Estimation of tissue stiffness, reflex activity, optimal muscle length and slack length in stroke patients using an electromyography driven antagonistic wrist model

2016 ◽  
Vol 35 ◽  
pp. 93-101 ◽  
Author(s):  
Karin L. de Gooijer-van de Groep ◽  
Erwin de Vlugt ◽  
Hanneke J. van der Krogt ◽  
Áróra Helgadóttir ◽  
J. Hans Arendzen ◽  
...  
Keyword(s):  
Muscle Length ◽  
Reflex Activity ◽  
Tissue Stiffness ◽  
Stroke Patients ◽  
Slack Length

scholarly journals The Evaluation of “Spasticity”

1987 ◽  
Vol 14 (S3) ◽  
pp. 497-500 ◽  
Author(s):  
P. Ashby ◽  
A. Mailis ◽  
J. Hunter
Keyword(s):  
Motor Neuron ◽  
Past History ◽  
Muscle Mechanics ◽  
Muscle Length ◽  
Scoring Systems ◽  
Reflex Activity ◽  
Descending Pathways ◽  
Voluntary Activity ◽  
Reflex Pathways ◽  
Segmental Reflex

ABSTRACT:Lesions of the upper motor neuron cause: 1. Alterations in segmental reflex activity. For example increased tendon jerks and velocity dependent stretch reflexes ("spasticity"), clonus, the clasp knife response, release of flexion reflexes and extensor plantar reflexes. 2. Impaired ability to activate motoneurons rapidly and selectively. Voluntary movements may also be restrained by co-contraction of antagonists muscles, by segmental reflexes (enhanced during voluntary effort) or by contractures. A combination of these factors may impair overall functional ability. Segmental reflexes, voluntary power and overall functional abilities can be assessed using clinical scoring systems. Recordings of muscle length, tension andEMG offer more objective measures of reflex and voluntary activity and of overall functions such as locomotion, and can separate weakness from co-contraction, spasticity from contracture. Methods are now available for exploring individual (transmitter specific) segmental reflex pathways and descending pathways in man. Lesions of the upper motor neuron are complicated by secondary changes in segmental neurons. Segmental reflex activity and muscle mechanics depend on the immediate past history of events. These factors must be taken into account.

Modeling pressure-flow relations in cardiac muscle in diastole and systole

1997 ◽  
Vol 272 (3) ◽  
pp. H1516-H1526 ◽  
Author(s):  
M. A. Vis ◽  
P. Sipkema ◽  
N. Westerhof
Keyword(s):  
Mechanical Properties ◽  
Cardiac Muscle ◽  
Coronary Flow ◽  
Perfusion Pressure ◽  
Muscle Length ◽  
Cardiac Contraction ◽  
Myocardial Tissue ◽  
Time Varying ◽  
Pressure Flow ◽  
Slack Length

Pressure-flow relations were calculated for a symmetrical, maximally dilated, crystalloid-perfused coronary vascular network embedded in cardiac muscle in (static) diastole and (static) systole at two muscle lengths: slack length and 90% of maximal muscle length (Lmax). The calculations are based on the "time-varying elastance concept." That is, the calculations include the mechanical properties of the vascular wall and the (varying) mechanical properties of the myocardial tissue (in cross-fiber direction). We found that, at any given perfusion pressure, coronary flow is smaller in systole than in diastole. Relative reduction in vascular cross-sectional area, which forms the basis of flow impediment, was largest for the smallest arterioles. At a constant perfusion pressure of 62.5 mmHg, the transition from (static) diastole to (static) systole at constant muscle length ("isometric contraction") was calculated to reduce flow by 74% (from 18.9 to 5.0 ml x min(-1) x g(-1)) and by 64% (from 12.6 to 4.6 ml x min(-1) x g(-1)) for the muscle fixed at slack length and 90% of Lmax, respectively. At this perfusion pressure, contraction with 14% shortening (from 90% of Lmax in diastole to slack length in systole) was calculated to reduce flow by 61% (from 12.6 to 5.0 ml x min(-1) x g(-1)). Increasing muscle length from slack length to 90% of Lmax decreases coronary flow by 34% in diastole and by 8% in systole. We conclude that modeling cardiac contraction on the basis of the time-varying elastic properties of the myocardial tissue can explain coronary flow impediment and that contractions, with or without shortening, have a larger effect on coronary flow than changes in muscle length.

Assessment by Finite Element Modeling Indicates That Surgical Intramuscular Aponeurotomy Performed Closer to the Tendon Enhances Intended Acute Effects in Extramuscularly Connected Muscle

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
Can A. Yucesoy ◽  
Peter A. Huijing
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Muscle Mechanics ◽  
Muscle Length ◽  
Optimum Length ◽  
Element Modeling ◽  
Optimal Force ◽  
Length Range ◽  
Muscle Geometry ◽  
Slack Length

The effects of location of aponeurotomy on the muscular mechanics of extramuscularly connected muscle were assessed. Using finite element modeling, extensor digitorum longus muscle of the rat was studied for the effects of aponeurotomy performed in each of three locations on the proximal aponeurosis: (1) a proximal location (case P), (2) an intermediate location (case I), and (3) a distal location (case D). Proximo-distal force differences were more pronounced for more proximal aponeurotomy. The location also affected proximally and distally assessed muscle length-force characteristics: (1) Muscle optimum length and active slack length shifted differentially to higher lengths, increasing slack to optimum length range (for D to P: distally by 15–44%; proximally by 2–6%). (2) Muscle forces decreased at all lengths (e.g., for D to P distal optimal force=88–68% and proximal optimal force=87–60% of intact values, respectively). Increased length range and force decreases were highest for case P, as were effects on muscle geometry: gap length within the proximal aponeurosis; decreased proximal fiber population pennation angle. Parallel, but not serial, heterogeneity of sarcomere length was highest in case P: (a) For the distal fiber population, sarcomere shortening was highest; (b) for the proximal population, sarcomeres were longer. It is concluded that if aponeurotomy is performed closer to the tendon, intended surgical effects are more pronounced. For bi-articular muscle, mechanics of both proximal and distal joints will be affected, which should be considered in selecting the location of aponeurotomy for optimal results at both joints.

scholarly journals In-vitro experiments to characterize ventricular electromechanics

2016 ◽  
Vol 2 (1) ◽  
pp. 263-266
Author(s):  
Robert Arnold ◽  
Anton J. Prassl ◽  
Ernst Hofer ◽  
Gernot Plank
Keyword(s):  
Muscle Length ◽  
Logistic Function ◽  
Linear Increase ◽  
Stress Strain ◽  
Active Stress ◽  
Order Polynomial ◽  
Strain Relationship ◽  
Spatio Temporal ◽  
Slack Length

AbstractComputer simulation turns out to be beneficial when clinical data lack spatio-temporal resolution or parameters cannot be measured at all. To derive trustworthy results, these in-silico models have to thoroughly parameterized and validated. In this work we present data from a simplified in-vitro setup for characterizing ventricular electromechanics. Right ventricular papillary muscles from New Zealand rabbits were isolated and stretched from slack length to lmax, i.e. the muscle length at maximum active force development. Active stress development showed an almost linear increase for moderate strain (90–100% of lmax) and a significant decrease for larger strain (100–105% of lmax). Passive strain development showed a nonlinear increase. Conduction velocity CV showed an increase of ≈10% between low and moderate strain and no significant decrease beyond. Fitting active active stress-strain relationship using a 5th-order polynomial yielded adequate results for moderate and high strain values, whereas fitting using a logistic function yielded more reasonable results for low strain values. Passive stress-strain relationship was satisfactorily fitted using an exponential function.

Fully Isometric Length-Force Curves of Rat Muscle Differ from Those during and after Concentric Contractions

1997 ◽  
Vol 13 (2) ◽  
pp. 164-181 ◽  
Author(s):  
Kenneth Meijer ◽  
Henk J. Grootenboer ◽  
Bart F.J.M. Koopman ◽  
Peter A. Huijing
Keyword(s):  
Muscle Force ◽  
Muscle Length ◽  
Negative Slope ◽  
Force Curve ◽  
Active Muscle ◽  
Remarkable Feature ◽  
Muscle Geometry ◽  
Force Curves ◽  
Slack Length ◽  
Force Characteristics

The effect of various shortening histories on postshortening isometric length-force characteristics of rat medial gastrocnemlus (GM) was studied. Active muscle force and muscle geometry were analyzed after isotonic as well as isokinetic shortening. Active shortening significantly changed GM length-force characteristics (i.e., maximal muscle force, optimum muscle length, and active slack length). Muscle geometry did not change, which indicates that the observed changes in length-force curves are related to intracellular processes. Length-force curves valid during shortening, derived from postshortening characteristics, were very different from the fully isometric length-force curve. Their most remarkable feature was the absence of a negative slope. It was concluded that the length-force curve valid during active shortening strongly depends upon shortening characteristics (i.e., initial length and shortening speed). As a consequence, the traditional, fully isometric, length-force curve is a poor estimator of the length-force curve during dynamic contractions of muscle. Implications for muscle function are discussed.

Decreasing stimulation frequency-dependent length-force characteristics of rat muscle

1994 ◽  
Vol 77 (5) ◽  
pp. 2115-2124 ◽  
Author(s):  
B. Roszek ◽  
G. C. Baan ◽  
P. A. Huijing
Keyword(s):  
Sarcomere Length ◽  
Muscle Length ◽  
Calcium Sensitivity ◽  
Stimulation Frequency ◽  
Medial Gastrocnemius ◽  
Frequency Dependent ◽  
Contractile System ◽  
Active Peak ◽  
Slack Length ◽  
Force Characteristics

Effects of decreasing stimulation frequency on length-force characteristics were determined for rat medial gastrocnemius muscle. The peripheral nerve was stimulated supramaximally with a succession of twitch and frequencies of 100, 50, 40, 30, and 15 Hz. Active peak tetanic and twitch forces and active muscle geometry were analyzed. Optimal muscle length and active slack length shifted significantly (P < 0.05) to higher muscle length by a maximum of 2.8 and 3.2 mm, respectively. Further significant effects were found for distal fiber length and mean sarcomere length of distal fiber (increases) and for fiber angle and aponeurosis length (decreases). Neither muscle length range between active slack and optimal length nor aponeurosis angle was altered significantly. We concluded that decreasing stimulation frequency-dependent length-force characteristics are affected by a complex interaction of length-dependent calcium sensitivity, potentiation of the contractile system, distribution of sarcomere length, and interactions between force exerted and aponeurosis length. Length-dependent calcium sensitivity seems to be a major factor determining the magnitude of the shift of optimal muscle length.

Myofascial force transmission between the human soleus and gastrocnemius muscles during passive knee motion

2012 ◽  
Vol 113 (4) ◽  
pp. 517-523 ◽  
Author(s):  
Maoyi Tian ◽  
Robert D. Herbert ◽  
Phu Hoang ◽  
Simon C. Gandevia ◽  
Lynne E. Bilston
Keyword(s):  
Soleus Muscle ◽  
Muscle Length ◽  
Image Correlation ◽  
Ultrasound Images ◽  
Force Transmission ◽  
Fascicle Length ◽  
Knee Motion ◽  
Myofascial Force Transmission ◽  
Muscle Fascicle ◽  
Slack Length

The plantarflexors of the lower limb are often assumed to act as independent actuators, but the validity of this assumption is the subject of considerable debate. This study aims to determine the degree to which passive changes in gastrocnemius muscle length, induced by knee motion, affect the tension in the adjacent soleus muscle. A second aim is to quantify the magnitude of myofascial passive force transmission between gastrocnemius and adjacent soleus. Fifteen healthy volunteers participated. Simultaneous ultrasound images of the gastrocnemius and soleus muscles were obtained during passive knee flexion (0–90°), while keeping the ankle angle fixed at either 70° or 115°. Image correlation analysis was used to quantify muscle fascicle lengths in both muscles. The data show that the soleus muscle fascicles elongate significantly during gastrocnemius shortening. The approximate change in passive soleus force as a result of the observed change in fascicle length was estimated and appears to be <5 N, but this estimate is sensitive to the assumed slack length of soleus.

scholarly journals Early Shortening of Wrist Flexor Muscles Coincides With Poor Recovery After Stroke

2018 ◽  
Vol 32 (6-7) ◽  
pp. 645-654 ◽  
Author(s):  
Karin L. de Gooijer-van de Groep ◽  
Jurriaan H. de Groot ◽  
Hanneke van der Krogt ◽  
Erwin de Vlugt ◽  
J. Hans Arendzen ◽  
...  
Keyword(s):  
Time Course ◽  
Robot Manipulator ◽  
Wrist Joint ◽  
Joint Stiffness ◽  
Peripheral Tissue ◽  
Tissue Stiffness ◽  
Wrist Flexion ◽  
Poor Recovery ◽  
Flexor Muscles ◽  
Slack Length

Background. The mechanism and time course of increased wrist joint stiffness poststroke and clinically observed wrist flexion deformity is still not well understood. The components contributing to increased joint stiffness are of neural reflexive and peripheral tissue origin and quantified by reflexive torque and muscle slack length and stiffness coefficient parameters. Objective. To investigate the time course of the components contributing to wrist joint stiffness during the first 26 weeks poststroke in a group of patients, stratified by prognosis and functional recovery of the upper extremity. Methods. A total of 36 stroke patients were measured on 8 occasions within the first 26 weeks poststroke using ramp-and-hold rotations applied to the wrist joint by a robot manipulator. Neural reflexive and peripheral tissue components were estimated using an electromyography-driven antagonistic wrist model. Outcome was compared between groups cross-sectionally at 26 weeks poststroke and development over time was analyzed longitudinally. Results. At 26 weeks poststroke, patients with poor recovery (Action Research Arm Test [ARAT] ≤9 points) showed a higher predicted reflexive torque of the flexors ( P < .001) and reduced predicted slack length ( P < .001) indicating shortened muscles contributing to higher peripheral tissue stiffness ( P < .001), compared with patients with good recovery (ARAT ≥10 points). Significant differences in peripheral tissue stiffness between groups could be identified around weeks 4 and 5; for neural reflexive stiffness, this was the case around week 12. Conclusions. We found onset of peripheral tissue stiffness to precede neural reflexive stiffness. Temporal identification of components contributing to joint stiffness after stroke may prompt longitudinal interventional studies to further evaluate and eventually prevent these phenomena.

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