, BionicGym can provide you with a demanding physical workout.

A role in weight control?

A normal TENS unit can’t help you burn enough calories to lose weight. It is meant for pain relief and doesn’t lead to large increases in oxygen consumption.

BionicGym is different.

Because BionicGym uses electrical pulses to stimulate your muscles using the “shivering hack”, it can lead to significant calorie burn. A TENS unit or regular muscle stimulator cannot do that.

It’s also important to realize that BionicGym is not a magic bullet. Losing weight requires both diet and exercise. But BionicGym can be your exercise. 

Read more about how BionicGym works.

BionicGym safety information

BionicGym is an exercise device for healthy adults. It gives you a workout by exercising the legs. Use in safe situations and settings.

You should ask your doctor if it is safe for you to exercise (any exercise, including BionicGym) especially if you are injured, over 40, smoke, are obese or diabetic, have heart disease or any potentially serious condition.

Intended Use

The BionicGym is intended to stimulate healthy muscles in order to exercise, improve or facilitate muscle performance. It is not intended to be used in conjunction with therapy or treatment of medical diseases or medical conditions of any kind. None of the training programs or operational parameters are designed to target injured or ailing muscles.


Do not use BionicGym if:

  • You have an electronic implant (e.g. cardiac pacemaker or defibrillator).
  • Consult your doctor if you have any other heart problem prior to using.
  • You are pregnant, or have given birth, or had a caesarean section within the last three months.
  • You suffer from cancer, epilepsy, or are under medical supervision for cognitive dysfunction.
  • You recently had acute trauma or subject to a surgical procedure - seek your Doctor’s advice.
  • Stimulation should not be applied over swollen, infected, or inflamed areas or skin eruptions, e.g. phlebitis, thrombophlebitis, varicose veins, etc.
  • If you suffer from any vascular problems, including clots /DVTs.


  • The long-term effects of chronic electronic stimulation are unknown.
  • Stimulation should not be applied over the carotid sinus nerves, particularly in individuals with a known sensitivity to the carotid sinus reflex.
  • Stimulation should not be applied over the neck or mouth. Severe spasm of the neck or airway muscles may occur, and the contractions may be strong enough to close the airway or cause difficulty in breathing.
  • Stimulation should not be applied near your heart in that the introduction of electrical current into the heart may cause cardiac arrhythmias.
  • Stimulation should not be applied on your head.
  • Stimulation should not be applied over, or in proximity to, cancerous lesions.
  • Do not use in close proximity (e.g. 1m) to shortwave or microwave therapy equipment, as this may produce instability in the controller’s output.
  • Do not use if injecting drugs /medicines into your thighs.
  • Do not resell BionicGym or use BionicGym if you’ve purchased a used one.
  • Simultaneous connection of a patient to high-frequency surgical equipment may result in burns at the site of the electrode pads and damage to the control unit.


  • Safety of powered muscle stimulators for use during pregnancy has not been established.
  • Caution should be used for individuals with suspected or diagnosed heart problems. Do not use unless your doctor recommends that it is both safe and good for you.
  • Caution should be used for individuals with suspected or diagnosed epilepsy. Do not use without your doctor’s permission.
  • Caution should be used in the presence of the following:
  • When there is a tendency to haemorrhage (bleed) following acute trauma
  • or fracture.
  • Following recent surgical procedures when muscle contraction may
  • disrupt the healing process. Do not use without your doctor’s permission.
  • Over the menstruating or pregnant uterus.
  • Over areas of the skin which lack normal sensation.
  • Some individuals may experience skin irritation or hypersensitivity due to the electrical stimulation or electrical conductive medium.
  • Electrode placement and stimulation settings should be based on the guidance of this manual.
  • BionicGym should be kept out of the reach of pets and children.
  • BionicGym should be used only with the leads and electrodes recommended for use by the manufacturer.
  • BionicGym must never be used while driving, operating machinery, or during any activity in which involuntary muscle contractions may put the user at undue risk of injury.
  • Skin irritation and burns beneath the electrodes have been reported with the use of powered muscle stimulators.

Note: It is normal for there to be mild skin redness after a stimulation session. This should disappear within a half hour.


  • Do not over-exert yourself when using muscle stimulation. Any workout should not exceed your comfort level.
  • Stop using the product if you are feeling light-headed or faint, have pain or breathlessness -beyond what you’d expect with the exercise. Consult your doctor if this happens or if in any doubt.
  • Do not touch the electrodes or metal studs with your fingers while the controller is switched on / during use.
  • Never use BionicGym over open wounds or damaged skin or if you have abnormal feeling. If you have a minor nick, cut or bite you can mask that with a small band- aid. (Only use BionicGym on clean, healthy, intact skin).
  • BionicGym is intended for adults (over 16 years old). If you are 16-18 years old, you must get a parent’s or guardian’s permission.
  • Always follow the guidelines, watch the tutorials and read the whole manual before use. Only use BionicGym as directed in this manual
  • ONLY use BionicGym when and where it is safe for you and others. It contracts your muscles which you need for balance and control. Wear flat shoes.


Using a TENS unit for pain relief is generally low-risk. It may provide pain relief for a wide range of conditions. But research into TENS therapy for pain management is still lacking. 

The efficacy of TENS may vary depending on the condition being treated, the position of the electrodes, the intensity of the electrical current, and the duration of treatment.

TENS devices are available both by prescription and over the counter. Before beginning TENS therapy, it’s important that you consult with a medical professional. 

Research into the related technology of electrical muscle stimulation (EMS) has shown that it can now be used for vigorous exercise. BionicGym is the only electrical muscle stimulator on the market that takes advantage of “nature’s hack” to help you burn calories and improve your aerobic fitness. It is backed by 20 years of peer-reviewed scientific research.

You can learn more about BionicGym here.


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