Electromyography - wikipedia Electromyography Jump to : navigation , search Not to be confused with other types of electrography . Electromyography EMG from gait termination , bottom left is the raw EMG , right is the rectified pattern ICD - 9 - CM 93.08 MeSH D004576 ( edit on Wikidata ) Electromyography ( EMG ) is an electrodiagnostic medicine 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 electric potential generated by muscle cells when these cells are electrically or neurologically activated . The signals can be analyzed to detect medical abnormalities , activation level , or recruitment order , or to analyze the biomechanics of human or animal movement . Contents ( hide ) 1 Medical uses 2 Technique 2.1 Skin preparation and risks 2.2 Surface and intramuscular EMG recording electrodes 2.3 Maximal voluntary contraction 2.4 Other measurements 2.5 EMG signal decomposition 2.6 EMG signal processing 2.7 Limitations 2.8 Electrical characteristics 3 Procedure outcomes 3.1 Normal results 3.2 Abnormal results 4 History 5 Research 6 See also 7 References 8 Further reading 9 External links Medical uses ( edit ) EMG testing has a variety of clinical and biomedical applications . EMG is used as a diagnostics tool for identifying neuromuscular diseases , or as a research tool for studying kinesiology , and disorders of motor control . EMG signals are sometimes used to guide botulinum toxin or phenol injections into muscles . EMG signals are also used as a control signal for prosthetic devices such as prosthetic hands , arms , and lower limbs . EMG then an acceleromyograph may be used for neuromuscular monitoring in general anesthesia with neuromuscular - blocking drugs , in order to avoid postoperative residual curarization ( PORC ) . Except in the case of some purely primary myopathic conditions EMG is usually performed with another electrodiagnostic medicine test that measures the conducting function of nerves . This is called a nerve conduction studies ( NCS ) . Needle EMG and NCSs are typically indicated when there is pain in the limbs , weakness from spinal nerve compression , or concern about some other neurologic injury or disorder . Spinal nerve injury does not cause neck , mid back pain or low back pain , and for this reason , evidence has not shown EMG or NCS to be helpful in diagnosing causes of axial lumbar pain , thoracic pain , or cervical spine pain . Needle EMG may aid with the diagnosis of nerve compression or injury ( such as carpal tunnel syndrome ) , nerve root injury ( such as sciatica ) , and with other problems of the muscles or nerves . Less common medical conditions include amyotrophic lateral sclerosis , myasthenia gravis , and muscular dystrophy . Technique ( edit ) Skin preparation and risks ( edit ) The first step before insertion of the needle electrode is skin preparation . This typically involves simply cleaning the skin with an alcohol pad . The actual placement of the needle electrode can be difficult and depends on a number of factors , such as specific muscle selection and the size of that muscle . Proper needle EMG placement is very important for accurate representation of the muscle of interest , although EMG is more effective on superficial muscles as it is unable to bypass the action potentials of superficial muscles and detect deeper muscles . Also , the more body fat an individual has , the weaker the EMG signal . When placing the EMG sensor , the ideal location is at the belly of the muscle : the longitudinal midline . The belly of the muscle can also be thought of as in - between the motor point ( middle ) of the muscle and the tendonus insertion point . Cardiac pacemakers and implanted cardiac defibrillators ( ICDs ) are used increasingly in clinical practice , and no evidence exists indicating that performing routine electrodiagnostic studies on patients with these devices pose a safety hazard . However , there are theoretical concerns that electrical impulses of nerve conduction studies ( NCS ) could be erroneously sensed by devices and result in unintended inhibition or triggering of output or reprogramming of the device . In general , the closer the stimulation site is to the pacemaker and pacing leads , the greater the chance for inducing a voltage of sufficient amplitude to inhibit the pacemaker . Despite such concerns , no immediate or delayed adverse effects have been reported with routine NCS . No known contraindications exist for performing needle EMG or NCS on pregnant patients . Additionally , no complications from these procedures have been reported in the literature . Evoked potential testing , likewise , has not been reported to cause any problems when it is performed during pregnancy . Patients with lymphedema or patients at risk for lymphedema are routinely cautioned to avoid percutaneous procedures in the affected extremity , namely venipuncture , to prevent development or worsening of lymphedema or cellulitis . Despite the potential risk , the evidence for such complications subsequent to venipuncture is limited . No published reports exist of cellulitis , infection , or other complications related to EMG performed in the setting of lymphedema or prior lymph node dissection . However , given the unknown risk of cellulitis in patients with lymphedema , reasonable caution should be exercised in performing needle examinations in lymphedematous regions to avoid complications . In patients with gross edema and taut skin , skin puncture by needle electrodes may result in chronic weeping of serous fluid . The potential bacterial media of such serous fluid and the violation of skin integrity may increase the risk of cellulitis . Before proceeding , the physician should weigh the potential risks of performing the study with the need to obtain the information gained . Surface and intramuscular EMG recording electrodes ( edit ) There are two kinds of EMG : surface EMG and intramuscular EMG . Surface EMG assesses muscle function by recording muscle activity from the surface above the muscle on the skin . Surface electrodes are able to provide only a limited assessment of the muscle activity . Surface EMG can be recorded by a pair of electrodes or by a more complex array of multiple electrodes . More than one electrode is needed because EMG recordings display the potential difference ( voltage difference ) between two separate electrodes . Limitations of this approach are the fact that surface electrode recordings are restricted to superficial muscles , are influenced by the depth of the subcutaneous tissue at the site of the recording which can be highly variable depending of the weight of a patient , and can not reliably discriminate between the discharges of adjacent muscles . Intramuscular EMG can be performed using a variety of different types of recording electrodes . The simplest approach is a monopolar needle electrode . This can be a fine wire inserted into a muscle with a surface electrode as a reference ; or two fine wires inserted into muscle referenced to each other . Most commonly fine wire recordings are for research or kinesiology studies . Diagnostic monopolar EMG electrodes are typically insulated and stiff enough to penetrate skin , with only the tip exposed using a surface electrode for reference . Needles for injecting therapeutic botulinum toxin or phenol are typically monopolar electrodes that use a surface reference , in this case , however , the metal shaft of a hypodermic needle , insulated so that only the tip is exposed , is used both to record signals and to inject . Slightly more complex in design is the concentric needle electrode . These needles have a fine wire , embedded in a layer of insulation that fills the barrel of a hypodermic needle , that has an exposed shaft , and the shaft serves as the reference electrode . The exposed tip of the fine wire serves as the active electrode . As a result of this configuration , signals tend to be smaller when recorded from a concentric electrode than when recorded from a monopolar electrode and they are more resistant to electrical artifacts from tissue and measurements tend to be somewhat more reliable . However , because the shaft is exposed throughout its length , superficial muscle activity can contaminate the recording of deeper muscles . Single fiber EMG needle electrodes are designed to have very tiny recording areas , and allow for the discharges of individual muscle fibers to be discriminated . To perform intramuscular EMG , typically either a monopolar or concentric needle electrode is inserted through the skin into the muscle tissue . The needle is then moved to multiple spots within a relaxed muscle to evaluate both insertional activity and resting activity in the muscle . Normal muscles exhibit a brief burst of muscle fiber activation when stimulated by needle movement , but this rarely lasts more than 100ms . The two most common pathologic types of resting activity in muscle are fasciculation and fibrillation potentials . A fasciculation potential is an involuntary activation of a motor unit within the muscle , sometimes visible with the naked eye as a muscle twitch or by surface electrodes . Fibrillations , however , are only detected by needle EMG , and represent the isolated activation of individual muscle fibers , usually as the result of nerve or muscle disease . Often , fibrillations are triggered by needle movement ( insertional activity ) and persist for several seconds or more after the movement ceases . After assessing resting and insertional activity , the electromyographer assess the activity of muscle during voluntary contraction . The shape , size , and frequency of the resulting electrical signals are judged . Then the electrode is retracted a few millimetres , and again the activity is analyzed . This is repeated , sometimes until data on 10 -- 20 motor units have been collected in order to draw conclusions about motor unit function . Each electrode track gives only a very local picture of the activity of the whole muscle . Because skeletal muscles differ in the inner structure , the electrode has to be placed at various locations to obtain an accurate study . Single fiber electromyography assesses the delay between the contractions of individual muscle fibers within a motor unit and is a sensitive test for dysfunction of the neuromuscular junction caused by drugs , poisons , or diseases such as myasthenia gravis . The technique is complicated and typically only performed by individuals with special advanced training . Surface EMG 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 ) . A review of the literature on surface EMG published in 2008 , concluded that surface EMG may be useful to detect the presence of neuromuscular disease ( level C rating , class III data ) , but there are insufficient data to support its utility for distinguishing between neuropathic and myopathic conditions or for the diagnosis of specific neuromuscular diseases . EMGs may be useful for additional study of fatigue associated with post-poliomyelitis syndrome and electromechanical function in myotonic dystrophy ( level C rating , class III data ) . Certain US states limit the performance of needle EMG by nonphysicians . New Jersey declared that it can not be delegated to a physician 's assistant . Michigan has passed legislation saying needle EMG is the practice of medicine . Special training in diagnosing medical diseases with EMG is required only in residency and fellowship programs in neurology , clinical neurophysiology , neuromuscular medicine , and physical medicine and rehabilitation . There are certain subspecialists in otolaryngology who have had selective training in performing EMG of the laryngeal muscles , and subspecialists in urology , obstetrics and gynecology who have had selective training in performing EMG of muscles controlling bowel and bladder function . Maximal voluntary contraction ( edit ) One basic function of EMG is to see how well a muscle can be activated . The most common way that can be determined is by performing a maximal voluntary contraction ( MVC ) of the muscle that is being tested . Muscle force , which is measured mechanically , typically correlates highly with measures of EMG activation of muscle . Most commonly this is assessed with surface electrodes , but it should be recognized that these typically only record from muscle fibers in close approximation to the surface . Several analytical methods for determining muscle activation are commonly used depending on the application . The use of mean EMG activation or the peak contraction value is a debated topic . Most studies commonly use the maximal voluntary contraction as a means of analyzing peak force and force generated by target muscles . According to the article , Peak and average rectified EMG measures : Which method of data reduction should be used for assessing core training exercises ? , concluded that the `` average rectified EMG data ( ARV ) is significantly less variable when measuring the muscle activity of the core musculature compared to the peak EMG variable . '' Therefore , these researchers would suggest that `` ARV EMG data should be recorded alongside the peak EMG measure when assessing core exercises . '' Providing the reader with both sets of data would result in enhanced validity of the study and potentially eradicate the contradictions within the research . Other measurements ( edit ) EMG can also be used for indicating the amount of fatigue in a muscle . The following changes in the EMG signal can signify muscle fatigue : an increase in the mean absolute value of the signal , increase in the amplitude and duration of the muscle action potential and an overall shift to lower frequencies . Monitoring the changes of different frequency changes the most common way of using EMG to determine levels of fatigue . The lower conduction velocities enable the slower motor neurons to remain active . A motor unit is defined as one motor neuron and all of the muscle fibers it innervates . When a motor unit fires , the impulse ( called an action potential ) is carried down the motor neuron to the muscle . The area where the nerve contacts the muscle is called the neuromuscular junction , 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 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 . EMG signal decomposition ( edit ) 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 . EMG signal processing ( edit ) Rectification is the translation of the raw EMG signal to a signal with a single polarity , usually positive . The purpose of rectifying the signal is to ensure the signal does not average to zero , due to the raw EMG signal having positive and negative components . Two types of rectification are used : full - wave and half - wave rectification . Full - wave rectification adds the EMG signal below the baseline to the signal above the baseline to make a conditioned signal that is all positive . If the baseline is zero , this is equivalent to taking the absolute value of the signal . This is the preferred method of rectification because it conserves all of the signal energy for analysis . Half - wave rectification discards the portion of the EMG signal that is below the baseline . In doing so , the average of the data is no longer zero therefore it can be used in statistical analyses . Limitations ( edit ) Needle EMG used in clinical settings has practical applications such as helping to discover disease . Needle EMG has limitations , however , in that it does involve voluntary activation of muscle , and as such is less informative in patients unwilling or unable to cooperate , children and infants , and in individuals with paralysis. , Surface EMG can have limited applications due to inherent problems associated with surface EMG . Adipose tissue ( fat ) can affect EMG recordings . Studies show that as adipose tissue increased the active muscle directly below the surface decreased . As adipose tissue increased , the amplitude of the surface EMG signal directly above the center of the active muscle decreased . EMG signal recordings are typically more accurate with individuals who have lower body fat , and more compliant skin , such as young people when compared to old . Muscle cross talk occurs when the EMG signal from one muscle interferes with that of another limiting reliability of the signal of the muscle being tested . Surface EMG is limited due to lack of deep muscles reliability . Deep muscles require intramuscular wires that are intrusive and painful in order to achieve an EMG signal . Surface EMG can only measure superficial muscles and even then it is hard to narrow down the signal to a single muscle . Electrical characteristics ( edit ) The electrical source is the muscle membrane potential 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 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 . Procedure outcomes ( edit ) Normal results ( edit ) 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 , 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 ( edit ) EMG findings vary with the type of disorder , the duration of the problem , the age of the patient , the degree to which the patient can be cooperative , the type of needle electrode used to study the patient , and sampling error in terms of the number of areas studied within a single muscle and the number of muscles studied overall . Interpreting EMG findings is usually best done by an individual informed by a focused history and physical examination of the patient , and in conjunction with the results of other relevant diagnostic studies performed including most importantly , nerve conduction studies , but also , where appropriate , imaging studies such as MRI and ultrasound , muscle and nerve biopsy , muscle enzymes , and serologic studies . Abnormal results may be caused by the following medical conditions ( please note this is not an exhaustive list of conditions that can result in abnormal EMG studies ) : Disorders of Muscle : Inflammatory myopathies Polymyositis Dermatomyositis Inclusion body myopathy Myotonia Congenita Muscular dystrophies : Duchenne Muscular Dystrophy Becker muscular dystrophy Facioscapulohumeral dystrophy Limb girdle muscular dystrophy Centronuclear myopathy Myotonic dystrophy Mitochondrial myopathies Disorders of the neuromuscular junction : Myasthenia Gravis Lambert -- Eaton myasthenic syndrome Botulism poisoning Organophosphate poisoning Hypermagnesemia Hypocalcemia Disorders of Nerves : Carpal tunnel syndrome Ulnar neuropathy at the elbow Radial nerve palsy ( Saturday night palsy ) Peroneal ( fibular ) nerve palsy Diabetic neuropathy Alcohol related neuropathy Nutritional neuropathy Amyloid neuropathy AIDP CIDP Bell 's palsy Laryngeal neuropathy Pudendal neuropathy Femoral neuropathy Sciatic Neuropathy Tibial neuropathy Tarsal tunnel syndrome Charcot - Marie - Tooth syndrome Zoster neuropathy Oculomotor , Facial , vagal , trigeminal , glossopharyngeal , spinal accessory neuropathies Hemifacial spasm Multifocal motor neuropathy Axillary neuropathy Long thoracic neuropathy Suprascapular neuropathy Toxic neuropathies Drug - induced neuropathies Plexus disorders : Neuralgic Amyotrophy ( idiopathic brachial plexitis ) Traumatic brachial plexopathy Lumbosacral radiculopathy Hirayama disease Root disorders : Cervical , thoracic , lumbar , sacral radiculopathy Spinal stenosis Arachnoiditis Leptomeningeal disorders Motor neuron disease Amyotrophic lateral sclerosis West Nile virus Poliomyelitis Kennedy 's syndrome ( Spinobulbar muscular atrophy ) . History ( edit ) The first documented experiments dealing with EMG started with Francesco Redi 's works in 1666 . Redi discovered a highly specialized muscle of the electric ray fish ( Electric Eel ) 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 , in which the author demonstrated that electricity could initiate muscle contraction . Six decades later , in 1849 , Emil du Bois - Reymond 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 in 1890 , who also introduced the term electromyography . In 1922 , Gasser and Erlanger used an oscilloscope 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 . The AANEM was formed in 1953 as one of several currently active medical societies with a special interest in advancing the science and clinical use of the technique . 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 was 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 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 , motor control , neuromuscular physiology , movement disorders , postural control , and physical therapy . Research ( edit ) EMG can be used to sense isometric 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 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 . 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 can not operate a joystick - controlled wheelchair . Surface EMG recordings may also be a suitable control signal for some interactive video games . In 1999 an EMG program called Echidna was used to enable a man with locked in syndrome to send a message to a computer . That program , now called NeuroSwitch , developed by Control Bionics enables people with severe disabilities to communicate by text , email , SMS , computer - generated voice and to control computer games and programs , and - through the internet - Anybots telepresence robots . A joint project involving Microsoft , the University of Washington in Seattle , and the University of Toronto in Canada has explored using muscle signals from hand gestures as an interface device . A patent based on this research was submitted on June 26 , 2008 . See also ( edit ) Chronaxie Compound muscle action potential Electrical muscle stimulation Electrodiagnostic medicine Electromyoneurography Magnetomyography Nerve conduction study Neuromuscular ultrasound Phonomyography References ( edit ) Jump up ^ Kamen , Gary . Electromyographic Kinesiology . In Robertson , DGE et al. Research Methods in Biomechanics . Champaign , IL : Human Kinetics Publ. , 2004 . Jump up ^ Electromyography at the US National Library of Medicine Medical Subject Headings ( MeSH ) Jump up ^ Harvey AM , Masland RL : Actions of durarizing preparations in the human . Journal of Pharmacology And Experimental Therapeutics , Vol. 73 , Issue 3 , 304 - 311 , 1941 Jump up ^ Botelho SY : Comparison of simultaneously recorded electrical and mechanical activity in myasthenia gravis patients and in partially curarized normal humans . Am J Med. 1955 Nov ; 19 ( 5 ) : 693 - 6 . PMID 13268466 Jump up ^ Christie TH , Churchill - Davidson HC : The St. Thomas 's Hospital nerve stimulator in the diagnosis of prolonged apnoea . Lancet . 1958 Apr 12 ; 1 ( 7024 ) : 776 . PMID 13526270 Jump up ^ Engbaek J , Ostergaard D , Viby - Mogensen J : Double burst stimulation ( DBS ) : a new pattern of nerve stimulation to identify residual neuromuscular block . Br J Anaesth. 1989 Mar ; 62 ( 3 ) : 274 - 8 . PMID 2522790 ^ Jump up to : North American Spine Society ( February 2013 ) , `` Five Things Physicians and Patients Should Question '' , Choosing Wisely : an initiative of the ABIM Foundation , North American Spine Society , retrieved 25 March 2013 , which cites Sandoval , AE ( Nov 2010 ) . `` Electrodiagnostics for low back pain '' . Physical Medicine and Rehabilitation Clincs of North America . 21 ( 4 ) : 767 -- 76 . doi : 10.1016 / j. pmr. 2010.06. 007 . PMID 20977959 . North American Spine Society ( 2011 ) . `` Diagnosis and treatment of degenerative lumbar spinal stenosis '' . Burr Ridge , Illinois : Agency for Healthcare Research and Quality : 104 . Jump up ^ https://www.delsys.com/Attachments_pdf/TN101%20-%20EMG%20Sensor%20Placement-web.pdf ^ Jump up to : http://www.aanem.org/getmedia/2034191e-583b-4c55-b725-fc38ea8262e2/risksinEDX.pdf.aspx . Jump up ^ Arthur C. Rothman , MD , v. Selective Insurance Company of America , Supreme Court of New Jersey , Jan. 19 Jump up ^ Texas Court of Appeals , Third District , at Austin , Cause No. 03 - 10 - 673 - CV. April 5 , 2012 Jump up ^ Section 333.17018 Michigan Compiled Laws http://legislature.mi.gov/doc.aspx?mcl-333-17018 Jump up ^ Behm , D.G. , Whittle , J. , Button , D. , & Power , K. ( 2002 ) . Intermuscle differences in activation . Muscle and Nerve . 25 ( 2 ) ; 236 - 243 . Jump up ^ Hibbs , A.E. , Thompson , K.G. , French , D.N. , Hodgson , D. , Spears , I.R. Peak and average rectified EMG measures : Which method of data reduction should be used for assessing core training exercises ? Journal of Electromyography and Kinesiology. 21 ( 1 ) , 102 -- 111 . 2011 . Jump up ^ Buchanan , T.S. , Lloyd , D.G. , Manal , K. , & Besier , T.F. ( 2004 ) . Neuromusculoskeletal modeling : estimation of muscle forces and joint moments and movements from measurements of neural command . Journal of applied biomechanics , 20 ( 4 ) , 367 . Jump up ^ Halperin , I. , Aboodarda , S.J. , Button , D.C. , Andersen , L.L. , & Behm , D.G. ( 2014 ) . ROLLER MASSAGER IMPROVES RANGE OF MOTION OF PLANTAR FLEXOR MUSCLES WITHOUT SUBSEQUENT DECREASES IN FORCE PARAMETERS . International journal of sports physical therapy , 9 ( 1 ) , 92 . Jump up ^ Cifrek , M. , Medved , V. , Tonković , S. , & Ostojić , S. ( 2009 ) . Surface EMG based muscle fatigue evaluation in biomechanics . Clinical Biomechanics , 24 ( 4 ) , 327 - 340 . Jump up ^ Raez , M.B.I. ; Hussain , M.S. ; Mohd - Yasin , F. ( Mar 23 , 2006 ) . `` Techniques of EMG signal analysis : detection , processing , classification and applications '' . Biol. Proced . Online ( 8 ) : 11 -- 35 . doi : 10.1251 / bpo115 . PMC 1455479 . PMID 16799694 . Jump up ^ Weir , JP ; Wagner , LL ; Housh , TJ ( 1992 ) . `` Linearity and reliability of the IEMG v. torque relationship for the forearm flexors and leg extensors '' . American Journal of Physical Medicine & Rehabilitation . 71 ( 5 ) : 283 -- 287 . Jump up ^ Vrendenbregt , J ; Rau , G ; Housh ( 1973 ) . `` Surface eletromyography in relation to force , muscle length and endurance '' . New developments in electromyography and clinical neurophysiology : 607 -- 622 . Jump up ^ Kuiken , TA ; Lowery , Stoykob ( April 2003 ) . `` The Effect of Subcutaneous Fat on myoelectric signal amplitude and cross talk '' . Prosthetics and Orthodontics International . 27 ( 1 ) : 48 -- 54 . Jump up ^ Nigg B.M. , & Herzog W. , 1999 . Biomechanics of the Musculo - Skeletal system . Wiley . Page : 349 . Jump up ^ Patterson , John R. `` Fitwise '' . Castillo . Brian T. Retrieved 24 June 2009 . Jump up ^ Cram , JR. ; Steger , JC . ( Jun 1983 ) . `` EMG scanning in the diagnosis of chronic pain '' . Biofeedback Self Regul. 8 ( 2 ) : 229 -- 41 . PMID 6227339 . Jump up ^ Andreasen , DS. ; Gabbert DG , : EMG Switch Navigation of Power Wheelchairs , RESNA 2006 . ( 1 ) Jump up ^ Park , DG. ; Kim , HC . Muscleman : Wireless input device for a fighting action game based on the EMG signal and acceleration of the human forearm. ( 2 ) Jump up ^ Hsu , Jeremy ( 2009 - 10 - 29 ) . `` The Future of Video Game Input : Muscle Sensors '' . Live Science . Retrieved 2010 - 01 - 16 . Jump up ^ `` Recognizing Gestures from Forearm EMG Signals '' . United States Patent and Trademark Office . 2008 - 06 - 26 . Archived from the original on 2017 - 01 - 12 . Retrieved 2010 - 01 - 16 . Further reading ( edit ) Piper , H. : Elektrophysiologie menschlicher Muskeln . Berlin , J. Springer , 1912 . External links ( edit ) Association of Electromyography Technologists of Canada ( AETC ) MedlinePlus entry on EMG describes EMG Neuromuscular.edu American Association of Neuromuscular & Electrodiagnostic Medicine EmedicineHealth page on EMG Risks in Electrodiagnostic Medicine Interactively design an EMG signal processing RMS envelope measurement application with the ASN Filter Designer ( ASN - AN024 ) ( hide ) Neurosurgical and other procedures ( ICD - 9 - CM V3 01 -- 05 + 89.1 , ICD - 10 - PCS 00 -- 01 ) Skull Craniotomy Decompressive craniectomy Cranioplasty CNS Brain thalamus and globus pallidus : Thalamotomy Thalamic stimulator Pallidotomy ventricular system : Ventriculostomy Suboccipital puncture Intracranial pressure monitoring cerebrum : Psychosurgery Lobotomy Bilateral cingulotomy Hemispherectomy Anterior temporal lobectomy pituitary gland : Hypophysectomy hippocampus : Amygdalohippocampectomy Brain biopsy Cerebral meninges Meningeal biopsy Spinal cord and spinal canal Spinal cord and roots Cordotomy Rhizotomy Vertebrae and intervertebral discs : see Template : Bone , cartilage , and joint procedures Medical imaging Computed tomography of the head Cerebral angiography Pneumoencephalography Echoencephalography / Transcranial Doppler Magnetic resonance imaging of the brain Brain PET Myelography Diagnostic Electroencephalography Lumbar puncture Polysomnography CPRs Glasgow Coma Scale Mini -- mental state examination National Institutes of Health Stroke Scale CHADS2 score PNS Cranial and peripheral nerves Nerve block Vagotomy Sympathetic nerves or ganglia Ganglionectomy Sympathectomy Endoscopic thoracic sympathectomy Nerves ( general ) Axotomy Neurectomy Nerve biopsy Diagnostic Nerve conduction study Electromyography Medical imaging Magnetic resonance neurography Retrieved from `` https://en.wikipedia.org/w/index.php?title=Electromyography&oldid=837966430 '' Categories : Electrodiagnosis Electrophysiology Neurology procedures Neurophysiology Neurotechnology Hidden categories : All articles with unsourced statements Articles with unsourced statements from February 2015 Talk Contents About Wikipedia Afrikaans Azərbaycanca Català Čeština Dansk Deutsch Español Euskara فارسی Français Gaeilge ગુજરાતી 한국어 Bahasa Indonesia Italiano Қазақша Кыргызча Nederlands 日本 語 Norsk Polski Português Română Русский Shqip Српски / srpski Suomi Svenska Türkçe Українська 22 more Edit links This page was last edited on 24 April 2018 , at 02 : 55 . 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Question: what features of muscle contraction can be determined from an emg (electromyogram)


Daylight saving time in the United states - Wikipedia Daylight saving time in the United states Jump to : navigation , search Ohio Clock in the U.S. Capitol being turned forward for the country 's first daylight saving time in 1918 Daylight saving time in the United States is the practice of setting the clock forward by one hour during the warmer part of the year , so that evenings have more daylight and mornings have less . Most areas of the United States observe daylight saving time ( DST ) , the exceptions being Arizona ( except for the Navajo , who do observe daylight saving time on tribal lands ) , Hawaii , and the overseas territories of American Samoa , Guam , the Northern Mariana Islands , Puerto Rico , and the United States Virgin Islands . The Uniform Time Act of 1966 established the system of uniform Daylight Saving Time throughout the US . In the U.S. , daylight saving time starts on the second Sunday in March and ends on the first Sunday in November , with the time changes taking place at 2 : 00 a.m. local time . With a mnemonic word play referring to seasons , clocks `` spring forward , fall back '' -- that is , in springtime the clocks are moved forward from 2 : 00 a.m. to 3 : 00 a.m. and in fall they are moved back from 2 : 00 a.m. to 1 : 00 a.m. Daylight saving time lasts for a total of 34 weeks ( 238 days ) every year , about 65 % of the entire year . The following table lists recent past and near future starting and ending dates of daylight saving time in the United States : Year Start End 2015 March 8 November 1 2016 March 13 November 6 2017 March 12 November 5 2018 March 11 November 4 2019 March 10 November 3 2020 March 8 November 1 2021 March 14 November 7 2022 March 13 November 6 2023 March 12 November 5 2024 March 10 November 3 Contents ( hide ) 1 History of DST in the United States 1.1 1916 -- 1966 : Early , inconsistent use 1.2 1966 -- 1972 : Federal standard established 1.3 1973 -- 1975 : Year - round experiment 1.4 1975 -- 1986 : Extension of daylight saving time 1.5 2005 -- 2009 : Second extension 2 Procedure for modifications 2.1 Changing an area 's time zone 2.2 Moving an area on or off DST 3 Local DST observance 3.1 Alaska 3.2 Arizona 3.2. 1 Reservations in Arizona 3.3 California 3.4 Florida 3.5 Hawaii 3.6 Indiana 3.7 Michigan 3.8 Nevada 3.9 Washington 3.10 Other U.S. locations 4 Time zones 5 See also 6 References 7 External links History of DST in the United states ( edit ) Benjamin Franklin proposed a form of daylight time in 1784 . His essay , `` An Economical Project for Diminishing the Cost of Light '' , written to the editor of The Journal of Paris , observed that Parisians could save on candles by getting out of bed earlier in the morning , making use of the natural morning light instead . Franklin 's suggestion seems to have been more of a joke than a real proposal , and nothing came of it . 1916 -- 1966 : early , inconsistent use ( edit ) During World War I , in an effort to conserve fuel , Germany began observing DST on May 1 , 1916 . The rest of Europe soon followed . The plan was not adopted in the United States until the Standard Time Act of March 19 , 1918 , which confirmed the existing standard time zone system and set summer DST to begin on March 31 , 1918 ( reverting October 27 ) . The idea was unpopular and Congress abolished DST after the war , overriding President Woodrow Wilson 's veto . DST became a local option and was observed in some states until World War II , when President Franklin Roosevelt instituted year - round DST , called `` War Time '' , on February 9 , 1942 . It lasted until the last Sunday ( the 30th ) in September 1945 . After 1945 many states and cities east of the Mississippi River ( and mostly north of the Ohio and Potomac rivers ) adopted summer DST . From 1945 to 1966 there was no federal law on daylight saving time , so localities could choose when it began and ended or drop it entirely . As of 1954 , only California and Nevada had statewide DST west of the Mississippi , and only a few cities between Nevada and St. Louis . In the 1964 Official Railway Guide , 21 of the 48 contiguous states had no DST anywhere . 1966 -- 1972 : federal standard established ( edit ) By 1962 , the transportation industry found the lack of consistency confusing enough to push for federal regulation . The result was the Uniform Time Act of 1966 ( P.L. 89 - 387 ) . Beginning in 1967 , the act mandated standard time within the established time zones and provided for advanced time : clocks would be advanced one hour beginning at 2 : 00 a.m. on the last Sunday in April and turned back one hour at 2 : 00 a.m. on the last Sunday in October . States were allowed to exempt themselves from DST as long as the entire state did so . If a state chose to observe DST , the time changes were required to begin and end on the established dates . In 1967 , Arizona and Michigan became the first states to exempt themselves from DST ( Michigan would begin observing DST in 1972 ) . In 1972 , the act was amended ( P.L. 92 - 267 ) , allowing those states split between time zones to exempt either the entire state or that part of the state lying within a different time zone . The newly created Department of Transportation ( DOT ) was given power to enforce the law . As of 2014 , the following states and territories are not observing DST : Arizona , Hawaii , American Samoa , Puerto Rico , and the Virgin Islands . 1973 -- 1975 : year - round Experiment ( edit ) During the 1973 oil embargo by the Organization of Arab Petroleum Exporting Countries ( OAPEC ) , in an effort to conserve fuel , Congress enacted a trial period of year - round DST ( P.L. 93 - 182 ) , beginning January 6 , 1974 , and ending April 27 , 1975 . The trial was hotly debated . Those in favor pointed to increased daylight hours in the summer evening : more time for recreation , reduced lighting and heating demands , reduced crime , and reduced automobile accidents . The opposition was concerned about children leaving for school in the dark . The act was amended in October 1974 ( P.L. 93 - 434 ) to return to standard time for the period beginning October 27 , 1974 , and ending February 23 , 1975 , when DST resumed . When the trial ended in 1975 , the country returned to observing summer DST ( with the aforementioned exceptions ) . 1975 -- 1986 : extension of daylight saving time ( edit ) The DOT , evaluating the plan of extending DST into March , reported in 1975 that `` modest overall benefits might be realized by a shift from the historic six - month DST ( May through October ) in areas of energy conservation , overall traffic safety and reduced violent crime . '' However , DOT also reported that these benefits were minimal and difficult to distinguish from seasonal variations and fluctuations in energy prices . Congress then asked the National Bureau of Standards ( NBS , today NIST ) to evaluate the DOT report . Its report , `` Review and Technical Evaluation of the DOT Daylight Saving Time Study '' ( April 1976 ) , found no significant energy savings or differences in traffic fatalities . It did find statistically significant evidence of increased fatalities among school - age children in the mornings during the four - month period January -- April 1974 as compared with the same period ( non-DST ) of 1973 . NBS stated that it was impossible to determine , what , if any , of this increase was due to DST . When this data was compared between 1973 and 1974 for the months of March and April , no significant difference was found in fatalities among school - age children in the mornings . In 1986 Congress enacted P.L. 99 - 359 , amending the Uniform Time Act by changing the beginning of DST to the first Sunday in April and having the end remain the last Sunday in October . These start and end dates were in effect from 1987 to 2006 . The time was adjusted at 2 : 00 a.m. local time . 2005 -- 2009 : second extension ( edit ) By the Energy Policy Act of 2005 , daylight saving time ( DST ) was extended in the United States beginning in 2007 . As from that year , DST begins on the second Sunday of March and ends on the first Sunday of November . In years when April 1 falls on Monday through Wednesday , these changes result in a DST period that is five weeks longer ; in all other years the DST period is instead four weeks longer . In 2008 daylight saving time ended at 2 : 00 a.m. DST ( 0200 ) ( 1 : 00 a.m. ST ) on Sunday , November 2 , and in 2009 it began at 2 : 00 a.m. ( 3 : 00 a.m. DST ) on Sunday , March 8 . Under Section 110 of the Act , the U.S. Department of Energy was required to study the impact of the 2007 DST extension no later than nine months after the change took effect . The report , released in October 2008 , reported a nationwide electricity savings of 0.03 % for the year of 2007 . An October 2008 study conducted by the University of California at Santa Barbara for the National Bureau of Economic Research found that the 2006 DST adoption in Indiana increased energy consumption in Indiana by an average of 1 % . Although consumption for lighting dropped as a result of the DST adoption , consumption for heating and cooling increased by 2 % to 4 % . The cost to the average Indiana household of the DST adoption was determined to be $3.29 per year , for an aggregate cost of $1.7 million to $5.5 million per year . The United States Chamber of Commerce has praised the extension of daylight 's saving under the 2005 law , which increased the amount of shopping and commerce from after work in evenings . In the golf industry , the group has noted exceptional increase in revenue of `` $200 million in additional sales of golf clubs and greens fees '' . The extension of Daylight 's Saving has also had a notable impact on Halloween and candy sales . Wyoming Senator Michael Enzi and Michigan Representative Fred Upton advocated the extension from October into November especially to allow children to go trick - or - treating in more daylight . In some areas , the extension of daylight saving time in March and November has pushed back sunrise to as late as 8 : 30 am . Procedure for modifications ( edit ) Changing an area 's time zone ( edit ) Under the Standard Time Act of 1918 , as amended by the Uniform Time Act of 1966 , moving a state or an area within a state from one time zone to another requires a regulation issued by DOT . The governor or state legislature may initiate a request for the state or any part of the state ; the highest elected officials in the county may make a request for that county . The standard in the statute for such decisions is the convenience of commerce in that area . The convenience of commerce is defined broadly to consider such circumstances as the shipment of goods within the community ; the origin of television and radio broadcasts ; the areas where most residents work , attend school , worship , or receive health care ; the location of airports , railway , and bus stations ; and the major elements of the community 's economy . After receiving a request for altering a time zone , DOT determines whether it meets the requirement of minimum statutory criteria before issuing a notice of proposed rulemaking , soliciting public comment and scheduling a public hearing . Usually the hearing is held in the area requesting the change so that all affected parties can be represented . After the close of the comment period , the comments are reviewed and appropriate final action taken . If the Secretary agrees that the statutory requirement has been met , the change is instituted , usually at the next changeover to or from DST . Moving an area on or off DST ( edit ) Under the Uniform Time Act , moving an area on or off DST is accomplished through legal action at the state level . Some states require legislation while others require executive action such as a governor 's executive order . Information on procedures required in a specific state may be obtained from that state 's legislature or governor 's office . Although it may exempt itself , if a state decides to observe DST , the dates of observance must comply with federal legislation . Local DST observance ( edit ) Alaska ( edit ) This section needs to be updated . Please update this article to reflect recent events or newly available information . ( November 2017 ) Alaska observes DST . Due to its high latitude , Alaska has nearly round - the - clock daylight during summer , and DST is seen by some Alaskans as unnecessary and a nuisance . Another issue is that the Alaskan mainland 's single time zone , which approximates solar time in the capital , Juneau , leads to a large disparity between civil time and solar time for much of the state , with solar noon occurring as late as 2 : 10 p.m. in the population centers of Anchorage and Fairbanks , and as late as 3 : 23 p.m. in places such as Nome . In Fairbanks , for example , sunset occurs well after civil midnight in the summer . Others argue that ending daylight saving time will place Alaska as much as five hours from Eastern Daylight Time , making coordination of travel and phone conversations more difficult . In March 2015 the Alaska Senate passed a bill , introduced by state senator Anna MacKinnon , to end daylight saving time . The Alaska House formed a sub-committee that was due to look into the issue during the 2016 legislative session . Arizona ( edit ) Arizona observed DST in 1967 under the Uniform Time Act because the state legislature did not enact an exemption statute that year . In March 1968 the DST exemption statute was enacted and the state of Arizona has not observed DST since 1967 . This is in large part due to an effort to conserve energy . Phoenix and Tucson are among the hottest U.S. metropolitan areas during the summer , resulting in more power usage from air conditioning units and evaporative coolers in homes and businesses . An extra hour of sunlight while people are active would cause people to run their cooling systems longer , thereby using more energy . Reservations in Arizona ( edit ) The Navajo Indian Reservation extends into Utah and New Mexico and does observe daylight saving time . The Hopi Reservation is entirely within the state of Arizona and is an enclave within the Navajo Indian Reservation , but does not observe DST . California ( edit ) California voters passed Proposition 12 in 1949 , approving DST in the state . In February 2017 , California Assembly member Kansen Chu introduced A.B. 807 , proposing to enable the legislature to eliminate DST in the state , or , if federal law allows , to adopt DST for the entire year . However , Chu later shelved his bill in September 2017 . Florida ( edit ) Daylight saving time is less useful in Florida compared to other states because its southern location leads to less variations in day length between winter and summer . Without DST , Miami , for instance , would experience similar sunrise and sunset times throughout the year to cities including Honolulu or Hong Kong , which have both abandoned DST for decades . There is opposition to DST in Florida . State senator Bill Posey introduced a bill in March 2008 to abolish daylight time in the state and keep Florida on year - round standard time . Because Florida straddles two time zones , the Florida legislature has the option of returning all or part of the state to standard time along time zone boundaries ( i.e. placing the portion of the state in the Eastern time zone on standard time , while leaving the portion in the Central time zone on DST , so that the whole state had a common time ) . There are currently no states that keep daylight saving time year round . On March 6 , 2018 , the Florida Senate approved the `` Sunshine Protection Act '' which would put Florida on permanent Daylight Saving Time year round , and Governor Rick Scott signed it March 23 . Congress would need to amend the existing 1966 federal law to allow the change . Hawaii ( edit ) Hawaii has never observed daylight saving time under the Uniform Time Act , having opted out of the Act 's provisions in 1967 . Because of Hawaii 's tropical latitude , there is not a large variation in daylight length between winter and summer . Advancing the clock in Hawaii would make sunrise times close to 7 : 00 a.m. even in June . Most of the inhabited islands are located close to the west end of the Hawaii - Aleutian time zone , but Oahu , Kauai , and Niihau are located more than 7 degrees west of the Hawaii - Aleutian time zone 's meridian and should , theoretically , be located in the next time zone to the west . ( Until about 1946 Hawaiian standard time was based on longitude 157.5 degrees west rather than 150 degrees . ) On April 26 , 1933 , the Territorial Legislature enacted a bill placing Hawaii on daylight saving time from the last Sunday in April ( April 30 in that year ) to the last Sunday in September , but the law was repealed three weeks later on May 21 , 1933 . During World War II between February 9 , 1942 and September 30 , 1945 , Hawaiian Standard Time was advanced one hour to so - called `` Hawaiian War Time , '' effectively placing the territory on year - round daylight saving time . Indiana ( edit ) See also : Time in Indiana From 1970 until 2006 , most of Indiana in the Eastern Time Zone did not observe daylight saving time , but the entire state started to do so in April 2006 after eight counties in western Indiana were shifted from the Central Time Zone to the Eastern Time Zone . One goal for observing DST was to get more Indiana counties observing the same time zone ; formerly , 77 counties observed EST , 5 observed EST / EDT ( the EDT usage being unofficial only ) , and 10 observed CST / CDT . As of 2016 , Indiana has 12 counties observing Central Daylight Time while the remaining 80 counties observe Eastern Daylight Time . Those counties observing CST are in two groups : one near or in the Chicago metropolitan area , and the other around Evansville in the southwest corner of the state . Michigan ( edit ) In 1967 , the Michigan Legislature adopted a statute , Act 6 of the Public Acts of 1967 , exempting the state from the observance of DST . The exemption statute was suspended on June 14 , 1967 , however , when the referendum was invoked . From June 14 , 1967 until the last Sunday in October 1967 , Michigan observed DST , and did so in 1968 as well . The exemption statute was submitted to the voters at the General Election held in November 1968 , and , in a close vote , the exemption statute was sustained . As a result , Michigan did not observe DST in 1969 , 1970 , 1971 , or 1972 . ( Radio station CKLW in Windsor , Ontario , just across the river from Detroit , was popular on both sides of the border and would often give both times on the air , e.g. `` It 's 4 : 30 in Detroit and 5 : 30 in Windsor ! '' ) In November 1972 , an initiative measure , repealing the exemption statute , was approved by the voters . Michigan again observed DST in 1973 , and has continued to do so since then . The vast majority of Michigan is in the Eastern Time Zone . Only the Upper Peninsula counties that border Wisconsin ( Gogebic , Iron , Dickinson , and Menominee ) are in the Central Time Zone . Nevada ( edit ) In 2015 , the Nevada Senate passed Nevada Assembly Joint Resolution 4 , which urged Congress to enact legislation allowing individual states to establish daylight saving time as the standard time in their respective states throughout the calendar year . This would mean that Nevada is on the same time as Arizona all year , but would be an hour ahead of California in the winter . The United States Congress has not yet enacted any enabling legislation in this regard . Washington ( edit ) In 2015 , Rep. Elizabeth Scott ( R - Monroe ) filed a House bill to end DST in Washington , and a companion bill was filed in the Senate . She told a House committee that the semiannual time switches are not only inconvenient but lead to health problems and accidents due to lost sleep . She added that the bill to drop daylight saving time would reduce heart attacks , car wrecks , and work accidents found to increase with the sleep - schedule disruptions . A different Senate Bill would petition the federal government for year - round DST . The bills were defeated . Other U.S. locations ( edit ) All U.S. insular territories with civilian government ( American Samoa , Guam , Northern Mariana Islands , Puerto Rico , and the Virgin Islands ) lie in the tropics and do not observe DST . While neighboring Samoa began observing DST in September 2010 , the smaller American Samoa can not legally follow because of the DST observation period mandated by the Uniform Time Act . This period is actually wintertime in this Southern Hemisphere territory . Time zones ( edit ) Many computer operating systems ( such as Microsoft Windows , Linux , UNIX , and macOS ) and programming languages ( such as Java , perl , and most shell languages ) allow a local time zone setting in the format of ( standard time zone abbreviation ) ( UTC hour difference ) ( daylight saving time zone abbreviation ) . This allows programs and programming languages that must do calculations based on local time to more easily calculate differences between local time and UTC , as well as knowing whether calculations should be changed during daylight saving time . For example , a time zone setting of EST5EDT indicates that local time on the computer is 5 hours behind UTC and should be adjusted for daylight saving time . Time Zone Standard Time Daylight Saving Time TZ Atlantic Time Zone AST ( UTC - 4 ) ADT ( UTC - 3 ) AST4ADT Eastern Time Zone EST ( UTC - 5 ) EDT ( UTC - 4 ) EST5EDT Central Time Zone CST ( UTC - 6 ) CDT ( UTC - 5 ) CST6CDT Mountain Time Zone MST ( UTC - 7 ) MDT ( UTC - 6 ) MST7MDT Pacific Time Zone PST ( UTC - 8 ) PDT ( UTC - 7 ) PST8PDT Alaska Time Zone AKST ( UTC - 9 ) AKDT ( UTC - 8 ) AKST9AKDT Hawaii -- Aleutian Time Zone HAST ( UTC - 10 ) HADT ( UTC - 9 ) Aleutian Islands only HAST10HADT See also ( edit ) General topic Daylight saving time Daylight saving time by country CHU distributes official time in Canada History of time in the United States includes a list of historical daylight saving dates back to 1918 Official civil time distribution WWV and WWVH ( NIST Shortwave ) WWVB ( NIST Longwave ) Quasi-governmental time distribution systems CDMA cellphone stratum 2 time distribution system GNSS global navigation stratum 1 time distribution system References ( edit ) Jump up ^ `` Most of Exempt from Daylight Saving Time '' , timeanddate.com . Retrieved February 14 , 2013 . Jump up ^ `` Daylight Time '' . United States Naval Observatory . Retrieved October 18 , 2012 . Jump up ^ History of Daylight Saving Time , timeanddate.com ; accesses 2017.03. 05 . Jump up ^ Editors ( 25 October 1918 ) . `` Clocks Change Tomorrow '' ( PDF ) . The New York Times Company . The New York Times . Retrieved 1 November 2015 . Jump up ^ 66th U.S. Congress . `` CHAP. 51 . An Act For the repeal of the daylight - saving law '' ( pdf ) . Legis Works . Retrieved November 3 , 2013 . ( Pub. L. 66 -- 40 , 41 Stat. 280 , enacted August 20 , 1919 ) Jump up ^ 77th U.S. Congress . `` AN ACT To promote the national security and defense by establishing daylight saving time '' ( pdf ) . Legis Works . Retrieved November 3 , 2013 . ( Pub. L. 77 -- 403 , 56 Stat. 9 , enacted January 20 , 1942 ) ^ Jump up to : Source : CRS Report to Congress s : Congressional Research Service Report RS22284 Daylight Saving Time Jump up ^ 93rd U.S. Congress . `` AN ACT To provide for daylight saving time on a year - round basis for a two - year trial period , ... '' ( pdf ) . United States Government Printing Office . Retrieved 2 November 2013 . ( Pub. L. 93 -- 182 , 87 Stat. 707 , enacted December 15 , 1973 ) Jump up ^ Dunning , Brian . `` Skeptoid # 172 : Daylight Saving Time Myths '' . Skeptoid . Retrieved June 19 , 2017 . Jump up ^ 109th U.S. Congress . `` Sec. 110 . Daylight Savings '' ( PDF ) . An Act To ensure jobs for our future with secure , affordable , and reliable energy . United States Government Printing Office . Retrieved November 3 , 2013 . ( Pub. L. 109 -- 58 , 119 Stat. 594 , enacted August 8 , 2005 ) Jump up ^ Douma , Michael ( 2008 ) . `` Daylight Saving Time -- When do we change our clocks ? '' . Institute for Dynamic Educational Advancement . Retrieved March 8 , 2008 . Jump up ^ `` Time and Frequency Division FAQ '' . National Institute of Standards and Technology . Jump up ^ Belzer , David B. ( October 2008 ) . `` Impact of Extended Daylight Saving Time on National Energy Consumption '' ( PDF ) . U.S. Department of Energy . Archived from the original ( PDF ) on 2013 - 05 - 18 . Jump up ^ Lotchen , Matthew ( October 2008 ) . `` Does Daylight Saving Time Save Energy ? Evidence from a Natural Experiment in Indiana '' ( PDF ) . National Bureau of Economic Research . ^ Jump up to : `` Sunshine daydream : Florida bill would make daylight saving time year - round '' . Retrieved 2018 - 03 - 12 . ^ Jump up to : `` The Reasoning Behind Changing Daylight - Saving '' . NPR.org . Retrieved 2018 - 03 - 12 . Jump up ^ Ast , William F. III ( October 30 , 2009 ) . `` Time shifts backward early Sunday morning '' . The Herald - Palladium . Retrieved October 30 , 2009 . Jump up ^ Moritz , Katie ( April 10 , 2015 ) . `` Clock Stopped on Daylight Saving Time Repeal -- For Now '' . Juneau Empire . Retrieved May 8 , 2015 . Jump up ^ Shimoda , Yoshiyuki ; Asahi , Takahiro ; Taniguchi , Ayako ; Mizuno , Minoru ( 2007 ) . `` Evaluation of city - scale impact of residential energy conservation measures using the detailed end - use simulation model '' . Energy . 32 ( 9 ) : 1617 . doi : 10.1016 / j. energy. 2007.01. 007 . Jump up ^ `` Navajo Nation '' . Wwp.greenwichmeantime.com . Retrieved June 25 , 2010 . Jump up ^ `` The Strange 100 - Year History of Daylight Saving Time '' . 2018 - 03 - 09 . Retrieved 2018 - 04 - 17 . Jump up ^ `` Proposition 12 : Daylight Saving Time '' . UC Hastings Scholarship Repository . University of California Hastings . 1949 . Retrieved March 23 , 2017 . Jump up ^ `` California Wants To Ban Daylight Saving Time '' . The Huffington Post . March 11 , 2016 . Retrieved March 13 , 2016 . Jump up ^ A.B. 807 , 2017 -- 2018 Reg . Sess . ( Cal. 2017 ) . An act to add Section 6808 to the Government Code , and to repeal Sections 1 , 2 , 3 , 4 , and 5 of the Daylight Saving Time Act , an initiative measure approved at the November 8 , 1949 , special election , relating to daylight saving time . Jump up ^ Murphy , Katy ( March 10 , 2017 ) . `` California debates daylight saving time -- again '' . San Jose Mercury News . Retrieved March 23 , 2017 . Jump up ^ Alexei , Koseff ( September 13 , 2017 ) . `` Daylight saving time survives another year in the California Legislature '' . Sacramento Bee . Retrieved March 4 , 2018 . Jump up ^ `` HB 701 -- Daylight Saving Time '' . Retrieved May 25 , 2015 . Jump up ^ Colavecchio - Van Sickler , Shannon ( March 27 , 2008 ) . `` Posey 's daylight savings bill moves '' . Tampa Bay Times . Jump up ^ `` Florida Gov. says yes to daylight saving time year - round '' . The Charlotte Observer . Associated Press . 2018 - 03 - 23 . Retrieved 2018 - 03 - 24 . Jump up ^ `` Hawaii Revised Statutes , § 1 - 31 '' . Capitol.hawaii.gov . Retrieved June 25 , 2010 . Jump up ^ `` Astronomical Data Applications '' . U.S. Naval Meteorology & Oceanography Command . Retrieved June 25 , 2010 . Jump up ^ Session Laws of Hawaii , 933 , enacted by Act 90 ( approved April 26 , 1933 ) and repealed by Act 163 ( approved May 21 , 1933 ) . Cited in Schmitt , Robert ; Cox , Doak ( 1992 ) . `` Hawaiian Time '' . The Hawaiian Journal of History . 26 : 220 . Archived from the original on November 5 , 2013 . Retrieved November 4 , 2013 . Jump up ^ Schmitt and Cox , p. 221 . Jump up ^ Standard Time Zone Boundary in the State of Indiana ( a 139 KB PDF file ) Jump up ^ Assembly Joint Resolution No. 4 ( PDF ) ( Report ) . Nevada Legislature. 2015 - 05 - 25 . Jump up ^ Chereb , Sandra ( 2015 - 05 - 18 ) . `` Nevada lawmakers urge Congress to allow state to stay on daylight savings time '' . Las Vegas Review - Journal . ^ Jump up to : `` Bill would end daylight saving time in Washington state '' . The Oregonian . AP . February 3 , 2015 . Retrieved November 5 , 2016 . Jump up ^ Nunnally , Derrick ( February 3 , 2015 ) . `` Lawmakers want to end Daylight Saving Time in Washington '' . AP . Retrieved November 5 , 2016 . Jump up ^ `` Senate bill to end Daylight Saving Time in Washington dies '' . Retrieved February 12 , 2018 . External links ( edit ) Washington Post : Overview of anti-DST initiatives by states in 2015 Steverman , Ben ( March 10 , 2017 ) . `` Proof daylight saving time is dumb , dangerous , and costly '' . Boston Globe . Bloomberg News . Retrieved March 10 , 2017 . ( hide ) Daylight saving time in the Americas North America South America Sovereign states Antigua and Barbuda Argentina Bahamas Barbados Belize Bolivia Brazil Canada Chile Colombia Costa Rica Cuba Dominica Dominican Republic Ecuador El Salvador Grenada Guatemala Guyana Haiti Honduras Jamaica Mexico Nicaragua Panama Paraguay Peru Saint Kitts and Nevis Saint Lucia Saint Vincent and the Grenadines Suriname Trinidad and Tobago United States Uruguay Venezuela Dependencies and other territories Anguilla Aruba Bermuda Bonaire British Virgin Islands Cayman Islands Curaçao Falkland Islands French Guiana Greenland Guadeloupe Martinique Montserrat Puerto Rico Saint Barthélemy Saint Martin Saint Pierre and Miquelon Saba Sint Eustatius Sint Maarten South Georgia and the South Sandwich Islands Turks and Caicos Islands US Virgin Islands Retrieved from `` https://en.wikipedia.org/w/index.php?title=Daylight_saving_time_in_the_United_States&oldid=838276214 '' Categories : Daylight saving time in the United States Daylight saving time by country 1918 introductions 1918 establishments in the United States Hidden categories : CS1 : Julian -- Gregorian uncertainty Wikipedia articles in need of updating from November 2017 All Wikipedia articles in need of updating Articles containing potentially dated statements from 2016 All articles containing potentially dated statements Talk Contents About Wikipedia Add links This page was last edited on 26 April 2018 , at 01 : 06 . 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Question: when did day light savings start in the us


Rocinante - wikipedia Rocinante Jump to : navigation , search Not to be confused with Rocinate . For other uses , see Rocinante ( disambiguation ) . Rocinante ( Spanish pronunciation : ( roθiˈnante ) ) is Don Quixote 's horse in the novel Don Quixote by Miguel de Cervantes . In many ways , Rocinante is not only Don Quixote 's horse , but also his double : like Don Quixote , he is awkward , past his prime , and engaged in a task beyond his capacities . Etymology ( edit ) Rocín in Spanish means a work horse or low - quality horse , but can also mean an illiterate or rough man . There are similar words in French ( roussin ; rosse ) , Portuguese ( rocim ) , and Italian ( ronzino ) . The etymology is uncertain . Rocinante Don Quixote character Rocinante . Detail of the Cervantes monument in Madrid ( L. Coullaut , 1930 ) Created by Miguel de Cervantes Information Species Horse Gender Male The name is a complex pun . In Spanish , ante has several meanings and can function as a standalone word as well as a suffix . One meaning is `` before '' or `` previously '' . Another is `` in front of '' . As a suffix , - ante in Spanish is adverbial ; rocinante refers to functioning as , or being , a rocín . `` Rocinante '' , then , follows Cervantes ' pattern using ambiguous , multivalent words , which is common throughout the novel . Rocinante 's name , then , signifies his change in status from the `` old nag '' of before to the `` foremost '' steed . As Cervantes describes Don Quixote 's choice of name : nombre a su parecer alto , sonoro y significativo de lo que había sido cuando fue rocín , antes de lo que ahora era , que era antes y primero de todos los rocines del mundo -- `` a name , to his thinking , lofty , sonorous , and significant of his condition as a hack before he became what he now was , the first and foremost of all the hacks in the world '' . In chapter 1 , Cervantes describes Don Quixote 's careful naming of his steed : Four days were spent in thinking what name to give him , because ( as he said to himself ) it was not right that a horse belonging to a knight so famous , and one with such merits of his own , should be without some distinctive name , and he strove to adapt it so as to indicate what he had been before belonging to a knight - errant , and what he then was . '' References ( edit ) ^ Jump up to : Mancing , Howard ( 2004 ) . `` Rocinante '' . The Cervantes Encyclopedia : L -- Z . Westport , CT : Greenwood Press . p. 618 . Jump up ^ Cull , John T. ( 1990 ) . `` The ' Knight of the Broken Lance ' and his ' Trusty Steed ' : On Don Quixote and Rocinante '' . Cervantes : Bulletin of the Cervantes Society of America . 10 ( 2 ) : 37 -- 53 . Jump up ^ de Cervantes , Miguel . Don Quijote , Editorial del Valle de México , 1st edition , p. 3 , 1981 . ^ Jump up to : Ormsby , John . `` Chapter 1 '' . Don Quixote by Miguel de Cervantes . Retrieved 2011 - 02 - 18 . Miguel de Cervantes 's Don Quixote ( 1606 / 1615 ) Characters Don Quixote Alonso Quijano Sancho Panza Clavileño Dulcinea del Toboso Ginés de Pasamonte Ricote Rocinante Stage The Comical History of Don Quixote ( 1694 play ) Double Falsehood ( 1727 play ) Don Quichotte auf der Hochzeit des Comacho ( 1761 opera ) Don Quixote ( 1869 ballet ) Don Quixote ( 1898 opera ) Don Quichotte ( 1910 opera ) Man of La Mancha ( 1964 musical ) Film Don Quixote ( 1923 ) Don Quixote ( 1933 ) Don Quixote ( 1947 ) Don Quixote ( 1955 -- 1969 , unfinished ) Don Quixote ( 1957 ) Dulcinea ( 1963 ) Don Chisciotte and Sancio Panza ( 1968 ) Man of La Mancha ( 1972 ) Don Quijote cabalga de nuevo ( 1973 ) Don Quixote ( 2000 ) Donkey Xote ( 2007 ) Don Quixote ( 2010 ) The Man Who Killed Don Quixote ( 2018 2002 documentary ) Television I , Don Quixote ( 1959 teleplay ) The Adventures of Don Coyote and Sancho Panda Don Quixote Related List of works influenced by Don Quixote Retrieved from `` https://en.wikipedia.org/w/index.php?title=Rocinante&oldid=836443640 '' Categories : Don Quixote characters Fictional characters introduced in 1605 Fictional horses Hidden categories : Articles containing Spanish - language text Pages using deprecated image syntax All articles with unsourced statements Articles with unsourced statements from October 2017 Talk About Wikipedia Brezhoneg Čeština Español Euskara Français Հայերեն Italiano Nederlands 日本 語 Norsk Polski Português Русский Suomi Türkçe Українська 7 more Edit links This page was last edited on 14 April 2018 , at 21 : 17 . About Wikipedia

Question: what is don quixote's horse's name