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.

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.

scholarly journals Common Synaptic Input to the Human Hypoglossal Motor Nucleus

2011 ◽  
Vol 105 (1) ◽  
pp. 380-387 ◽  
Author(s):  
Christopher M. Laine ◽  
E. Fiona Bailey
Keyword(s):  
Firing Rate ◽  
Motor Unit ◽  
Synaptic Input ◽  
Motor Units ◽  
Motor Nucleus ◽  
Tongue Protrusion ◽  
Ongoing Research ◽  
Airway Patency ◽  
Significant Difference ◽  
Common Drive

The tongue plays a key role in various volitional and automatic functions such as swallowing, maintenance of airway patency, and speech. Precisely how hypoglossal motor neurons, which control the tongue, receive and process their often concurrent input drives is a subject of ongoing research. We investigated common synaptic input to the hypoglossal motor nucleus by measuring the coordination of spike timing, firing rate, and oscillatory activity across motor units recorded from unilateral (i.e., within a belly) or bilateral (i.e., across both bellies) locations within the genioglossus (GG), the primary protruder muscle of the tongue. Simultaneously recorded pairs of motor units were obtained from 14 healthy adult volunteers using tungsten microelectrodes inserted percutaneously into the GG while the subjects were engaged in volitional tongue protrusion or rest breathing. Bilateral motor unit pairs showed concurrent low frequency alterations in firing rate (common drive) with no significant difference between tasks. Unilateral motor unit pairs showed significantly stronger common drive in the protrusion task compared with rest breathing, as well as higher indices of synchronous spiking (short-term synchrony). Common oscillatory input was assessed using coherence analysis and was observed in all conditions for frequencies up to ∼5 Hz. Coherence at frequencies up to ∼10 Hz was strongest in motor unit pairs recorded from the same GG belly in tongue protrusion. Taken together, our results suggest that cortical drive increases motor unit coordination within but not across GG bellies, while input drive during rest breathing is distributed uniformly to both bellies of the muscle.

scholarly journals Influence of common synaptic input to motor neurons on the neural drive to muscle in essential tremor

2015 ◽  
Vol 113 (1) ◽  
pp. 182-191 ◽  
Author(s):  
Juan A. Gallego ◽  
Jakob L. Dideriksen ◽  
Ales Holobar ◽  
Jaime Ibáñez ◽  
José L. Pons ◽  
...  
Keyword(s):  
Motor Unit ◽  
Motor Neurons ◽  
Synaptic Input ◽  
Motor Units ◽  
Spike Trains ◽  
Neural Drive ◽  
Systematic Analysis ◽  
Synaptic Inputs ◽  
Tremor Frequency ◽  
Unit Spike

Tremor in essential tremor (ET) is generated by pathological oscillations at 4–12 Hz, likely originating at cerebello-thalamo-cortical pathways. However, the way in which tremor is represented in the output of the spinal cord circuitries is largely unknown because of the difficulties in identifying the behavior of individual motor units from tremulous muscles. By using novel methods for the decomposition of multichannel surface EMG, we provide a systematic analysis of the discharge properties of motor units in nine ET patients, with concurrent recordings of EEG activity. This analysis allowed us to infer the contribution of common synaptic inputs to motor neurons in ET. Motor unit short-term synchronization was significantly greater in ET patients than in healthy subjects. Furthermore, the strong association between the degree of synchronization and the peak in coherence between motor unit spike trains at the tremor frequency indicated that the high synchronization levels were generated mainly by common synaptic inputs specifically at the tremor frequency. The coherence between EEG and motor unit spike trains demonstrated the presence of common cortical input to the motor neurons at the tremor frequency. Nonetheless, the strength of this input was uncorrelated to the net common synaptic input at the tremor frequency, suggesting a contribution of spinal afferents or secondary supraspinal pathways in projecting common input at the tremor frequency. These results provide the first systematic analysis of the neural drive to the muscle in ET and elucidate some of its characteristics that determine pathological tremulous muscle activity.

scholarly journals The Relationship Between Additional Heads of the Quadriceps Femoris, the Vasti Muscles and the Patellar Ligament

2021 ◽  
Author(s):  
Łukasz Olewnik ◽  
Kacper Ruzik ◽  
Bartłomiej Szewczyk ◽  
Michał Podgórski ◽  
Paloma Aragonés ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Quadriceps Femoris ◽  
The Other ◽  
Lower Limbs ◽  
Patellar Ligament ◽  
Vastus Medialis ◽  
Vastus Intermedius ◽  
Deep Layers ◽  
The Relationship

Abstract Introduction: The quadriceps femoris consists of four muscles: the rectus femoris, vastus medialis, vastus intermedius and vastus lateralis. However, the effect of additional quadriceps femoris heads on the vasti muscles and patellar ligaments is unknown.Materials and Methods: One hundred and six lower limbs (34 male and 19 female cadavers) fixed in 10% formalin were examined.Results: On all lower extremities, the vastus lateralis consisted of superficial, intermediate and deep layers. The vastus medialis, on the other hand, consisted of only the longus and obliquus layers. Additional quadriceps femoris heads affected both the vasti muscles and the patellar ligaments.Conclusion: There is a strong correlation between the presence of accessory quadriceps femoris heads and effects on vasti muscles and patellar ligament.

scholarly journals A comparison of peripheral and rubrospinal synaptic input to slow and fast twitch motor units of triceps surae

1970 ◽  
Vol 207 (3) ◽  
pp. 709-732 ◽  
Author(s):  
R. E. Burke ◽  
Elzbieta Jankowska ◽  
G. ten Bruggencate
Keyword(s):  
Synaptic Input ◽  
Motor Units ◽  
Triceps Surae ◽  
Fast Twitch

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 Dynamics of Quadriceps Muscles during Isometric Contractions: Velocity-Encoded Phase Contrast MRI Study

Diagnostics ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2280
Author(s):  
Toshiaki Oda ◽  
Vadim Malis ◽  
Taija Finni ◽  
Ryuta Kinugasa ◽  
Shantanu Sinha
Keyword(s):  
Phase Contrast ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Voluntary Contraction ◽  
Ensemble Average ◽  
The Other ◽  
Phase Contrast Mri ◽  
Axial Section ◽  
Measured Velocity ◽  
Thigh Muscles

Objective: To quantify the spatial heterogeneity of displacement during voluntary isometric contraction within and between the different compartments of the quadriceps. Methods: The thigh muscles of seven subjects were imaged on an MRI scanner while performing isometric knee extensions at 40% maximal voluntary contraction. A gated velocity-encoded phase contrast MRI sequence in axial orientations yielded tissue velocity-encoded dynamic images of the four different compartments of the thigh muscles (vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), and rectus femoris (RF)) at three longitudinal locations of the proximal–distal length: 17.5% (proximal), 50% (middle), and 77.5% (distal). The displacement, which is the time integration of the measured velocity, was calculated along the three orthogonal axes using a tracking algorithm. Results: The displacement of the muscle tissues was clearly nonuniform within each axial section as well as between the three axial locations. The ensemble average of the magnitude of the total displacement as a synthetic vector of the X, Y, and Z displacements was significantly larger in the VM at the middle location (p < 0.01), and in the VI at the distal location than in the other three muscles. The ensemble average of Z-axis displacement, which was almost aligned with the line of action, was significantly larger in VI than in the other three muscles in all three locations. Displacements of more than 20 mm were observed around the central aponeuroses, such as those between VI and the other surrounding muscles. Conclusions: These results imply that the quadriceps muscles act as one functional unit in normal force generation through the central aponeuroses despite complex behavior in each of the muscles, each of which possesses different physiological characteristics and architectures.

scholarly journals REDUCTION IN KNEE PAIN SYMPTOMS IN ATHLETES USING AN ACUPUNCTURE PROTOCOL

2018 ◽  
Vol 26 (6) ◽  
pp. 418-422 ◽  
Author(s):  
Ana Paula Rehme Siqueira ◽  
Lucas Menghin Beraldo ◽  
Eddy Krueger ◽  
Leandra Ulbricht
Keyword(s):  
Knee Pain ◽  
Vastus Lateralis ◽  
Case Series ◽  
Rectus Femoris ◽  
Motor Units ◽  
Lower Limbs ◽  
Limiting Factor ◽  
Level Of Evidence ◽  
Positive Effects ◽  
Pain Symptoms

ABSTRACT Pain in the lower limbs is common in athletes and a limiting factor in performance. Acupuncture has shown positive effects as an analgesic treatment and may potentially be used for pain reduction in runners. This study aimed to analyze the parameters associated with knee pain by correlating strength parameters of the musculature assessed in runners treated with acupuncture. A descriptive longitudinal study was conducted on 34 runners of both sexes aged 20 to 52 years, who presented with knee-related pain from January to June, 2015. Two pain questionnaires and a maximal strength test with electromyographic evaluation of the rectus femoris, vastus lateralis, and medialis muscles were used, and patients were monitored during five follow-up visits after an acupuncture protocol. All participants reported experiencing a decrease in knee pain after treatment. The affected limbs showed an increase in average strength by 34% and 25% compared to the contralateral limb. An increase in the number of motor units recruited for the three muscles was observed in both limbs. In conclusion, the proposed acupuncture protocol was effective in reducing pain symptoms in the knee region of athletes, thus influencing their gain in strength and muscle balance. Level of Evidence IV, Case series.

Vastus lateralis fatigue alters recruitment of musculus quadriceps femoris in humans

2002 ◽  
Vol 92 (2) ◽  
pp. 679-684 ◽  
Author(s):  
Hiroshi Akima ◽  
Jeanne M. Foley ◽  
Barry M. Prior ◽  
Gary A. Dudley ◽  
Ronald A. Meyer
Keyword(s):  
Vastus Lateralis ◽  
Transverse Relaxation Time ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Magnetic Resonance Images ◽  
Quadriceps Femoris ◽  
The Other ◽  
Musculus Quadriceps Femoris ◽  
Musculus Quadriceps ◽  
Before And After

This study tested the hypothesis that fatigue of a single member of musculus quadriceps femoris (QF) would alter use of the other three muscles during knee extension exercise (KEE). Six men performed KEE with the left QF at a load equal to 50% of the 4 × 10 repetitions maximum. Subsequently, electromyostimulation (EMS), intended to stimulate and fatigue the left m. vastus lateralis (VL), was applied for 30 min. Immediately after EMS, subjects repeated the KEE. Transverse relaxation time (T2)-weighted magnetic resonance images were taken before and after each bout of KEE and at 3 and 30 min of EMS to assess use and stimulation, respectively, of the QF. T2 of each of the QF muscles was increased 8–13% after the first KEE. During EMS, T2 increased ( P < 0.05) even more in VL (10%), whereas it decreased ( P < 0.05) to pre-KEE levels in m. vastus medials (VM) and m. rectus femoris (RF). The VL and, to some extent, the m. vastus intermedius were stimulated, whereas the VM and RF were not, thereby recovering from the first bout of KEE. Isometric torque, initially 30% of maximal voluntary, was reduced to 13% at 3 min and 7% at 30 min. T2 was greater ( P < 0.05) after the second than the first bout of KEE, especially the increase for the VM and RF. These results suggest that subjects were able to perform the second bout with little contribution of the VL by greater use of the other QF muscles. The simplest explanation is increased central command to the QF such that the intended act could be accomplished despite acute fatigue of one of its synergists.

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