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

2020 ◽  
Author(s):  
François Hug ◽  
Alessandro Del Vecchio ◽  
Simon Avrillon ◽  
Dario Farina ◽  
Kylie J. Tucker
Keyword(s):  
Motor Units ◽  
Muscle Group ◽  
Triceps Surae ◽  
Neural Drive ◽  
Flexible Control ◽  
Neural Origin ◽  
Density Surface ◽  
Motor Unit Action ◽  
Common Drive ◽  
Human Participants

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: i) whether three muscles of the same muscle group (soleus, gastrocnemius medialis [GM] and lateralis [GL]) are activated by a common neural drive ; and ii) whether the neural drive to GM and GL could be differentially modified by altering the mechanical requirements of the task. Eighteen human participants performed an isometric standing heel raise and submaximal isometric plantarflexions (10%, 30%, 50% of maximal effort). High-density surface electromyography recordings were decomposed into motor unit action potentials and coherence analysis was applied on the motor units spike trains. We identified strong common drive to each muscle, but minimal common drive between the muscles. Further, large between-muscle differences were observed during the isometric plantarflexions, such as a delayed recruitment time of GL compared to GM and soleus motor units and opposite time-dependent changes in the estimates of neural drive to muscles during the torque plateau. Finally, the feet position adopted during the heel raise task (neutral vs internally rotated) affected only the GL neural drive with no change for GM. These results provide conclusive that not all anatomically defined synergist muscles are controlled by strong common neural drive. Independent drive to some muscles from the same muscle group may allow for more flexible control to comply with secondary goals such as joint stabilization.

Less common synaptic input between muscles from the same group allows for more flexible coordination strategies during a fatiguing task

2022 ◽  
Author(s):  
Julien Rossato ◽  
Kylie J. Tucker ◽  
Simon Avrillon ◽  
Lilian Lacourpaille ◽  
Ales Holobar ◽  
...  
Keyword(s):  
Synaptic Input ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Motor Units ◽  
The Other ◽  
Triceps Surae ◽  
Strong Positive Correlation ◽  
Neural Drive ◽  
Coordination Strategies ◽  
Common Drive

This study aimed to determine whether neural drive is redistributed between muscles during a fatiguing isometric contraction, and if so, whether the initial level of common synaptic input between these muscles constrains this redistribution. We studied two muscle groups: triceps surae (14 participants) and quadriceps (15 participants). Participants performed a series of submaximal isometric contractions and a torque-matched contraction maintained until task failure. We used high-density surface electromyography to identify the behavior of 1874 motor units from the soleus, gastrocnemius medialis (GM), gastrocnemius lateralis(GL), rectus femoris, vastus lateralis (VL), and vastus medialis(VM). We assessed the level of common drive between muscles in absence of fatigue using a coherence analysis. We also assessed the redistribution of neural drive between muscles during the fatiguing contraction through the correlation between their cumulative spike trains (index of neural drive). The level of common drive between VL and VM was significantly higher than that observed for the other muscle pairs, including GL-GM. The level of common drive increased during the fatiguing contraction, but the differences between muscle pairs persisted. We also observed a strong positive correlation of neural drive between VL and VM during the fatiguing contraction (r=0.82). This was not observed for the other muscle pairs, including GL-GM, which exhibited differential changes in neural drive. These results suggest that less common synaptic input between muscles allows for more flexible coordination strategies during a fatiguing task, i.e., differential changes in neural drive across muscles. The role of this flexibility on performance remains to be elucidated.

Common Drive in Motor Units of a Synergistic Muscle Pair

2002 ◽  
Vol 87 (4) ◽  
pp. 2200-2204 ◽  
Author(s):  
Carlo J. De Luca ◽  
Zeynep Erim
Keyword(s):  
Motor Units ◽  
Motor Unit Action Potential ◽  
Time Varying ◽  
Firing Rates ◽  
Muscle Pair ◽  
Synergistic Muscles ◽  
Motor Unit Action ◽  
Common Drive ◽  
The Individual ◽  
Extensor Carpi Radialis

The interaction among the motor units of the extensor carpi radialis longus (ECRL) and the extensor carpi ulnaris (ECU) muscles in man was studied during wrist extensions in which the two muscles acted as synergists. Intramuscular recordings were obtained using special quadrifilar needle electrodes. Isometric wrist extensions at 20–30% of the maximal effort were studied. The electromyographic (EMG) signals were decomposed into the individual motor-unit action potential trains comprising the signal. The interaction among motor units were characterized by the estimated time-varying mean firing rate and the cross-correlation between the time-varying mean firing rates of pairs of motor units. Pairs of motor units within each muscle as well as pairs of motor units across the muscles were considered. In-phase common fluctuations, termed common drive, were observed in the mean firing rates of motor units within each muscle, consistent with earlier work on other muscles. Common fluctuations were also observed between the firing rates of ECU and ECRL motor units albeit with a variable phase shift. The existence of common drive across synergistic muscles was interpreted as implying that the CNS considers the muscles as a functional unit when they act as synergists.

scholarly journals Control properties of motor units

1985 ◽  
Vol 115 (1) ◽  
pp. 125-136 ◽  
Author(s):  
C. J. De Luca
Keyword(s):  
Motor Units ◽  
Motor Unit Action Potential ◽  
Myoelectric Signal ◽  
Force Output ◽  
The Past ◽  
Motor Unit Action ◽  
Common Drive ◽  
The Common ◽  
Unit Action ◽  
Simple Schema

This review will deal with two evolving concepts which describe and attempt to unify various observations concerning the behaviour of motor units that have been reported during the past decade. The two concepts are: The common drive which describes the behaviour of the firing rates of motor units, and appears to provide a simple schema for controlling motor units; and the firing rate/recruitment interaction which appears to enhance the smoothness of the force output of a muscle. The evolution of these concepts has been expedited by the development of recent techniques such as our decomposition technique which enables us accurately to decompose the myoelectric signal into the constituent motor unit action potential trains. For details refer to LeFever & De Luca (1982), Mambrito & De Luca (1983) and Mambrito & De Luca (1984).

scholarly journals Individual differences in the neural strategies to control the lateral and medial head of the quadriceps during a mechanically constrained task

2020 ◽  
Author(s):  
Simon Avrillon ◽  
Alessandro Del Vecchio ◽  
Dario Farina ◽  
José L. Pons ◽  
Clément Vogel ◽  
...  
Keyword(s):  
Individual Differences ◽  
Motor Neurons ◽  
Interindividual Variability ◽  
Vastus Lateralis ◽  
Motor Units ◽  
Peak Torque ◽  
Motor Tasks ◽  
Neural Drive ◽  
Density Surface ◽  
The Individual

The interindividual variability in the neural drive sent from the spinal cord to muscles is largely unknown, even during highly constrained motor tasks. Here, we investigated individual differences in the strength of neural drive received by the vastus lateralis (VL) and vastus medialis (VM) during an isometric task. We also assessed the proportion of common neural drive within and between these muscles. Twenty-two participants performed a series of submaximal isometric knee extensions at 25% of their peak torque. High-density surface electromyography recordings were decomposed into motor unit action potentials. Coherence analyses were applied on the motor units spike trains to assess the degree of neural drive that was shared between motor neurons. Six participants were re-tested approximately 20 months after the first session. The distribution of the strength of neural drive between VL and VM varied between participants and was correlated with the distribution of normalized interference EMG (r > 0.56). The level of within and between muscle coherence varied across individuals, with a significant positive correlation between these two outcomes (VL: r=0.48; VM: r=0.58). We also observed a large interindividual variability in the proportion of muscle-specific drive, i.e. the drive unique to each muscle (VL range: 6-83%, VM range:6-86%). All the outcome measures were robust across sessions, providing evidence that the individual differences did not depend solely on the variability of the measures. Together, these results demonstrate that the neural strategies to control the VL and VM muscles widely vary across individuals, even during a constrained task.

scholarly journals Muscle Heating With Megapulse II Shortwave Diathermy and ReBound Diathermy

2013 ◽  
Vol 48 (4) ◽  
pp. 477-482 ◽  
Author(s):  
David O. Draper ◽  
Amanda R. Hawkes ◽  
A. Wayne Johnson ◽  
Mike T. Diede ◽  
Justin H. Rigby
Keyword(s):  
Heat Dissipation ◽  
Subcutaneous Fat ◽  
Muscle Group ◽  
Triceps Surae ◽  
Tissue Temperature ◽  
Measured Temperature ◽  
Temperature Decay ◽  
Triceps Surae Muscle ◽  
Subcutaneous Fat Thickness ◽  
Shortwave Diathermy

Context: A new continuous diathermy called ReBound recently has been introduced. Its effectiveness as a heating modality is unknown. Objective: To compare the effects of the ReBound diathermy with an established deep-heating diathermy, the Megapulse II pulsed shortwave diathermy, on tissue temperature in the human triceps surae muscle. Design:  Crossover study. Setting: University research laboratory. Patients or Other Participants: Participants included 12 healthy, college-aged volunteers (4 men, 8 women; age = 22.2 ± 2.25 years, calf subcutaneous fat thickness = 7.2 ± 1.9 mm). Intervention(s):  Each modality treatment was applied to the triceps surae muscle group of each participant for 30 minutes. After 30 minutes, we removed the modality and recorded temperature decay for 20 minutes. Main Outcome Measure(s): We horizontally inserted an implantable thermocouple into the medial triceps surae muscle to measure intramuscular tissue temperature at 3 cm deep. We measured temperature every 5 minutes during the 30-minute treatment and each minute during the 20-minute temperature decay. Results: Tissue temperature at a depth of 3 cm increased more with Megapulse II than with ReBound diathermy over the course of the treatment (F6,66 = 10.78, P < .001). ReBound diathermy did not produce as much intramuscular heating, leading to a slower heat dissipation rate than the Megapulse II (F20,220 = 28.84, P < .001). Conclusions:  During a 30-minute treatment, the Megapulse II was more effective than ReBound diathermy at increasing deep, intramuscular tissue temperature of the triceps surae muscle group.

scholarly journals Reorganization of multidigit physiological tremors after repetitive contractions of a single finger

2009 ◽  
Vol 106 (3) ◽  
pp. 966-974 ◽  
Author(s):  
Ing-Shiou Hwang ◽  
Zong-Ru Yang ◽  
Chien-Ting Huang ◽  
Mei-Chun Guo
Keyword(s):  
Principal Component ◽  
Motor Units ◽  
Middle Finger ◽  
Neuromuscular Function ◽  
Transfer Effect ◽  
Position Tracking ◽  
Single Finger ◽  
Common Drive ◽  
Middle Ring ◽  
Flexor Digitorum

In light of the interplay among physiological finger tremors, this study was undertaken to investigate the transfer effect of fatigue on coordinative strategies of multiple fingers. Fourteen volunteers performed prolonged position tracking with a loaded middle finger while measures of neuromuscular function, including electromyographic activities of the extensor digitorum (ED)/flexor digitorum superficialis (FDS) and physiological tremors of the index, middle, ring, and little fingers, were monitored. The subjects exhibited inferior tracking congruence and an increase in ED activity at the end of the tracking. Fatigue spread was manifested in a remarkable increase in tremor across fingers, in association with enhanced involuntary tremor coupling among fingers that was topologically organized in relation to the distance of the digits from the middle finger. Principal component analysis suggested that an enhanced 8- to 12-Hz central rhythm contributed primarily to the tremor restructure following fatigue spread. The observed tremor reorganization validated the hypothesis that the effect of fatigue was not limited to the instructed finger and that fatigue functionally decreased independence of the digits. The spreading of fatigue weakens neural inputs that diverge to motor units acting on various digits because of fatigue-related enhancement of common drive at the supraspinal level.

scholarly journals The innervation and organization of motor units in a series-fibered human muscle: the brachioradialis

2010 ◽  
Vol 108 (6) ◽  
pp. 1530-1541 ◽  
Author(s):  
Zoia C. Lateva ◽  
Kevin C. McGill ◽  
M. Elise Johanson
Keyword(s):  
Human Subjects ◽  
Standing Waves ◽  
Motor Units ◽  
Human Muscle ◽  
Motor Unit Action Potential ◽  
Distal Muscle ◽  
Normal Human ◽  
Motor Unit Action ◽  
Unit Action ◽  
Individual Motor

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.

scholarly journals Stroke increases ischemia-related decreases in motor unit discharge rates

2018 ◽  
Vol 120 (6) ◽  
pp. 3246-3256 ◽  
Author(s):  
Spencer A. Murphy ◽  
Francesco Negro ◽  
Dario Farina ◽  
Tanya Onushko ◽  
Matthew Durand ◽  
...  
Keyword(s):  
Motor Unit ◽  
Time Constant ◽  
Motor Units ◽  
Unit Discharge ◽  
Firing Rates ◽  
Sensory Pathways ◽  
Discharge Rates ◽  
Motor Unit Firing ◽  
Motor Unit Discharge ◽  
Density Surface

Following stroke, hyperexcitable sensory pathways, such as the group III/IV afferents that are sensitive to ischemia, may inhibit paretic motor neurons during exercise. We quantified the effects of whole leg ischemia on paretic vastus lateralis motor unit firing rates during submaximal isometric contractions. Ten chronic stroke survivors (>1 yr poststroke) and 10 controls participated. During conditions of whole leg occlusion, the discharge timings of motor units were identified from decomposition of high-density surface electromyography signals during repeated submaximal knee extensor contractions. Quadriceps resting twitch responses and near-infrared spectroscopy measurements of oxygen saturation as an indirect measure of blood flow were made. There was a greater decrease in paretic motor unit discharge rates during the occlusion compared with the controls (average decrease for stroke and controls, 12.3 ± 10.0% and 0.1 ± 12.4%, respectively; P < 0.001). The motor unit recruitment thresholds did not change with the occlusion (stroke: without occlusion, 11.68 ± 5.83%MVC vs. with occlusion, 11.11 ± 5.26%MVC; control: 11.87 ± 5.63 vs. 11.28 ± 5.29%MVC). Resting twitch amplitudes declined similarly for both groups in response to whole leg occlusion (stroke: 29.16 ± 6.88 vs. 25.75 ± 6.78 Nm; control: 38.80 ± 13.23 vs 30.14 ± 9.64 Nm). Controls had a greater exponential decline (lower time constant) in oxygen saturation compared with the stroke group (stroke time constant, 22.90 ± 10.26 min vs. control time constant, 5.46 ± 4.09 min; P < 0.001). Ischemia of the muscle resulted in greater neural inhibition of paretic motor units compared with controls and may contribute to deficient muscle activation poststroke. NEW & NOTEWORTHY Hyperexcitable inhibitory sensory pathways sensitive to ischemia may play a role in deficient motor unit activation post stroke. Using high-density surface electromyography recordings to detect motor unit firing instances, we show that ischemia of the exercising muscle results in greater inhibition of paretic motor unit firing rates compared with controls. These findings are impactful to neurophysiologists and clinicians because they implicate a novel mechanism of force-generating impairment poststroke that likely exacerbates baseline weakness.

Identifying Motor Units in Longitudinal Studies with High-Density Surface Electromyography

2016 ◽  
pp. 147-151
Author(s):  
Eduardo Martinez-Valdes ◽  
Francesco Negro ◽  
Christopher M. Laine ◽  
Deborah L. Falla ◽  
Frank Mayer ◽  
...  
Keyword(s):  
Longitudinal Studies ◽  
Surface Electromyography ◽  
Motor Units ◽  
High Density ◽  
Density Surface

scholarly journals Three-Dimensional Innervation Zone Imaging from Multi-Channel Surface EMG Recordings

2015 ◽  
Vol 25 (06) ◽  
pp. 1550024 ◽  
Author(s):  
Yang Liu ◽  
Yong Ning ◽  
Sheng Li ◽  
Ping Zhou ◽  
William Z. Rymer ◽  
...  
Keyword(s):  
High Performance ◽  
Unmet Need ◽  
Three Dimensional ◽  
Motor Units ◽  
Decomposition Methods ◽  
Surface Emg ◽  
Source Imaging ◽  
Dynamic Propagation ◽  
Channel Surface ◽  
Density Surface

There is an unmet need to accurately identify the locations of innervation zones (IZs) of spastic muscles, so as to guide botulinum toxin (BTX) injections for the best clinical outcome. A novel 3D IZ imaging (3DIZI) approach was developed by combining the bioelectrical source imaging and surface electromyogram (EMG) decomposition methods to image the 3D distribution of IZs in the target muscles. Surface IZ locations of motor units (MUs), identified from the bipolar map of their MU action potentials (MUAPs) were employed as a prior knowledge in the 3DIZI approach to improve its imaging accuracy. The performance of the 3DIZI approach was first optimized and evaluated via a series of designed computer simulations, and then validated with the intramuscular EMG data, together with simultaneously recorded 128-channel surface EMG data from the biceps of two subjects. Both simulation and experimental validation results demonstrate the high performance of the 3DIZI approach in accurately reconstructing the distributions of IZs and the dynamic propagation of internal muscle activities in the biceps from high-density surface EMG recordings.

Sign in / Sign up

Export Citation Format

Share Document