Electromyography
Encyclopedia
Electromyography is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

s when these cells are electrically or neurologically activated. The signals can be analyzed to detect medical abnormalities, activation level, recruitment order or to analyze the biomechanics
Biomechanics
Biomechanics is the application of mechanical principles to biological systems, such as humans, animals, plants, organs, and cells. Perhaps one of the best definitions was provided by Herbert Hatze in 1974: "Biomechanics is the study of the structure and function of biological systems by means of...

 of human or animal movement.

Electrical characteristics

The electrical source is the muscle membrane potential
Membrane potential
Membrane potential is the difference in electrical potential between the interior and exterior of a biological cell. All animal cells are surrounded by a plasma membrane composed of a lipid bilayer with a variety of types of proteins embedded in it...

 of about -90 mV. Measured EMG potentials range between less than 50 μV and up to 20 to 30 mV, depending on the muscle under observation.

Typical repetition rate of muscle motor unit
Motor unit
”A motor unit is a single α-motor neuron and all of the corresponding muscle fibers it innervates; all of these fibers will be of the same type . When a motor unit is activated, all of its fibers contract...

 firing is about 7–20 Hz, depending on the size of the muscle (eye muscles versus seat (gluteal) muscles), previous axonal damage and other factors. Damage to motor units can be expected at ranges between 450 and 780 mV.

History

The first documented experiments dealing with EMG started with Francesco Redi
Francesco Redi
Francesco Redi was an Italian physician, naturalist, and poet.-Biography:The son of Gregorio Redi and Cecilia de Ghinci was born in Arezzo on February 18, 1626. After schooling with the Jesuits, he attended the University of Pisa...

’s works in 1666. Redi discovered a highly specialized muscle of the electric ray fish (Electric Eel
Electric eel
The electric eel , is an electric fish, and the only species of the genus Electrophorus. It is capable of generating powerful electric shocks, of up to six hundred volts, which it uses for both hunting and self-defense. It is an apex predator in its South American range...

) generated electricity. By 1773, Walsh had been able to demonstrate that the Eel fish’s muscle tissue could generate a spark of electricity. In 1792, a publication entitled De Viribus Electricitatis in Motu Musculari Commentarius appeared, written by Luigi Galvani
Luigi Galvani
Luigi Aloisio Galvani was an Italian physician and physicist who lived and died in Bologna. In 1791, he discovered that the muscles of dead frogs legs twitched when struck by a spark...

, in which the author demonstrated that electricity could initiate muscle contractions. Six decades later, in 1849, Emil du Bois-Reymond
Emil du Bois-Reymond
Emil du Bois-Reymond was a German physician and physiologist, the discoverer of nerve action potential, and the father of experimental electrophysiology.-Life:...

 discovered that it was also possible to record electrical activity during a voluntary muscle contraction. The first actual recording of this activity was made by Marey
Étienne-Jules Marey
Étienne-Jules Marey was a French scientist and chronophotographer.His work was significant in the development of cardiology, physical instrumentation, aviation, cinematography and the science of labor photography...

 in 1890, who also introduced the term electromyography. In 1922, Gasser and Erlanger
Joseph Erlanger
Joseph Erlanger was an American physiologist.Erlanger was born on January 5, 1874, at San Francisco, California. He completed his B.S. in chemistry from the University of California, Berkeley and completed his M.D. in 1899 from the Johns Hopkins University...

 used an oscilloscope
Oscilloscope
An oscilloscope is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional graph of one or more electrical potential differences using the vertical or 'Y' axis, plotted as a function of time,...

 to show the electrical signals from muscles. Because of the stochastic nature of the myoelectric signal, only rough information could be obtained from its observation. The capability of detecting electromyographic signals improved steadily from the 1930s through the 1950s, and researchers began to use improved electrodes more widely for the study of muscles. Clinical use of surface EMG (sEMG) for the treatment of more specific disorders began in the 1960s. Hardyck and his researchers were the first (1966) practitioners to use sEMG. In the early 1980s, Cram and Steger introduced a clinical method for scanning a variety of muscles using an EMG sensing device.

It is not until the middle of the 1980s that integration techniques in electrodes had sufficiently advanced to allow batch production of the required small and lightweight instrumentation and amplifiers. At present, a number of suitable amplifiers are commercially available. In the early 1980s, cables that produced signals in the desired microvolt range became available. Recent research has resulted in a better understanding of the properties of surface EMG recording. Surface electromyography is increasingly used for recording from superficial muscles in clinical or kinesiological
Kinesiology
Kinesiology, also known as human kinetics is the scientific study of human movement. Kinesiology addresses physiological, mechanical, and psychological mechanisms. Applications of kinesiology to human health include: biomechanics and orthopedics, rehabilitation, such as physical and occupational...

 protocols, where intramuscular electrodes are used for investigating deep muscles or localized muscle activity.

There are many applications for the use of EMG. EMG is used clinically for the diagnosis of neurological and neuromuscular problems. It is used diagnostically by gait laboratories and by clinicians trained in the use of biofeedback or ergonomic assessment. EMG is also used in many types of research laboratories, including those involved in biomechanics
Biomechanics
Biomechanics is the application of mechanical principles to biological systems, such as humans, animals, plants, organs, and cells. Perhaps one of the best definitions was provided by Herbert Hatze in 1974: "Biomechanics is the study of the structure and function of biological systems by means of...

, motor control, neuromuscular physiology, movement disorders, postural control, and physical therapy
Physical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...

.

Procedure

There are two kinds of EMG in widespread use: surface EMG and intramuscular (needle and fine-wire) EMG. To perform intramuscular EMG, a needle electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

 or a needle containing two fine-wire electrodes is inserted through the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 into the muscle tissue. A trained professional (such as a neurologist
Neurologist
A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...

, physiatrist, chiropractor
Chiropractor
A Chiropractor, according to the Association of Chiropractic Colleges , "focuses on the relationship between the body's main structures – the skeleton, the muscles and the nerves – and the patient's health. Chiropractors believe that health can be improved and preserved by making adjustments to...

, or physical therapist) observes the electrical activity while inserting the electrode. The insertional activity provides valuable information about the state of the muscle and its innervating nerve. Normal muscles at rest make certain, normal electrical signals when the needle is inserted into them. Then the electrical activity when the muscle is at rest is studied. Abnormal spontaneous activity might indicate some nerve and/or muscle damage. Then the patient is asked to contract the muscle smoothly. The shape, size, and frequency of the resulting motor unit potentials are judged. Then the electrode is retracted a few millimeters, and again the activity is analyzed until at least 10–20 units have been collected. Each electrode track gives only a very local picture of the activity of the whole muscle. Because skeletal muscle
Skeletal muscle
Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...

s differ in the inner structure, the electrode has to be placed at various locations to obtain an accurate study.

Intramuscular EMG may be considered too invasive or unnecessary in some cases. Instead, a surface electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...

 may be used to monitor the general picture of muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 activation, as opposed to the activity of only a few fibres as observed using an intramuscular EMG. This technique is used in a number of settings; for example, in the physiotherapy clinic, muscle activation is monitored using surface EMG and patients have an auditory or visual stimulus to help them know when they are activating the muscle (biofeedback
Biofeedback
Biofeedback is the process of becoming aware of various physiological functions using instruments that provide information on the activity of those same systems, with a goal of being able to manipulate them at will...

).

A motor unit
Motor unit
”A motor unit is a single α-motor neuron and all of the corresponding muscle fibers it innervates; all of these fibers will be of the same type . When a motor unit is activated, all of its fibers contract...

 is defined as one motor neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

 and all of the muscle fibers it innervates. When a motor unit fires, the impulse (called an action potential
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...

) is carried down the motor neuron to the muscle. The area where the nerve contacts the muscle is called the neuromuscular junction
Neuromuscular junction
A neuromuscular junction is the synapse or junction of the axon terminal of a motor neuron with the motor end plate, the highly-excitable region of muscle fiber plasma membrane responsible for initiation of action potentials across the muscle's surface, ultimately causing the muscle to contract...

, or the motor end plate. After the action potential is transmitted across the neuromuscular junction, an action potential is elicited in all of the innervated muscle fibers of that particular motor unit. The sum of all this electrical activity is known as a motor unit action potential (MUAP). This electrophysiologic activity from multiple motor units is the signal typically evaluated during an EMG. The composition of the motor unit, the number of muscle fibres per motor unit, the metabolic type of muscle fibres and many other factors affect the shape of the motor unit potentials in the myogram.

Nerve conduction testing
Nerve conduction study
A nerve conduction study is a test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body.Nerve conduction velocity is a common measurement made during this test...

 is also often done at the same time as an EMG to diagnose neurological diseases.

Some patients can find the procedure somewhat painful, whereas others experience only a small amount of discomfort when the needle is inserted. The muscle or muscles being tested may be slightly sore for a day or two after the procedure.

Normal results

Muscle tissue at rest is normally electrically inactive. After the electrical activity caused by the irritation of needle insertion subsides, the electromyograph should detect no abnormal spontaneous activity (i.e., a muscle at rest should be electrically silent, with the exception of the area of the neuromuscular junction
Neuromuscular junction
A neuromuscular junction is the synapse or junction of the axon terminal of a motor neuron with the motor end plate, the highly-excitable region of muscle fiber plasma membrane responsible for initiation of action potentials across the muscle's surface, ultimately causing the muscle to contract...

, which is, under normal circumstances, very spontaneously active). When the muscle is voluntarily contracted, action potentials begin to appear. As the strength of the muscle contraction is increased, more and more muscle fibers produce action potentials. When the muscle is fully contracted, there should appear a disorderly group of action potentials of varying rates and amplitudes (a complete recruitment and interference pattern).

Abnormal results

EMG is used to diagnose diseases that generally may be classified into one of the following categories: neuropathies, neuromuscular junction disease
Neuromuscular junction disease
Neuromuscular junction disease is a medical condition where the normal conduction through the neuromuscular junction fails to function correctly.-Autoimmune:...

s and myopathies.

Neuropathic disease has the following defining EMG characteristics:
  • An action potential
    Action potential
    In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...

     amplitude
    Amplitude
    Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...

     that is twice normal due to the increased number of fibres per motor unit because of reinnervation
    Reinnervation
    In living tissues, reinnervation describes the process by which post-synaptic neurons form new synapses or increase existing synaptic efficacy in order to compensate for a lack of pre-synaptic input from dead or otherwise dysfunctional pre-synaptic neurons....

     of denervated fibres
  • An increase in duration
    Time
    Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....

     of the action potential
  • A decrease in the number of motor unit
    Motor unit
    ”A motor unit is a single α-motor neuron and all of the corresponding muscle fibers it innervates; all of these fibers will be of the same type . When a motor unit is activated, all of its fibers contract...

    s in the muscle (as found using motor unit number estimation
    Motor unit number estimation
    Motor Unit Number Estimation is a technique that uses electromyography to estimate the number of motor units in a muscle.- Principles :A motor unit consists of one alpha motoneuron and all the muscle fibres it innervates....

     techniques)


Myopathic disease has these defining EMG characteristics:
  • A decrease in duration of the action potential
  • A reduction in the area
    Area
    Area is a quantity that expresses the extent of a two-dimensional surface or shape in the plane. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat...

     to amplitude
    Amplitude
    Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...

     ratio of the action potential
  • A decrease in the number of motor units in the muscle (in extremely severe cases only)


Because of the individuality of each patient and disease, some of these characteristics may not appear in every case.

Abnormal results may be caused by the following medical conditions (please note this is nowhere near an exhaustive list of conditions that can result in abnormal EMG studies):
  • Alcoholic neuropathy
  • Amyotrophic lateral sclerosis
    Amyotrophic lateral sclerosis
    Amyotrophic lateral sclerosis , also referred to as Lou Gehrig's disease, is a form of motor neuron disease caused by the degeneration of upper and lower neurons, located in the ventral horn of the spinal cord and the cortical neurons that provide their efferent input...

  • Anterior compartment syndrome of the lower leg
    Anterior compartment syndrome of the lower leg
    A compartment syndrome is an increased pressure within a muscular compartment that compromises the circulation of the muscles.-Pathology:A compartment space is anatomically determined by an unyielding fascial enclosure of the muscles...

  • Axillary nerve dysfunction
    Axillary nerve dysfunction
    Axillary nerve dysfunction is a general term that refers to any type of dysfunction of the axillary nerve. The axillary nerve is a branch of the brachial plexus that innervates the deltoid and teres minor muscles...

  • Becker's muscular dystrophy
    Becker's muscular dystrophy
    Becker muscular dystrophy is an X-linked recessive inherited disorder characterized by slowly progressive muscle weakness of the legs and pelvis....

  • Brachial plexopathy
  • Carpal tunnel syndrome
    Carpal tunnel syndrome
    Carpal Tunnel Syndrome is an entrapment idiopathic median neuropathy, causing paresthesia, pain, and other symptoms in the distribution of the median nerve due to its compression at the wrist in the carpal tunnel. The pathophysiology is not completely understood but can be considered compression...

  • Centronuclear myopathy
  • Cervical spondylosis
  • Charcot-Marie-Tooth disease
    Charcot-Marie-Tooth disease
    Charcot–Marie–Tooth disease- , known also as Morbus Charcot-Marie-Tooth, Charcot-Marie-Tooth neuropathy, hereditary motor and sensory neuropathy , hereditary sensorimotor neuropathy , or peroneal muscular atrophy, is an inherited disorder of nerves that takes different forms...

  • Chronic Immune Demyelinating Poly[radiculo]neuropathy (CIDP)
  • Common peroneal nerve dysfunction
  • Denervation (reduced nervous stimulation)
  • Dermatomyositis
    Dermatomyositis
    Dermatomyositis is a connective-tissue disease related to polymyositis and Bramaticosis that is characterized by inflammation of the muscles and the skin.- Causes :...

  • Distal median nerve
    Median nerve
    The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus....

     dysfunction

  • Duchenne muscular dystrophy
    Duchenne muscular dystrophy
    Duchenne muscular dystrophy is a recessive X-linked form of muscular dystrophy, which results in muscle degeneration, difficulty walking, breathing, and death. The incidence is 1 in 3,000 boys. Females and males are affected, though females are rarely affected and are more often carriers...

  • Facioscapulohumeral muscular dystrophy
    Facioscapulohumeral muscular dystrophy
    Facioscapulohumeral muscular dystrophy , which is also known as Landouzy-Dejerine, is a usually autosomal dominant inherited form of muscular dystrophy that initially affects the skeletal muscles of the face , scapula and upper arms...

     (Landouzy-Dejerine)
  • Familial periodic paralysis
  • Femoral nerve
    Femoral nerve
    The femoral nerve, the largest branch of the lumbar plexus, arises from the dorsal divisions of the ventral rami of the second, third, and fourth lumbar nerves...

     dysfunction
  • Fields condition http://news.bbc.co.uk/2/hi/uk_news/wales/south_west/4335454.stm
  • Friedreich's ataxia
    Friedreich's ataxia
    Friedreich's ataxia is an inherited disease that causes progressive damage to the nervous system, resulting in symptoms ranging from gait disturbance to speech problems; it can also lead to heart disease and diabetes....

  • Guillain-Barre
  • Lambert-Eaton Syndrome
  • Mononeuritis multiplex
  • Mononeuropathy
  • Motor neurone disease
    Motor neurone disease
    The motor neurone diseases are a group of neurological disorders that selectively affect motor neurones, the cells that control voluntary muscle activity including speaking, walking, breathing, swallowing and general movement of the body. They are generally progressive in nature, and can cause...

  • Multiple system atrophy
    Multiple system atrophy
    Multiple system atrophy is a degenerative neurological disorder. MSA is associated with the degeneration of nerve cells in specific areas of the brain. This cell degeneration causes problems with movement, balance and other autonomic functions of the body such as bladder control or blood pressure...

  • Myasthenia gravis
    Myasthenia gravis
    Myasthenia gravis is an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability...

  • Myopathy
    Myopathy
    In medicine, a myopathy is a muscular disease in which the muscle fibers do not function for any one of many reasons, resulting in muscular weakness. "Myopathy" simply means muscle disease...

     (muscle degeneration, which may be caused by a number of disorders, including muscular dystrophy)

  • Myotubular myopathy
  • Neuromyotonia
    Neuromyotonia
    Neuromyotonia , also known as Isaacs' syndrome, is a form of peripheral nerve hyperexcitability that causes spontaneous muscular activity resulting from repetitive motor unit action potentials of peripheral origin.-Causes:...

  • Peripheral neuropathy
    Peripheral neuropathy
    Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of or trauma to the nerve or the side-effects of systemic illness....

  • Poliomyelitis
    Poliomyelitis
    Poliomyelitis, often called polio or infantile paralysis, is an acute viral infectious disease spread from person to person, primarily via the fecal-oral route...

  • Polymyositis
    Polymyositis
    Polymyositis is a type of chronic inflammation of the muscles related to dermatomyositis and inclusion body myositis.-Signs and symptoms:...

  • Radial nerve
    Radial nerve
    The radial nerve is a nerve in the human body that supplies the upper limb. It supplies the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.It...

     dysfunction
  • Sciatic nerve
    Sciatic nerve
    The sciatic nerve is a large nerve fiber in humans and other animals. It begins in the lower back and runs through the buttock and down the lower limb...

     dysfunction
  • Sensorimotor polyneuropathy
  • Sleep bruxism
  • Spinal stenosis
    Spinal stenosis
    Lumbar spinal stenosis is a medical condition in which the spinal canal narrows and compresses the spinal cord and nerves at the level of the lumbar vertebra. This is usually due to the common occurrence of spinal degeneration that occurs with aging. It can also sometimes be caused by spinal disc...

  • Thyrotoxic periodic paralysis
    Thyrotoxic periodic paralysis
    Thyrotoxic periodic paralysis is a condition featuring attacks of muscle weakness in the presence of hyperthyroidism . Hypokalemia is usually present during attacks...

  • Tibial nerve
    Tibial nerve
    The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus.In the popliteal fossa the nerve gives off branches to gastrocnemius, popliteus, soleus and plantaris muscles, an articular branch to the knee joint, and a...

     dysfunction
  • Ulnar nerve
    Ulnar nerve
    In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body , so injury is common...

     dysfunction


EMG signal decomposition

EMG signals are essentially made up of superimposed motor unit action potentials (MUAPs) from several motor units. For a thorough analysis, the measured EMG signals can be decomposed into their constituent MUAPs. MUAPs from different motor units tend to have different characteristic shapes, while MUAPs recorded by the same electrode from the same motor unit are typically similar. Notably MUAP size and shape depend on where the electrode is located with respect to the fibers and so can appear to be different if the electrode moves position. EMG decomposition is non-trivial, although many methods have been proposed.

Applications of EMG

EMG signals are used in many clinical and biomedical applications. EMG is used as a diagnostics tool for identifying neuromuscular diseases, assessing low-back pain, kinesiology
Kinesiology
Kinesiology, also known as human kinetics is the scientific study of human movement. Kinesiology addresses physiological, mechanical, and psychological mechanisms. Applications of kinesiology to human health include: biomechanics and orthopedics, rehabilitation, such as physical and occupational...

, and disorders of motor control. EMG signals are also used as a control signal for prosthetic devices such as prosthetic hands, arms, and lower limbs.

EMG can be used to sense isometric
Isometric
The term isometric comes from the Greek for "having equal measurement".isometric may mean:* Isometric projection , a method for the visual representation of three-dimensional objects in two dimensions; a form of orthographic projection, or more specifically, an axonometric projection.* Isometry and...

 muscular activity where no movement is produced. This enables definition of a class of subtle motionless gestures to control interfaces without being noticed and without disrupting the surrounding environment. These signals can be used to control a prosthesis or as a control signal for an electronic device such as a mobile phone or PDA.

EMG signals have been targeted as control for flight systems. The Human Senses Group at the NASA Ames Research Center
NASA Ames Research Center
The Ames Research Center , is one of the United States of America's National Aeronautics and Space Administration 10 major field centers.The centre is located in Moffett Field in California's Silicon Valley, near the high-tech companies, entrepreneurial ventures, universities, and other...

 at Moffett Field, CA seeks to advance man-machine interfaces by directly connecting a person to a computer. In this project, an EMG signal is used to substitute for mechanical joysticks and keyboards. EMG has also been used in research towards a "wearable cockpit," which employs EMG-based gestures to manipulate switches and control sticks necessary for flight in conjunction with a goggle-based display.

Unvoiced speech recognition recognizes speech by observing the EMG activity of muscles associated with speech. It is targeted for use in noisy environments, and may be helpful for people without vocal cords and people with aphasia
Aphasia
Aphasia is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write....

.

EMG has also been used as a control signal for computers and other devices. An interface device based on EMG could be used to control moving objects, such as mobile robots or an electric wheelchair. This may be helpful for individuals that cannot operate a joystick-controlled wheelchair. Surface EMG recordings may also be a suitable control signal for some interactive video games.

A joint project involving Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

, the University of Washington
University of Washington
University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...

 in Seattle, and the University of Toronto
University of Toronto
The University of Toronto is a public research university in Toronto, Ontario, Canada, situated on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution of higher learning in Upper Canada...

 in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 has explored using muscle signals from hand gestures as an interface device. A patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 based on this research was submitted on June 26, 2008.

See also

  • Compound muscle action potential
    Compound muscle action potential
    The compound muscle action potential or compound motor action potential is a electromyography investigation ....

  • Phonomyography
    Phonomyography
    Phonomyography is a technique to measure the force of muscle contraction by recording the low frequency sounds created during muscular activity.Although less precise than the more traditional mechanomyography, it is considerably easier to set up...

  • Magnetomyography
    Magnetomyography
    Magnetomyography is a technique for mapping muscle activity by recording magnetic fields produced by electrical currents occurring naturally in the muscles, using arrays of SQUIDs . It has a better capability than electromyography for detecting slow or direct currents.-External links:***...

  • Electrical muscle stimulation
    Electrical muscle stimulation
    Electrical muscle stimulation , also known as neuromuscular electrical stimulation or electromyostimulation, is the elicitation of muscle contraction using electric impulses...


External links

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