1,535 results match your criteria Motor Unit Recruitment in EMG


Estimates of persistent inward currents in tibialis anterior motor units during standing ramped contraction tasks in humans.

J Neurophysiol 2021 06 16. Epub 2021 Jun 16.

Department of Health and Rehabilitation Sciences, Temple University, Philadelphia, PA, United States.

Persistent inward currents (PICs) play an essential role in setting motor neuron gain and shaping motor unit firing patterns. Estimates of PICs in humans can be made using the paired motor unit analysis technique, which quantifies the difference in discharge rate of a lower-threshold motor unit at the recruitment onset and offset of a higher-threshold motor unit (∆F). Because PICs are highly dependent on the level of neuromodulatory drive, ∆F represents an estimate of level of neuromodulation at the level of the spinal cord. Read More

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Neural control of the healthy pectoralis major from low-to-moderate isometric contractions.

J Neurophysiol 2021 Jun 9. Epub 2021 Jun 9.

Department of Kinesiology, grid.46078.3dUniversity of Waterloo, Canada.

The pectoralis major critically enables arm movement in several directions. However, its neural control remains unknown. High-density electromyography (HD-sEMG) was acquired from the pectoralis major in two sets of experiments in healthy young adults. Read More

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A Case of Elsberg Syndrome in the Setting of Asymptomatic SARS-CoV-2 Infection.

J Clin Neuromuscul Dis 2021 Jun;22(4):228-231

Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY; and.

Abstract: Elsberg syndrome is a rare cause of lumbosacral radiculitis with concomitant thoracic and lumbosacral myelitis that can be seen after an acute or reactivated viral infection. After the initial coronavirus surge in New York City, a 68-year-old man developed progressive lower extremity weakness and a defined sensory level at the lower abdomen. He had highly elevated SARS-CoV-2 IgG antibodies despite an absence of preceding COVID-19 symptoms. Read More

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Extended Neuralgic Amyotrophy Syndrome in a Confirmed COVID-19 Patient After Intensive Care Unit and Inpatient Rehabilitation Stay: A Case Report.

Am J Phys Med Rehabil 2021 May 17. Epub 2021 May 17.

Department of Physical Medicine and Rehabilitation, University of Miami/Jackson Memorial Hospital, Miami, FL, USA. University of Miami Miller School of Medicine Department of Physical Medicine and Rehabilitation, University of Miami Leonard M. Miller School of Medicine, Miami, Florida Department of Radiology, Jackson Memorial Hospital, Miami, FL, USA.

Abstract: The cause of neuralgic amyotrophy (NA) is often unknown but is commonly associated with a recent upper respiratory viral tract infection. Since the beginning of the COVID-19 pandemic, there has been a tireless effort to understand the sequelae of the virus. A 46-year-old woman who presented after a COVID-19 hospitalization complicated by hypoxic respiratory failure requiring intubation and mechanical ventilation for 23 days was subsequently found to have lower extremity sensorium changes as well as upper extremity weakness. Read More

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Vocal fold injection material does not preclude interpretation of laryngeal electromyography.

Muscle Nerve 2021 Jul 20;64(1):104-108. Epub 2021 May 20.

Department of Otolaryngology, University of Pittsburgh Voice Center, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.

Introduction/aims: Temporary vocal fold injection (VFI) is a common treatment for acute and subacute vocal fold paralysis (VFP). Laryngeal electromyography (LEMG) is useful for diagnosing neurogenic causes of VFP. This study evaluated whether the presence of VFI material prevents interpretation of LEMG in patients with acute and subacute VFP. Read More

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Neural control of matched motor units during muscle shortening and lengthening at increasing velocities.

J Appl Physiol (1985) 2021 Jun 6;130(6):1798-1813. Epub 2021 May 6.

Department of Clinical and Experimental Sciences, Università degli Studi di Brescia, Brescia, Italy.

Modulation of movement velocity is necessary during daily life tasks, work, and sports activities. However, assessing motor unit behavior during muscle shortening and lengthening at different velocities is challenging. High-density surface electromyography (HD-sEMG) is an established method to identify and track motor unit behavior in isometric contractions. Read More

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Analysis of motor unit spike trains estimated from high-density surface electromyography is highly reliable across operators.

J Electromyogr Kinesiol 2021 Jun 30;58:102548. Epub 2021 Mar 30.

Department of Bioengineering, Faculty of Engineering, Imperial College London, UK.

There is a growing interest in decomposing high-density surface electromyography (HDsEMG) into motor unit spike trains to improve knowledge on the neural control of muscle contraction. However, the reliability of decomposition approaches is sometimes questioned, especially because they require manual editing of the outputs. We aimed to assess the inter-operator reliability of the identification of motor unit spike trains. Read More

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Characteristics of the Electrophysiological Properties of Neuromuscular Motor Units and Its Adaptive Strategy Response in Lower Extremity Muscles for Seniors with Pre-Sarcopenia: A Preliminary Study.

Int J Environ Res Public Health 2021 03 16;18(6). Epub 2021 Mar 16.

Department of Sports Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.

Older adults with sarcopenia, which is an aging-related phenomenon of muscle mass loss, usually suffer from decreases in both strength and functional performance. However, the causality between function loss and physiological changes is unclear. This study aimed to explore the motor unit characteristics of the neurological factors between normal subjects and those with sarcopenia. Read More

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Quercetin ingestion modifies human motor unit firing patterns and muscle contractile properties.

Exp Brain Res 2021 May 19;239(5):1567-1579. Epub 2021 Mar 19.

Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia.

Quercetin is a polyphenolic flavonoid that has reported to block the binding of adenosine to A1 receptors at central nervous system and increase calcium release from the sarcoplasmic reticulum at skeletal muscle. The aim of the present study was to investigate the acute effect of quercetin ingestion on motor unit activation and muscle contractile properties. High-density surface electromyography during submaximal contractions and electrically elicited contraction torque in knee extensor muscles were measured before (PRE) and 60 min after (POST) quercetin glycosides or placebo ingestions in 13 young males. Read More

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Negative motor responses to direct electrical stimulation: Behavioral assessment hides different effects on muscles.

Cortex 2021 Apr 29;137:194-204. Epub 2021 Jan 29.

Laboratory of Motor Control, Department of Medical Biotechnologies and Translational Medicine, Università degli Studi di Milano, Humanitas Research Hospital IRCSS, Rozzano, Milano, Italy. Electronic address:

A negative motor response (NMR) is defined as the inability to continue voluntary movements without losing consciousness when direct electrical stimulation (DES) is applied during awake neurosurgery. While visual inspection is most commonly used to define an NMR, the actual effect of stimulation on muscle activity has been neglected by recent neurosurgical literature. We show that behavioral assessment of NMRs hides different site-dependent effects on muscles as revealed by electromyography (EMG), describing ten cases of brain tumor patients undergoing awake neurosurgery while performing a hand-object manipulation task. Read More

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Toward improving functional recovery in spinal cord injury using robotics: a pilot study focusing on ankle rehabilitation.

Expert Rev Med Devices 2021 Mar 5:1-13. Epub 2021 Mar 5.

IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy.

Conventional physical therapy interventions are strongly recommended to improve ambulation potential and upright mobility in persons with incomplete spinal cord injury (iSCI). Ankle rehabilitation plays a significant role, as it aims to stem drop foot consequences. This pilot study aimed to assess the neurophysiological underpinnings of robot-aided ankle rehabilitation (using a platform robot) compared to conventional physiotherapy and its efficacy in improving gait performance and balance in persons with iSCI. Read More

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Effects of vibratory massage therapy on grip strength, endurance time and forearm muscle performance.

Work 2021 ;68(3):619-632

Ergonomics Research Division, Department of Mechanical Engineering, ZHCET Faculty of Engineering & Technology, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.

Background: Vibration therapy (VT) causes an increase in motor unit activation tendency, an involuntary recruitment of earlier sedentary motor units, which increases the muscle fiber force generating capacity and muscle performance.

Objective: To evaluate the effect of vibratory massage therapy at 23 Hz and 35 Hz on grip strength, endurance, and forearm muscle performance (in terms of EMG activity).

Methods: Ten healthy and right-handed men participated voluntarily in this study. Read More

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January 2021

Motor unit reserve capacity in spinal muscular atrophy during fatiguing endurance performance.

Clin Neurophysiol 2021 Mar 28;132(3):800-807. Epub 2021 Jan 28.

Faculty of Behavioral and Movement Sciences, Vrije Universiteit Amsterdam, Van der Boechorststraat 7, 1081 BT Amsterdam, the Netherlands.

Objective: To investigate the availability of any motor unit reserve capacity during fatiguing endurance testing in patients with spinal muscular atrophy (SMA).

Methods: We recorded surface electromyography (sEMG) of various muscles of upper- and lower extremities of 70 patients with SMA types 2-4 and 19 healthy controls performing endurance shuttle tests (ESTs) of arm and legs. We quantitatively evaluated the development of fatigability and motor unit recruitment using time courses of median frequencies and amplitudes of sEMG signals. Read More

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Comparison between surface electrodes and ultrasound monitoring to measure TMS evoked muscle contraction.

Muscle Nerve 2021 05 25;63(5):724-729. Epub 2021 Feb 25.

Department of Clinical and Movement Neuroscience, UCL Queen Square Institute of Neurology, London, UK.

Introduction: Transcranial magnetic stimulation (TMS) is widely used to explore cortical physiology in health and disease. Surface electromyography (sEMG) is appropriate for superficial muscles, but cannot be applied easily to less accessible muscles. Muscle ultrasound (mUS) may provide an elegant solution to this problem, but fundamental questions remain. Read More

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Quantitative T -mapping magnetic resonance imaging for assessment of muscle motor unit recruitment patterns.

Muscle Nerve 2021 05 12;63(5):703-709. Epub 2021 Feb 12.

Department of Radiology and Imaging, Hospital for Special Surgery, New York, New York, USA.

Introduction: In this study, we aimed to determine whether muscle transverse relaxation time (T ) magnetic resonance (MR) mapping results correlate with motor unit loss, as defined by motor unit recruitment patterns on electromyography (EMG).

Methods: EMG and 3-Tesla MRI exams were acquired no more than 31 days apart in subjects referred for peripheral nerve MRI. Two musculoskeletal radiologists qualitatively graded T -weighted, fat-suppressed sequences for severity of muscle edema-like patterns and manually placed regions of interest within muscles to obtain T values from T -mapping sequences. Read More

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Motor unit action potential amplitude during low torque fatiguing contractions versus high torque non-fatiguing contractions: a multilevel analysis.

Eur J Appl Physiol 2021 Apr 23;121(4):1145-1157. Epub 2021 Jan 23.

Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, 12805 Pegasus Drive, HS 1, Room 258, Orlando, FL, 32816-2205, USA.

Purpose: The ability to maintain an absolute, submaximal torque level during fatiguing contractions is controlled, in part, by the recruitment of larger motor units. These motor units are commonly identified based on greater action potential peak-to-peak amplitude values. It is unclear, however, if motor unit action potential (MUAP) amplitude values during low torque, fatiguing contractions reach similar levels as those observed during non-fatigued, high torque contractions. Read More

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The Effects of Spinal Manipulation on Motor Unit Behavior.

Brain Sci 2021 Jan 14;11(1). Epub 2021 Jan 14.

Centre for Chiropractic Research, New Zealand College of Chiropractic, Auckland 1060, New Zealand.

Over recent years, a growing body of research has highlighted the neural plastic effects of spinal manipulation on the central nervous system. Recently, it has been shown that spinal manipulation improved outcomes, such as maximum voluntary force and limb joint position sense, reflecting improved sensorimotor integration and processing. This study aimed to further evaluate how spinal manipulation can alter neuromuscular activity. Read More

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January 2021

Identification of the laterality of motor unit behavior in female patients with parkinson's disease using high-density surface electromyography.

Eur J Neurosci 2021 Mar 12;53(6):1938-1949. Epub 2021 Jan 12.

Faculty of Frontier Engineering, Institute of Science & Engineering, Kanazawa University, Kanazawa, Japan.

Patients with Parkinson's disease (PD) have greater laterality of muscle contraction properties than other people with parkinsonism diseases. However, few studies have reported the laterality of MU activation properties of the lower extremity muscles in patients with PD. The aim of the present study was to identify the laterality of MU behavior in PD patients using high-density surface electromyography (HD-SEMG). Read More

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Is the 'reverse onion skin' phenomenon more prevalent than we thought during intramuscular myoelectric recordings from low to maximal force outputs?

Neurosci Lett 2021 01 19;743:135583. Epub 2020 Dec 19.

Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, L2S 3A1, Canada.

There are isolated instances in the literature that suggest the 'onion skin' phenomenon is not always present. That is, newly recruited high threshold motor units (MU) have higher discharge rates than previously recruited low threshold MUs. Therefore, the purpose of this paper was to investigate the presence of the 'onion skin' phenomenon in a large sample of intramuscular myoelectric recordings from low to maximal force outputs. Read More

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January 2021

Rigorous performance assessment of the algorithms for resolving motor unit action potential superpositions.

J Electromyogr Kinesiol 2021 Feb 13;56:102510. Epub 2020 Dec 13.

Department of Automatic Control, Biomedical Engineering Research Center, Universitat Politècnica de Catalunya, BarcelonaTech (UPC), Barcelona, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), Barcelona, Spain. Electronic address:

It is necessary to decompose the intra-muscular EMG signal to extract motor unit action potential (MUAP) waveforms and firing times. Some algorithms were proposed in the literature to resolve superimposed MUAPs, including Peel-Off (PO), branch and bound (BB), genetic algorithm (GA), and particle swarm optimization (PSO). This study aimed to compare these algorithms in terms of overall accuracy and running time. Read More

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February 2021

The Effect of Spinal Manipulation on the Electrophysiological and Metabolic Properties of the Tibialis Anterior Muscle.

Healthcare (Basel) 2020 Dec 10;8(4). Epub 2020 Dec 10.

Centre for Chiropractic Research, New Zealand College of Chiropractic, Auckland 1060, New Zealand.

There is growing evidence showing that spinal manipulation increases muscle strength in healthy individuals as well as in people with some musculoskeletal and neurological disorders. However, the underlying mechanism by which spinal manipulation changes muscle strength is less clear. This study aimed to assess the effects of a single spinal manipulation session on the electrophysiological and metabolic properties of the tibialis anterior (TA) muscle. Read More

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December 2020

Muscles from the same muscle group do not necessarily share common drive: evidence from the human triceps surae.

J Appl Physiol (1985) 2021 Feb 26;130(2):342-354. Epub 2020 Nov 26.

School of Biomedical Sciences, The University of Queensland, Brisbane, Australia.

It has been proposed that movements are produced through groups of muscles, or motor modules, activated by common neural commands. However, the neural origin of motor modules is still debated. Here, we used complementary approaches to determine: ) whether three muscles of the same muscle group [soleus, gastrocnemius medialis (GM), and gastrocnemius lateralis (GL)] are activated by a common neural drive, and ) whether the neural drive to GM and GL could be differentially modified by altering the mechanical requirements of the task. Read More

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February 2021

Dysfunctional muscle activities and co-contraction in the lower-limb of lumbar disc herniation patients during walking.

Sci Rep 2020 11 24;10(1):20432. Epub 2020 Nov 24.

Department of Physical Medicine and Rehabilitation, Qilu Hospital, Cheeloo College of Medicine, Shandong University, 107 Wenhuaxi Road, Jinan, 250012, Shandong, China.

This study aimed to investigate lower-limb muscle activities in gait phases and co-contraction of one gait cycle in patients with lumbar disc herniation (LDH). This study enrolled 17 LDH patients and 17 sex- and age-matched healthy individuals. Bilateral muscle activities of the rectus femoris (RF), biceps femoris long head (BL), tibialis anterior (TA), and lateral gastrocnemius (LG) during walking were recorded. Read More

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November 2020

Impaired Firing Behavior of Individually Tracked Paretic Motor Units During Fatiguing Contractions of the Dorsiflexors and Functional Implications Post Stroke.

Front Neurol 2020 29;11:540893. Epub 2020 Oct 29.

Department of Physical Therapy, Marquette University, Milwaukee, WI, United States.

This study quantified stroke-related changes in the following: (1) the averaged discharge rate of motor units (individually tracked and untracked) identified from high-density electromyography (HD-EMG) recordings, (2) global muscle EMG properties of the dorsiflexors during a fatiguing contraction, and the relationship between task endurance and measures of leg function. Ten individuals with chronic stroke performed a sustained sub-maximal, isometric, fatiguing dorsiflexion contraction in paretic and non-paretic legs. Motor-unit firing behavior, task duration, maximal voluntary contraction strength (MVC), and clinical measures of leg function were obtained. Read More

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October 2020

SWEAT² study: effectiveness of trunk training on muscle activity after stroke. A randomized controlled trial.

Eur J Phys Rehabil Med 2020 Nov 9. Epub 2020 Nov 9.

MOVANT/REVAKI, Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Science, University of Antwerp, Antwerp, Belgium.

Background: Trunk training after stroke is an effective method for improving trunk control, standing balance and mobility. The SWEAT² study attempts to discover the underlying mechanisms leading to the observed mobility carry-over effects after trunk training.

Aim: A secondary analysis investigating the effect of trunk training on muscle activation patterns, muscle synergies and motor unit recruitment of trunk and lower limbs muscles, aimed to provide new insights in gait recovery after stroke. Read More

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November 2020

Neural Drive is Greater for a High-Intensity Contraction Than for Moderate-Intensity Contractions Performed to Fatigue.

J Strength Cond Res 2020 Nov;34(11):3013-3021

Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, Kansas; and.

Miller, JD, Lippman, JD, Trevino, MA, and Herda, TJ. Larger motor units are recruited for high-intensity contractions than for fatiguing moderate-intensity contractions. J Strength Cond Res 34(11): 3013-3021, 2020-The purpose of this study was to investigate whether moderate-intensity contractions performed to fatigue activate the motor unit (MU) pool to the same extent as a higher-intensity contraction. Read More

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November 2020

Sensitivity and specificity of single and combined clouds analyses compared with quantitative motor unit potential analysis.

Muscle Nerve 2021 02 13;63(2):225-230. Epub 2020 Nov 13.

Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China.

Introduction: Turns-amplitude, number of small segments (NSS)-activity, and envelope-activity clouds are three methods of electromyography (EMG) interference pattern analysis. Our objective was to evaluate the sensitivity and specificity of each individual cloud analysis and combined clouds analysis to compare with that of quantitative motor unit potential (QMUP) analysis.

Methods: A total of 379 muscles from 100 patients were analyzed by both QMUP and clouds analyses. Read More

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February 2021

Differential value of external anal- and urethral-sphincter electromyography in multiple system atrophy cerebellar type and spinocerebellar ataxias.

J Clin Neurosci 2020 Oct 15;80:16-22. Epub 2020 Aug 15.

Department of Neurology, Sixth Medical Center of Chinese PLA General Hospital, Beijing, China. Electronic address:

Objective: Clinically differentiating multiple system atrophy cerebellar type (MSA-C) and spinocerebellar ataxias (SCAs) is challenging, especially at early disease stages, because of their similarities in clinical manifestation and imaging results. The purpose of this study was to explore the value of external anal-sphincter electromyography (EAS-EMG) and urethral-sphincter electromyography (US-EMG) for distinguishing between MSA-C and SCAs.

Methods: A total of 51 subjects, including 33 MSA-C and 18 SCAs, were recruited. Read More

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October 2020

Motor axonal neuropathy associated with GNE mutations.

Muscle Nerve 2021 03 24;63(3):396-401. Epub 2020 Dec 24.

Côte d'Azur University, Peripheral Nervous System and Muscle Department, Nice University Hospital, Nice, France.

Background: Mutations in the GNE gene have been so far described as predominantly associated with distal lower-limb myopathies. Recent reports describe mutations in this gene in patients with peripheral neuropathy and motor neuron disease.

Methods: We describe three patients displaying motor neuropathy in association with GNE mutations. Read More

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The effect of electrical muscle stimulation on quadriceps muscle strength and activation patterns in healthy young adults.

Eur J Sport Sci 2020 Nov 10:1-9. Epub 2020 Nov 10.

Department of Rehabilitation Medicine, Hiroshima University Hospital, Hiroshima, Japan.

The aim of the present study was to clarify the effect of electrical muscle stimulation (EMS) on the spatial distribution pattern of electromyographic activity in healthy young adults using multi-channel surface electromyography (SEMG). A total of 32 men (age = 21-26 years) were randomly assigned to the intervention group (= 18) and control group (= 14). Participants in the intervention group performed EMS to stimulate the bilateral lower limb muscle for four weeks (20 min/3 days/week). Read More

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November 2020