Does increasing the number of channels during neuromuscular electrical stimulation reduce fatigability and produce larger contractions with less discomfort?

2021 ◽  
Author(s):  
Trevor Scott Barss ◽  
Bailey WM Sallis ◽  
Dylan J Miller ◽  
David F Collins
Keyword(s):  
Electrical Stimulation ◽  
High Current Density ◽  
Neuromuscular Electrical Stimulation ◽  
Motor Units ◽  
Voluntary Contraction ◽  
Secondary Outcome ◽  
High Current ◽  
Firing Rates ◽  
Multiple Electrodes ◽  
Neurologically Intact

Abstract Purpose: Neuromuscular electrical stimulation (NMES) recruits motor units (MUs) at unphysiologically high rates, leading to contraction fatigability. Rotating NMES pulses between multiple electrodes recruits different MUs from each site, reducing MU firing rates and fatigability. This study aimed to determine whether rotating pulses between an increasing number of stimulation channels (cathodes) reduces contraction fatigability and increases the ability to generate torque during NMES. A secondary outcome was perceived discomfort. Methods: Fifteen neurologically-intact volunteers completed 4 sessions. NMES was delivered over the quadriceps through 1 (NMES1), 2 (NMES2), 4 (NMES4) or 8 (NMES8) channels. Fatigability was assessed over 100 contractions (1s on/1s off) at an initial contraction amplitude that was 20% of a maximal voluntary contraction (MVC). Torque-frequency relationships were characterized over 6 frequencies from 20-120Hz. Results: NMES4 and NMES8 resulted in less decline in torque (42% and 41%) and generated more torque over the 100 contractions than NMES1 and NMES2 (53% and 50% decline in torque). Increasing frequency from 20-120Hz increased torque by 7, 13, 21 and 24% MVC, for NMES1, NMES2, NMES4 and NMES8, respectively. Perceived discomfort was highest during NMES8 . Conclusion: NMES4 and NMES8 reduced contraction fatigability and generated larger contractions across a range of frequencies than NMES1 and NMES2 . NMES8 produced the most discomfort, likely due to small electrodes and high current density. During NMES, more is not better and rotating pulses between 4-channels may be optimal to reduce contraction fatigability and produce larger contractions with minimal discomfort compared to conventional NMES configurations.

scholarly journals Insights into the combination of neuromuscular electrical stimulation and motor imagery in a training-based approach

2021 ◽  
Author(s):  
Amandine Bouguetoch ◽  
Alain Martin ◽  
Sidney Grosprêtre
Keyword(s):  
Electrical Stimulation ◽  
Motor Imagery ◽  
Neural Plasticity ◽  
Neuromuscular Electrical Stimulation ◽  
Voluntary Contraction ◽  
Muscle Architecture ◽  
Fascicle Length ◽  
Before And After ◽  
V Wave ◽  
And Control

Abstract Introduction Training stimuli that partially activate the neuromuscular system, such as motor imagery (MI) or neuromuscular electrical stimulation (NMES), have been previously shown as efficient tools to induce strength gains. Here the efficacy of MI, NMES or NMES + MI trainings has been compared. Methods Thirty-seven participants were enrolled in a training program of ten sessions in 2 weeks targeting plantar flexor muscles, distributed in four groups: MI, NMES, NMES + MI and control. Each group underwent forty contractions in each session, NMES + MI group doing 20 contractions of each modality. Before and after, the neuromuscular function was tested through the recording of maximal voluntary contraction (MVC), but also electrophysiological and mechanical responses associated with electrical nerve stimulation. Muscle architecture was assessed by ultrasonography. Results MVC increased by 11.3 ± 3.5% in NMES group, by 13.8 ± 5.6% in MI, while unchanged for NMES + MI and control. During MVC, a significant increase in V-wave without associated changes in superimposed H-reflex has been observed for NMES and MI, suggesting that neural adaptations occurred at supraspinal level. Rest spinal excitability was increased in the MI group while decreased in the NMES group. No change in muscle architecture (pennation angle, fascicle length) has been found in any group but muscular peak twitch and soleus maximal M-wave increased in the NMES group only. Conclusion Finally, MI and NMES seem to be efficient stimuli to improve strength, although both exhibited different and specific neural plasticity. On its side, NMES + MI combination did not provide the expected gains, suggesting that their effects are not simply cumulative, or even are competitive.

scholarly journals Modulation of torque evoked by wide-pulse, high-frequency neuromuscular electrical stimulation and the potential implications for rehabilitation and training

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Donnelly ◽  
Jonathan Stegmüller ◽  
Anthony J. Blazevich ◽  
Fabienne Crettaz von Roten ◽  
Bengt Kayser ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Neuromuscular Electrical Stimulation ◽  
Motor Units ◽  
Progressive Increase ◽  
Great Promise ◽  
Measured Parameter ◽  
Time Integral ◽  
Spinal Circuitry ◽  
Evoked Force

AbstractThe effectiveness of neuromuscular electrical stimulation (NMES) for rehabilitation is proportional to the evoked torque. The progressive increase in torque (extra torque) that may develop in response to low intensity wide-pulse high-frequency (WPHF) NMES holds great promise for rehabilitation as it overcomes the main limitation of NMES, namely discomfort. WPHF NMES extra torque is thought to result from reflexively recruited motor units at the spinal level. However, whether WPHF NMES evoked force can be modulated is unknown. Therefore, we examined the effect of two interventions known to change the state of spinal circuitry in opposite ways on evoked torque and motor unit recruitment by WPHF NMES. The interventions were high-frequency transcutaneous electrical nerve stimulation (TENS) and anodal transcutaneous spinal direct current stimulation (tsDCS). We show that TENS performed before a bout of WPHF NMES results in lower evoked torque (median change in torque time-integral: − 56%) indicating that WPHF NMES-evoked torque might be modulated. In contrast, the anodal tsDCS protocol used had no effect on any measured parameter. Our results demonstrate that WPHF NMES extra torque can be modulated and although the TENS intervention blunted extra torque production, the finding that central contribution to WPHF NMES-evoked torques can be modulated opens new avenues for designing interventions to enhance WPHF NMES.

scholarly journals Assessment of muscle activity using electrical stimulation and mechanomyography: a systematic review

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Raphael Uwamahoro ◽  
Kenneth Sundaraj ◽  
Indra Devi Subramaniam
Keyword(s):  
Electrical Stimulation ◽  
Processing Speed ◽  
Muscle Activity ◽  
Neuromuscular Electrical Stimulation ◽  
Voluntary Contraction ◽  
Electrical Signal ◽  
Muscle Performance ◽  
Inclusion Criteria ◽  
Activity Assessment ◽  
Experimental Protocols

AbstractThis research has proved that mechanomyographic (MMG) signals can be used for evaluating muscle performance. Stimulation of the lost physiological functions of a muscle using an electrical signal has been determined crucial in clinical and experimental settings in which voluntary contraction fails in stimulating specific muscles. Previous studies have already indicated that characterizing contractile properties of muscles using MMG through neuromuscular electrical stimulation (NMES) showed excellent reliability. Thus, this review highlights the use of MMG signals on evaluating skeletal muscles under electrical stimulation. In total, 336 original articles were identified from the Scopus and SpringerLink electronic databases using search keywords for studies published between 2000 and 2020, and their eligibility for inclusion in this review has been screened using various inclusion criteria. After screening, 62 studies remained for analysis, with two additional articles from the bibliography, were categorized into the following: (1) fatigue, (2) torque, (3) force, (4) stiffness, (5) electrode development, (6) reliability of MMG and NMES approaches, and (7) validation of these techniques in clinical monitoring. This review has found that MMG through NMES provides feature factors for muscle activity assessment, highlighting standardized electromyostimulation and MMG parameters from different experimental protocols. Despite the evidence of mathematical computations in quantifying MMG along with NMES, the requirement of the processing speed, and fluctuation of MMG signals influence the technique to be prone to errors. Interestingly, although this review does not focus on machine learning, there are only few studies that have adopted it as an alternative to statistical analysis in the assessment of muscle fatigue, torque, and force. The results confirm the need for further investigation on the use of sophisticated computations of features of MMG signals from electrically stimulated muscles in muscle function assessment and assistive technology such as prosthetics control.

Effect of adding neuromuscular electrical stimulation training to pulmonary rehabilitation in patients with chronic obstructive pulmonary disease: randomized clinical trial

2018 ◽  
Vol 33 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Marwa Mekki ◽  
Thierry Paillard ◽  
Sonia Sahli ◽  
Zouhair Tabka ◽  
Yassine Trabelsi
Keyword(s):  
Electrical Stimulation ◽  
Pulmonary Rehabilitation ◽  
Center Of Pressure ◽  
Intervention Group ◽  
Neuromuscular Electrical Stimulation ◽  
Berg Balance Scale ◽  
Voluntary Contraction ◽  
Control Group ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease

Objective: To investigate the effectiveness of neuromuscular electrical stimulation added to pulmonary rehabilitation on walking tolerance and balance in patients with chronic obstructive pulmonary disease (COPD). Design: Randomized clinical trial. Setting: Outpatient, Faculty of Medicine of Sousse, Tunisia. Subjects: A total of 45 patients with COPD were assigned to an intervention group ( n = 25) or a control group ( n = 20). Interventions: The intervention group underwent a neuromuscular electrical stimulation added to pulmonary rehabilitation, and the control group underwent only a pulmonary rehabilitation, three times per week during six months. Main Measures: Measures were taken at baseline and after six months of training. A stabilometric platform, time up and go, Berg balance scale tests, 6 minute walking test, and the maximal voluntary contraction were measured. Results: In the intervention group, an increase in an exercise tolerance manifested by a longer distance walked in 6 minute walking test 619.5 (39.6) m was observed in comparison to the control group 576.3 (31.5) m. The values of the time up and go, Berg balance scale, and maximal voluntary contraction in the intervention group at follow-up were significantly higher than those in the control group ( P  = 0.02, P  = 0.01, P  = 0.0002, respectively). The center of pressure in the mediolateral and in the anteroposterior directions, as well as the center of pressure area was significantly more improved in open eyes and closed eyes in the intervention group compared to the control group ( P < 0.001). Conclusion: The neuromuscular electrical stimulation added to pulmonary rehabilitation group benefited from better walking tolerance and greater balance improvement than the only pulmonary rehabilitation.

scholarly journals The Number of Active Motor Units and Their Firing Rates in Voluntary Contraction of Human Brachialis Muscle

1979 ◽  
Vol 29 (4) ◽  
pp. 427-443 ◽  
Author(s):  
Kazuyuki KANOSUE ◽  
Masaki YOSHIDA ◽  
Kenzo AKAZAWA ◽  
Katsuhiko FUJII
Keyword(s):  
Motor Units ◽  
Voluntary Contraction ◽  
Firing Rates ◽  
Brachialis Muscle ◽  
Active Motor

Probabilities Associated With Counting Average Motor Unit Firing Rates in Active Human Muscle

1998 ◽  
Vol 23 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Christopher Rich ◽  
George L. O′Brien ◽  
Enzo Cafarelli
Keyword(s):  
Motor Unit ◽  
Vastus Lateralis ◽  
Small Diameter ◽  
Motor Units ◽  
Voluntary Contraction ◽  
Human Muscle ◽  
Cell Diameter ◽  
Unit Recording ◽  
Firing Rates ◽  
Motor Unit Firing

Motor unit firing rates in human muscle can be determined from recordings made with small-diameter microelectrodes inserted directly into the muscle during voluntary contraction. Frequently, these counts are pooled to give an average motor unit firing rate under a given set of conditions. Since the fibers of one motor unit are dispersed among the cells of several others, it is conceivable that discharge rates can be measured in more than one cell from the same unit. If this occurred frequently, the distribution of firing rates could be influenced by those from units counted more than once. Based on literature values, we made the following assumptions: vastus lateralis contains approximately 300 motor units, with an average innervation ratio of 1500. Muscle cell diameter is about 50 to 100 μm and cells are randomly distributed over a motor unit territory of 10 μm diameter. The recording range of a microelectrode is about 600 μm. Given the distribution of cells normally found in whole human muscle, the probability of recording from two or more cells of the same motor unit at 50% MVC follows a Poisson distribution with a mean of 0.44. This model suggests that although there is a low probability of some duplication in this technique, the extent to which it influences the distribution of average motor unit firing rates is minimal over the entire range of forces produced by vastus lateralis. Key words: probability, motor unit, single unit recording, human muscle, rate coding

scholarly journals Motor Neuron Firing Dysfunction in Spastic Patients With Primary Lateral Sclerosis

2005 ◽  
Vol 94 (2) ◽  
pp. 919-927 ◽  
Author(s):  
Mary Kay Floeter ◽  
Ping Zhai ◽  
Rajiv Saigal ◽  
Yongkyun Kim ◽  
Jeffrey Statland
Keyword(s):  
Firing Rate ◽  
Motor Neurons ◽  
Motor Units ◽  
Voluntary Contraction ◽  
Muscle Vibration ◽  
Force Level ◽  
Primary Lateral Sclerosis ◽  
Firing Rates ◽  
Primary Lateral ◽  
Lateral Sclerosis

Patients with corticospinal tract dysfunction have slow voluntary movements with brisk stretch reflexes and spasticity. Previous studies reported reduced firing rates of motor units during voluntary contraction. To assess whether this firing behavior occurs because motor neurons do not respond normally to excitatory inputs, we studied motor units in patients with primary lateral sclerosis, a degenerative syndrome of progressive spasticity. Firing rates were measured from motor units in the wrist extensor muscles at varying levels of voluntary contraction ≤10% maximal force. At each force level, the firing rate was measured with and without added muscle vibration, a maneuver that repetitively activates muscle spindles. In motor units from age-matched control subjects, the firing rate increased with successively stronger contractions as well as with the addition of vibration at each force level. In patients with primary lateral sclerosis, motor-unit firing rates remained stable, or in some cases declined, with progressively stronger contractions or with muscle vibration. We conclude that excitatory inputs produce a blunted response in motor neurons in patients with primary lateral sclerosis compared with age-matched controls. The potential explanations include abnormal activation of voltage-activated channels that produce stable membrane plateaus at low voltages, abnormal recruitment of the motor pool, or tonic inhibition of motor neurons.

scholarly journals Effects of neuromuscular electrical stimulation and core muscle strengthening on trunk instability following stroke

2021 ◽  
Vol 9 (12) ◽  
pp. 3596
Author(s):  
Riyas Basheer K. B. ◽  
Dinesh K. V. ◽  
Subhashchandra Rai ◽  
Mohammed Arshak A. T.
Keyword(s):  
Electrical Stimulation ◽  
Neuromuscular Electrical Stimulation ◽  
Berg Balance Scale ◽  
Rehabilitation Program ◽  
Secondary Outcome ◽  
Combination Group ◽  
Muscle Strengthening ◽  
Before And After ◽  
Trunk Balance ◽  
Risk Of Fall

Background: Postural instability leads to balance dysfunction in stroke subjects, which always increase the risk of fall. This study aimed to compare the effect of neuromuscular electrical stimulation and core muscle strengthening on trunk balance following stroke.Methods: Forty five stroke subjects were participated and assigned randomly into three groups; all groups received standard rehabilitation program; and core group received additional core strengthening, neuromuscular electrical stimulation (NMES) group received added electrical stimulation over paraspinal region and combination group received core muscle strengthening and NMES along with standard rehabilitation protocol. After four weeks of the interventions, primary and secondary outcome measures are evaluated. Berg Balance Scale (BBS), Postural Assessment Scale for Stroke (PASS), Trunk Impairment Scale (TIS) and Barthel Index (BI) were evaluated before and after the intervention.Results: All the three (core MS, NMES and combination) groups showed significant improvement after the intervention (BBS 10.07, 15.54 and 18.27, PASS 6.54, 13.06 and 14.00, TIS 0.25, 0.25 and 0.51, BI 16.40, 29.93 and 36.53). The combination group (NMES and core muscle strengthening) showed better improvement than other two groups. TIS and BI total score showed positive (0.849) correlation.Conclusions: Addition of NMES along with core muscle strengthening for stroke rehabilitation will improve trunk stability, balance and ADLs.

Influence of wide-pulse neuromuscular electrical stimulation frequency and superimposed tendon vibration on occurrence and magnitude of extra torque

2021 ◽  
Author(s):  
Loïc Espeit ◽  
Vianney Rozand ◽  
Guillaume Y. Millet ◽  
Julien Gondin ◽  
Nicola A. Maffiuletti ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Plantar Flexion ◽  
Neuromuscular Electrical Stimulation ◽  
Low Frequency ◽  
Force Production ◽  
Voluntary Contraction ◽  
Tendon Vibration ◽  
Afferent Pathways ◽  
Design Decisions

Low-frequency and high-frequency wide-pulse neuromuscular electrical stimulation (NMES) can generate extra-torque (ET) via afferent pathways. Superimposing tendon vibration (TV) to NMES can increase the activation of these afferent pathways and favour ET generation. Knowledge of the characteristics of ET is essential to implement these stimulation paradigms in clinical practice. Thus, we aimed at investigating the effects of frequency and TV superimposition on the occurrence and magnitude of ET in response to wide-pulse NMES. NMES-induced isometric plantar flexion torque was recorded in 30 healthy individuals who performed five NMES protocols: wide-pulse low-frequency (1 ms; 20 Hz; WPLF) and wide-pulse high-frequency (1 ms; 100 Hz; WPHF) without and with superimposed TV (1 mm; 100 Hz) and conventional NMES (50 µs; 20 Hz; reference protocol). Each NMES protocol began with an adjustment of NMES intensity in order to reach 10% of maximal voluntary contraction then consisted of three 20-s trains interspersed by 90 s of rest. The ET occurrence was similar for WPLF and WPHF (p=0.822). In the responders, the ET magnitude was greater for WPHF than WPLF (p<0.001). There was no effect of superimposed TV on ET characteristics. This study reported an effect of NMES frequency on ET magnitude, whereas TV superimposition did not affect this parameter. In the context of our experimental design decisions, the present findings question the clinical use of wide-pulse NMES and its combination with superimposed TV. Yet, further research is needed in order to maximize force production through the occurrence and magnitude of ET.

scholarly journals Modulation of motor unit activity in biceps brachii by neuromuscular electrical stimulation applied to the contralateral arm

2015 ◽  
Vol 118 (12) ◽  
pp. 1544-1552 ◽  
Author(s):  
Ioannis G. Amiridis ◽  
Diba Mani ◽  
Awad Almuklass ◽  
Boris Matkowski ◽  
Jeffrey R. Gould ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Motor Unit ◽  
Unit Activity ◽  
Pulse Width ◽  
Biceps Brachii ◽  
Neuromuscular Electrical Stimulation ◽  
Motor Units ◽  
Elbow Flexors ◽  
Discharge Characteristics ◽  
Low Threshold

The purpose of the study was to determine the influence of neuromuscular electrical stimulation (NMES) current intensity and pulse width applied to the right elbow flexors on the discharge characteristics of motor units in the left biceps brachii. Three NMES current intensities were applied for 5 s with either narrow (0.2 ms) or wide (1 ms) stimulus pulses: one at 80% of motor threshold and two that evoked contractions at either ∼10% or ∼20% of maximal voluntary contraction (MVC) force. The discharge times of 28 low-threshold (0.4–21.6% MVC force) and 16 high-threshold (31.7–56.3% MVC force) motor units in the short head of biceps brachii were determined before, during, and after NMES. NMES elicited two main effects: one involved transient deflections in the left-arm force at the onset and offset of NMES and the other consisted of nonuniform modulation of motor unit activity. The force deflections, which were influenced by NMES current intensity and pulse width, were observed only when low-threshold motor units were tracked. NMES did not significantly influence the discharge characteristics of tracked single-threshold motor units. However, a qualitative analysis indicated that there was an increase in the number of unique waveforms detected during and after NMES. The findings indicate that activity of motor units in the left elbow flexors can be modulated by NMES current and pulse width applied to right elbow flexors, but the effects are not distributed uniformly to the involved motor units.

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