Journal articles: 'Motor Unit Action Potentials (MUAP)'

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Sandercock, T. G., J. A. Faulkner, J. W. Albers, and P. H. Abbrecht. "Single motor unit and fiber action potentials during fatigue." Journal of Applied Physiology 58, no. 4 (April 1, 1985): 1073–79. http://dx.doi.org/10.1152/jappl.1985.58.4.1073.

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Muscle fatigue is defined as a loss of tension development during constant stimulation. Although the relationship is not well documented, muscle fatigue has been inferred from electromyogram (EMG) signals. The purpose of this study was to determine the relationship between the amplitude and duration of single motor unit action potentials (MUAPs) and the loss of tension development (fatigue) in the medial gastrocnemius muscles of cats. Single motor units were fatigued by continuous stimulation at 10 or 80 Hz or with trains of 40-Hz stimuli. When motor units were stimulated at 10 Hz and with trains at 40 Hz (low frequency), tension declined and remained depressed during recovery. The changes in the MUAP correlated poorly with changes in tension. During and after stimulation at 80 Hz (high frequency), changes in the amplitude and duration of MUAPs correlated highly with changes in tension development. Since the EMG signal is dependent on a summation and cancellation of individual MUAPs, the EMG provides a reasonable estimate of high-frequency fatigue but an unreliable measure of low-frequency fatigue.

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McManus, Lara, Xiaogang Hu, William Z. Rymer, Madeleine M. Lowery, and Nina L. Suresh. "Changes in motor unit behavior following isometric fatigue of the first dorsal interosseous muscle." Journal of Neurophysiology 113, no. 9 (May 2015): 3186–96. http://dx.doi.org/10.1152/jn.00146.2015.

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The neuromuscular strategies employed to compensate for fatigue-induced muscle force deficits are not clearly understood. This study utilizes surface electromyography (sEMG) together with recordings of a population of individual motor unit action potentials (MUAPs) to investigate potential compensatory alterations in motor unit (MU) behavior immediately following a sustained fatiguing contraction and after a recovery period. EMG activity was recorded during abduction of the first dorsal interosseous in 12 subjects at 20% maximum voluntary contraction (MVC), before and directly after a 30% MVC fatiguing contraction to task failure, with additional 20% MVC contractions following a 10-min rest. The amplitude, duration and mean firing rate (MFR) of MUAPs extracted with a sEMG decomposition system were analyzed, together with sEMG root-mean-square (RMS) amplitude and median frequency (MPF). MUAP duration and amplitude increased immediately postfatigue and were correlated with changes to sEMG MPF and RMS, respectively. After 10 min, MUAP duration and sEMG MPF recovered to prefatigue values but MUAP amplitude and sEMG RMS remained elevated. MU MFR and recruitment thresholds decreased postfatigue and recovered following rest. The increase in MUAP and sEMG amplitude likely reflects recruitment of larger MUs, while recruitment compression is an additional compensatory strategy directly postfatigue. Recovery of MU MFR in parallel with MUAP duration suggests a possible role for metabolically sensitive afferents in MFR depression postfatigue. This study provides insight into fatigue-induced neuromuscular changes by examining the properties of a large population of concurrently recorded single MUs and outlines possible compensatory strategies involving alterations in MU recruitment and MFR.

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Kidd, GL, and JA Oldham. "Motor unit action potential (MUAP) sequence and electrotherapy." Clinical Rehabilitation 2, no. 1 (February 1988): 23–33. http://dx.doi.org/10.1177/026921558800200105.

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Bischoff, Christian, Erik Stålberg, Björn Falck, and Karin Edebol Eeg-Olofsson. "Reference values of motor unit action potentials obtained with multi-MUAP analysis." Muscle & Nerve 17, no. 8 (August 1994): 842–51. http://dx.doi.org/10.1002/mus.880170803.

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Doherty, T. J., A. A. Vandervoort, A. W. Taylor, and W. F. Brown. "Effects of motor unit losses on strength in older men and women." Journal of Applied Physiology 74, no. 2 (February 1, 1993): 868–74. http://dx.doi.org/10.1152/jappl.1993.74.2.868.

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The influence of age-associated motor unit loss on contractile strength was investigated in a representative sample of healthy, active young and older men and women. In 24 younger subjects (22–38 yr) and 20 older subjects (60–81 yr) spike-triggered averaging was employed to extract a sample of surface-recorded single motor unit action potentials (S-MUAPs) from the biceps brachii and brachialis muscles. The amplitude of the maximum compound muscle action potential of the biceps brachii and brachialis muscles was divided by the mean S-MUAP amplitude to estimate the numbers of motor units present. The maximum isometric twitch contraction (MTC) and maximum voluntary contraction (MVC) of the elbow flexors were also recorded in 18 of the younger subjects and in all older subjects. The estimated numbers of motor units were significantly reduced (47%, P < 0.001) in older subjects with a mean value of 189 +/- 77 compared with a mean of 357 +/- 97 in younger subjects. The sizes of the S-MUAPs, however, were significantly larger in older subjects (23%, P < 0.01). Significant but less marked age-associated reductions in the MTC (33%, P < 0.05) and MVC (33%, P < 0.001) were also found and were similar for both men and women. These results suggest that motor unit losses, even in healthy active individuals, are a primary factor in the age-associated reductions in contractile strength.

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Fatela, Pedro, Goncalo V. Mendonca, António Prieto Veloso, Janne Avela, and Pedro Mil-Homens. "Blood Flow Restriction Alters Motor Unit Behavior During Resistance Exercise." International Journal of Sports Medicine 40, no. 09 (July 10, 2019): 555–62. http://dx.doi.org/10.1055/a-0888-8816.

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AbstractWe aimed to determine whether blood flow restriction (BFR) alters the characteristics of individual motor units during low-intensity (LI) exercise. Eight men (26.0±3.8 yrs) performed 5 sets of 15 knee extensions at 20% of one-repetition maximum (with and without BFR). Maximal isometric voluntary contractions (MVC) were performed before and after exercise to quantify force decrement. Submaximal isometric voluntary contractions were additionally performed for 18 s, matching trapezoidal target-force trajectories at 40% pre-MVC. EMG activity was recorded from the vastus lateralis muscle. Then, signals were decomposed to extract motor unit recruitment threshold, firing rates and action potential amplitudes (MUAP). Force decrement was only seen after LI BFR exercise (–20.5%; p<0.05). LI BFR exercise also induced greater decrements in the linear slope coefficient of the regression lines between motor unit recruitment threshold and firing rate (BFR: –165.1±120.4 vs. non-BFR: –44.4±33.1%, p<0.05). Finally, there was a notable shift towards higher values of firing rate and MUAP amplitude post-LI BFR exercise. Taken together, our data indicate that LI BFR exercise increases the activity of motor units with higher MUAP amplitude. They also indicate that motor units with similar MUAP amplitudes become activated at higher firing rates post-LI BFR exercise.

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De Luca, Carlo J., Shey-Sheen Chang, Serge H. Roy, Joshua C. Kline, and S. Hamid Nawab. "Decomposition of surface EMG signals from cyclic dynamic contractions." Journal of Neurophysiology 113, no. 6 (March 15, 2015): 1941–51. http://dx.doi.org/10.1152/jn.00555.2014.

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Over the past 3 decades, various algorithms used to decompose the electromyographic (EMG) signal into its constituent motor unit action potentials (MUAPs) have been reported. All are limited to decomposing EMG signals from isometric contraction. In this report, we describe a successful approach to decomposing the surface EMG (sEMG) signal collected from cyclic (repeated concentric and eccentric) dynamic contractions during flexion/extension of the elbow and during gait. The increased signal complexity introduced by the changing shapes of the MUAPs due to relative movement of the electrodes and the lengthening/shortening of muscle fibers was managed by an incremental approach to enhancing our established algorithm for decomposing sEMG signals obtained from isometric contractions. We used machine-learning algorithms and time-varying MUAP shape discrimination to decompose the sEMG signal from an increasingly challenging sequence of pseudostatic and dynamic contractions. The accuracy of the decomposition results was assessed by two verification methods that have been independently evaluated. The firing instances of the motor units had an accuracy of ∼90% with a MUAP train yield as high as 25. Preliminary observations from the performance of motor units during cyclic contractions indicate that during repetitive dynamic contractions, the control of motor units is governed by the same rules as those evidenced during isometric contractions. Modifications in the control properties of motoneuron firings reported by previous studies were not confirmed. Instead, our data demonstrate that the common drive and hierarchical recruitment of motor units are preserved during concentric and eccentric contractions.

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Boonstra, Tjeerd W., and Michael Breakspear. "Neural mechanisms of intermuscular coherence: implications for the rectification of surface electromyography." Journal of Neurophysiology 107, no. 3 (February 2012): 796–807. http://dx.doi.org/10.1152/jn.00066.2011.

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Oscillatory activity plays a crucial role in corticospinal control of muscle synergies and is widely investigated using corticospinal and intermuscular synchronization. However, the neurophysiological mechanisms that translate these rhythmic patterns into surface electromyography (EMG) are not well understood. This is underscored by the ongoing debate on the rectification of surface EMG before spectral analysis. Whereas empirical studies commonly rectify surface EMG, computational approaches have argued against it. In the present study, we employ a computational model to investigate the role of the motor unit action potential (MAUP) on the translation of oscillatory activity. That is, diverse MUAP shapes may distort the transfer of common input into surface EMG. We test this in a computational model consisting of two motor unit pools receiving common input and compare it to empirical results of intermuscular coherence between bilateral leg muscles. The shape of the MUAP was parametrically varied, and power and coherence spectra were investigated with and without rectification. The model shows that the effect of EMG rectification depends on the uniformity of MUAP shapes. When output spikes of different motor units are convolved with identical MUAPs, oscillatory input is evident in both rectified and nonrectified EMG. In contrast, a heterogeneous MAUP distribution distorts common input and oscillatory components are only manifest as periodic amplitude modulations, i.e., in rectified EMG. The experimental data showed that intermuscular coherence was mainly discernable in rectified EMG, hence providing empirical support for a heterogeneous distribution of MUAPs. These findings implicate that the shape of MUAPs is an essential parameter to reconcile experimental and computational approaches.

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Bossaghzadeh, Zeynab, Firoozeh Niazvand, Medi Saneie, Shahram Rahimi-Dehgolan, Hooshan Sahariati Ghadikolaei, and Sara Mobarak. "Common Peroneal Nerve Injury in a Patient with COVID-19 Infection." Bionatura 3, no. 3 (August 15, 2021): 2043–45. http://dx.doi.org/10.21931/rb/2021.06.03.26.

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This report described a 46-year man with the characteristic Computerized Tomography (CT) scan findings of Corona Virus Disease Infection 19 (COVID-19) who presented to the hospital with right ankle weakness three weeks after the pneumonitis. He had been initially hospitalized, complaining of fever, myalgia, cough, and dyspnea. Electromyogram (EMG) revealed obvious evidence of increased insertional activity (IA) and significant denervation potentials, including positive sharp waves (PSW) and fibrillation potentials, particularly in ankle dorsiflexor muscles. Moreover, no voluntary motor unit action potential (MUAP) was observed. Eventually, the patient was diagnosed with severe axonal mononeuropathy of the right CPN, which could be considered a rare complication of COVID-19.

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Ullah, Khalil, Khalil Khan, Muhammad Amin, Muhammad Attique, Tae-Sun Chung, and Rabia Riaz. "Multi-Channel Surface EMG Spatio-Temporal Image Enhancement Using Multi-Scale Hessian-Based Filters." Applied Sciences 10, no. 15 (July 24, 2020): 5099. http://dx.doi.org/10.3390/app10155099.

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Surface electromyography (sEMG) signals acquired with linear electrode array are useful in analyzing muscle anatomy and physiology. Most algorithms for signal processing, detection, and estimation require adequate quality of the input signals, however, multi-channel sEMG signals are commonly contaminated due to several noise sources. The sEMG signal needs to be enhanced prior to the digital signal and image processing to achieve the best results. This study is using spatio-temporal images to represent surface EMG signals. The motor unit action potential (MUAP) in these images looks like a linear structure, making certain angles with the x-axis, depending on the conduction velocity of the MU. A multi-scale Hessian-based filter is used to enhance the linear structure, i.e., the MUAP region, and to suppress the background noise. The proposed framework is compared with some of the existing algorithms using synthetic, simulated, and experimental sEMG signals. Results show improved detection accuracy of the motor unit action potential after the proposed enhancement as a preprocessing step.

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Mesin, Luca. "Motor Unit Discharges from Multi-Kernel Deconvolution of Single Channel Surface Electromyogram." Electronics 10, no. 16 (August 21, 2021): 2022. http://dx.doi.org/10.3390/electronics10162022.

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Surface electromyogram (EMG) finds many applications in the non-invasive characterization of muscles. Extracting information on the control of motor units (MU) is difficult when using single channels, e.g., due to the low selectivity and large phase cancellations of MU action potentials (MUAPs). In this paper, we propose a new method to face this problem in the case of a single differential channel. The signal is approximated as a sum of convolutions of different kernels (adapted to the signal) and firing patterns, whose sum is the estimation of the cumulative MU firings. Three simulators were used for testing: muscles of parallel fibres with either two innervation zones (IZs, thus, with MUAPs of different phases) or one IZ and a model with fibres inclined with respect to the skin. Simulations were prepared for different fat thicknesses, distributions of conduction velocity, maximal firing rates, synchronizations of MU discharges, and variability of the inter-spike interval. The performances were measured in terms of cross-correlations of the estimated and simulated cumulative MU firings in the range of 0–50 Hz and compared with those of a state-of-the-art single-kernel algorithm. The median cross-correlations for multi-kernel/single-kernel approaches were 92.2%/82.4%, 98.1%/97.6%, and 95.0%/91.0% for the models with two IZs, one IZ (parallel fibres), and inclined fibres, respectively (all statistically significant differences, which were larger when the MUAP shapes were of greater difference).

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Bromberg, Mark B. "Motor unit action potential analysis of the paraspinal muscles : Paraspinal muap analysis is useful." Muscle & Nerve 29, no. 3 (2004): 451–53. http://dx.doi.org/10.1002/mus.10562.

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Malik Mohd Ali, Abdul, Syed Faiz Ahmed, Athar Ali, M. Kamran Joyo, Kushairy A. Kadir, and Radzi Ambar. "EMG-Based Spasticity Robotic Arm Forupper Arm Fatigue Identification." International Journal of Engineering & Technology 7, no. 2.34 (June 8, 2018): 79. http://dx.doi.org/10.14419/ijet.v7i2.34.13917.

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Electromyogram (EMG) signal reflect the electrical activity of human muscle and contains information about the structure of muscle. Furthermore, motor unit action potential (MUAP) is the results from spatial and temporal summation of difference muscle fibers of a single motor. The EMG signal results, in turn is from the summation of different MUAPs which are sufficiently near the recording electrode. EMG signal can identify the differences between signals from bicep, triceps and forearms during exercise. Raw data from the experiment is vital to assist physiotherapy to understand when the subject fatigue of noise high pick signal during rehabilitation. Several normal subjects were selected to perform experiments to understand the pattern of fatigue in early state, middle stage and last stage of exercises.

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Lateva, Zoia C., Kevin C. McGill, and M. Elise Johanson. "The innervation and organization of motor units in a series-fibered human muscle: the brachioradialis." Journal of Applied Physiology 108, no. 6 (June 2010): 1530–41. http://dx.doi.org/10.1152/japplphysiol.01163.2009.

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We studied the innervation and organization of motor units in the brachioradialis muscle of 25 normal human subjects. We recorded intramuscular EMG signals at points separated by 15 mm along the proximodistal muscle axis during moderate isometric contractions, identified from 27 to 61 (mean 39) individual motor units per subject using EMG decomposition, and estimated the locations of the endplates and distal muscle/tendon junctions from the motor-unit action potential (MUAP) propagation patterns and terminal standing waves. In three subjects all the motor units were innervated in a single endplate zone. In the other 22 subjects, the motor units were innervated in 3–6 (mean 4) distinct endplate zones separated by 15–55 mm along the proximodistal axis. One-third of the motor units had fibers innervated in more than one zone. The more distally innervated motor units had distinct terminal waves indicating tendonous termination, while the more proximal motor units lacked terminal waves, indicating intrafascicular termination. Analysis of blocked MUAP components revealed that 19% of the motor units had at least one doubly innervated fiber, i.e., a fiber innervated in two different endplate zones by two different motoneurons, and thus belonging to two different motor units. These results are consistent with the brachioradialis muscle having a series-fibered architecture consisting of multiple, overlapping bands of muscle fibers in most individuals and a simple parallel-fibered architecture in some individuals.

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Nikolic, M., and Ch Krarup. "FC13.4 Properties of fasciculation potentials (FascPs) compared to motor unit action potentials (MUAPs)." Clinical Neurophysiology 117 (September 2006): 1. http://dx.doi.org/10.1016/j.clinph.2006.06.045.

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Islam, Ihtesham ul, Khalil Ullah, Muhammad Afaq, Muhammad Hasanain Chaudary, and Muhammad Kashif Hanif. "Spatio-temporal sEMG image enhancement and motor unit action potential (MUAP) detection: algorithms and their analysis." Journal of Ambient Intelligence and Humanized Computing 10, no. 10 (July 20, 2019): 3809–19. http://dx.doi.org/10.1007/s12652-019-01411-1.

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TOKUNAGA, Tohru, Shunsuke BABA, Masahiro TANAKA, and Takayoshi KAWAZOE. "Propagation of motor unit action potential in the masticatory muscle detected by 187 pole surface electrodes." Proceeding of Japanese Society of Stomatognathic Function 9 (1991): 97–102. http://dx.doi.org/10.7144/sgf1982.9.97.

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TOKUNAGA, Tohru, Masahiro TANAKA, Tetsuji KUSUMOTO, and Takayoshi KAWAZOE. "The propagation of motor unit action potentials of masticatory muscle detected by a surface EMG electrode array." Proceeding of Japanese Society of Stomatognathic Function 6 (1988): 143–50. http://dx.doi.org/10.7144/sgf1982.6.143.

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Fortier, P. A. "Use of spike triggered averaging of muscle activity to quantify inputs to motoneuron pools." Journal of Neurophysiology 72, no. 1 (July 1, 1994): 248–65. http://dx.doi.org/10.1152/jn.1994.72.1.248.

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1. The goal of this study was to determine the extent to which postspike facilitation (PSpF) of electromyograms (EMGs) could be used to estimate the inputs to separate motoneuron pools, under conditions where there was wide variability in the parameters of muscle activity. These parameters included cancellation of motor unit action potentials (MUAPs), variations in EMG noise, and changes in MUAP amplitude and duration. A systematic series of computer simulations with increasing complexity were used to achieve this goal. The initial simulations (model I) included a premotoneuronal (PreM) cell connected to a single postsynaptic motoneuron (Mn), which in turn projected to a muscle. The next simulations (model II) included other target motoneurons with their efferents each projecting to separate muscles. The last simulations (model III) included more than one postsynaptic motoneuron per Mn-pool, as is the case in mammalian neuromuscular systems. 2. A sample simulation (model I) was performed to determine if the PreM-evoked effects were within physiologically observed values. A cross-correlogram (XC) calculated from a PreM cell and its target Mn, receiving a PreM-evoked excitatory postsynaptic potential (EPSP) of 0.5 mV, produced a XC peak area of 0.04 Mn-spikes/PreM-trigger. The PSpF of EMG activity evoked by this PreM cell had a mean percent increase of 4.6% (MPI = mean bin amplitude of PSpF above baseline/mean baseline level x 100). These XC and PSpF values were within the range of values previously obtained from animal experiments. 3. The magnitude of MUAP cancellation in the EMG was tested by calculating two spike-triggered averages (SpTAs) of EMGs from Mn-triggers (not PreM-triggers as in the other SpTAs): one using typical bipolar MUAPs and another using their rectified counterpart of only positive polarity to eliminate the possibility of MUAP cancellation. The PSpF calculated from bipolar spikes was 24.8% smaller than the one calculated using unipolar spikes. This cancellation could be greater or smaller depending on the state of parameters, such as the shape and number of MUAPs, that determine the probability of overlap between MUAP components of opposite polarity. All subsequent computer simulations used typical bipolar MUAPs. 4. A series of increasing motoneuron EPSP amplitudes were used to determine the relationship between PreM-Mn connection strength and PSpF area. A nearly perfect linear relationship between EPSP amplitude and PSpF area was obtained for SpTAs of rectified EMGs (r = 0.99). An equally linear relationship was obtained when averaging nonrectified EMGs (r = 0.99), but the smaller EPSPs or weaker synaptic connections were not detected.(ABSTRACT TRUNCATED AT 400 WORDS)

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Márquez-Figueroa, Sandra, Yuriy S. Shmaliy, and Oscar Ibarra-Manzano. "Analysis and Smoothing of EMG Signal Envelope Using Kalman and UFIR Filtering under Colored Measurement Noise." MATEC Web of Conferences 292 (2019): 04002. http://dx.doi.org/10.1051/matecconf/201929204002.

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This article describes some filtering methods to remove artifacts from the EMG signal envelope. Diverse EMG waveforms are studied using the Kalman filter (KF) and unbiased finite impulse response (UFIR) filter. The filters are developed in discrete-time state-space for Gauss-Markov colored measurement noise (CMN) and termed as cKF and cUFIR. It is shown that a choice of a proper CMN factor allows extracting the EMG waveform envelope with a high robustness. Extensive investigation have shown that the cKF and cUFIR filter are most efficient when the density is low of the motor unit action potential (MUAP) of the EMG and the Hilbert transform is required. Otherwise, when the envelope is well-pronounced and well-shaped with sharp edges due to a high MUAP density, the filters can be applied directly without using the Hilbert transform.

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Williams, J. M., C. Johnson, R. Bales, G. Lloyd, L. Barron, and D. Quest. "Analysis of Temporalis and Masseter adaptation after routine dental treatment in the horse via surface electromyography." Comparative Exercise Physiology 10, no. 4 (January 1, 2014): 223–32. http://dx.doi.org/10.3920/cep143004.

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Limited knowledge of how routine dental treatment (rasping) alters the mastication cycle exists. To our knowledge, Masseter and Temporalis muscle activity after rasping has not been previously evaluated. A descriptive, experimental study compared muscle activity pre- and post-routine dental treatment using surface electromyography (sEMG) to investigate the hypothesis that Masseter activity would increase and Temporalis activity decrease, over a 6 week time period after routine dentistry. Motor unit action potential amplitude (MUAP) and peak amplitude contraction (PAC), for 5 chewing cycles, were measured using sEMG in the right and left Masseter and Temporalis muscles of 10 horses, selected opportunistically due to their dental pathology that required routine rasping (week 0). Routine dental treatment was undertaken and sEMG measurements repeated at 1, 3 and 6 weeks post treatment. Mean MUAP and PAC were calculated for each week and compared both across the cohort and for each horse. For the cohort: Temporalis MUAP fluctuated after rasping, but was only significant in the left muscle between weeks 0 and 6, and weeks 1 and 6 (P<0.02). PAC did not differ significantly, with the exception of a decrease occurring on the left from week 0 to 1 (P<0.01). Masseter activity varied throughout the investigation, but few significant differences were found. A non-significant but consistent reduction in magnitude of PAC was found. For the individuals: MUAP and PAC in the Masseter and Temporalis muscles varied (increased / decreased) on an individual basis throughout the six weeks post rasping, although only MUAP fluctuations between weeks were significant (P<0.01). Adaptation occurs in the Masseter and Temporalis of individual horses after routine rasping; this appears to be associated with kinematic changes within the chewing cycle and is still occurring 6 weeks post-treatment.

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Höke, Ahmet, Douglas W. Zochodne, and N. B. Rewcastle. "Acute Quadriplegic Myopathy Unrelated to Steroids or Paralyzing Agents: Quantitative EMG Studies." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 26, no. 4 (November 1999): 325–29. http://dx.doi.org/10.1017/s0317167100000482.

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Background:Quadriplegic myopathy (QM) and its variants generally are described in critically ill patients who are exposed to steroids and nondepolarizing muscle blocking agents (NDMBAs).Methods:A patient with sepsis who was not exposed to steroids or an NDMBA infusion developed QM and was studied using serial quantitative electromyography.Results:Clinical and electrophysiological studies identified evidence of a severe myopathy and muscle biopsy showed necrosis, calcifications and selective loss of myosin filaments in non-necrotic fibers. Her clinical recovery paralleled rises in motor unit action potential (MUAP) amplitudes studied by serial automatic decomposition electromyography (ADEMG).Conclusion:QM can develop with sepsis and without significant exposure to steroids and NDMBAs. ADEMG can be a useful tool in electrophysiological evaluation of critically ill patients with weakness.

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HE, JINBAO, XINHUA YI, and ZAIFEI LUO. "CHARACTERIZATION OF MOTOR UNIT AT DIFFERENT STRENGTHS WITH MULTI-CHANNEL SURFACE ELECTROMYOGRAPHY." Journal of Mechanics in Medicine and Biology 17, no. 01 (February 2017): 1750024. http://dx.doi.org/10.1142/s0219519417500245.

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In this study, specific changes in electromyographic characteristics of individual motor units (MUs) associated with different muscle contraction forces are investigated using multi-channel surface electromyography (SEMG). The gradient convolution kernel compensation (GCKC) algorithm is employed to separate individual MUs from their surface interferential electromyography (EMG) signals and provide the discharge instants, which is later used in the spike-triggered averaging (STA) techniques to obtain the complete waveform. The method was tested on experimental SEMG signals acquired during constant force contractions of biceps brachii muscles in five subjects. Electromyographic characteristics including the recruitment number, waveform amplitude, discharge pattern and innervation zone (IZ) are studied. Results show that changes in the action potential of single MU with different contraction force levels are consistent with those for all MUs, and that the amplitude of MU action potentials (MUAPs) provides a useful estimate of the muscle contraction forces.

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Merlo, Andrea, Maria Giulia Montecchi, Francesco Lombardi, Xhejsi Vata, Aurora Musi, Mirco Lusuardi, Roberto Merletti, and Isabella Campanini. "Monitoring Involuntary Muscle Activity in Acute Patients with Upper Motor Neuron Lesion by Wearable Sensors: A Feasibility Study." Sensors 21, no. 9 (April 30, 2021): 3120. http://dx.doi.org/10.3390/s21093120.

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Sustained involuntary muscle activity (IMA) is a highly disabling and not completely understood phenomenon that occurs after a central nervous system lesion. We tested the feasibility of in-field IMA measuring at an acute rehabilitation ward. We used wearable probes for single differential surface EMG (sEMG), inclusive of a 3D accelerometer, onboard memory and remote control. We collected 429 h of data from the biceps brachii of 10 patients with arm plegia. Data quality was first verified in the time and frequency domains. Next, IMA was automatically identified based on the steady presence of motor unit action potential (MUAP) trains at rest. Feasibility was excellent in terms of prep time and burden to the clinical staff. A total of 350.5 h of data (81.7%) were reliable. IMA was found in 85.9 h (25%). This was often present in the form of exceedingly long-lasting trains of one or a few MUAPs, with differences among patients and variability, both within and between days in terms of IMA duration, root mean square (RMS) and peak-to-peak amplitude. Our results proved the feasibility of using wearable probes for single differential sEMG to identify and quantify IMA in plegic muscles of bedridden acute neurological patients. Our results also suggest the need for long-lasting acquisitions to properly characterize IMA. The possibility of easily assessing IMA in acute inpatients can have a huge impact on the management of their postures, physiotherapy and treatments.

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Chen, Maoqi, Xu Zhang, Zhiyuan Lu, Xiaoyan Li, and Ping Zhou. "Two-Source Validation of Progressive FastICA Peel-Off for Automatic Surface EMG Decomposition in Human First Dorsal Interosseous Muscle." International Journal of Neural Systems 28, no. 09 (September 26, 2018): 1850019. http://dx.doi.org/10.1142/s0129065718500193.

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This study aims to assess the accuracy of a novel high density surface electromyogram (SEMG) decomposition method, namely automatic progressive FastICA peel-off (APFP), for automatic decomposition of experimental electrode array SEMG signals. A two-source method was performed by simultaneous concentric needle EMG and electrode array SEMG recordings from the human first dorsal interosseous (FDI) muscle, using a protocol commonly applied in clinical EMG examination. The electrode array SEMG was automatically decomposed by the APFP while the motor unit action potential (MUAP) trains were also independently identified from the concentric needle EMG. The degree of agreement of the common motor unit (MU) discharge timings decomposed from the two different categories of EMG signals was assessed. A total of 861 and 217 MUs were identified from the 114 trials of simultaneous high density SEMG and concentric needle EMG recordings, respectively. Among them 168 common (MUs) were found with a high average matching rate of [Formula: see text] for the discharge timings. The outcomes of this study show that the APFP can reliably decompose at least a subset of MUs in the high density SEMG signals recorded from the human FDI muscle during low contraction levels using a protocol analog to clinical EMG examination.

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Messaoudi, Noureddine, Raïs El’hadi Bekka, and Samia Belkacem. "Effects of detection system parameters on cross-correlations between MUAPs generated from parallel and inclined muscle fibres." Polish Journal of Medical Physics and Engineering 27, no. 1 (March 1, 2021): 87–97. http://dx.doi.org/10.2478/pjmpe-2021-0011.

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Abstract The aim of this study was to investigate the effects of inter-electrode distance (IED), electrode radius (ER) and electrodes configurations on cross-correlation coefficient (CC) between motor unit action potentials (MUAPs) generated in a motor unit (MU) of parallel fibres and in a MU of inclined fibres with respect to the detection system. The fibres inclination angle (FIA) varied from 0° to 180° by a step of 5°. Six spatial filters (the longitudinal single differential (LSD), longitudinal double differential (LDD), bi-transversal double differential (BiTDD), normal double differential (NDD), an inverse binomial filter of order two (IB2) and maximum kurtosis filter (MKF)), three values of IED and three values of ER were considered. A cylindrical multilayer volume conductor constituted by bone, muscle, fat and skin layers was used to simulate the MUAPs. The cross-correlation coefficient analysis showed that with the increase of the FIA, the pairs of MUAPs detected by the IB2 system were more correlated than those detected by the five other systems. For each FIA, the findings also showed that the MUAPs pairs detected by BiTDD, NDD, IB2 and MKF systems were more correlated with smaller IEDs than with larger ones, while inverse results were found with the LSD and LDD systems. In addition, the pairs of MUAPs detected by the LDD, BiTDD, IB2 and MKF systems were more correlated with large ERs than with smaller ones. However, inverse results were found with the LSD and NDD systems.

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Rui, J., X. Zhao, Y. Zhu, Y. Gu, and J. Lao. "Posterior approach for accessory-suprascapular nerve transfer: an electrophysiological outcomes study." Journal of Hand Surgery (European Volume) 38, no. 3 (May 22, 2012): 242–47. http://dx.doi.org/10.1177/1753193412447495.

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The aim of this study was to retrospectively investigate the electrophysiological results obtained after employing the posterior approach for spinal accessory nerve-suprascapular nerve (SAN-SSN) transfer, and to compare this with the traditional anterior approach. SAN-SSN transfer was performed in 74 patients with brachial plexus injury. The posterior approach was used in 35 patients and the anterior approach was used in 39 patients. Electrophysiological examination was conducted and analyzed postoperatively. There was no significant difference between approaches in the time it took for the infraspinatus to show low-incidence motor unit action potentials (MUAPs) and an incomplete interference pattern. In addition, the final ratio of patients that showed regeneration potential of the infraspinatus was not significantly different between the approaches. Furthermore, latency and wave amplitude showed a linear regression with post-operative time in the posterior approach group. In the posterior approach group, the final abduction of the shoulder was positively correlated with the amplitude. The posterior approach for SAN-SSN is an effective potential alternative technique that may be appropriate for some clinical situations.

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Fernández-Cuadros, Marcos Edgar, Gabriela Goizueta-San-Martin, Blanca Varas-de-Dios, Luz Otilia Casique-Bocanegra, Pablo Manrique-de-Lara-Cadiñanos, María Jesus Albaladejo-Florin, Ruben Algarra-López, and Olga Susana Pérez-Moro. "Colchicine-Induced Rhabdomyolysis: Clinical, Biochemical, and Neurophysiological Features and Review of the Literature." Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders 12 (January 2019): 117954411984988. http://dx.doi.org/10.1177/1179544119849883.

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We report the case of a 46-years-old man with long-term asymptomatic hyperuricemia who started taking colchicine (0.5 mg/day) and allopurinol (100 mg/d) for normalization of biochemical values. After the third week of starting treatment, acute weakness was present; and by the fifth week, profound weakness in lower extremities and tenderness and cramps on thighs and calves with inability to climb stairs were also observed. Biochemical evaluation showed elevated muscle enzymes (creatinine kinase [CK] raised to five-folds its normal value) and electromyographic features were consistent with myopathy (at rest, fibrillations, positive sharp waves, high-frequency myotonic discharges; motor unit action potentials [MUAPs] of small amplitude, small duration, increased polyphasic Index and occasional satellite potentials; at maximal effort, interferential recruitment pattern with reduced amplitudes were observed). Normal motor and sensitive nerve conduction studies and normal late F-responses and H-reflex discarded neuropathy. Rapid improvement in muscle strength and prompt resolution of abnormal elevated muscle enzymes was observed after withdrawal of both medications. Colchicine is associated with some cases of myotoxicity but very small cases of colchicine-induced rhabdomyolysis are reported on the literature. Colchicine-induced rhabdomyolysis is related to the concomitant use of drugs (statins, steroids, erythromycin, and cyclosporine), renal, and/or hepatic impairment. To the best of our knowledge, this is an uncommon presentation of a case of colchicine-induced rhabdomyolysis reported in a patient without renal or hepatic dysfunction. Therefore, patients receiving colchicine even in the absence of renal insufficiency should be monitored for the development of myopathy and more rarely to rhabdomyolysis.

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Elouaham, S., A. Dliou, Mostafa Laaboubi, R. Latif, N. Elkamoun, and H. Zougagh. "Filtering and analyzing normal and abnormal electromyogram signals." Indonesian Journal of Electrical Engineering and Computer Science 20, no. 1 (October 1, 2020): 176. http://dx.doi.org/10.11591/ijeecs.v20.i1.pp176-184.

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<p><span>The electromyogram (EMG) is an important measurement to assess the health of muscles and the nerve cells that control them. The appearance of noise in electromyography (EMG) signals may unquestionably minimize the efficiency of the analysis of the signal. The denoising techniques are inevitable for minimizing noise affecting the EMG signals; these methods are Complete Ensemble Empirical Mode Decompositions with Adaptive Noise (CEEMDAN) and the Ensemble Empirical Mode Decomposition (EEMD). After that, we analyze these signals by time-frequency techniques as Adaptive Optimal Kernel (AOK) and Choi-Williams. Firstly, the obtained results illustrate the effectiveness of the CEEMDAN that permits reducing noise that interferes with normal and abnormal EMG signals with higher resolution than other techniques used as EEMD. Secondly, they show that the AOK technique is adapted to the detection and classification of these types of normal and abnormal EMG signals by the good localization of the Motor Unit Action Potentials (MUAPs) in the time-frequency plan. This paper shows the efficiency of the combination of the AOK and CEEMDAN techniques in analyzing the EMG signals. </span></p>

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Botwin, Kenneth P. "Electromyographically Guided Trigger Point Injections in the Cervicothoracic Musculature of Obese Patients: A New and Unreported Technique." November 2007 6;10, no. 6;11 (November 14, 2007): 753–56. http://dx.doi.org/10.36076/ppj.2007/10/753.

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Background: Myofascial pain is defined as pain that originates from myofascial trigger points in skeletal muscle. It is prevalent in regional musculoskeletal pain syndromes, either alone or in combination with other pain generators. The myofascial pain syndrome is one of the largest groups of under-diagnosed and under-treated medical problems encountered in clinical practice. Trigger points are commonly seen in patients with myofascial pain that can be responsible for localized pain in the affected muscles as well as referred pain patterns. Correct needle placement in a myofascial trigger point is vital to prevent complications and improve efficacy of the trigger point injection to help reduce or relieve myofascial pain. In the obese patients, these injections may not reach the target tissue. In the cervicothoracic spine, a misguided or misplaced injection can result in a pneumothorax. Here, we review an electromyographically guided trigger point injection technique to avoid this potential pitfall. Methods: Using a disposable Teflon coated hypodermic injection needle attached to an electromyography (EMG) machine, a trigger point injection can be performed utilizing electromyographic guidance. This guidance by observing motor unit action potentials (MUAPs) on the EMG screen helps confirm the needle placement to be within the muscle tissue and not in an adipose tissue or any other non-musculature structure. Results: The technique is simple when performed by a pain management specialist who has electromyographic training. Conclusion: This technique helps confirm proper needle placement within the cervicothoracic musculature in an obese patient in whom the musculature is not readily palpated. This, thus, reduces the potential for a pneumothorax by an improperly placed injection. Key words: Trigger point injection, myofascial pain, electromyography

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SCHACK, BÄRBEL, PETER RAPPELSBERGER, CHRISTOPH ANDERS, SABINE WEISS, and EVA MÖLLER. "QUANTIFICATION OF SYNCHRONIZATION PROCESSES BY COHERENCE AND PHASE AND ITS APPLICATION IN ANALYSIS OF ELECTROPHYSIOLOGICAL SIGNALS." International Journal of Bifurcation and Chaos 10, no. 11 (November 2000): 2565–86. http://dx.doi.org/10.1142/s0218127400001651.

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Neuronal activity during information processing and muscle activity are generally characterized by oscillations. Mostly, widespread areas are involved and electrophysiological signals are measured on different sites of the cortex or of the muscle. In order to investigate functional relationships between different components of multidimensional electrophysiological signals, coherence and phase analyses turned out to be useful tools. These parameters allow the investigation of synchronization phenomena with regard to oscillations of defined frequencies or frequency bands. Coherence and phase are closely connected spectral parameters. Coherence may be understood as a measure of phase stability. Whereas coherence describes the amount of common information with regard to oscillations within certain frequency bands, the corresponding phase, from which time delays of these oscillations can be computed, hints at the direction of information transfer through oscillation. Coherence and phase analysis of surface EMG during continuous activity of deep and superficial muscles show distinct differences due to volume conduction properties of myoelectrical signals. Superficial activity therefore is characterized by significant coherence and stable phase relationships, which, additionally, can be used to determine motor unit action potential (MUAP) propagation velocity along the fibre direction without application of invasive methods. Deep muscle activity lacks significant coherence. Mental processes can be very brief and cooperation between different areas may be highly dynamic. For this reason in addition to usual Fourier estimation of coherence and phase, a two-dimensional approach of adaptive filtering was developed to estimate coherence and phase continuously in time. Statistical and dynamic properties of instantaneous phase are discussed. In order to demonstrate the value of this method for studying higher cognitive processes the method was applied to EEG recorded during word processing. During visual presentation of abstract nouns an information transfer through the propagation of oscillations from visual areas to frontal association areas in the α1-frequency band could be verified within the first 400 ms. In contrast, in case of auditory presentation positive phases from the temporal electrode locations T3 and T4 towards the occipital areas appear within the time interval of 300 ms–600 ms. The α1-band predominately seems to reflect sensory processing and attention processes.

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32

Etawil, H., and D. Stashuk. "Resolving superimposed motor unit action potentials." Medical & Biological Engineering & Computing 34, no. 1 (January 1996): 33–40. http://dx.doi.org/10.1007/bf02637020.

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33

Özdemirkiran, Tolga, and Cumhur Ertekin. "Cremaster muscle motor unit action potentials." Clinical Neurophysiology 122, no. 8 (August 2011): 1679–85. http://dx.doi.org/10.1016/j.clinph.2010.12.057.

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34

Dobrowolski, A., K. Tomczykiewicz, and P. Komur. "Spectral Analysis of Motor Unit Action Potentials." IEEE Transactions on Biomedical Engineering 54, no. 12 (December 2007): 2300–2302. http://dx.doi.org/10.1109/tbme.2007.895752.

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35

Nandedkar, Sanjeev D., and Donald B. Sanders. "Simulation of myopathic motor unit action potentials." Muscle & Nerve 12, no. 3 (March 1989): 197–202. http://dx.doi.org/10.1002/mus.880120306.

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Krarup, C., K. Dahl, L. S. Jakobsen, A. Talbot, and J. A. Sørensen. "Unbiased acquisition of motor unit action potentials." Electroencephalography and Clinical Neurophysiology 87, no. 2 (August 1993): S100. http://dx.doi.org/10.1016/0013-4694(93)91319-v.

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37

Doherty, Timothy J., and William F. Brown. "Age-related changes in the twitch contractile properties of human thenar motor units." Journal of Applied Physiology 82, no. 1 (January 1, 1997): 93–101. http://dx.doi.org/10.1152/jappl.1997.82.1.93.

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Doherty, Timothy J., and William F. Brown. Age-related changes in the twitch contractile properties of human thenar motor units. J. Appl. Physiol. 82(1): 93–101, 1997.—The purpose of this study was to examine the effects of aging on the contractile and electrophysiological properties of human thenar motor units (MUs). Percutaneous electrical stimulation of single motor axons within the median nerve was used to isolate and examine the twitch tensions, contractile speeds, and surface-detected MU action potential (S-MUAP) sizes of 48 thenar MUs in 17 younger subjects (25–53 yr) and 44 thenar MUs in 9 older subjects (64–77 yr). A wide range of twitch tensions, contractile speeds, and S-MUAP sizes was observed in both age groups. However, older subjects had significantly larger MU twitch tensions and slower MU twitch contraction and half-relaxation times. These changes were accompanied by increased S-MUAP sizes. These findings suggest that the human thenar MU pool undergoes significant age-related increase in MU size and slowing of contractile speed. Such adaptation may help to overcome previously reported age-related losses of thenar MUs.

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38

Pattichis, C. S., and M. S. Pattichis. "Time-scale analysis of motor unit action potentials." IEEE Transactions on Biomedical Engineering 46, no. 11 (1999): 1320–29. http://dx.doi.org/10.1109/10.797992.

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39

Stashuk, D., and G. M. Paoli. "Robust supervised classification of motor unit action potentials." Medical & Biological Engineering & Computing 36, no. 1 (January 1998): 75–82. http://dx.doi.org/10.1007/bf02522861.

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40

Lööf, Y. "Model for decomposition of the motor unit action potential 2 Analysis of simulated motor unit action potentials." Medical & Biological Engineering & Computing 24, no. 5 (September 1986): 513–20. http://dx.doi.org/10.1007/bf02443968.

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Pattichis, Constantinos S., and Andreas G. Elia. "Autoregressive and cepstral analyses of motor unit action potentials." Medical Engineering & Physics 21, no. 6-7 (July 1999): 405–19. http://dx.doi.org/10.1016/s1350-4533(99)00072-7.

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42

Stashuk, Daniel William. "Detecting single fiber contributions to motor unit action potentials." Muscle & Nerve 22, no. 2 (February 1999): 218–29. http://dx.doi.org/10.1002/(sici)1097-4598(199902)22:2<218::aid-mus10>3.0.co;2-s.

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43

Nandedkar, Sanjeev D., Donald B. Sanders, Erik V. Stälberg, and Steen Andreassen. "Simulation of concentric needle EMG motor unit action potentials." Muscle & Nerve 11, no. 2 (February 1988): 151–59. http://dx.doi.org/10.1002/mus.880110211.

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Merletti, Roberto, and Dario Farina. "Analysis of intramuscular electromyogram signals." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, no. 1887 (November 11, 2008): 357–68. http://dx.doi.org/10.1098/rsta.2008.0235.

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Intramuscular electromyographic (EMG) signals are detected with needles or wires inserted into muscles. With respect to non-invasive techniques, intramuscular electromyography has high selectivity for individual motor unit action potentials and is thus used to measure motor unit activity. Decomposition of intramuscular signals into individual motor unit action potentials consists in detection and classification, usually followed by separation of superimposed action potentials. Although intramuscular EMG signal decomposition is the primary tool for physiological investigations of motor unit properties, it is rarely applied in clinical routine, because of the need for human interaction and the difficulty in interpreting the quantitative data provided by EMG signal decomposition to support clinical decisions. The current clinical use of intramuscular EMG signals relates to the diagnosis of myopathies, of diseases of the α-motor neuron and of the neuromuscular junction through the analysis of the interference signal or of the shape of some motor unit action potentials, usually without a full decomposition of the signal.

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Ozdemirkiran, T., and C. Ertekin. "P13-19 Motor unit action potentials of the cremaster muscle." Clinical Neurophysiology 121 (October 2010): S183. http://dx.doi.org/10.1016/s1388-2457(10)60750-x.

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Dumitru, Daniel, John C. King, and Sanjeev D. Nandedkar. "Motor unit action potentials recorded with concentric electrodes: physiologic implications." Electroencephalography and Clinical Neurophysiology/Electromyography and Motor Control 105, no. 5 (October 1997): 333–39. http://dx.doi.org/10.1016/s0924-980x(97)00025-8.

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Gregory, W. Thomas, Amanda L. Clark, Joshua Johnson, Kimberly Willis, Amy Stuyvesant, and Jau-Shin Lou. "Anal sphincter electromyography: Editing of sampled motor unit action potentials." Muscle & Nerve 31, no. 2 (2005): 256–59. http://dx.doi.org/10.1002/mus.20165.

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Sleutjes, B. T. H. M., M. De Vos, J. H. Blok, I. Montfoort, B. Mijović, M. Signoretto, S. Van Huffel, and I. Gligorijević. "Motor Unit Tracking Using High Density Surface Electromyography (HDsEMG)." Methods of Information in Medicine 54, no. 03 (2015): 221–26. http://dx.doi.org/10.3414/me13-02-0049.

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SummaryIntroduction: This article is part of the Focus Theme of Methods of Information in Medicine on “Biosignal Interpretation: Advanced Methods for Neural Signals and Images”.Objectives: The study discusses a technique to automatically correct for effects of electrode grid displacement across serial surface EMG measurements with high-density electrode arrays (HDsEMG). The goal is to match motor unit signatures from subsequent measurements and by this, achieve automated motor unit tracking.Methods: Test recordings of voluntary muscle contractions using HDsEMG were performed on three healthy individuals. Electrode grid displacements were mimicked in repeated recordings while measuring the exact position of the grid. A concept of accounting for translational and rotational displacements by making the projection of the recorded motor unit action potentials is first introduced. Then, this concept was tested for the performed measurements attempting the automated matching of the similar motor unit action potentials across different trials.Results: The ability to perform automated correction (projection) of the isolated motor unit action potentials was first shown using large angular displacements. Then, for accidental (small) displacements of the recording grid, the ability to automatically track motor units across different measurement trials was shown. It was possible to track 10 –15% of identified motor units.Conclusions: This proof of concept study demonstrates an automated correction allowing the identification of an increased number of same motor unit action potentials across different measurements. By this, great potential is demonstrated for assisting motor unit tracking studies, indicating that otherwise electrode displacements cannot always be precisely described.

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Howard, Januarye E., Kevin C. McGill, and Leslie J. Dorfman. "Age effects on properties of motor unit action potentials: ADEMG analysis." Annals of Neurology 24, no. 2 (August 1988): 207–13. http://dx.doi.org/10.1002/ana.410240206.

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Beck, Rebecca B., Mark J. O'malley, Dick F. Stegeman, Caroline J. Houtman, Sean Connolly, and Machiel J. Zwarts. "Tracking motor unit action potentials in the tibialis anterior during fatigue." Muscle & Nerve 32, no. 4 (2005): 506–14. http://dx.doi.org/10.1002/mus.20375.

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Journal articles on the topic 'Motor Unit Action Potentials (MUAP)'

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