Editing Biofeedback (section)

===Electromyograph===
[[File:Muscle Whistler with EMG surface electrodes (1971).jpg|thumb|The "Muscle Whistler", shown here with surface EMG electrodes, was an early biofeedback device developed by [[Harry Garland]] and [[Roger Melen]] in 1971.<ref>{{Cite journal | journal = Popular Electronics | title = Build the Muscle Whistler | last1 = Garland | first1 = Harry | last2 = Melen | first2 = Roger | name-list-style = vanc | volume = 35 | issue = 5 | pages = 60–62 | year = 1971 }}</ref><ref name="Whistler"/>]]
An [[electromyograph]] ([[Electromyography|EMG]]) uses surface electrodes to detect muscle action potentials from underlying skeletal muscles that initiate muscle contraction. Clinicians record the surface electromyogram (SEMG) using one or more active electrodes that are placed over a target muscle and a reference electrode that is placed within six inches of either active. The SEMG is measured in [[microvolt]]s (millionths of a volt).<ref>{{cite book | vauthors = Tassinary LG, Cacioppo JT, Vanman EJ | date = 2007 | chapter = The skeletomotor system: Surface electromyography. | veditors = Cacioppo JT, Tassinary LG, Berntson GG | title = Handbook of psychophysiology | edition = 3rd | location = New York | publisher = Cambridge University Press }}</ref><ref>{{cite book | vauthors = Florimond V | date = 2009 | title = Basics of surface electromyography applied to physical rehabilitation and biomechanics | location = Montreal | publisher = Thought Technology Ltd. }}</ref>

In addition to surface electrodes, clinicians may also insert wires or needles intramuscularly to record an EMG signal. While this is more painful and often costly, the signal is more reliable since surface electrodes pick up cross talk from nearby muscles.  The use of surface electrodes is also limited to superficial muscles, making the intramuscular approach beneficial to access signals from deeper muscles. The electrical activity picked up by the electrodes is recorded and displayed in the same fashion as the surface electrodes.<ref>{{cite web|title=Electromyography (EMG)|url=http://www.hopkinsmedicine.org/healthlibrary/test_procedures/neurological/electromyography_emg_92,P07656/|work=Johns Hopkins Medicine|access-date=2014-03-18}}</ref> Prior to placing surface electrodes, the skin is normally shaved, cleaned and exfoliated to get the best signal. Raw EMG signals resemble noise (electrical signal not coming from the muscle of interest) and the voltage fluctuates; therefore, they are processed normally in three ways: rectification, filtering, and integration. This processing allows for a unified signal that is then able to be compared to other signals using the same processing techniques.

Biofeedback therapists use EMG biofeedback when treating [[anxiety]] and [[worry]], [[chronic pain]], computer-related disorder, [[essential hypertension]], headache (migraine, mixed headache, and [[tension-type headache]]), [[low back pain]], [[physical rehabilitation]] ([[cerebral palsy]], incomplete spinal cord lesions, and [[stroke]]), [[temporomandibular joint dysfunction]] (TMD), [[torticollis]], and [[fecal incontinence]], [[urinary incontinence]], and [[pelvic pain]].<ref>{{cite book | vauthors = Peper E, Gibney KH | year = 2006 | title = Muscle biofeedback at the computer: A manual to prevent repetitive strain injury (RSI) by taking the guesswork out of assessment, monitoring, and training | location = Amersfoort, The Netherlands | publisher = BFE | url = http://www.aapb.org/tl_files/AAPB/files/biof_35_2_biofeedback.pdf | archive-url = https://web.archive.org/web/20101019023511/http://aapb.org/tl_files/AAPB/files/biof_35_2_biofeedback.pdf | archive-date = 2010-10-19 }}</ref><ref name = Yucha2008>{{cite book | vauthors = Yucha C, Montgomery D | year = 2008 | title = Evidence-based practice in biofeedback and neurofeedback | location =Wheat Ridge, CO | publisher = AAPB | url = http://www.isnr.org/uploads/EvidenceBasedYuchaMontgomeryW.pdf | archive-url = https://web.archive.org/web/20101009135554/http://isnr.org/uploads/EvidenceBasedYuchaMontgomeryW.pdf | archive-date = 2010-10-09 }}</ref> Physical therapists have also used EMG biofeedback for evaluating muscle activation and providing feedback for their patients.<ref name="Whistler">{{cite journal | vauthors = Forward E | title = Patient evaluation with an audio electromyogram monitor: "The Muscle Whistler" | journal = Physical Therapy | volume = 52 | issue = 4 | pages = 402–3 | date = April 1972 | pmid = 5012359 | doi = 10.1093/ptj/52.4.402 }}</ref>