Electrical muscle stimulation — often called “e-stim” or “TENS” — is a type of treatment often used in physical therapy or other rehabilitation settings. The two primary uses for this treatment are pain relief and muscle re-education. In most settings, there is a machine that provides an electrical current. Wires from the machine are connected to adhesive patches that are placed on the skin over a predetermined area. Electrical current is then sent from the machine to the patches and delivered into the muscle tissue below, causing a sensory or motor response.
For Pain Relief
Electrical stimulation can be used for pain relief. There are two theories as to why it relieves pain. The Gate Control Theory says that pain signals are sent to the brain via nerves but must pass through a “gate.” The stimulation sensation from e-stim is said to pass through the gate, thus blocking the nerves that deliver pain sensations. Another theory is that the stimulation causes the brain to release the body’s natural painkillers — endorphins and enkephalins — resulting in pain relief. Studies have shown marked increases in these chemicals after the use of low-frequency electrical stimulation.
For Muscle Re-Education
Electrical stimulation is also used for re-training muscles that are having trouble contracting. Though used for various conditions, it is commonly used for people who have had a stroke or an orthopedic surgery. Many times these patients have trouble trying to move a muscle or joint. When the electrical impulse is sent into into the muscle tissue with e-stim, under the appropriate settings, the muscle can contract without the help of the patient. Doing this while having the subject actively try to contract the muscle can sometimes get the brain to re-learn how to contract the muscle on its own.