Changes in muscle spindle firing in response to length changes of neighboring muscles

Smilde, Hiltsje A; Vincent, Jacob; Baan, Guus C.; Nardelli, Paul; Lodder, J.C.; Mansvelder, Huibert D.; Cope, Timothy C.; Maas, Huub

doi:10.1152/jn.00937.2015

Cited by 18 publications

(29 citation statements)

References 66 publications

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“…In contrast with our results, myofascial loads have been detected by muscle spindles within rat SO (Smilde et al 2016), suggesting changes in fiber length. Although we measured the length of the whole SO muscle belly, the small pennation angle and simple architecture of SO in rats (Close 1964;Eng et al 2008) indicate that the absence of muscle belly length changes also indicates an absence of fiber length changes.…”

Section: Fascicle Length Changes Caused By Myofascial Loadscontrasting

confidence: 99%

Myofascial Loads Can Occur without Fascicle Length Changes

Tijs

Bernabei

Dieën

et al. 2018

Integrative and Comparative Biology

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Many studies have shown that connective tissue linkages can transmit force between synergistic muscles and that such force transmission depends on the position of these muscles relative to each other and on properties of their intermuscular connective tissues. Moving neighboring muscles has been reported to cause longitudinal deformations within passive muscles held at a constant muscle-tendon unit (MTU) length (e.g., soleus [SO]), but muscle forces were not directly measured. Deformations do not provide a direct measure of the force transmitted between muscles. We combined two different muscle preparations to assess whether myofascial loads exerted by neighboring muscles result in length changes of SO fascicles. We investigated the effects of proximal MTU length changes of two-joint gastrocnemius (GA) and plantaris (PL) muscles on the fascicle length of the one-joint SO muscle within (1) an intact muscle compartment and (2) a disrupted compartment that allowed measurements of fascicle length and distal tendon force of SO simultaneously. SO muscle bellies of Wistar rats (n = 5) were implanted with sonomicrometry crystals. In three animals, connectivity between SO and GA+PL was enhanced. Measurements were performed before and during maximal excitation of all plantar flexor muscles. In both setups, MTU length of GA+PL did not affect the length of SO fascicles, neither during passive nor active conditions. However, lengthening the MTU of GA+PL increased distal tendon force of SO by 43.3-97.8% (P < 0.001) and 27.5-182.6% (P < 0.001), respectively. This indicates that substantial myofascial force transmission between SO and synergistic muscle can occur via a connective tissue network running parallel to the series of SO sarcomeres without substantial length changes of SO fascicles.

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Section: Fascicle Length Changes Caused By Myofascial Loadscontrasting

confidence: 99%

Myofascial Loads Can Occur without Fascicle Length Changes

Tijs

Bernabei

Dieën

et al. 2018

Integrative and Comparative Biology

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“…86) Experimental evidence for such between-and within-fiber strains, however, is rather limited. Changing the length and relative position of a synergistic muscle, and hence the passive load exerted via epimuscular connections, affected the firing behavior of muscle spindles and tendon organs located within an adjacent muscle in the rat (50,70,71), suggesting local muscle deformations. Passive knee flexion in the rat was found to change the length of in series sarcomeres within passive fibers of the tibialis anterior muscle (78), which does not span the knee joint.…”

Section: Muscle Strains As a Measure Of Epimuscular Myofascial Loads mentioning

confidence: 99%

“…For balance control, sensory feedback especially from passive muscles has been proposed to play an important role (11,13). Passive epimuscular myofascial loads were shown to affect sensory feedback also during physiological muscle conditions (50,70,71) and hence the specific information that is sensed by muscle receptors (42,59). As a consequence, muscle spindles of one-joint muscles may contain information about the angle of joints other than that spanned by the muscle in which they are located.…”

Section: Potential Implicationsmentioning

confidence: 99%

Significance of epimuscular myofascial force transmission under passive muscle conditions

Maas

2019

Journal of Applied Physiology

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In the past 20 yr, force transmission via connective tissue linkages at the muscle belly surface, called epimuscular myofascial force transmission, has been studied extensively. In this article, the effects of epimuscular linkages under passive muscle conditions are reviewed. Several animal studies that included direct (invasive) measurements of force transmission have shown that different connective tissue structures serve as an epimuscular pathway and that these tissues have sufficient stiffness, especially at supraphysiological muscle lengths and relative positions, to transmit substantial passive forces (up to 15% of active optimal force). Exact values of lumped tissue stiffness for different connective tissue structures have not yet been estimated. Experiments using various imaging techniques (ultrasound, MRI, shear wave elastography) have yielded some, but weak, evidence of epimuscular myofascial force transmission for passive muscles in humans. At this point, the functional consequences of epimuscular pathways for muscle and joint mechanics in the intact body are still unknown. Potentially, however, these pathways may affect sensory feedback and, thereby, neuromuscular control. In addition, altered epimuscular force transmission in pathological conditions may also contribute to changes in passive range of joint motion.

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“…Additionally, intermuscular force transmission may result in local length changes within a length-restrained muscle. Muscle spindles within these length-restrained muscles may detect such deformations, thereby affecting sensory encoding (Smilde et al, 2016 ).…”

Section: Discussionmentioning

confidence: 99%

Synergistic Co-activation Increases the Extent of Mechanical Interaction between Rat Ankle Plantar-Flexors

et al. 2016

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Force transmission between rat ankle plantar-flexors has been found for physiological muscle lengths and relative positions, but only with all muscles maximally activated. The aims of this study were to assess intermuscular mechanical interactions between ankle plantar-flexors during (i) fully passive conditions, (ii) excitation of soleus (SO), (iii) excitation of lateral gastrocnemius (LG), and (iv) during co-activation of SO, and LG (SO&LG). We assessed effects of proximal lengthening of LG and plantaris (PL) muscles (i.e., simulating knee extension) on forces exerted at the distal SO tendon (FSO) and on the force difference between the proximal and distal LG+PL tendons (ΔFLG+PL) of the rat. LG+PL lengthening increased FSO to a larger extent (p = 0.017) during LG excitation (0.0026 N/mm) than during fully passive conditions (0.0009 N/mm). Changes in FSO in response to LG+PL lengthening were lower (p = 0.002) during SO only excitation (0.0056 N/mm) than during SO&LG excitation (0.0101 N/mm). LG+PL lengthening changed ΔFLG+PL to a larger extent (p = 0.007) during SO excitation (0.0211 N/mm) than during fully passive conditions (0.0157 N/mm). In contrast, changes in ΔFLG+PL in response to LG+PL lengthening during LG excitation (0.0331 N/mm) were similar (p = 0.161) to that during SO&LG excitation (0.0370 N/mm). In all conditions, changes of FSO were lower than those of ΔFLG+PL. This indicates that muscle forces were transmitted not only between LG+PL and SO, but also between LG+PL and other surrounding structures. In addition, epimuscular myofascial force transmission between rat ankle plantar-flexors was enhanced by muscle activation. However, the magnitude of this interaction was limited.

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Changes in muscle spindle firing in response to length changes of neighboring muscles

Cited by 18 publications

References 66 publications

Myofascial Loads Can Occur without Fascicle Length Changes

Myofascial Loads Can Occur without Fascicle Length Changes

Significance of epimuscular myofascial force transmission under passive muscle conditions

Synergistic Co-activation Increases the Extent of Mechanical Interaction between Rat Ankle Plantar-Flexors

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