1,612 results match your criteria Motor Unit Recruitment in EMG

Sex differences in the detection of motor unit action potentials identified using high-density surface electromyography.

J Electromyogr Kinesiol 2022 Jun 9;65:102675. Epub 2022 Jun 9.

Department of Health and Rehabilitation Sciences, Temple University, United States. Electronic address:

Sex-related disparities in force production of humans have been widely observed. Previous literature has attributed differences in peripheral traits, such as muscle size, to explain these disparities. However, less is known about potential sex-related differences in central neuromuscular traits and many comparable studies, not exploring sex-related differences, exhibit a selection-bias in the recruitment of subjects making the generalization of their findings difficult. Read More

View Article and Full-Text PDF

Motor Unit Recruitment is Altered When Acute Experimental Pain is Induced at a Site Distant to the Contracting Muscle.

Neuroscience 2022 Jun 13. Epub 2022 Jun 13.

The University of Queensland, School of Biomedical Sciences, Brisbane, Queensland, Australia. Electronic address:

Acute pain alters motor unit discharge properties in muscles that are painful or influence loading of painful structures. Less is known about the changes in discharge when pain is induced in distant tissues that are unable or have limited capacity to modify the load of the contracting muscle. We aimed to determine whether acute experimental pain alters quadriceps motor unit discharge when pain is induced in; (i) a muscle that is unlikely to be mechanically influenced by modified quadriceps activity (tibialis anterior: TA), or (ii) the antagonist muscle (biceps femoris: BF). Read More

View Article and Full-Text PDF

Differences in motor unit recruitment patterns and low frequency oscillation of discharge rates between unilateral and bilateral isometric muscle contractions.

Hum Mov Sci 2022 Jun 23;83:102952. Epub 2022 Apr 23.

Department of Health and Kinesiology, Texas A&M University, College Station, TX 77843, United States of America. Electronic address:

Introduction: Distinct cortical activities contribute to unilateral and bilateral motor control. However, it remains largely unknown whether the behavior of motor neurons differs between unilateral and bilateral isometric force generation. Here, we first investigated motor units (MUs) recruitment patterns during unilateral and bilateral force generation. Read More

View Article and Full-Text PDF

Motor Unit and Capillary Recruitment During Fatiguing Arm-Cycling Exercise in Spinal Muscular Atrophy Types 3 and 4.

J Neuromuscul Dis 2022 ;9(3):397-409

Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, Utrecht University, Utrecht, The Netherlands.

Background: Exercise intolerance is an important impairment in patients with SMA, but little is known about the mechanisms underlying this symptom.

Objective: To investigate if reduced motor unit and capillary recruitment capacity in patients with SMA contribute to exercise intolerance.

Methods: Adolescent and adult patients with SMA types 3 and 4 (n = 15) and age- and gender matched controls (n = 15) performed a maximal upper body exercise test. Read More

View Article and Full-Text PDF

How to Work with Electromyography Decomposition in Practical Classes of Exercise Physiology and Biomechanics.

Life (Basel) 2022 Mar 26;12(4). Epub 2022 Mar 26.

Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, 4000-008 Porto, Portugal.

Concepts about motor unit recruitment are important learning contents in exercise physiology and biomechanics classes that are usually taught theoretically. In the last few years, great advances have occurred in the decomposition of surface electromyography, allowing the learning of theoretical contents in an experimental way. In this tutorial paper, we have described the decomposition of surface electromyography methodological aspects and examples to teach motor unit recruitment concepts in exercise physiology and biomechanics practical lessons. Read More

View Article and Full-Text PDF

Late-Onset Pompe Disease Presenting with Isolated Tongue Involvement.

Case Rep Neurol 2022 Jan-Apr;14(1):98-103. Epub 2022 Mar 10.

Department of Neurology, Ibn Sina Hospital, Kuwait, Kuwait.

Late-onset Pompe disease (LOPD) is a rare autosomal recessive metabolic disorder that is caused by deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA), which is responsible for glycogen breakdown. It has a wide clinical spectrum but usually presents with limb girdle and respiratory muscles weakness. Tongue involvement has been rarely reported as the sole initial symptom of LOPD. Read More

View Article and Full-Text PDF

Implications of median sensory study to the thumb and deltoid/biceps motor unit recruitment on identifying C6 root avulsion in upper neonatal brachial plexus palsy.

Muscle Nerve 2022 Jul 27;66(1):24-30. Epub 2022 Apr 27.

Department of Physical Medicine & Rehabilitation, University of Michigan Medical School, Ann Arbor, Michigan.

Introduction/aims: Anatomic representation suggests that a median sensory nerve conduction study recording the thumb (median D1 NCS) may effectively assess upper neonatal brachial plexus palsy (NBPP). We sought to determine the feasibility of technique, establish reference data, and assess its ability to: (a) identify focal upper plexus lesions; and (b) identify C6 root avulsion. In a secondary analysis, we explored the association between absence/presence of motor unit action potentials (MUAPs) during needle electromyography (EMG) of the deltoid and biceps brachii muscles and C6 avulsion status. Read More

View Article and Full-Text PDF

Arthrogenic muscle inhibition manifests in thigh musculature motor unit characteristics after anterior cruciate ligament injury.

Eur J Sport Sci 2022 May 2:1-11. Epub 2022 May 2.

Department of Orthopedics, Mayo Clinic, Rochester, MN, USA.

Joint trauma induces a presynaptic reflex inhibition termed arthrogenic muscle inhibition (AMI) that prevents complete activation of muscles. Reduced motor unit (MU) output is a hypothesised mechanism for persistent strength deficits. The objective of this study was to determine MU characteristics of thigh musculature and determine how they change with anterior cruciate ligament (ACL) injury compared to healthy controls. Read More

View Article and Full-Text PDF

Improved online decomposition of non-stationary electromyogram via signal enhancement using a neuron resonance model: a simulation study.

J Neural Eng 2022 04 5;19(2). Epub 2022 Apr 5.

Institute of Engineering & Medicine Interdisciplinary Studies, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China.

. Motor unit (MU) discharge information obtained via the online electromyogram (EMG) decomposition has shown promising prospects in multiple applications. However, the nonstationarity of EMG signals caused by the rotation (recruitment-derecruitment) of MUs and the variation of MU action potentials (MUAP) can significantly degrade the online decomposition performance. Read More

View Article and Full-Text PDF

Cervical spinal hemisection alters phrenic motor neuron glutamatergic mRNA receptor expression.

Exp Neurol 2022 07 2;353:114030. Epub 2022 Mar 2.

Department of Physiology & Biomedical Engineering, College of Medicine and Science, Mayo Clinic, Rochester, MN, United States of America; Department of Anesthesiology & Perioperative Medicine, College of Medicine and Science, Mayo Clinic, Rochester, MN, United States of America. Electronic address:

Upper cervical spinal cord injuries (SCI) disrupt descending inputs to phrenic motor neurons (PhMNs), impairing respiratory function. Unilateral spinal hemisection at C2 (C2SH) results in loss of ipsilateral rhythmic diaphragm muscle (DIAm) EMG activity associated with lower force behaviors accomplished by recruitment of smaller PhMNs in rats. Activity during higher force, non-ventilatory behaviors that recruit larger PhMNs is minimally impaired following C2SH. Read More

View Article and Full-Text PDF

Method of analysis influences interpretations of sex-related differences in firing rates during prolonged submaximal isometric contractions.

J Musculoskelet Neuronal Interact 2022 03;22(1):27-36

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

Objective: This study examined motor unit (MU) firing rates during a prolonged isometric contraction of the vastus lateralis (VL) for females and males.

Methods: Surface electromyographic (sEMG) signals were recorded from the VL for eleven females and twelve males during a 45-second isometric trapezoid muscle actions at 40% of maximal voluntary contraction (MVC). For each MU, mean firing rate (MFR) was calculated for the initial and final 10-second epochs of the steady torque segment and regressed against recruitment threshold (RT, expressed as %MVC), as well as time at recruitment (T, seconds). Read More

View Article and Full-Text PDF

Quantitative MRI Differentiates Electromyography Severity Grades of Denervated Muscle in Neuropathy of the Brachial Plexus.

J Magn Reson Imaging 2022 Feb 23. Epub 2022 Feb 23.

Department of Radiology and Imaging, Hospital for Special Surgery, New York, 10021, New York, USA.

Background: Quantitative MRI (qMRI) metrics reflect microstructural skeletal muscle changes secondary to denervation and may correspond to conventional electromyography (EMG) assessments of motor unit recruitment (MUR) and denervation.

Hypothesis: Differences in quantitative T , diffusion-based apparent fiber diameter (AFD), and fat fraction (FF) exist between EMG grades, in patients with clinically suspected neuropathy of the brachial plexus.

Study Type: Prospective. Read More

View Article and Full-Text PDF
February 2022

Neuromuscular recruitment strategies of the vastus lateralis according to sex.

Acta Physiol (Oxf) 2022 06 2;235(2):e13803. Epub 2022 Mar 2.

Centre of Metabolism, Ageing & Physiology (COMAP), MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and National Institute for Health Research, (NIHR) Nottingham Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, UK.

Aim: Despite males typically exhibiting greater muscle strength and fatigability than females, it remains unclear if there are sex-based differences in neuromuscular recruitment strategies e.g. recruitment and modulation of motor unit firing rate (MU FR) at normalized forces and during progressive increases in force. Read More

View Article and Full-Text PDF

Log-Transformed Electromyography Amplitude Power Output Relationship: Nondominant vs. Dominant Limb.

J Strength Cond Res 2022 Mar;36(3):851-856

Physical Therapy Program, Department of Health Care Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and.

Abstract: Boccomino, HL, Daoud, BT, Hudas, A, North, WA, and Malek, MH. Log-transformed electromyography amplitude power output relationship: nondominant vs. dominant limb. Read More

View Article and Full-Text PDF

Laterality of the activation of the vastus lateralis muscle in females with Parkinson's disease during the medication state compared with healthy controls.

J Integr Neurosci 2022 Jan;21(1):40

Department of Physical Therapy, Marquette University, Milwaukee, WI 53201, USA.

The aim of this study was to quantify the laterality of motor unit (MU) activation properties in people with Parkinson's disease (PD) during force production (low- to high-intensity contraction) using high-density surface electromyography (HD-SEMG). Sixteen females with PD (age = 69.9 ± 7. Read More

View Article and Full-Text PDF
January 2022

The effect of small changes in rate of force development on muscle fascicle velocity and motor unit discharge behaviour.

Eur J Appl Physiol 2022 Apr 10;122(4):1035-1044. Epub 2022 Feb 10.

School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, QLD, Australia.

When rate of force development is increased, neural drive increases. There is presently no accepted explanation for this effect. We propose and experimentally test the theory that a small increase in rate of force development increases medial gastrocnemius fascicle shortening velocity, reducing the muscle's force-generating capacity, leading to active motor units being recruited at lower forces and with increased discharge frequencies. Read More

View Article and Full-Text PDF

Localization of Brachial Plexopathies Using a Novel Diagnostic Program.

HSS J 2022 Feb 20;18(1):78-82. Epub 2021 Mar 20.

Center for Brachial Plexus and Traumatic Nerve Injury, Hospital for Special Surgery, New York, NY, USA.

: Assessing the extent and specific location of brachial plexus injuries can be difficult given the variety of mechanisms of injury and anatomic complexity of the plexus. We developed a program to accurately assess the location of a patient's neurologic injury based on electromyographic data. : We sought to test our hypothesis that the location of traumatic brachial plexopathies could be accurately assessed with a novel program that processed electromyogram (EMG) and mechanism of injury data. Read More

View Article and Full-Text PDF
February 2022

Electromyographic study assessing swallowing function in subacute stroke patients with respiratory muscle weakness.

Medicine (Baltimore) 2021 Dec;100(48):e27780

Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital Kaohsiung Medical Center, Chang Gung University College of Medicine, Taiwan.

Background: Dysphagia has been reported to be associated with the descent of the hyolaryngeal complex. Further, suprahyoid muscles play a greater role than infrahyoid muscles in elevation of the hyolarngeal complex. Respiratory muscle training (RMT) can improve lung function, and expiratory muscle strength training can facilitate elevation of the hyoid bone and increase the motor unit recruitment of submental muscles during normal swallowing. Read More

View Article and Full-Text PDF
December 2021

Effects of continuous cycling training on motor unit firing rates, input excitation, and myosin heavy chain of the vastus lateralis in sedentary females.

Exp Brain Res 2022 Mar 20;240(3):825-839. Epub 2022 Jan 20.

Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, 1301 Sunnyside Ave., Room 101BE, Lawrence, KS, 66045, USA.

This study examined the effects of continuous endurance training on motor unit (MU) mean firing rates (MFR), percent myosin heavy chain (%MHC) isoforms, and muscle cross-sectional area (mCSA) of the vastus lateralis (VL). Twelve females completed 5-weeks of continuous cycling-training (CYC), while 8 females were controls (CON). Participants performed maximal voluntary contractions (MVCs) and 40% MVCs of the knee extensors before (PRE) and after the 5-week treatment period at the same absolute pre-treatment submaximal torque (POST) and relative to post-treatment MVCs (POST). Read More

View Article and Full-Text PDF

A multidimensional facial surface EMG analysis for objective assessment of bulbar involvement in amyotrophic lateral sclerosis.

Clin Neurophysiol 2022 03 23;135:74-84. Epub 2021 Dec 23.

Neurology Associates P.C, 2631 S 70th St, Lincoln, NE 68506, USA. Electronic address:

Objective: To develop a multidimensional facial surface electromyographic (EMG) analysis for assessing bulbar involvement in amyotrophic lateral sclerosis (ALS).

Methods: Fifty-four linear and nonlinear features were extracted from the surface EMG recordings for masseter, temporalis, and anterior belly of digastric in 13 patients with ALS and 10 healthy controls, each performed a speech task three times. The features were factor analyzed and then evaluated in terms of internal consistency, relation to functional speech outcomes, and efficacy for patient-control classification. Read More

View Article and Full-Text PDF

Motor impairment evoked by direct electrical stimulation of human parietal cortex during object manipulation.

Neuroimage 2022 03 25;248:118839. Epub 2021 Dec 25.

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:

In primates, the parietal cortex plays a crucial role in hand-object manipulation. However, its involvement in object manipulation and related hand-muscle control has never been investigated in humans with a direct and focal electrophysiological approach. To this aim, during awake surgery for brain tumors, we studied the impact of direct electrical stimulation (DES) of parietal lobe on hand-muscles during a hand-manipulation task (HMt). Read More

View Article and Full-Text PDF

Blockade of 5-HT receptors suppresses rate of torque development and motor unit discharge rate during rapid contractions.

J Neurophysiol 2022 01 22;127(1):150-160. Epub 2021 Dec 22.

Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.

Serotonin (5-HT) is a neuromodulator that is critical for regulating the excitability of spinal motoneurons and the generation of muscle torque. However, the role of 5-HT in modulating human motor unit activity during rapid contractions has yet to be assessed. Nine healthy participants (23. Read More

View Article and Full-Text PDF
January 2022

Alterations of tibialis anterior muscle activation pattern in subjects with type 2 diabetes and diabetic peripheral neuropathy.

Biomed Phys Eng Express 2022 01 5;8(2). Epub 2022 Jan 5.

Institute of Biomedical Engineering, Department of Electrical and Electronic Engineering, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil.

Diabetic peripheral neuropathy (DPN) is associated with loss of motor units (MUs), which can cause changes in the activation pattern of muscle fibres. This study investigated the pattern of muscle activation using high-density surface electromyography (HD-sEMG) signals from subjects with type 2 diabetes mellitus (T2DM) and DPN. Thirty-five adults participated in the study: 12 healthy subjects (HV), 12 patients with T2DM without DPN (No-DPN) and 11 patients with T2DM with DPN (DPN). Read More

View Article and Full-Text PDF
January 2022

Lack of increased rate of force development after strength training is explained by specific neural, not muscular, motor unit adaptations.

J Appl Physiol (1985) 2022 01 18;132(1):84-94. Epub 2021 Nov 18.

Department of Bioengineering, Imperial College London, London, United Kingdom.

Although maximal force increases following short-term isometric strength training, the rate of force development (RFD) may remain relatively unaffected. The underlying neural and muscular mechanisms during rapid contractions after strength training are largely unknown. Since strength training increases the neural drive to muscles, it may be hypothesized that there are distinct neural or muscular adaptations determining the change in RFD independently of an increase in maximal force. Read More

View Article and Full-Text PDF
January 2022

Sensing and decoding the neural drive to paralyzed muscles during attempted movements of a person with tetraplegia using a sleeve array.

J Neurophysiol 2021 12 17;126(6):2104-2118. Epub 2021 Nov 17.

Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania.

Motor neurons convey information about motor intent that can be extracted and interpreted to control assistive devices. However, most methods for measuring the firing activity of single neurons rely on implanted microelectrodes. Although intracortical brain-computer interfaces (BCIs) have been shown to be safe and effective, the requirement for surgery poses a barrier to widespread use that can be mitigated by instead using noninvasive interfaces. Read More

View Article and Full-Text PDF
December 2021

Skilled independent control of individual motor units via a non-invasive neuromuscular-machine interface.

J Neural Eng 2021 11 23;18(6). Epub 2021 Nov 23.

Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley, CA 94720, United States of America.

Brain-machine interfaces (BMIs) have the potential to augment human functions and restore independence in people with disabilities, yet a compromise between non-invasiveness and performance limits their relevance.Here, we hypothesized that a non-invasive neuromuscular-machine interface providing real-time neurofeedback of individual motor units within a muscle could enable independent motor unit control to an extent suitable for high-performance BMI applications.Over 6 days of training, eight participants progressively learned to skillfully and independently control three biceps brachii motor units to complete a 2D center-out task. Read More

View Article and Full-Text PDF
November 2021

Intrinsic motoneuron excitability is reduced in soleus and tibialis anterior of older adults.

Geroscience 2021 12 30;43(6):2719-2735. Epub 2021 Oct 30.

School of Exercise and Nutrition Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, Australia.

Age-related deterioration within both motoneuron and monoaminergic systems should theoretically reduce neuromodulation by weakening motoneuronal persistent inward current (PIC) amplitude. However, this assumption remains untested. Surface electromyographic signals were collected using two 32-channel electrode matrices placed on soleus and tibialis anterior of 25 older adults (70 ± 4 years) and 17 young adults (29 ± 5 years) to investigate motor unit discharge behaviors. Read More

View Article and Full-Text PDF
December 2021

Distribution of motor unit properties across human muscles.

J Appl Physiol (1985) 2022 01 28;132(1):1-13. Epub 2021 Oct 28.

Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado.

The purpose of our review was to compare the distribution of motor unit properties across human muscles of different sizes and recruitment ranges. Although motor units can be distinguished based on several different attributes, we focused on four key parameters that have a significant influence on the force produced by muscle during voluntary contractions: the number of motor units, average innervation number, the distributions of contractile characteristics, and discharge rates within motor unit pools. Despite relatively few publications on this topic, current data indicate that the most influential factor in the distribution of these motor unit properties between muscles is innervation number. Read More

View Article and Full-Text PDF
January 2022

Antagonist surface electromyogram decomposition and the case of the missing motor units.

J Neurophysiol 2021 12 27;126(6):1943-1947. Epub 2021 Oct 27.

School of Health & Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada.

Reece and Herda ( 125: 2094-2106, 2021) reported that an antagonist muscle exhibited an organized motor unit (MU) recruitment scheme during isometric elbow flexion contractions. This control scheme, however, differed from the typical MU control scheme in that MU firing rates did not change between force levels (40% and 70% maximal voluntary contractions) in the triceps brachii when it acted as an antagonist to isometric elbow flexion. Here, we suggest technological considerations with evidence that may have affected these findings. Read More

View Article and Full-Text PDF
December 2021

Optimizing nerve transfer surgery in tetraplegia: clinical decision making based on innervation patterns in spinal cord injury.

J Neurosurg Spine 2021 Oct 22:1-11. Epub 2021 Oct 22.

1Departments of Neurological Surgery, and.

Objective: Nerve transfers are increasingly being utilized in the treatment of chronic tetraplegia, with increasing literature describing significant improvements in sensorimotor function up to years after injury. However, despite technical advances, clinical outcomes remain heterogenous. Preoperative electrodiagnostic testing is the most direct measure of nerve health and may provide prognostic information that can optimize preoperative patient selection. Read More

View Article and Full-Text PDF
October 2021