scholarly journals Nonlinear summation of force in cat tibialis anterior: a muscle with intrafascicularly terminating fibers

2003 ◽  
Vol 94 (5) ◽  
pp. 1955-1963 ◽  
Author(s):  
Thomas G. Sandercock
Keyword(s):  
Tibialis Anterior ◽  
Muscle Length ◽  
Tissue Structure ◽  
Isometric Contractions ◽  
Linear Summation ◽  
In Series ◽  
The Common ◽  
Ventral Roots ◽  
Whole Muscle ◽  
Connective Tissue Structure

The complex connective tissue structure of muscle and tendon suggests that forces from two parts of a muscle may not summate linearly, particularly in muscles with intrafasciculary terminating fibers, such as cat tibialis anterior (TA). In four anesthetized cats, the TA was attached to a servomechanism to control muscle length and record force. The ventral roots were divided into two bundles, each innervating about half the TA, so the two parts could be stimulated alone or together. Nonlinear summation of force ( F nl) was measured during isometric contractions. F nl was small and negative, indicating less than linear summation of the parts, which is consistent with the predicted F nl of muscle fibers connected in series. F nl was more significant when smaller parts of the muscle were tested (21.8 vs. 8% for whole muscle). These data were fit to a model where both parts of the muscle were assumed to stretch a common elasticity. Compensatory movements of the servomechanism showed the common elasticity is very stiff, and the model cannot account for F nl in cat TA.

scholarly journals Nonlinear summation of force in cat soleus muscle results primarily from stretch of the common-elastic elements

2000 ◽  
Vol 89 (6) ◽  
pp. 2206-2214 ◽  
Author(s):  
Thomas G. Sandercock
Keyword(s):  
Muscle Activation ◽  
Muscle Force ◽  
Muscle Length ◽  
Stimulus Train ◽  
The Common ◽  
Tension Peak ◽  
Whole Muscle ◽  
Tetanic Tension ◽  
Connective Tissue Structure ◽  
Elastic Elements

The complex connective tissue structure of muscle and tendon suggests that forces from two parts of a muscle may not summate linearly. This study measured the nonlinear summation of force (Fnl) in whole cat soleus during isometric and ramp movements. In six anesthetized cats, the soleus was attached to a servomechanism to control muscle length and record force. The ventral roots were divided into two bundles, each innervating about half the soleus; thus the two parts could be stimulated alone or together. In all experiments, Fnl was small (<6% of maximum tetanic tension). Peak Fnl occurred during changes in muscle force, either as a result of imposed muscle movement or the onset or offset of a stimulus train. The data were fit to a model in which both parts of the muscle were assumed to stretch to a common elasticity. The servomechanism was programmed to compensate for reduced stretch of the common elasticity during partial compared with whole muscle activation. These compensatory movements showed how the model could account for most, but not all, of Fnl.

Extra Force From Asynchronous Stimulation of Cat Soleus Muscle Results From Minimizing the Stretch of the Common Elastic Elements

2006 ◽  
Vol 96 (3) ◽  
pp. 1401-1405 ◽  
Author(s):  
Thomas G. Sandercock
Keyword(s):  
Low Frequency ◽  
Muscle Length ◽  
Test Frequency ◽  
The Common ◽  
Tension Curve ◽  
Ventral Roots ◽  
The Difference ◽  
Dynamic Stretch ◽  
Elastic Elements ◽  
Stimulation Of

Rack and Westbury showed that low-frequency asynchronous stimulation of a muscle produces greater force compared with synchronous stimulation. This study tested the hypothesis that the difference results from the dynamic stretch of the common elastic elements. In eight anesthetized cats, the soleus was attached to a servomechanism to control muscle length and record force. The ventral roots were divided into four bundles so each innervated approximately 1/4 of the soleus. The elasticity shared by each part of the muscle was estimated and the servomechanism programmed to compensate for its stretch. At each test frequency (5, 7.5, and 10 Hz), the muscle was stimulated by asynchronous stimulation, synchronous stimulation, summation of force with each part stimulated individually, and summation with each part stimulated individually and the servomechanism mimicking tendon stretch during asynchronous stimulation. Muscle length was isometric except for the last protocol. The observed differences were small. The greatest difference occurred during stimulation at 5 Hz with muscle length on the ascending limb of the length-tension curve. Here, the average forces, normalized by asynchronous force, were asynchronous, 100%; synchronous, 73%; summation, 110%; and summation with stretch compensation, 98%. The results support the hypothesis and suggest that the common elasticity can be used to predict force gains from asynchronous stimulation.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

2020 ◽  
pp. 1-8
Author(s):  
Dasom Oh ◽  
Wootaek Lim
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Isometric Contraction ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Significant Difference ◽  
Extension Force ◽  
Long Head

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

The Effect of Two Rigid Spherical Inclusions on the Stresses in an Infinite Elastic Solid

1966 ◽  
Vol 33 (1) ◽  
pp. 68-74 ◽  
Author(s):  
Joseph F. Shelley ◽  
Yi-Yuan Yu
Keyword(s):  
Stress Field ◽  
Uniaxial Tension ◽  
Elastic Solid ◽  
Displacement Function ◽  
Hydrostatic Tension ◽  
Series Form ◽  
Spherical Inclusions ◽  
Spherical Cavities ◽  
In Series ◽  
The Common

Presented in this paper is a solution in series form for the stresses in an infinite elastic solid which contains two rigid spherical inclusions of the same size. The stress field at infinity is assumed to be either hydrostatic tension or uniaxial tension in the direction of the common axis of the inclusions. The solution is based upon the Papkovich-Boussinesq displacement-function approach and makes use of the spherical dipolar harmonics developed by Sternberg and Sadowsky. The problem is closely related to, but turns out to be much more involved than, the corresponding problem of two spherical cavities solved by these authors.

scholarly journals Reports of the length dependence of fatigue are greatly exaggerated

2006 ◽  
Vol 101 (1) ◽  
pp. 23-29 ◽  
Author(s):  
M. B. MacNaughton ◽  
B. R. MacIntosh
Keyword(s):  
Muscle Length ◽  
Repetitive Stimulation ◽  
Double Pulse ◽  
Medial Gastrocnemius ◽  
Passive Force ◽  
Active Force ◽  
Rightward Shift ◽  
Length Dependence ◽  
Force Depression ◽  
In Series

Relative force depression associated with muscle fatigue is reported to be greater when assessed at short vs. long muscle lengths. This appears to be due to a rightward shift in the force-length relationship. This rightward shift may be caused by stretch of in-series structures, making sarcomere lengths shorter at any given muscle length. Submaximal force-length relationships (twitch, double pulse, 50 Hz) were evaluated before and after repetitive contractions (50 Hz, 300 ms, 1/s) in an in situ preparation of the rat medial gastrocnemius muscle. In some experiments, fascicle lengths were measured with sonomicrometry. Before repetitive stimulation, fascicle lengths were 11.3 ± 0.8, 12.8 ± 0.9, and 14.4 ± 1.2 mm at lengths corresponding to −3.6, 0, and 3.6 mm where 0 is a reference length that corresponds with maximal active force for double-pulse stimulation. After repetitive stimulation, there was no change in fascicle lengths; these lengths were 11.4 ± 0.8, 12.6 ± 0.9, and 14.2 ± 1.2 mm. The length dependence of fatigue was, therefore, not due to a stretch of in-series structures. Interestingly, the rightward shift that was evident when active force was calculated in the traditional way (subtraction of the passive force measured before contraction) was not seen when active force was calculated by subtracting the passive force that was associated with the fascicle length reached at the peak of the contraction. This calculation is based on the assumption that passive force decreases as the fascicles shorten during a fixed-end contraction. This alternative calculation revealed similar postfatigue absolute active force depression at all lengths. In relative terms, a length dependence of fatigue was still evident, but this was greatly diminished compared with that observed when active force was calculated with the traditional method.

Effect of quadriceps femoris muscle length on neural activation during isometric and concentric contractions

2003 ◽  
Vol 94 (3) ◽  
pp. 983-990 ◽  
Author(s):  
Nicolas Babault ◽  
Michel Pousson ◽  
Anne Michaut ◽  
Jacques Van Hoecke
Keyword(s):  
Knee Flexion ◽  
Muscle Length ◽  
Isometric Contractions ◽  
Neural Activation ◽  
Length Effect ◽  
Neural Drive ◽  
Concentric Contractions ◽  
Twitch Interpolation ◽  
Predominant Effect ◽  
Femoris Muscle

The effect of muscle length on neural drive (here termed “neural activation”) was investigated from electromyographic activities and activation levels (twitch interpolation). The neural activation was measured in nine men during isometric and concentric (30 and 120°/s) knee extensions for three muscle lengths (35, 55, and 75° knee flexion, i.e., shortened, intermediate, and lengthened muscles, respectively). Long (76°), medium (56°), and short (36°) ranges of motion were used to investigate the effect of the duration of concentric contraction. Neural activation was found to depend on muscle length. Reducing the duration of contraction had no effect. Neural activation was higher with short muscle length during isometric contractions and was weaker for shortened than for intermediate and lengthened muscles performing 120°/s concentric contractions. Muscle length had no effect on 30°/s concentric neural activation. Peripheral mechanisms and discharge properties of the motoneurons could partly explain the observed differences in the muscle length effect. We thus conclude that muscle length has a predominant effect on neural activation that would modulate the angular velocity dependency.

scholarly journals Influence of muscle length on muscle atrophy in the mouse tibialis anterior and soleus muscles

2009 ◽  
Vol 30 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Naoto Fujita ◽  
Taro Fujimoto ◽  
Hiromitsu Tasaki ◽  
Takamitsu Arakawa ◽  
Takako Matsubara ◽  
...  
Keyword(s):  
Muscle Atrophy ◽  
Tibialis Anterior ◽  
Muscle Length

scholarly journals The Structure of the Terminal Filament, the Ovariole Sheath and the Oviduct Musculature of the Colorado Beetle (Leptinotarsa Decemlineata Say, 1824)

1977 ◽  
Vol 46 (2) ◽  
pp. 136-150 ◽  
Author(s):  
H.A. Akster ◽  
W.A. Smit
Keyword(s):  
Colorado Beetle ◽  
Tendon Cells ◽  
Terminal Filament ◽  
Form Part ◽  
Leptinotarsa Decemlineata Say ◽  
Tunica Propria ◽  
The Common ◽  
Whole Muscle ◽  
Muscle Sheath ◽  
T System

In the Colorado Beetle, the terminal filament cells resemble the epidermal cells which connect muscle cells with the cuticle, the so-called tendon cells. They contain many microtubules which have projections interconnecting them. The microtubules are also connected by these projections to desmosomes. The tunica propria is a basement membrane-like layer of low elasticity. It separates the terminal filament from the germarium. The outer ovariole sheath is a muscle sheath which is continuous with the muscle sheath around the oviducts. The whole muscle sheath consists of a monolayer network. Sarcolemmal invaginations at the I band and at the Z line probably form part of one T system. The cuticle of the common oviduct has scales with long caudally directed spines. The rostral attachment of the muscle sheath corresponds to the existing descriptions of tendon cells. The attachment of the muscle sheath to the cuticle of the common oviduct is different.

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