The Influence of Modeling Separate Neuromuscular Compartments on the Force and Moment Generating Capacities of Muscles of the Feline Hindlimb

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Lisa N. MacFadden ◽  
Nicholas A. T. Brown
Keyword(s):  
Muscle Force ◽  
Spinal Cord Injuries ◽  
Biceps Femoris ◽  
Single Line ◽  
Single Muscle ◽  
Simulation Environment ◽  
Stimulation Parameters ◽  
Musculoskeletal Models ◽  
Neuromuscular Compartments ◽  
Multielectrode Stimulation

Functional electrical stimulation (FES) has the capacity to regenerate motion for individuals with spinal cord injuries. However, it is not straightforward to determine the stimulation parameters to generate a coordinated movement. Musculoskeletal models can provide a noninvasive simulation environment to estimate muscle force and activation timing sequences for a variety of tasks. Therefore, the purpose of this study was to develop a musculoskeletal model of the feline hindlimb for simulations to determine stimulation parameters for intrafascicular multielectrode stimulation (a method of FES). Additionally, we aimed to explore the differences in modeling neuromuscular compartments compared with representing these muscles as a single line of action. When comparing the modeled neuromuscular compartments of biceps femoris, sartorius, and semimembranosus to representations of these muscles as a single line of action, we observed that modeling the neuromuscular compartments of these three muscles generated different force and moment generating capacities when compared with single muscle representations. Differences as large as 4 N m (∼400% in biceps femoris) were computed between the summed moments of the neuromuscular compartments and the single muscle representations. Therefore, modeling neuromuscular compartments may be necessary to represent physiologically reasonable force and moment generating capacities of the feline hindlimb.

scholarly journals Modeling of Muscle Activation from Electromyography Recordings in Patients with Cerebral Palsy

2018 ◽  
Vol 8 (12) ◽  
pp. 2345
Author(s):  
Susmita Roy ◽  
Ana Alves-Pinto ◽  
Renée Lampe
Keyword(s):  
Cerebral Palsy ◽  
Reference Values ◽  
Muscle Activation ◽  
Muscle Force ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Force Modeling ◽  
Lower Extremity Muscle ◽  
Musculus Gastrocnemius ◽  
Parameter Dependent

The present study estimated muscle activation from electromyographic (EMG) recordings in patients with cerebral palsy (CP) during cycling on an ergometer. This could be used as an input to the modeling of muscle force following the neuromusculoskeletal modeling technique which can help to understand the alterations in neuromotor processes underlying disabilities in CP. EMG signals of lower extremity muscle activity from 14 adult patients with CP and 10 adult healthy participants were used here to derive muscle activation. With a self developed EMG system, signals from the following muscles were recorded: Musculus tibialis anterior, Musculus gastrocnemius, Musculus rectus femoris, and Musculus biceps femoris. Collected EMG signals were mathematically transformed into muscle activation following a parameter dependent and a nonlinear transformation. Muscle activation values from patients with CP were compared to equivalent reference values obtained from healthy controls. Muscle activation calculated at specific foot positions deviated clearly from reference values. The deviation was larger for patients with higher degree of spasticity. Observations underline the need of muscle force modeling during cycling for individualized cycling training for rehabilitation strategy.

Subject-Specific Estimates of Tendon Slack Length: A Numerical Method

2004 ◽  
Vol 20 (2) ◽  
pp. 195-203 ◽  
Author(s):  
Kurt Manal ◽  
Thomas S. Buchanan
Keyword(s):  
Numerical Method ◽  
Fiber Length ◽  
Muscle Force ◽  
Specific Input ◽  
Musculoskeletal Models ◽  
Subject Specific ◽  
Input Parameters ◽  
Slack Length

Tendon develops force proportional to the distance it is stretched beyond its slack length. Tendon slack length is an important parameter for musculoskeletal models because it can greatly affect estimations of muscle force. Unfortunately, tendon slack length is a difficult parameter to measure, and therefore values for it are not often reported in the literature. In this paper we present a numerical method for estimating tendon slack length from architectural parameters of the muscle. Specifically, tendon slack length is computed iteratively from musculotendon lengths determined when a corresponding joint is held at two angles, and from knowledge of the muscle's optimal fiber length. Idealized data generated using SIMM were used to test the tendon slack length algorithm. The method converged to within 1% of the “true” tendon slack length specified in the SIMM model. The advantage of the method outlined in this paper is that it yields subject-specific estimates of tendon slack length, given subject-specific input parameters.

Comparison of Estimated and Measured Muscle Activity During Inclined Walking

2016 ◽  
Vol 32 (2) ◽  
pp. 150-159 ◽  
Author(s):  
Nathalie Alexander ◽  
Hermann Schwameder
Keyword(s):  
Trend Analysis ◽  
Muscle Activity ◽  
Tibialis Anterior ◽  
Vastus Lateralis ◽  
A Priori ◽  
Correlation Coefficients ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Musculoskeletal Models ◽  
Downhill Walking

While inclined walking is a frequent daily activity, muscle forces during this activity have rarely been examined. Musculoskeletal models are commonly used to estimate internal forces in healthy populations, but these require a priori validation. The aim of this study was to compare estimated muscle activity using a musculoskeletal model with measured EMG data during inclined walking. Ten healthy male participants walked at different inclinations of 0°, ± 6°, ± 12°, and ± 18° on a ramp equipped with 2 force plates. Kinematics, kinetics, and muscle activity of the musculus (m.) biceps femoris, m. rectus femoris, m. vastus lateralis, m. tibialis anterior, and m. gastrocnemius lateralis were recorded. Agreement between estimated and measured muscle activity was determined via correlation coefficients, mean absolute errors, and trend analysis. Correlation coefficients between estimated and measured muscle activity for approximately 69% of the conditions were above 0.7. Mean absolute errors were rather high with only approximately 38% being ≤ 30%. Trend analysis revealed similar estimated and measured muscle activities for all muscles and tasks (uphill and downhill walking), except m. tibialis anterior during uphill walking. This model can be used for further analysis in similar groups of participants.

scholarly journals Effect of electrical stimulation on motor nerve regeneration in sciatic nerve ligated-mice

2017 ◽  
Vol 27 (3) ◽  
Author(s):  
Farzaneh Samiee ◽  
Mohammad-Reza Zarrindast
Keyword(s):  
Electrical Stimulation ◽  
Sciatic Nerve ◽  
Nerve Regeneration ◽  
Muscle Force ◽  
Motor Nerve ◽  
Nerve Repair ◽  
Gluteus Maximus ◽  
Biceps Femoris ◽  
Surface Emg ◽  
Significant Difference

The purpose of this study was to investigate the effect of electrical stimulation on sciatic nerve regeneration and functional recovery of target muscles. Mice were randomly divided into 3 groups: ligated without electrical stimulation, ligated with electrical stimulation and control (non-ligated). The unilateral peripheral mononeuropathy was produced on the right hind limb. Sciatic nerve was then electrically stimulated daily for a period of 2 weeks (duration: 0.2 msec, frequency: 100Hz, amplitude: 15mA). Evoked surface EMG was recorded from biceps femoris (BF) and gluteus maximus (GM) muscles on the 3rd, 7th, 10th and 14th day after sciatic nerve ligation. Muscle force and sensitivity was determined by processing of the recorded EMG signals in time and frequency domains respectively. The results showed electrical stimulation (ES) produced a significant increase in the EMG response of BF, and muscle force significantly increased on the 14th day (p<0.001), however no significant difference was found in GM muscle force between experimental groups. This may be due to possible innervation by inferior gluteal nerve. Frequency analysis of BF signals indicates that hyperalgesia remained after 14 days in both ligated groups. On the 14th day no difference in GM muscle sensitivity was found between groups. In conclusion, the results of this study have shown that the electrical stimulation of sciatic nerve accelerates nerve repair and indirectly improves BF muscle force to a comparable level with control without effect on muscle sensitivity. However, ES had no effect on GM muscle force and sensitivity.

scholarly journals Towards Subject-Specific Strength Training Design through Predictive Use of Musculoskeletal Models

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Michael Plüss ◽  
Florian Schellenberg ◽  
William R. Taylor ◽  
Silvio Lorenzetti
Keyword(s):  
Muscle Force ◽  
Inverse Dynamics ◽  
Gluteus Medius ◽  
The Body ◽  
External Loading ◽  
Detailed Knowledge ◽  
Muscle Forces ◽  
Specific Strength ◽  
Musculoskeletal Models ◽  
Flexion Extension

Lower extremity dysfunction is often associated with hip muscle strength deficiencies. Detailed knowledge of the muscle forces generated in the hip under specific external loading conditions enables specific structures to be trained. The aim of this study was to find the most effective movement type and loading direction to enable the training of specific parts of the hip muscles using a standing posture and a pulley system. In a novel approach to release the predictive power of musculoskeletal modelling techniques based on inverse dynamics, flexion/extension and ab-/adduction movements were virtually created. To demonstrate the effectiveness of this approach, three hip orientations and an external loading force that was systematically rotated around the body were simulated using a state-of-the art OpenSim model in order to establish ideal designs for training of the anterior and posterior parts of the M. gluteus medius (GM). The external force direction as well as the hip orientation greatly influenced the muscle forces in the different parts of the GM. No setting was found for simultaneous training of the anterior and posterior parts with a muscle force higher than 50% of the maximum. Importantly, this study has demonstrated the use of musculoskeletal models as an approach to predict muscle force variations for different strength and rehabilitation exercise variations.

Methodology to Customize Maximal Isometric Forces for Hill-Type Muscle Models

2017 ◽  
Vol 33 (1) ◽  
pp. 80-86 ◽  
Author(s):  
Fabien Dal Maso ◽  
Mickaël Begon ◽  
Maxime Raison
Keyword(s):  
Muscle Force ◽  
Biceps Brachii ◽  
Isometric Force ◽  
Force Estimation ◽  
Triceps Brachii ◽  
Joint Torques ◽  
Musculoskeletal Models ◽  
Flexion Extension ◽  
Isometric Forces ◽  
Maximal Isometric Force

One approach to increasing the confidence of muscle force estimation via musculoskeletal models is to minimize the root mean square error (RMSE) between joint torques estimated from electromyographic-driven musculoskeletal models and those computed using inverse dynamics. We propose a method that reduces RMSE by selecting subsets of combinations of maximal voluntary isometric contraction (MVIC) trials that minimize RMSE. Twelve participants performed 3 elbow MVIC in flexion and in extension. An upper-limb electromyographic-driven musculoskeletal model was created to optimize maximum muscle stress and estimate the maximal isometric force of the biceps brachii, brachialis, brachioradialis, and triceps brachii. Maximal isometric forces were computed from all possible combinations of flexion-extension trials. The combinations producing the smallest RMSE significantly reduced the normalized RMSE to 7.4% compared with the combination containing all trials (9.0%). Maximal isometric forces ranged between 114–806 N, 64–409 N, 236–1511 N, and 556–3434 N for the brachii, brachialis, brachioradialis, and triceps brachii, respectively. These large variations suggest that customization is required to reduce the difference between models and actual participants’ maximal isometric force. While the smallest previously reported RMSE was 10.3%, the proposed method reduced the RMSE to 7.4%, which may increase the confidence of muscle force estimation.

Tandem scanning reflected light microscopy: How it works and applications

1986 ◽  
Vol 44 ◽  
pp. 84-87
Author(s):  
Alan Boyde ◽  
Milan Hadravský ◽  
Mojmír Petran ◽  
Timothy F. Watson ◽  
Sheila J. Jones ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Focal Plane ◽  
Central Symmetry ◽  
Single Line ◽  
Scanning Microscope ◽  
Reflected Light ◽  
Illuminating Light ◽  
Illuminating Beam

The principles of tandem scanning reflected light microscopy and the design of recent instruments are fully described elsewhere and here only briefly. The illuminating light is intercepted by a rotating aperture disc which lies in the intermediate focal plane of a standard LM objective. This device provides an array of separate scanning beams which light up corresponding patches in the plane of focus more intensely than out of focus layers. Reflected light from these patches is imaged on to a matching array of apertures on the opposite side of the same aperture disc and which are scanning in the focal plane of the eyepiece. An arrangement of mirrors converts the central symmetry of the disc into congruency, so that the array of apertures which chop the illuminating beam is identical with the array on the observation side. Thus both illumination and “detection” are scanned in tandem, giving rise to the name Tandem Scanning Microscope (TSM). The apertures are arranged on Archimedean spirals: each opposed pair scans a single line in the image.

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