Principles of the Mechanism for Epimuscular Myofascial Loads Leading to Non-uniform Strain Distributions Along Muscle Fiber Direction: Finite Element Modeling

Pamuk, Uluç; Cankaya, Alican O.; Yücesoy, Can A.

doi:10.3389/fphys.2020.00789

Cited by 10 publications

(4 citation statements)

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“…The effects of myofascial force transmission on adjacent synergistic muscles have been further studied by the finite element modeling (Yucesoy et al, 2003a ; Pamuk et al, 2020 ). These studies suggest that the myofascial force transmission has major effects on skeletal muscle mechanics.…”

Section: Discussionmentioning

confidence: 99%

Effective Assessments of a Short-Duration Poor Posture on Upper Limb Muscle Fatigue Before Physical Exercise

Robinson

Tan

et al. 2020

Front. Physiol.

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A forward head and rounded shoulder posture is a poor posture that is widely seen in everyday life. It is known that sitting in such a poor posture with long hours will bring health issues such as muscle pain. However, it is not known whether sitting in this poor posture for a short period of time will affect human activities. This paper investigates the effects of a short-duration poor posture before some typical physical activities such as push-ups. The experiments are set up as follows. Fourteen male subjects are asked to do push-ups until fatigue with two surface electromyography (sEMG) at the upper limb. Two days later, they are asked to sit in this poor posture for 15 min with eight sEMG sensors located at given back muscles. Then they do the push-ups after the short-duration poor posture. The observations from the median frequency of sEMG signals at the upper limb indicate that the short-duration poor posture does affect the fatigue procedure of push-ups. A significant decreasing trend of the performance of push-ups is obtained after sitting in this poor posture. Such effects indicate that some parts of the back muscles indeed get fatigued with only 15 min sitting in this poor posture. By further investigating the time-frequency components of sEMG of back muscles, it is observed that the low and middle frequencies of sEMG signals from the infraspinatus muscle of the dominant side are demonstrated to be more prone to fatigue with the poor posture. Although this study focuses only on push-ups, similar experiments can be arranged for other physical exercises as well. This study provides new insights into the effect of a short-duration poor posture before physical activities. These insights can be used to guide athletes to pay attention to postures before physical activities to improve performance and reduce the risk of injury.

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Section: Discussionmentioning

confidence: 99%

Effective Assessments of a Short-Duration Poor Posture on Upper Limb Muscle Fatigue Before Physical Exercise

Robinson

Tan

et al. 2020

Front. Physiol.

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“…It has been shown that muscle's extramuscular and epimuscular (i.e., collagen reinforced connective tissue structures including neurovascular tracts, general and compartmental fascia, intermuscular septa, interosseous membranes connecting muscle's epimysium to non-muscular structures and also other muscles, respectively), connections affect not only the global mechanics of the muscle i.e., the muscle force (Maas et al 2003;Yucesoy et al 2006), but also locally the myofascial loads Yucesoy 2010) can alter the mechanical equilibrium determining length changes along the muscle fascicles (Pamuk et al 2016;Karakuzu et al 2017). Principles of effects of such epimuscular myofascial force transmission (EMFT) leading to local muscle fiber direction length changes have been shown recently (Pamuk et al 2020). Consequently, compared to truly isolated muscle, we hypothesized that for such integrated muscle the effects of active state titin as the third myofilament on muscular mechanics are manipulated by EMFT.…”

Section: Introductionmentioning

confidence: 99%

“…position changes were shown to include strains opposing those determined by the globally imposed conditions(Pamuk et al 2020): (1) in passively lengthened integrated muscle, locally shortened regions and (2) in isometrically activated integrated muscle locally lengthened regions were shown.Note that, those model scenarios represent principles of previous experiments conducted in human muscle in vivo(Huijing et al 2011;Pamuk et al 2016) in which e.g., passively imposed proximal lengthening of the biarticular target muscle led to relative position differences with the monoarticular synergist. The distally directed myofascial loads arising from the stretching of the intermuscular connections, overcoming locally the globally imposed lengthening and yielding shortening in the distal ends of fascicles was the proposed explanation.…”

mentioning

confidence: 98%

Finite element modeling shows that epimuscular myofascial loads manipulate the effects of active state titin on mechanics of muscle integrated with its surroundings

Cankaya

Yücesoy

2022

Preprint

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Shorter sarcomere effect was shown in recent modeling of truly isolated muscle as the characteristic mechanism determining active state titin’s contribution to muscular mechanics via manipulation of muscle fiber direction strains. For muscle with extra- and epimuscular connections to surrounding tissues, epimuscular myofascial force transmission (EMFT) leads to myofascial loads, which affects mechanical equilibrium that determines local strains. Consequently, compared to truly isolated muscle, we hypothesized that for such integrated muscle active state titin’s effects on muscular mechanics are manipulated by EMFT. The aim was to test this. Isolated vs. integrated rat extensor digitorum longus muscles were modeled at long muscle lengths (λm = 28.7-32.7mm) and three cases were studied: passive state titin (no change in titin constitutive equation in the active state), active state titin-I (constitutive equation involves a higher stiffness in the active state) and active state titin-II (constitutive equation also involves a strain shift coefficient accounting for titin’s reduced free spring length). For isolated muscle, shorter sarcomere effect i.e., limited lengthening locally along the muscle fiber direction and force enhancement (maximally 77.4%) was consistent. However, for integrated muscles, variable fiber direction strains showed even longer or shortened sarcomeres locally and consequently, force enhancement was inconsistent being even diminished (7.8%) or elevated (96.8%) at different lengths. Shift of muscle’s optimum length to a longer length in isolated muscle (λm = 29.6mm) increased (λm = 29.9mm) or vanished (λm = 28.7mm) for extra- or epimuscularly connected muscles, respectively. In conclusion, in the integrated muscle context, effects of active state titin on muscular mechanics are manipulated by EMFT.

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“…More details on muscle function on the tissue scale can be obtained by employing three-dimensional, continuum-mechanical skeletal muscle models (based on the theory of finite elasticity), as it is possible to resolve the anatomical structure of tissues and spatial heterogeneities. Such continuum-mechanical models have, for example, been used to study intramuscular force transmission (Huijing, 1999 ; Yucesoy et al, 2003 ), the influence of the muscle fiber architecture and geometry on force output and tissue deformations (Huijing and Slawnych, 2000 ; Blemker and Delp, 2005 ; Fiorentino and Blemker, 2014 ; Seydewitz et al, 2019 ; Cankaya et al, 2021 ), the influence of motor unit activity and distribution (Röhrle et al, 2012 ; Schmid et al, 2019 ), or the interplay between different tissues/structures (Röhrle et al, 2017 ; Ramasamy et al, 2018 ; Pamuk et al, 2020 ). Further, employing the concept of classical field theories, continuum-mechanical muscle models offer great flexibility within multi-physics modeling frameworks and thus represent an important component to realize the vision of in silico laboratories (cf.…”

Section: Introductionmentioning

confidence: 99%

A Physiology-Guided Classification of Active-Stress and Active-Strain Approaches for Continuum-Mechanical Modeling of Skeletal Muscle Tissue

2021

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The well-established sliding filament and cross-bridge theory explain the major biophysical mechanism responsible for a skeletal muscle's active behavior on a cellular level. However, the biomechanical function of skeletal muscles on the tissue scale, which is caused by the complex interplay of muscle fibers and extracellular connective tissue, is much less understood. Mathematical models provide one possibility to investigate physiological hypotheses. Continuum-mechanical models have hereby proven themselves to be very suitable to study the biomechanical behavior of whole muscles or entire limbs. Existing continuum-mechanical skeletal muscle models use either an active-stress or an active-strain approach to phenomenologically describe the mechanical behavior of active contractions. While any macroscopic constitutive model can be judged by it's ability to accurately replicate experimental data, the evaluation of muscle-specific material descriptions is difficult as suitable data is, unfortunately, currently not available. Thus, the discussions become more philosophical rather than following rigid methodological criteria. Within this work, we provide a extensive discussion on the underlying modeling assumptions of both the active-stress and the active-strain approach in the context of existing hypotheses of skeletal muscle physiology. We conclude that the active-stress approach resolves an idealized tissue transmitting active stresses through an independent pathway. In contrast, the active-strain approach reflects an idealized tissue employing an indirect, coupled pathway for active stress transmission. Finally the physiological hypothesis that skeletal muscles exhibit redundant pathways of intramuscular stress transmission represents the basis for considering a mixed-active-stress-active-strain constitutive framework.

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Principles of the Mechanism for Epimuscular Myofascial Loads Leading to Non-uniform Strain Distributions Along Muscle Fiber Direction: Finite Element Modeling

Cited by 10 publications

References 57 publications

Effective Assessments of a Short-Duration Poor Posture on Upper Limb Muscle Fatigue Before Physical Exercise

Effective Assessments of a Short-Duration Poor Posture on Upper Limb Muscle Fatigue Before Physical Exercise

Finite element modeling shows that epimuscular myofascial loads manipulate the effects of active state titin on mechanics of muscle integrated with its surroundings

A Physiology-Guided Classification of Active-Stress and Active-Strain Approaches for Continuum-Mechanical Modeling of Skeletal Muscle Tissue

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