Shared muscle synergies in human walking and cycling

2014 ◽  
Vol 112 (8) ◽  
pp. 1984-1998 ◽  
Author(s):  
Filipe O. Barroso ◽  
Diego Torricelli ◽  
Juan C. Moreno ◽  
Julian Taylor ◽  
Julio Gomez-Soriano ◽  
...  
Keyword(s):  
Nonnegative Matrix ◽  
Muscular Activity ◽  
Muscle Synergy ◽  
Emg Activity ◽  
Modular Organization ◽  
Muscle Synergies ◽  
Supporting Evidence ◽  
Healthy Humans ◽  
Common Control ◽  
Secondary Objective

The motor system may rely on a modular organization (muscle synergies activated in time) to execute different tasks. We investigated the common control features of walking and cycling in healthy humans from the perspective of muscle synergies. Three hypotheses were tested: 1) muscle synergies extracted from walking trials are similar to those extracted during cycling; 2) muscle synergies extracted from one of these motor tasks can be used to mathematically reconstruct the electromyographic (EMG) patterns of the other task; 3) muscle synergies of cycling can result from merging synergies of walking. A secondary objective was to identify the speed (and cadence) at which higher similarities emerged. EMG activity from eight muscles of the dominant leg was recorded in eight healthy subjects during walking and cycling at four matched cadences. A factorization technique [nonnegative matrix factorization (NNMF)] was applied to extract individual muscle synergy vectors and the respective activation coefficients behind the global muscular activity of each condition. Results corroborated hypotheses 2 and 3, showing that 1) four synergies from walking and cycling can successfully explain most of the EMG variability of cycling and walking, respectively, and 2) two of four synergies from walking appear to merge together to reconstruct one individual synergy of cycling, with best reconstruction values found for higher speeds. Direct comparison of the muscle synergy vectors of walking and the muscle synergy vectors of cycling ( hypothesis 1) produced moderated values of similarity. This study provides supporting evidence for the hypothesis that cycling and walking share common neuromuscular mechanisms.

scholarly journals Modular Organization of Muscle Synergies to Achieve Movement Behaviors

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Kunkun Zhao ◽  
Zhisheng Zhang ◽  
Haiying Wen ◽  
Zihan Wang ◽  
Jiankang Wu
Keyword(s):  
Motion Control ◽  
Control Mechanism ◽  
Nonnegative Matrix ◽  
Movement Patterns ◽  
Motor Dysfunction ◽  
Muscle Synergy ◽  
Modular Organization ◽  
Muscle Synergies ◽  
Motion Primitives ◽  
Motion Control Mechanism

Muscle synergy has been applied to comprehend how the central nervous system (CNS) controls movements for decades. However, it is not clear about the motion control mechanism and the relationship between motions and muscle synergies. In this paper, we designed two experiments to corroborate the hypothesis: (1) motions can be decomposed to motion primitives, which are driven by muscle synergy primitives and (2) variations of motion primitives in direction and scale are modulated by activation coefficients rather than muscle synergy primitives. Surface electromyographic (EMG) signals were recorded from nine muscles of the upper limb. Nonnegative matrix factorization (NMF) was applied to extract muscle synergy vectors and corresponding activation coefficients. We found that synergy structures of different movement patterns were similar (α=0.05). The motion modulation indexes (MMI) among movement patterns in reaching movements showed apparent differences. Merging coefficients and reconstructed similarity of synergies between simple motions and complex motions were significant. This study revealed the motion control mechanism of the CNS and provided a rehabilitation and evaluation method for patients with motor dysfunction in exercise and neuroscience.

scholarly journals Muscle Synergies Reliability in the Power Clean Exercise

2020 ◽  
Vol 5 (4) ◽  
pp. 75
Author(s):  
Paulo D. G. Santos ◽  
João R. Vaz ◽  
Paulo F. Correia ◽  
Maria J. Valamatos ◽  
António P. Veloso ◽  
...  
Keyword(s):  
Nonnegative Matrix Factorization ◽  
Nonnegative Matrix ◽  
Human Movement ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Complex Task ◽  
Muscle Coordination ◽  
High Similarity ◽  
Strength Tests ◽  
Power Clean

Muscle synergy extraction has been utilized to investigate muscle coordination in human movement, namely in sports. The reliability of the method has been proposed, although it has not been assessed previously during a complex sportive task. Therefore, the aim of the study was to evaluate intra- and inter-day reliability of a strength training complex task, the power clean, assessing participants’ variability in the task across sets and days. Twelve unexperienced participants performed four sets of power cleans in two test days after strength tests, and muscle synergies were extracted from electromyography (EMG) data of 16 muscles. Three muscle synergies accounted for almost 90% of variance accounted for (VAF) across sets and days. Intra-day VAF, muscle synergy vectors, synergy activation coefficients and individual EMG profiles showed high similarity values. Inter-day muscle synergy vectors had moderate similarity, while the variables regarding temporal activation were still strongly related. The present findings revealed that the muscle synergies extracted during the power clean remained stable across sets and days in unexperienced participants. Thus, the mathematical procedure for the extraction of muscle synergies through nonnegative matrix factorization (NMF) may be considered a reliable method to study muscle coordination adaptations from muscle strength programs.

scholarly journals Subject-Specific Muscle Synergies in Human Balance Control Are Consistent Across Different Biomechanical Contexts

2010 ◽  
Vol 103 (6) ◽  
pp. 3084-3098 ◽  
Author(s):  
Gelsy Torres-Oviedo ◽  
Lena H. Ting
Keyword(s):  
Muscle Activation ◽  
Balance Control ◽  
Nonnegative Matrix ◽  
The Body ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Support Surface ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Specific Muscle

The musculoskeletal redundancy of the body provides multiple solutions for performing motor tasks. We have proposed that the nervous system solves this unconstrained problem through the recruitment of motor modules or functional muscle synergies that map motor intention to action. Consistent with this hypothesis, we showed that trial-by-trial variations in muscle activation for multidirectional balance control in humans were constrained by a small set of muscle synergies. However, apparent muscle synergy structures could arise from characteristic patterns of sensory input resulting from perturbations or from low-dimensional optimal motor solutions. Here we studied electromyographic (EMG) responses for balance control across a range of biomechanical contexts, which alter not only the sensory inflow generated by postural perturbations, but also the muscle activation patterns used to restore balance. Support-surface translations in 12 directions were delivered to subjects standing in six different postural configurations: one-leg, narrow, wide, very wide, crouched, and normal stance. Muscle synergies were extracted from each condition using nonnegative matrix factorization. In addition, muscle synergies from the normal stance condition were used to reconstruct muscle activation patterns across all stance conditions. A consistent set of muscle synergies were recruited by each subject across conditions. When balance demands were extremely different from the normal stance (e.g., one-legged or crouched stance), task-specific muscle synergies were recruited in addition to the preexisting ones, rather generating de novo muscle synergies. Taken together, our results suggest that muscle synergies represent consistent motor modules that map intention to action, regardless of the biomechanical context of the task.

scholarly journals On the Reliability and Repeatability of Surface Electromyography Factorization by Muscle Synergies in Daily Life Activities

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Juri Taborri ◽  
Eduardo Palermo ◽  
Zaccaria Del Prete ◽  
Stefano Rossi
Keyword(s):  
Activity Patterns ◽  
Intraclass Correlation ◽  
Nonnegative Matrix ◽  
Cosine Similarity ◽  
Muscle Synergy ◽  
Coefficient Of Determination ◽  
Muscle Synergies ◽  
Daily Life Activities ◽  
Research Fields ◽  
Emg Signal

Muscle synergy theory is a new appealing approach for different research fields. This study is aimed at evaluating the robustness of EMG reconstruction via muscle synergies and the repeatability of muscle synergy parameters as potential neurophysiological indices. Eight healthy subjects performed walking, stepping, running, and ascending and descending stairs’ trials for five repetitions in three sessions. Twelve muscles of the dominant leg were analyzed. The “nonnegative matrix factorization” and “variability account for” were used to extract muscle synergies and to assess EMG goodness reconstruction, respectively. Intraclass correlation was used to quantify methodology reliability. Cosine similarity and coefficient of determination assessed the repeatability of the muscle synergy vectors and the temporal activity patterns, respectively. A 4-synergy model was selected for EMG signal factorization. Intraclass correlation was excellent for the overall reconstruction, while it ranged from fair to excellent for single muscles. The EMG reconstruction was found repeatable across sessions and subjects. Considering the selection of neurophysiological indices, the number of synergies was not repeatable neither within nor between subjects. Conversely, the cosine similarity and coefficient of determination values allow considering the muscle synergy vectors and the temporal activity patterns as potential neurophysiological indices due to their similarity both within and between subjects. More specifically, some synergies in the 4-synergy model reveal themselves as more repeatable than others, suggesting focusing on them when seeking at the neurophysiological index identification.

scholarly journals Neuromechanics of Dynamic Balance Tasks in the Presence of Perturbations

2021 ◽  
Vol 14 ◽  
Author(s):  
Victor Munoz-Martel ◽  
Alessandro Santuz ◽  
Sebastian Bohm ◽  
Adamantios Arampatzis
Keyword(s):  
Motor Control ◽  
Mechanical Loading ◽  
Lower Limb ◽  
The Body ◽  
Muscle Synergy ◽  
Emg Activity ◽  
Modular Organization ◽  
Joint Moments ◽  
Lower Limb Muscles ◽  
Limb Muscles

Understanding the neuromechanical responses to perturbations in humans may help to explain the reported improvements in stability performance and muscle strength after perturbation-based training. In this study, we investigated the effects of perturbations, induced by unstable surfaces, on the mechanical loading and the modular organization of motor control in the lower limb muscles during lunging forward and backward. Fifteen healthy adults performed 50 forward and 50 backward lunges on stable and unstable ground. Ground reaction forces, joint kinematics, and the electromyogram (EMG) of 13 lower limb muscles were recorded. We calculated the resultant joint moments and extracted muscle synergies from the stepping limb. We found sparse alterations in the resultant joint moments and EMG activity, indicating a little if any effect of perturbations on muscle mechanical loading. The time-dependent structure of the muscle synergy responsible for the stabilization of the body was modified in the perturbed lunges by a shift in the center of activity (later in the forward and earlier in the backward lunge) and a widening (in the backward lunge). Moreover, in the perturbed backward lunge, the synergy related to the body weight acceptance was not present. The found modulation of the modular organization of motor control in the unstable condition and related minor alteration in joint kinetics indicates increased control robustness that allowed the participants to maintain functionality in postural challenging settings. Triggering specific modulations in motor control to regulate robustness in the presence of perturbations may be associated with the reported benefits of perturbation-based training.

COMMON AND DISTINCT MUSCLE SYNERGIES DURING LEVEL AND SLOPE LOCOMOTION IN THE CAT

2021 ◽  
Author(s):  
Alexander N Klishko ◽  
Adil Akyildiz ◽  
Ricky Mehta ◽  
Boris I. Prilutsky
Keyword(s):  
Stance Phase ◽  
Rectus Femoris ◽  
Emg Activity ◽  
Modular Organization ◽  
Muscle Synergies ◽  
Cycle Duration ◽  
Hindlimb Muscles ◽  
Level Walking ◽  
Adult Cats ◽  
Activity Cluster

Although it is well established that the motor control system is modular, the organization of muscle synergies during locomotion and their change with ground slope are not completely understood. For example, typical reciprocal flexor-extensor muscle synergies of level walking in cats break down in downslope: one-joint hip extensors are silent throughout the stride cycle, whereas hindlimb flexors demonstrate an additional stance phase-related EMG burst (Smith et al. 1998a). Here we investigated muscle synergies during Level, Upslope (27o) and Downslope (-27o) walking in adult cats to examine common and distinct features of modular organization of locomotor EMG activity. Cluster analysis of EMG burst onset-offset times of 12 hindlimb muscles revealed 5 flexor and extensor burst groups that were generally shared across slopes. Stance-related bursts of flexor muscles in downslope were placed in a burst group from Level and Upslope walking formed by the rectus femoris. Walking Upslope changed swing/stance phase durations of Level walking but not the cycle duration. Five muscle synergies computed using non-negative matrix factorization accounted for at least 95% of variance in EMG patterns in each slope. Five synergies were shared between Level and Upslope walking, whereas only 3 of those were shared with Downslope synergies; these synergies were active during the swing phase and phase transitions. Two stance-related synergies of downslope walking were distinct; they comprised a mixture of flexors and extensors. We suggest that the modular organization of muscle activity during Level and Slope walking results from interactions between motion-related sensory feedback, CPG, and supraspinal inputs.

Muscle Synergies Based on a Biomechanical Biaxial Isometric Shoulder Model Minimizing Fatigue

2010 ◽  
Author(s):  
Mohamadreza Nassajian Moghadam ◽  
Kamiar Aminian ◽  
Mohsen Asghari ◽  
Mohammad Parnianpour
Keyword(s):  
Shoulder Joint ◽  
Degrees Of Freedom ◽  
Muscle Activation ◽  
Glenohumeral Joint ◽  
Nonnegative Matrix ◽  
Factorization Method ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Specific Direction ◽  
Activation Data

In this study we utilize the concept of synergy formation as a simplifying control strategy to manage the high number of degrees of freedom presented in the maintenance of the posture of the shoulder joint. We address how to find the muscle synergy recruitment map to the biomechanical demands (biaxial external torque) during an isometric shoulder task. We use a numerical optimization based shoulder model to obtain muscle activation levels when a biaxial external isometric torque is exposed at the shoulder glenohumeral joint. In the numerical simulations, different shoulder torque vectors parallel to the horizontal plane are considered. For each selected direction for the torque, the resulting muscle activation data are calculated and then used for grouping muscles in some fixed element synergies by nonnegative matrix factorization method Next, the muscle synergies are converted from activation level to the torque space to see how muscle synergy recruitment addresses the torque production in a specific direction at the shoulder joint. The results confirmed our expectation that the few dominant synergies are sufficient to address the torque vectors in directions which coincide to the basic vectors of torque space, such that each muscle contributed to more than one synergy.

Is interindividual variability of EMG patterns in trained cyclists related to different muscle synergies?

2010 ◽  
Vol 108 (6) ◽  
pp. 1727-1736 ◽  
Author(s):  
François Hug ◽  
Nicolas A. Turpin ◽  
Arnaud Guével ◽  
Sylvain Dorel
Keyword(s):  
Interindividual Variability ◽  
Nonnegative Matrix ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Surface Emg ◽  
Constant Load ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Lower Limb Muscles ◽  
Emg Patterns

Our aim was to determine whether muscle synergies are similar across trained cyclists (and thus whether the same locomotor strategies for pedaling are used), despite interindividual variability of individual EMG patterns. Nine trained cyclists were tested during a constant-load pedaling exercise performed at 80% of maximal power. Surface EMG signals were measured in 10 lower limb muscles. A decomposition algorithm (nonnegative matrix factorization) was applied to a set of 40 consecutive pedaling cycles to differentiate muscle synergies. We selected the least number of synergies that provided 90% of the variance accounted for VAF. Using this criterion, three synergies were identified for all of the subjects, accounting for 93.5 ± 2.0% of total VAF, with VAF for individual muscles ranging from 89.9 ± 8.2% to 96.6 ± 1.3%. Each of these synergies was quite similar across all subjects, with a high mean correlation coefficient for synergy activation coefficients (0.927 ± 0.070, 0.930 ± 0.052, and 0.877 ± 0.110 for synergies 1– 3, respectively) and muscle synergy vectors (0.873 ± 0.120, 0.948 ± 0.274, and 0.885 ± 0.129 for synergies 1– 3, respectively). Despite a large consistency across subjects in the weighting of several monoarticular muscles into muscle synergy vectors, we found larger interindividual variability for another monoarticular muscle (soleus) and for biarticular muscles (rectus femoris, gastrocnemius lateralis, biceps femoris, and semimembranosus). This study demonstrated that pedaling is accomplished by the combination of the similar three muscle synergies among trained cyclists. The interindividual variability of EMG patterns observed during pedaling does not represent differences in the locomotor strategy for pedaling.

scholarly journals Absence of postural muscle synergies for balance after spinal cord transection

2013 ◽  
Vol 110 (6) ◽  
pp. 1301-1310 ◽  
Author(s):  
Stacie A. Chvatal ◽  
Jane M. Macpherson ◽  
Gelsy Torres-Oviedo ◽  
Lena H. Ting
Keyword(s):  
Spinal Cord ◽  
Muscle Activity ◽  
Balance Control ◽  
Neural Mechanisms ◽  
Spinal Cord Transection ◽  
Muscle Synergy ◽  
Modular Organization ◽  
Muscle Synergies ◽  
Weight Support ◽  
Postural Muscle

Although cats that have been spinalized can also be trained to stand and step with full weight support, directionally appropriate long-latency responses to perturbations are impaired, suggesting that these behaviors are mediated by distinct neural mechanisms. However, it remains unclear whether these responses reflect an attenuated postural response using the appropriate muscular coordination patterns for balance or are due to fundamentally different neural mechanisms such as increased muscular cocontraction or short-latency stretch responses. Here we used muscle synergy analysis on previously collected data to identify whether there are changes in the spatial organization of muscle activity for balance within an animal after spinalization. We hypothesized that the modular organization of muscle activity for balance control is disrupted by spinal cord transection. In each of four animals, muscle synergies were extracted from postural muscle activity both before and after spinalization with nonnegative matrix factorization. Muscle synergy number was reduced after spinalization in three animals and increased in one animal. However, muscle synergy structure was greatly altered after spinalization with reduced direction tuning, suggesting little consistent organization of muscle activity. Furthermore, muscle synergy recruitment was correlated to subsequent force production in the intact but not spinalized condition. Our results demonstrate that the modular structure of sensorimotor feedback responses for balance control is severely disrupted after spinalization, suggesting that the muscle synergies for balance control are not accessible by spinal circuits alone. Moreover, we demonstrate that spinal mechanisms underlying weight support are distinct from brain stem mechanisms underlying directional balance control.

scholarly journals Robustness of muscle synergies underlying three-dimensional force generation at the hand in healthy humans

2012 ◽  
Vol 107 (8) ◽  
pp. 2123-2142 ◽  
Author(s):  
Jinsook Roh ◽  
William Z. Rymer ◽  
Randall F. Beer
Keyword(s):  
Nervous System ◽  
Matrix Factorization ◽  
Isometric Force ◽  
Three Dimensional ◽  
Movement Control ◽  
Force Generation ◽  
Muscle Synergy ◽  
Muscle Synergies ◽  
Healthy Humans ◽  
Isometric Forces

Previous studies using advanced matrix factorization techniques have shown that the coordination of human voluntary limb movements may be accomplished using combinations of a small number of intermuscular coordination patterns, or muscle synergies. However, the potential use of muscle synergies for isometric force generation has been evaluated mostly using correlational methods. The results of such studies suggest that fixed relationships between the activations of pairs of muscles are relatively rare. There is also emerging evidence that the nervous system uses independent strategies to control movement and force generation, which suggests that one cannot conclude a priori that isometric force generation is accomplished by combining muscle synergies, as shown in movement control. In this study, we used non-negative matrix factorization to evaluate the ability of a few muscle synergies to reconstruct the activation patterns of human arm muscles underlying the generation of three-dimensional (3-D) isometric forces at the hand. Surface electromyographic (EMG) data were recorded from eight key elbow and shoulder muscles during 3-D force target-matching protocols performed across a range of load levels and hand positions. Four synergies were sufficient to explain, on average, 95% of the variance in EMG datasets. Furthermore, we found that muscle synergy composition was conserved across biomechanical task conditions, experimental protocols, and subjects. Our findings are consistent with the view that the nervous system can generate isometric forces by assembling a combination of a small number of muscle synergies, differentially weighted according to task constraints.

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