What is Electromyographic Biofeedback?
Surface electromyography (sEMG) uses surface electrodes to detect muscle action potentials (i.e., electrical activity) from underlying skeletal muscles that initiate muscle contraction. Clinicians record the surface EMG using one or more active electrodes that are placed over a targeted muscle and a reference electrode (sometimes called a ground electrode) that is placed within 10-20 cm of either active electrode. The sEMG is measured in microvolts (i.e., millionths of a volt).
A different form of electromyography used in medical assessment uses very fine needle electrodes inserted into the muscle through the skin to assess motor nerve conduction.
Biofeedback therapists use sEMG to measure changes in muscle contraction (i.e., muscle tension) and feedback this information to the patient so that the patient may learn increased awareness and control of muscle activity. sEMG can also be used to simultaneously examine the complex interaction of a number of muscles involved in a particular movement (i.e., myotactic unit) such as throwing a ball with the right arm. A related application of sEMG is in the treatment of chronic musculoskeletal pain resulting from poor posture or movement habits that are commonly seen in persons who spend a lot of time working at computers or doing repetitive assembly-line tasks.
sEMG biofeedback is most often used in the treatment of musculoskeletal movement (e.g., inefficient or unbalanced movement) and pain problems (e.g., low back pain, tension headache, temporomandibular joint disorder, torticollis) as well as in physical rehabilitation after injury, stroke, cerebral palsy, or incomplete spinal cord lesions. It is also applied to relaxation training and sports performance training. A very specialized form of sEMG biofeedback may be applied to the treatment of fecal or urinary incontinence and pelvic floor muscle dysfunction.