Modulation of finger muscle activation patterns across postures is coordinated across all muscle groups

We examined how hand muscles adapt to changing external (force direction) and internal (posture) conditions. Muscle activations, particularly of the extrinsic extensors, were significantly affected by postural changes of the interphalangeal, but not metacarpophalangeal, joints. Joint impedance was modulated so that the effects of the signal-dependent motor noise on the force output were reduced. Comparisons with theoretical solutions showed that the chosen activation patterns occupied a small portion of the possible solution space, minimizing the maximum activation of any one muscle.

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Is the Occurrence of the Sticking Region in Maximum Smith Machine Squats the Result of Diminishing Potentiation and Co-Contraction of the Prime Movers among Recreationally Resistance Trained Males?

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18031366 ◽

2021 ◽

Vol 18 (3) ◽

pp. 1366

Author(s):

Roland van den Tillaar ◽

Eirik Lindset Kristiansen ◽

Stian Larsen

Keyword(s):

Muscle Activity ◽

Muscle Activation ◽

Gluteus Maximus ◽

Knee Extensors ◽

Force Output ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Prime Movers ◽

Almost All ◽

Height Data

This study compared the kinetics, barbell, and joint kinematics and muscle activation patterns between a one-repetition maximum (1-RM) Smith machine squat and isometric squats performed at 10 different heights from the lowest barbell height. The aim was to investigate if force output is lowest in the sticking region, indicating that this is a poor biomechanical region. Twelve resistance trained males (age: 22 ± 5 years, mass: 83.5 ± 39 kg, height: 1.81 ± 0.20 m) were tested. A repeated two-way analysis of variance showed that Force output decreased in the sticking region for the 1-RM trial, while for the isometric trials, force output was lowest between 0–15 cm from the lowest barbell height, data that support the sticking region is a poor biomechanical region. Almost all muscles showed higher activity at 1-RM compared with isometric attempts (p < 0.05). The quadriceps activity decreased, and the gluteus maximus and shank muscle activity increased with increasing height (p ≤ 0.024). Moreover, the vastus muscles decreased only for the 1-RM trial while remaining stable at the same positions in the isometric trials (p = 0.04), indicating that potentiation occurs. Our findings suggest that a co-contraction between the hip and knee extensors, together with potentiation from the vastus muscles during ascent, creates a poor biomechanical region for force output, and thereby the sticking region among recreationally resistance trained males during 1-RM Smith machine squats.

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Development of an Apparatus for Bilateral Rhythmical Training of Arm Movement Via Linear and Elliptical Trajectories of Various Directions

Journal of Medical Devices ◽

10.1115/1.4027796 ◽

2014 ◽

Vol 8 (3) ◽

Cited By ~ 1

Author(s):

Zlatko Matjačić ◽

Matjaž Zadravec ◽

Jakob Oblak

Keyword(s):

Muscle Activation ◽

Arm Movement ◽

Emg Activity ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Arm Cycling ◽

Arm Reaching ◽

Direction Of Movement ◽

Muscle Groups ◽

Neurologically Intact

Clinical rehabilitation of individuals with various neurological disorders requires a significant number of movement repetitions in order to improve coordination and restoration of appropriate muscle activation patterns. Arm reaching movement is frequently practiced via motorized arm cycling ergometers where the trajectory of movement is circular thus providing means for practicing a single and rather nonfunctional set of muscle activation patterns, which is a significant limitation. We have developed a novel mechanism that in the combination with an existing arm ergometer device enables nine different movement modalities/trajectories ranging from purely circular trajectory to four elliptical and four linear trajectories where the direction of movement may be varied. The main objective of this study was to test a hypothesis stating that different movement modalities facilitate differences in muscle activation patterns as a result of varying shape and direction of movement. Muscle activation patterns in all movement modalities were assessed in a group of neurologically intact individuals in the form of recording the electromyographic (EMG) activity of four selected muscle groups of the shoulder and the elbow. Statistical analysis of the root mean square (RMS) values of resulting EMG signals have shown that muscle activation patterns corresponding to each of the nine movement modalities significantly differ in order to accommodate to variation of the trajectories shape and direction. Further, we assessed muscle activation patterns following the same protocol in a selected clinical case of hemiparesis. These results have shown the ability of the selected case subject to produce different muscle activation patterns as a response to different movement modalities which show some resemblance to those assessed in the group of neurologically intact individuals. The results of the study indicate that the developed device may significantly extend the scope of strength and coordination training in stroke rehabilitation which is in current clinical rehabilitation practice done through arm cycling.

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Alterations in muscle activation patterns during robot-assisted bilateral training: A pilot study

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411918819115 ◽

2018 ◽

Vol 233 (2) ◽

pp. 219-231 ◽

Cited By ~ 3

Author(s):

Bo Sheng ◽

Lihua Tang ◽

Shengquan Xie ◽

Chao Deng ◽

Yanxin Zhang

Keyword(s):

Muscle Activation ◽

Interaction Force ◽

Robot Assisted ◽

Activation Patterns ◽

Recovery Processes ◽

Muscle Activation Patterns ◽

Bilateral Training ◽

Muscle Groups ◽

Highly Correlated ◽

Training Protocols

Robot-assisted bilateral training is being developed as a new rehabilitation approach for stroke patients. However, there is still a lack of understanding of muscle functions when performing robot-assisted synchronous movements. The aim of this work is to explore the muscle activation patterns and the voluntary effort of participants during different robot-assisted bilateral training protocols. To this end, 10 healthy participants were recruited to take part in a 60-minute experiment. The experiment included two different bilateral exercises, and each exercise contained four different training protocols. Trajectories of the robots, interaction force and surface electromyogram signals were recorded during training. The results show that the robots do affect the muscle activation patterns during different training protocols and exercises rather than the controller. Specifically, the activity of muscles is reduced in robot-assisted training but is increased in active force involved robot-assisted training when compared to robot-unassisted training. Meanwhile, the voluntary effort of participants can be presented by the adjusted trajectories via the controller. In addition, the results also suggest that the activations for the same muscle groups in the left and right arms are highly correlated with each other in both exercises. Furthermore, the training protocols and methods developed in this work could be further extended in future clinical trials to investigate therapeutic outcomes for patients as well as to better understand bilateral recovery processes.

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Lower complexity of motor primitives ensures robust control of high-speed human locomotion

10.1101/2020.04.24.055277 ◽

2020 ◽

Cited By ~ 3

Author(s):

Alessandro Santuz ◽

Antonis Ekizos ◽

Yoko Kunimasa ◽

Kota Kijima ◽

Masaki Ishikawa ◽

...

Keyword(s):

High Speed ◽

Muscle Activation ◽

Human Locomotion ◽

Muscle Synergies ◽

Activation Patterns ◽

Motor Primitives ◽

Muscle Activation Patterns ◽

Relative Contribution ◽

Muscle Activations ◽

Low Dimensional

AbstractWalking and running are mechanically and energetically different locomotion modes. For selecting one or another, speed is a parameter of paramount importance. Yet, both are likely controlled by similar low-dimensional neuronal networks that reflect in patterned muscle activations called muscle synergies. Here, we investigated how humans synergistically activate muscles during locomotion at different submaximal and maximal speeds. We analysed the duration and complexity (or irregularity) over time of motor primitives, the temporal components of muscle synergies. We found that the challenge imposed by controlling high-speed locomotion forces the central nervous system to produce muscle activation patterns that are wider and less complex relative to the duration of the gait cycle. The motor modules, or time-independent coefficients, were redistributed as locomotion speed changed. These outcomes show that robust locomotion control at challenging speeds is achieved by modulating the relative contribution of muscle activations and producing less complex and wider control signals, whereas slow speeds allow for more irregular control.

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Primary motor cortex neurons classified in a postural task predict muscle activation patterns in a reaching task

Journal of Neurophysiology ◽

10.1152/jn.00971.2015 ◽

2016 ◽

Vol 115 (4) ◽

pp. 2021-2032 ◽

Cited By ~ 10

Author(s):

Ethan A. Heming ◽

Timothy P. Lillicrap ◽

Mohsen Omrani ◽

Troy M. Herter ◽

J. Andrew Pruszynski ◽

...

Keyword(s):

Motor Cortex ◽

Muscle Activation ◽

Primary Motor Cortex ◽

Network Connectivity ◽

Spatiotemporal Patterns ◽

Neural Population ◽

Activation Patterns ◽

Reaching Task ◽

Muscle Activation Patterns ◽

Muscle Groups

Primary motor cortex (M1) activity correlates with many motor variables, making it difficult to demonstrate how it participates in motor control. We developed a two-stage process to separate the process of classifying the motor field of M1 neurons from the process of predicting the spatiotemporal patterns of its motor field during reaching. We tested our approach with a neural network model that controlled a two-joint arm to show the statistical relationship between network connectivity and neural activity across different motor tasks. In rhesus monkeys, M1 neurons classified by this method showed preferred reaching directions similar to their associated muscle groups. Importantly, the neural population signals predicted the spatiotemporal dynamics of their associated muscle groups, although a subgroup of atypical neurons reversed their directional preference, suggesting a selective role in antagonist control. These results highlight that M1 provides important details on the spatiotemporal patterns of muscle activity during motor skills such as reaching.

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Predicting muscle activation patterns from motion and anatomy: modelling the skull of Sphenodon (Diapsida: Rhynchocephalia)

Journal of The Royal Society Interface ◽

10.1098/rsif.2009.0139 ◽

2009 ◽

Vol 7 (42) ◽

pp. 153-160 ◽

Cited By ~ 40

Author(s):

Neil Curtis ◽

Marc E. H. Jones ◽

Susan E. Evans ◽

JunFen Shi ◽

Paul O'Higgins ◽

...

Keyword(s):

Muscle Activity ◽

Muscle Activation ◽

Element Analysis ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Highly Active ◽

Novel Approach ◽

Food Size ◽

Muscle Groups ◽

Musculoskeletal Systems

The relationship between skull shape and the forces generated during feeding is currently under widespread scrutiny and increasingly involves the use of computer simulations such as finite element analysis. The computer models used to represent skulls are often based on computed tomography data and thus are structurally accurate; however, correctly representing muscular loading during food reduction remains a major problem. Here, we present a novel approach for predicting the forces and activation patterns of muscles and muscle groups based on their known anatomical orientation (line of action). The work was carried out for the lizard-like reptile Sphenodon (Rhynchocephalia) using a sophisticated computer-based model and multi-body dynamics analysis. The model suggests that specific muscle groups control specific motions, and that during certain times in the bite cycle some muscles are highly active whereas others are inactive. The predictions of muscle activity closely correspond to data previously recorded from live Sphenodon using electromyography. Apparent exceptions can be explained by variations in food resistance, food size, food position and lower jaw motions. This approach shows considerable promise in advancing detailed functional models of food acquisition and reduction, and for use in other musculoskeletal systems where no experimental determination of muscle activity is possible, such as in rare, endangered or extinct species.

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EMG-Assisted Neuromusculoskeletal Models Can Estimate Physiological Muscle Activations and Joint Moments Across the Neck Before Impacts

Journal of Biomechanical Engineering ◽

10.1115/1.4052555 ◽

2021 ◽

Author(s):

Pavlos Silvestros ◽

Claudio Pizzolato ◽

David G. Lloyd ◽

Ezio Preatoni ◽

Harinderjit S. Gill ◽

...

Keyword(s):

Cervical Spine ◽

Muscle Activation ◽

Inverse Dynamics ◽

A Priori ◽

Neck Muscle ◽

Joint Moments ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Flexion Extension ◽

Muscle Activations

Abstract Knowledge of neck muscle activation strategies prior to sporting impacts is crucial for investigating mechanisms of severe spinal injuries. However, measurement of muscle activations during impacts is experimentally challenging and computational estimations are not often guided by experimental measurements. We investigated neck muscle activations prior to impacts with the use of electromyography (EMG)-assisted neuromusculoskeletal models. Kinematics and EMG recordings from four major neck muscles of a rugby player were experimentally measured during rugby activities. A subject-specific musculoskeletal model was created with muscle parameters informed from MRI measurements. The model was used in the Calibrated EMG-Informed Neuromusculoskeletal Modelling toolbox and three neural solutions were compared: i) static optimisation (SO), ii) EMG-assisted (EMGa) and iii) MRI-informed EMG-assisted (EMGaMRI). EMGaMRI and EMGa significantly (p¡0.01) outperformed SO when tracking cervical spine net joint moments from inverse dynamics in flexion/extension (RMSE = 0.95, 1.14 and 2.32 Nm) but not in lateral bending (RMSE = 1.07, 2.07 and 0.84 Nm). EMG-assisted solutions generated physiological muscle activation patterns and maintained experimental co-contractions significantly (p¡0.01) outperforming SO, which was characterised by saturation and non-physiological "on-off" patterns. This study showed for the first time that physiological neck muscle activations and cervical spine net joint moments can be estimated without assumed a priori objective criteria prior to impacts. Future studies could use this technique to provide detailed initial loading conditions for theoretical simulations of neck injury during impacts.

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The Capacity of Generic Musculoskeletal Simulations to Predict Knee Joint Loading Using the CAMS-Knee Datasets

Annals of Biomedical Engineering ◽

10.1007/s10439-020-02465-5 ◽

2020 ◽

Vol 48 (4) ◽

pp. 1430-1440 ◽

Cited By ~ 1

Author(s):

Zohreh Imani Nejad ◽

Khalil Khalili ◽

Seyyed Hamed Hosseini Nasab ◽

Pascal Schütz ◽

Philipp Damm ◽

...

Keyword(s):

Muscle Activation ◽

Biceps Femoris ◽

Contact Forces ◽

Generic Model ◽

Model Parameters ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Level Walking ◽

Muscle Activations

Abstract Musculoskeletal models enable non-invasive estimation of knee contact forces (KCFs) during functional movements. However, the redundant nature of the musculoskeletal system and uncertainty in model parameters necessitates that model predictions are critically evaluated. This study compared KCF and muscle activation patterns predicted using a scaled generic model and OpenSim static optimization tool against in vivo measurements from six patients in the CAMS-knee datasets during level walking and squatting. Generally, the total KCFs were under-predicted (RMS: 47.55%BW, R 2: 0.92) throughout the gait cycle, but substiantially over-predicted (RMS: 105.7%BW, R 2: 0.81) during squatting. To understand the underlying etiology of the errors, muscle activations were compared to electromyography (EMG) signals, and showed good agreement during level walking. For squatting, however, the muscle activations showed large descrepancies especially for the biceps femoris long head. Errors in the predicted KCF and muscle activation patterns were greatest during deep squat. Hence suggesting that the errors mainly originate from muscle represented at the hip and an associated muscle co-contraction at the knee. Furthermore, there were substaintial differences in the ranking of subjects and activities based on peak KCFs in the simulations versus measurements. Thus, future simulation study designs must account for subject-specific uncertainties in musculoskeletal predictions.

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Electromyographic activation patterns during swallowing in older adults

Scientific Reports ◽

10.1038/s41598-021-84972-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jin Young Ko ◽

Hayoung Kim ◽

Joonyoung Jang ◽

Jun Chang Lee ◽

Ju Seok Ryu

Keyword(s):

Older Adults ◽

Viscous Fluid ◽

Muscle Activation ◽

Fatty Infiltration ◽

Liquid Volume ◽

Type I ◽

Type Ii ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Age Related

AbstractAge-related weakness due to atrophy and fatty infiltration in oropharyngeal muscles may be related to dysphagia in older adults. However, little is known about changes in the oropharyngeal muscle activation pattern in older adults. This was a prospective and experimental study. Forty healthy participants (20 older [> 60 years] and 20 young [< 60 years] adults) were enrolled. Six channel surface electrodes were placed over the bilateral suprahyoid (SH), bilateral retrohyoid (RH), thyrohyoid (TH), and sternothyroid (StH) muscles. Electromyography signals were then recorded twice for each patient during swallowing of 2 cc of water, 5 cc of water, and 5 cc of a highly viscous fluid. Latency, duration, and peak amplitude were measured. The activation patterns were the same, in the order of SH, TH, and StH, in both groups. The muscle activation patterns were classified as type I and II; the type I pattern was characterized by a monophasic shape, and the type II comprised a pre-reflex phase and a main phase. The oropharyngeal muscles and SH muscles were found to develop a pre-reflex phase specifically with increasing volume and viscosity of the swallowed fluid. Type I showed a different response to the highly viscous fluid in the older group compared to that in the younger group. However, type II showed concordant changes in the groups. Therefore, healthy older people were found to compensate for swallowing with a pre-reflex phase of muscle activation in response to increased liquid volume and viscosity, to adjust for age-related muscle weakness.

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