Mechanics of Slope Walking in the Cat: Quantification of Muscle Load, Length Change, and Ankle Extensor EMG Patterns

2006 ◽  
Vol 95 (3) ◽  
pp. 1397-1409 ◽  
Author(s):  
Robert J. Gregor ◽  
D. Webb Smith ◽  
Boris I. Prilutsky
Keyword(s):  
Muscle Activation ◽  
Inverse Dynamics ◽  
Geometric Model ◽  
Muscle Length ◽  
Length Change ◽  
Knee Extensors ◽  
Ground Reaction Forces ◽  
Reaction Forces ◽  
Length Changes ◽  
Inverse Dynamics Analysis

Unexpected changes in flexor–extensor muscle activation synergies during slope walking in the cat have been explained previously by 1) a reorganization of circuitry in the central pattern generator or 2) altered muscle and cutaneous afferent inputs to motoneurons that modulate their activity. The aim of this study was to quantify muscle length changes, muscle loads, and ground reaction forces during downslope, level, and upslope walking in the cat. These mechanical variables are related to feedback from muscle length and force, and paw pad cutaneous afferents, and differences in these variables between the slope walking conditions could provide additional insight into possible mechanisms of the muscle control. Kinematics, ground reaction forces, and EMG were recorded while cats walked on a walkway in three conditions: downslope (−26.6 deg), level (0 deg), and upslope (26.6 deg). The resultant joint moments were calculated using inverse dynamics analysis; length and velocity of major hindlimb muscle-tendon units (MTUs) were calculated using a geometric model and calculated joint angles. It was found that during stance in downslope walking, the MTU stretch of ankle and knee extensors and MTU peak stretch velocities of ankle extensors were significantly greater than those in level or upslope conditions, whereas forces applied to the paw pad and peaks of ankle and hip extensor moments were significantly smaller. The opposite was true for upslope walking. It was suggested that these differences between upslope and downslope walking might affect motion-dependent feedback, resulting in muscle activity changes recorded here or reported in the literature.

Mechanical actions of heterogenic reflexes linking long toe flexors with ankle and knee extensors of the cat hindlimb

1994 ◽  
Vol 71 (3) ◽  
pp. 1096-1110 ◽  
Author(s):  
S. J. Bonasera ◽  
T. R. Nichols
Keyword(s):  
Muscle Activation ◽  
Muscle Force ◽  
Muscle Length ◽  
Knee Extensors ◽  
Flexor Hallucis Longus ◽  
Force Output ◽  
Small Magnitude ◽  
Dramatic Decline ◽  
Muscle Pair ◽  
Length Changes

1. To study the means whereby ankle biomechanics are represented in the interneuronal circuitry of the spinal cord we examined stretch-evoked reflex interactions between the physiological extensors flexor hallucis longus (FHL) and flexor digitorum longus (FDL) as well as their interactions with gastrocnemius (G), soleus (S), and the quadriceps group (Q) in 34 unanesthetized decerebrate cats. To evoke stretch, DC motors provided ramp-hold-release length changes to tendons detached from their bony insertions. Semiconductor myographs measured resultant muscle force response. Reflexes were examined under both quiescent (no active force generation) and activated conditions; muscle activation was achieved through either crossed-extension or flexion reflexes. 2. FHL and FDL share mutual excitatory stretch-evoked interactions under most conditions examined. These interactions depended on muscle length, were asymmetric (with FHL contributing a larger magnitude of reflex excitation onto FDL), and occurred at a latency of 16 ms. Mutual Ia synergism previously described for these two muscles provides a basis for all of the above findings. Our data demonstrate that for this muscle pair, reflex connectivities revealed at the intracellular level can be extrapolated to cover the entire motoneuron pool; further, our data directly demonstrate the net mechanical result of ensemble synaptic events. 3. FHL was found to share strong, mutually inhibitory stretch-evoked interactions with G, S, and Q. Stepwise regression statistical analyses determined that these interactions depended on recipient muscle force and donor muscle force. These reflex interactions all occurred at a latency of 28 +/- 4 (SE) ms. Further, the heterogenic inhibition between FHL/G and FHL/S was attenuated by strychnine infusion (intravenous) but unaffected by either mecamylamine, picrotoxin, or baclofen infusion (intravenous, intrathecal). Disynaptic Ib inhibition previously described among hindlimb extensors provides a basis for the above findings; our data demonstrate that under certain conditions the ensemble activity of this system can cause a dramatic decline in whole muscle force output. 4. By contrast, FDL was found to share mutually inhibitory, stretch-evoked reflex interactions with G, S, and Q that were much weaker than those observed between FHL and these same muscles. The small magnitude of inhibition observed in these interactions made it difficult to assess reflex latency or to determine the factor(s) that best predicted the heterogenic inhibition. 5. This study provides further evidence of intrinsic differences in interneuronal organization between muscles whose activity occurs in a periodic manner during locomotion ("stereotypical") and a muscle whose locomotor activity is characterized by both periodic and nonperiodic components ("facultative").(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals P 054 - Evaluation of ground reaction forces by inverse dynamics analysis

2018 ◽  
Vol 65 ◽  
pp. 72-73
Author(s):  
R. Van Hulle ◽  
C. Schwartz ◽  
V. Denoël ◽  
J.L. Croisier ◽  
B. Forthomme ◽  
...  
Keyword(s):  
Inverse Dynamics ◽  
Ground Reaction Forces ◽  
Dynamics Analysis ◽  
Reaction Forces ◽  
Inverse Dynamics Analysis

Lower Extremity Muscle Functions during Full Squats

2008 ◽  
Vol 24 (4) ◽  
pp. 333-339 ◽  
Author(s):  
D.G.E. Robertson ◽  
Jean-Marie J. Wilson ◽  
Taunya A. St. Pierre
Keyword(s):  
Inverse Dynamics ◽  
Vastus Lateralis ◽  
Muscle Length ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extensors ◽  
Plantar Flexors ◽  
Lower Extremity Muscle ◽  
Length Changes

The purpose of this research was to determine the functions of the gluteus maximus, biceps femoris, semitendinosus, rectus femoris, vastus lateralis, soleus, gastrocnemius, and tibialis anterior muscles about their associated joints during full (deep-knee) squats. Muscle function was determined from joint kinematics, inverse dynamics, electromyography, and muscle length changes. The subjects were six experienced, male weight lifters. Analyses revealed that the prime movers during ascent were the monoarticular gluteus maximus and vasti muscles (as exemplified by vastus lateralis) and to a lesser extent the soleus muscles. The biarticular muscles functioned mainly as stabilizers of the ankle, knee, and hip joints by working eccentrically to control descent or transferring energy among the segments during ascent. During the ascent phase, the hip extensor moments of force produced the largest powers followed by the ankle plantar flexors and then the knee extensors. The hip and knee extensors provided the initial bursts of power during ascent with the ankle extensors and especially a second burst from the hip extensors adding power during the latter half of the ascent.

scholarly journals P 054–Evaluation of ground reaction forces by inverse dynamics analysis

2018 ◽  
Vol 65 ◽  
pp. 322
Author(s):  
R. Van Hulle ◽  
C. Schwartz ◽  
V. Denoël ◽  
J.L. Croisier ◽  
B. Forthomme ◽  
...  
Keyword(s):  
Inverse Dynamics ◽  
Ground Reaction Forces ◽  
Dynamics Analysis ◽  
Reaction Forces ◽  
Inverse Dynamics Analysis

Influence of the Musculotendon Dynamics on the Muscle Force-Sharing Problem of the Shoulder—A Fully Inverse Dynamics Approach

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Quental Carlos ◽  
Azevedo Margarida ◽  
Ambrósio Jorge ◽  
Gonçalves S. B. ◽  
Folgado João
Keyword(s):  
Muscle Activation ◽  
Inverse Dynamics ◽  
Glenohumeral Joint ◽  
Inverse Dynamic ◽  
Force Sharing ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Muscle Activations ◽  
Joint Reaction

Abstract Most dynamic simulations are based on inverse dynamics, being the time-dependent physiological nature of the muscle properties rarely considered due to numerical challenges. Since the influence of muscle physiology on the consistency of inverse dynamics simulations remains unclear, the purpose of the present study is to evaluate the computational efficiency and biological validity of four musculotendon models that differ in the simulation of the muscle activation and contraction dynamics. Inverse dynamic analyses are performed using a spatial musculoskeletal model of the upper limb. The muscle force-sharing problem is solved for five repetitions of unloaded and loaded motions of shoulder abduction and shoulder flexion. The performance of the musculotendon models is evaluated by comparing muscle activation predictions with electromyography (EMG) signals, measured synchronously with motion for 11 muscles, and the glenohumeral joint reaction forces estimated numerically with those measured in vivo. The results show similar muscle activations for all muscle models. Overall, high cross-correlations are computed between muscle activations and the EMG signals measured for all movements analyzed, which provides confidence in the results. The glenohumeral joint reaction forces estimated compare well with those measured in vivo, but the influence of the muscle dynamics is found to be negligible. In conclusion, for slow-speed, standard movements of the upper limb, as those studied here, the activation and musculotendon contraction dynamics can be neglected in inverse dynamic analyses without compromising the prediction of muscle and joint reaction forces.

scholarly journals Spring-like leg behaviour, musculoskeletal mechanics and control in maximum and submaximum height human hopping

2011 ◽  
Vol 366 (1570) ◽  
pp. 1516-1529 ◽  
Author(s):  
Maarten F. Bobbert ◽  
L. J. Richard Casius
Keyword(s):  
Energy Expenditure ◽  
Muscle Activation ◽  
Mechanical Energy ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Centre Of Mass ◽  
Leg Stiffness ◽  
Reaction Forces ◽  
And Control ◽  
The Relationship

The purpose of this study was to understand how humans regulate their ‘leg stiffness’ in hopping, and to determine whether this regulation is intended to minimize energy expenditure. ‘Leg stiffness’ is the slope of the relationship between ground reaction force and displacement of the centre of mass (CM). Variations in leg stiffness were achieved in six subjects by having them hop at maximum and submaximum heights at a frequency of 1.7 Hz. Kinematics, ground reaction forces and electromyograms were measured. Leg stiffness decreased with hopping height, from 350 N m −1 kg −1 at 26 cm to 150 N m −1 kg −1 at 14 cm. Subjects reduced hopping height primarily by reducing the amplitude of muscle activation. Experimental results were reproduced with a model of the musculoskeletal system comprising four body segments and nine Hill-type muscles, with muscle stimulation STIM( t ) as only input. Correspondence between simulated hops and experimental hops was poor when STIM( t ) was optimized to minimize mechanical energy expenditure, but good when an objective function was used that penalized jerk of CM motion, suggesting that hopping subjects are not minimizing energy expenditure. Instead, we speculated, subjects are using a simple control strategy that results in smooth movements and a decrease in leg stiffness with hopping height.

scholarly journals Machine Learning to Extract Muscle Fascicle Length Changes from Dynamic Ultrasound Images in Real-Time

2021 ◽  
Author(s):  
Luis G. Rosa ◽  
Jonathan S. Zia ◽  
Omer T. Inan ◽  
Gregory S. Sawicki
Keyword(s):  
Machine Learning ◽  
Real Time ◽  
Muscle Length ◽  
Ground Truth ◽  
Length Change ◽  
Fascicle Length ◽  
Automated Tracking ◽  
Direct Training ◽  
Muscle Fascicle ◽  
Length Changes

AbstractBackground and objectiveDynamic muscle fascicle length measurements through B-mode ultrasound have become popular for the non-invasive physiological insights they provide regarding musculoskeletal structure-function. However, current practices typically require time consuming post-processing to track muscle length changes from B-mode images. A real-time measurement tool would not only save processing time but would also help pave the way toward closed-loop applications based on feedback signals driven by in vivo muscle length change patterns. In this paper, we benchmark an approach that combines traditional machine learning (ML) models with B-mode ultrasound recordings to obtain muscle fascicle length changes in real-time. To gauge the utility of this framework for ‘in-the-loop’ applications, we evaluate accuracy of the extracted muscle length change signals against time-series’ derived from a standard, post-hoc automated tracking algorithm.MethodsWe collected B-mode ultrasound data from the soleus muscle of six participants performing five defined ankle motion tasks: (a) seated, constrained ankle plantarflexion, (b) seated, free ankle dorsi/plantarflexion, (c) weight-bearing, calf raises (d) walking, and then a (e) mix. We trained machine learning (ML) models by pairing muscle fascicle lengths obtained from standardized automated tracking software (UltraTrack) with the respective B-mode ultrasound image input to the tracker, frame-by-frame. Then we conducted hyperparameter optimizations for five different ML models using a grid search to find the best performing parameters for a combination of high correlation and low RMSE between ML and UltraTrack processed muscle fascicle length trajectories. Finally, using the global best model/hyperparameter settings, we comprehensively evaluated training-testing outcomes within subject (i.e., train and test on same subject), cross subject (i.e., train on one subject, test on another) and within/direct cross task (i.e., train and test on same subject, but different task).ResultsSupport vector machine (SVM) was the best performing model with an average r = 0.70 ±0.34 and average RMSE = 2.86 ±2.55 mm across all direct training conditions and average r = 0.65 ±0.35 and average RMSE = 3.28 ±2.64 mm when optimized for all cross-participant conditions. Comparisons between ML vs. UltraTrack (i.e., ground truth) tracked muscle fascicle length versus time data indicated that ML tracked images reliably capture the salient qualitative features in ground truth length change data, even when correlation values are on the lower end. Furthermore, in the direct training, calf raises condition, which is most comparable to previous studies validating automated tracking performance during isolated contractions on a dynamometer, our ML approach yielded 0.90 average correlation, in line with other accepted tracking methods in the field.ConclusionsBy combining B-mode ultrasound and classical ML models, we demonstrate it is possible to achieve real-time tracking of human soleus muscle fascicles across a number of functionally relevant contractile conditions. This novel sensing modality paves the way for muscle physiology in-the-loop applications that could be used to modify gait via biofeedback or unlock novel wearable device control techniques that could enable restored or augmented locomotion performance.

Landing Constraints Influence Ground Reaction Forces and Lower Extremity EMG in Female Volleyball Players

2004 ◽  
Vol 20 (1) ◽  
pp. 38-50 ◽  
Author(s):  
Mark D. Tillman ◽  
Rachel M. Criss ◽  
Denis Brunt ◽  
Chris J. Hass
Keyword(s):  
Muscle Activity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Vertical Jump ◽  
Lateral Loading ◽  
Initial Contact ◽  
Ground Reaction Forces ◽  
Vertical Loading ◽  
Volleyball Players ◽  
Reaction Forces

The purposes of this study were to analyze double-limb, dominant-limb, and nondominant-limb landings, each with a two-footed takeoff, in order to detect potential differences in muscle activity and ground reaction forces and to examine the possible influence of leg dominance on these parameters. Each of the three jump landing combinations was analyzed in 11 healthy female volleyball players (age 21 ± 3 yrs; height 171 ± 5 cm, mass 61.6 ± 5.5 kg, max. vertical jump height 28 ± 4 cm). Ground reaction forces under each limb and bilateral muscle activity of the vastus medialis, hamstrings, and lateral gastrocnemius muscles were synchronized and collected at 1,000 Hz. Normalized EMG amplitude and force platform data were averaged over five trials for each participant and analyzed using repeated-measures ANOVA. During the takeoff phase in jumps with one-footed landings, the non-landing limb loaded more than the landing limb (p= 0.003). During the 100 ms prior to initial contact, single-footed landings generated higher EMG values than two-footed landings (p= 0.004). One-footed landings resulted in higher peak vertical loading, lateral loading, and rate of lateral loading than two-footed landings (p< 0.05). Trends were observed indicating that muscle activation during one-footed landings is greater than for two-footed landings (p= 0.053 vs.p= 0.077). The greater forces and rate of loading produced during single-limb landings implies a higher predisposition to injury. It appears that strategic planning and training of jumps in volleyball and other jumping sports is critical.

Study on the Length Changes of Bearings in Continuous Motion of Complex Mechanical System Based on ADMAS Simulation

2014 ◽  
Vol 539 ◽  
pp. 29-33
Author(s):  
Ning Li ◽  
Yue Juan Li
Keyword(s):  
Muscle Length ◽  
Surface Force ◽  
Length Change ◽  
Basketball Player ◽  
Validity And Reliability ◽  
Basketball Players ◽  
Concentrated Force ◽  
Virtual Displacement ◽  
Training Time ◽  
Length Changes

In this paper, based on the volume force, surface force, concentrated force of elastic-plastic body, combining with the principle of virtual displacement, we use virtual prototype analysis software ADAMS to design the displacement simulation system of basketball players muscle length change in continued training. In order to verify the validity and reliability of the system, we establish muscle simulation model of basketball player continued training, and input parameters of simulation training time and training task in the model, import the simulation results into the MATLAB software, obtain the curve changes of muscle displacement with time, and combining with the curve get the muscle length changing parameter. It provides a technical reference for the training of basketball players.

scholarly journals ANALYSIS OF MUSCLE STRENGTH EFFECTS ON EXERCISE PERFORMANCE USING DYNAMIC STABILIZATION EXERCISE DEVICE

2020 ◽  
Vol 20 (09) ◽  
pp. 2040004
Author(s):  
KAP-SOO HAN ◽  
SEUNG-ROK KANG ◽  
TAE-KYU KWON
Keyword(s):  
Muscle Strength ◽  
Muscle Activation ◽  
Muscle Force ◽  
Inverse Dynamics ◽  
Body Tilt ◽  
Whole Body ◽  
Stabilization Exercise ◽  
Spine Stabilization ◽  
Exercise Effect ◽  
Inverse Dynamics Analysis

Muscle strength may vary depending on the pathological issues and static life habits. These conditions lead to abnormal spinal loads and change muscle strength as well as activation patterns, thereby causing spinal disorders. In this study, the effects of muscle strength on the spine stabilization exercise were analyzed using a whole-body tilt device. Musculoskeletal modeling was performed and the results were validated through a comparison with the electromyography (EMG) analysis results. Based on the validated basic model, modeling was performed for the whole-body tilt device. To examine the exercise effect and muscle activation while the maximum muscle force capacity (MFC) was varied from 30[Formula: see text]N/cm2 to 60[Formula: see text]N/cm2 and 90[Formula: see text]N/cm2, the muscle force was predicted through inverse dynamics analysis. When MFC was 30[Formula: see text]N/cm2, the posterior direction of the tilt could not be analyzed (no solution found). When MFC was 60[Formula: see text]N/cm2, it could be analyzed, but the muscle force was predicted to be higher compared to when MFC was 90[Formula: see text]N/cm2. It was confirmed that muscle strength is a very important element for maintaining postural activities and performing exercise. Therefore, for rehabilitation patients and elderly people with weak muscle strength, hard or extreme exercise may cause musculoskeletal injuries.

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