If you’ve ever visited a physical therapist to rehabilitate a soft tissue injury, it’s possible you’ve experienced a form of electrical muscle stimulation, or e-stim therapy (also referred to as EMS, electromyostimulation or neuromuscular electrical stimulation, and NMES). Another form of e-stim therapy called TENS (transcutaneous electrical nerve stimulation) works on nerves rather than muscles.
During e-stim treatment, a therapist secures electrode pads to your skin. He or she then turns a dial or presses a button on an electrical muscle stimulation device, a console that’s either plugged into the wall or battery-operated. This machine generates electric impulses that stimulate your skeletal muscles to contract. An e-stim device has various settings, meaning the contractions may be barely noticeable or they may feel, and look, like involuntary muscle twitches.
The primary purpose of e-stim therapy is to simulate what happens in the body when you voluntarily contract and release a muscle many times in a row. This process strengthens and repairs tissue, particularly muscles which have become shortened, weakened, or atrophied due to injury or disease. For example:
- If you’ve torn an Achilles tendon, the muscles in your calf and foot may become atrophied from wearing a boot to immobilize the ankle, or from changing your gait to favor the injured ankle.
- If you have a shoulder injury (e.g., a rotator cuff tear or impingement), resting, immobilizing, or favoring the shoulder may cause the muscles in and around that shoulder to weaken.
- If you have neuromuscular dysfunction or a neuromuscular disorder (such as muscular dystrophy), muscles throughout the body may weaken progressively; e-stim can help to slow this progression and improve motor control.
E-stim can also be used by athletes as a muscle conditioning or recovery tool. Some studies have indicated that e-stim can be targeted to create contractions in different types of muscle fibers, allowing athletes (with the guidance and help of professional sports therapists) to train injured or weakened muscles for particular functions and responses. For example, a long-distance runner might use e-stim therapy as a complementary technique to train muscle fibers to resist fatigue.
How Exactly Does E-stim Work?
EMS therapy mimics the action potential that comes from the central nervous system. Action potential is what we call it when a neuron (cell in the nervous system) transmits information (electrical impulses) along an axon (the thread-like conduit leading away from the neuron body, toward other cells). When these impulses pass a threshold, the action potential is fired and something happens. In this case, that something is a muscle contraction.
EMS therapy creates steady electric impulses that stimulate muscle contractions–many of them over a sustained therapy session. This repetitive contracting and relaxing of the muscle has the effect of:
- Increasing circulation (blood flow) to the affected tissue area, which aids in repair.
- improving strength by flexing and working weakened muscles.
- slowing the process of muscle atrophy by strengthening weakened or unused muscles.
- adapting (training or “educating”) muscle fibers to certain patterns of response (e.g., contracts the fibers that are responsible for force, which results in building strength).
Another form of e-stim therapy called TENS (transcutaneous electrical nerve stimulation) works on nerves rather than muscles. It’s used primarily for managing or blocking pain signals to the brain, and has been in regular use by doctors and physical therapists since the 1960s.
TENS therapy can issue electrical stimulation at different wavelengths for different purposes (relaxation, circulation, blocking pain) and can sometimes be performed at home, after the patient has been taught proper and safe use of the equipment.
Uses and Benefits of E-stim Therapy
When used for recovery, rehabilitation, muscle training, or pain relief, EMS and TENS devices are normally prescription-only and administered by professionals: for example, sports medicine physicians, physical therapists, or orthopedists. There are however, some devices available for over-the-counter purchase and home use.
Some of the common uses of prescription EMS therapy include:
- Relieving back spasms. Electric muscle stimulation can relax back muscles, easing tightness and soreness in the lower back area. Sciatica symptoms, for example, can be caused by back muscles in spasm. Stopping the spasm may relieve the pressure on the sciatic nerve. EMS can also help with muscle tightness and soreness from other spinal issues, including postural problems and scoliosis.
- Working weakened or atrophied muscles. Broken bones, soft tissue injuries, spinal cord injuries, neuromuscular disorders, stroke, and certain forms of illness can inhibit movement and exercise, causing muscles to become weak from disuse. E-stim can be used to keep these muscles active and prevent atrophy.
- Retraining muscles after surgery or illness. Occasionally, following orthopedic surgery or illness (such as a stroke), a patient may have difficulty contracting muscles at will. In such cases, e-stim can be used for “muscle re-education.” The electrical impulses contract the muscle involuntarily. If the patient concentrates on voluntarily contracting this muscle during the therapy, the brain may re-learn how to do so without help.
- Aiding athletic recovery. E-stim active recovery program settings use specific low-level frequencies to increase blood flow, remove lactic acid, release endorphins, and promote muscle relaxation. Athletes working out at high intensity levels–who may be prone to intense cramping or spasms–may find this program beneficial. Endurance athletes, for example, may wish to work regular e-stim sessions into their routines so they can keep their muscles loose and continue training without injury.
TENS therapy, on the other hand, is normally used to manage pain (acute or chronic), rather than working with muscle function. Many varieties of TENS devices can be purchased without a prescription for use at home. However, patients are advised to consult with a doctor first, to receive instruction and guidance regarding how to select and use the equipment.
TENS sessions can be helpful in managing pain and discomfort from the following conditions:
- Back or neck problems (including sciatica)
- Carpal tunnel syndrome
- Foot and toe issues (OA, plantar fasciitis, metatarsalgia, bunions, hammer toes, sore arches, peripheral neuropathy)
- Multiple sclerosis
Both EMS and TENS have been in wide use for decades. When administered by professionals, they are safe and painless and have very few if any side effects. Administered correctly, these techniques can make a difference in pain levels and can aid muscle recovery, relaxation, and rehabilitation.
To find out if you can benefit from this therapy, you should first have an assessment by a physician. People with open wounds or certain health conditions (such as a pacemaker) should not use use e-stim or TENS therapy without approval from a doctor.
Please contact Coastal Orthopedics in Corpus Christi with any questions about the use of E-Stim or TENS at (361) 994-1166.
Article written by: Rob Williams, MD
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