How does passive lengthening change the architecture of the human medial gastrocnemius muscle?

There are few comprehensive investigations of the changes in muscle architecture that accompany muscle contraction or change in muscle length in vivo. For this study, we measured changes in the three-dimensional architecture of the human medial gastrocnemius at the whole muscle level, the fascicle level and the fiber level using anatomical MRI and diffusion tensor imaging (DTI). Data were obtained from eight subjects under relaxed conditions at three muscle lengths. At the whole muscle level, a 5.1% increase in muscle belly length resulted in a reduction in both muscle width (mean change −2.5%) and depth (−4.8%). At the fascicle level, muscle architecture measurements obtained at 3,000 locations per muscle showed that for every millimeter increase in muscle-tendon length above the slack length, average fascicle length increased by 0.46 mm, pennation angle decreased by 0.27° (0.17° in the superficial part and 0.37° in the deep part), and fascicle curvature decreased by 0.18 m−1. There was no evidence of systematic variation in architecture along the muscle’s long axis at any muscle length. At the fiber level, analysis of the diffusion signal showed that passive lengthening of the muscle increased diffusion along fibers and decreased diffusion across fibers. Using these measurements across scales, we show that the complex shape changes that muscle fibers, whole muscles, and aponeuroses of the medial gastrocnemius undergo in vivo cannot be captured by simple geometrical models. This justifies the need for more complex models that link microstructural changes in muscle fibers to macroscopic changes in architecture. NEW & NOTEWORTHY Novel MRI and DTI techniques revealed changes in three-dimensional architecture of the human medial gastrocnemius during passive lengthening. Whole muscle belly width and depth decreased when the muscle lengthened. Fascicle length, pennation, and curvature changed uniformly or near uniformly along the muscle during passive lengthening. Diffusion of water molecules in muscle changes in the same direction as fascicle strains.

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Three-dimensional architecture of the whole human soleus muscle in vivo

PeerJ ◽

10.7717/peerj.4610 ◽

2018 ◽

Vol 6 ◽

pp. e4610 ◽

Cited By ~ 25

Author(s):

Bart Bolsterlee ◽

Taija Finni ◽

Arkiev D’Souza ◽

Junya Eguchi ◽

Elizabeth C. Clarke ◽

...

Keyword(s):

Soleus Muscle ◽

Diffusion Tensor ◽

Three Dimensional ◽

Muscle Length ◽

Fascicle Length ◽

Cross Sectional ◽

Quantitative Measurements ◽

Muscle Fascicle ◽

Total Muscle

Background Most data on the architecture of the human soleus muscle have been obtained from cadaveric dissection or two-dimensional ultrasound imaging. We present the first comprehensive, quantitative study on the three-dimensional anatomy of the human soleus muscle in vivo using diffusion tensor imaging (DTI) techniques. Methods We report three-dimensional fascicle lengths, pennation angles, fascicle curvatures, physiological cross-sectional areas and volumes in four compartments of the soleus at ankle joint angles of 69 ± 12° (plantarflexion, short muscle length; average ± SD across subjects) and 108 ± 7° (dorsiflexion, long muscle length) of six healthy young adults. Microdissection and three-dimensional digitisation on two cadaveric muscles corroborated the compartmentalised structure of the soleus, and confirmed the validity of DTI-based muscle fascicle reconstructions. Results The posterior compartments of the soleus comprised 80 ± 5% of the total muscle volume (356 ± 58 cm3). At the short muscle length, the average fascicle length, pennation angle and curvature was 37 ± 8 mm, 31 ± 3° and 17 ± 4 /m, respectively. We did not find differences in fascicle lengths between compartments. However, pennation angles were on average 12° larger (p < 0.01) in the posterior compartments than in the anterior compartments. For every centimetre that the muscle-tendon unit lengthened, fascicle lengths increased by 3.7 ± 0.8 mm, pennation angles decreased by −3.2 ± 0.9° and curvatures decreased by −2.7 ± 0.8 /m. Fascicles in the posterior compartments rotated almost twice as much as in the anterior compartments during passive lengthening. Discussion The homogeneity in fascicle lengths and inhomogeneity in pennation angles of the soleus may indicate a functionally different role for the anterior and posterior compartments. The data and techniques presented here demonstrate how DTI can be used to obtain detailed, quantitative measurements of the anatomy of complex skeletal muscles in living humans.

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Three-dimensional geometrical changes of the human tibialis anterior muscle and its central aponeurosis measured with three-dimensional ultrasound during isometric contractions

PeerJ ◽

10.7717/peerj.2260 ◽

2016 ◽

Vol 4 ◽

pp. e2260 ◽

Cited By ~ 36

Author(s):

Brent J. Raiteri ◽

Andrew G. Cresswell ◽

Glen A. Lichtwark

Keyword(s):

Three Dimensional ◽

Muscle Length ◽

Pennation Angle ◽

Human Muscle ◽

Muscle Fibres ◽

Isometric Contractions ◽

Fascicle Length ◽

Cross Sectional ◽

Shape Changes

Background.Muscles not only shorten during contraction to perform mechanical work, but they also bulge radially because of the isovolumetric constraint on muscle fibres. Muscle bulging may have important implications for muscle performance, however quantifying three-dimensional (3D) muscle shape changes in human muscle is problematic because of difficulties with sustaining contractions for the duration of anin vivoscan. Although two-dimensional ultrasound imaging is useful for measuring local muscle deformations, assumptions must be made about global muscle shape changes, which could lead to errors in fully understanding the mechanical behaviour of muscle and its surrounding connective tissues, such as aponeurosis. Therefore, the aims of this investigation were (a) to determine the intra-session reliability of a novel 3D ultrasound (3DUS) imaging method for measuringin vivohuman muscle and aponeurosis deformations and (b) to examine how contraction intensity influencesin vivohuman muscle and aponeurosis strains during isometric contractions.Methods.Participants (n= 12) were seated in a reclined position with their left knee extended and ankle at 90° and performed isometric dorsiflexion contractions up to 50% of maximal voluntary contraction. 3DUS scans of the tibialis anterior (TA) muscle belly were performed during the contractions and at rest to assess muscle volume, muscle length, muscle cross-sectional area, muscle thickness and width, fascicle length and pennation angle, and central aponeurosis width and length. The 3DUS scan involved synchronous B-mode ultrasound imaging and 3D motion capture of the position and orientation of the ultrasound transducer, while successive cross-sectional slices were captured by sweeping the transducer along the muscle.Results.3DUS was shown to be highly reliable across measures of muscle volume, muscle length, fascicle length and central aponeurosis length (ICC ≥ 0.98, CV < 1%). The TA remained isovolumetric across contraction conditions and progressively shortened along its line of action as contraction intensity increased. This caused the muscle to bulge centrally, predominantly in thickness, while muscle fascicles shortened and pennation angle increased as a function of contraction intensity. This resulted in central aponeurosis strains in both the transverse and longitudinal directions increasing with contraction intensity.Discussion.3DUS is a reliable and viable method for quantifying multidirectional muscle and aponeurosis strains during isometric contractions within the same session. Contracting muscle fibres do work in directions along and orthogonal to the muscle’s line of action and central aponeurosis length and width appear to be a function of muscle fascicle shortening and transverse expansion of the muscle fibres, which is dependent on contraction intensity. How factors other than muscle force change the elastic mechanical behaviour of the aponeurosis requires further investigation.

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In vivo determination of fascicle curvature in contracting human skeletal muscles

Journal of Applied Physiology ◽

10.1152/jappl.2002.92.1.129 ◽

2002 ◽

Vol 92 (1) ◽

pp. 129-134 ◽

Cited By ~ 73

Author(s):

Tadashi Muramatsu ◽

Tetsuro Muraoka ◽

Yasuo Kawakami ◽

Akira Shibayama ◽

Tetsuo Fukunaga

Keyword(s):

Maximum Voluntary Contraction ◽

Muscle Length ◽

Muscle Thickness ◽

Voluntary Contraction ◽

Pennation Angle ◽

Medial Gastrocnemius ◽

Fascicle Length ◽

Fascicle Curvature

Fascicle curvature of human medial gastrocnemius muscle (MG) was determined in vivo by ultrasonography during isometric contractions at three (distal, central, and proximal) locations ( n = 7) and at three ankle angles ( n = 7). The curvature significantly ( P < 0.05) increased from rest to maximum voluntary contraction (MVC) (0.4–5.2 m−1). In addition, the curvature at MVC became larger in the order dorsiflexed, neutral, plantar flexed ( P < 0.05). Thus both contraction levels and muscle length affected the curvature. Intramuscular differences in neither the curvature nor the fascicle length were found. The direction of curving was consistent along the muscle: fascicles were concave in the proximal side. Fascicle length estimated from the pennation angle and muscle thickness, under the assumption that the fascicle was straight, was underestimated by ∼6%. In addition, the curvature was significantly correlated to pennation angle and muscle thickness. These findings are particularly important for understanding the mechanical functions of human skeletal muscle in vivo.

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Method for Calibration of Left Ventricle Material Properties Using Three-Dimensional Echocardiography Endocardial Strains

Journal of Biomechanical Engineering ◽

10.1115/1.4044215 ◽

2019 ◽

Vol 141 (9) ◽

Cited By ~ 4

Author(s):

Yaghoub Dabiri ◽

Kevin L. Sack ◽

Nuno Rebelo ◽

Peter Wang ◽

Yunjie Wang ◽

...

Keyword(s):

Mechanical Properties ◽

Left Ventricle ◽

Diffusion Tensor ◽

Diastolic Pressure ◽

Three Dimensional ◽

Heart Association ◽

Mean Difference ◽

Imaging Data ◽

The Mean

We sought to calibrate mechanical properties of left ventricle (LV) based on three-dimensional (3D) speckle tracking echocardiographic imaging data recorded from 16 segments defined by American Heart Association (AHA). The in vivo data were used to create finite element (FE) LV and biventricular (BV) models. The orientation of the fibers in the LV model was rule based, but diffusion tensor magnetic resonance imaging (MRI) data were used for the fiber directions in the BV model. A nonlinear fiber-reinforced constitutive equation was used to describe the passive behavior of the myocardium, whereas the active tension was described by a model based on tissue contraction (Tmax). isight was used for optimization, which used abaqus as the forward solver (Simulia, Providence, RI). The calibration of passive properties based on the end diastolic pressure volume relation (EDPVR) curve resulted in relatively good agreement (mean error = −0.04 ml). The difference between the experimental and computational strains decreased after segmental strain metrics, rather than global metrics, were used for calibration: for the LV model, the mean difference reduced from 0.129 to 0.046 (circumferential) and from 0.076 to 0.059 (longitudinal); for the BV model, the mean difference nearly did not change in the circumferential direction (0.061) but reduced in the longitudinal direction from 0.076 to 0.055. The calibration of mechanical properties for myocardium can be improved using segmental strain metrics. The importance of realistic fiber orientation and geometry for modeling of the LV was shown.

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Combined diffusion and strain tensor MRI reveals a heterogeneous, planar pattern of strain development during isometric muscle contraction

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00474.2010 ◽

2011 ◽

Vol 300 (5) ◽

pp. R1079-R1090 ◽

Cited By ~ 33

Author(s):

Erin K. Englund ◽

Christopher P. Elder ◽

Qing Xu ◽

Zhaohua Ding ◽

Bruce M. Damon

Keyword(s):

Muscle Contraction ◽

Muscle Fiber ◽

Diffusion Tensor ◽

Strain Tensor ◽

Three Dimensional ◽

Fiber Direction ◽

Strain Pattern ◽

Isometric Muscle Contraction ◽

Diffusion Tensors

The purposes of this study were to create a three-dimensional representation of strain during isometric contraction in vivo and to interpret it with respect to the muscle fiber direction. Diffusion tensor MRI was used to measure the muscle fiber direction of the tibialis anterior (TA) muscle of seven healthy volunteers. Spatial-tagging MRI was used to measure linear strains in six directions during separate 50% maximal isometric contractions of the TA. The strain tensor (E) was computed in the TA's deep and superficial compartments and compared with the respective diffusion tensors. Diagonalization of E revealed a planar strain pattern, with one nonzero negative strain (εN) and one nonzero positive strain (εP); both strains were larger in magnitude ( P < 0.05) in the deep compartment [εN = −40.4 ± 4.3%, εP = 35.1 ± 3.5% (means ± SE)] than in the superficial compartment (εN = −24.3 ± 3.9%, εP = 6.3 ± 4.9%). The principal shortening direction deviated from the fiber direction by 24.0 ± 1.3° and 39.8 ± 6.1° in the deep and superficial compartments, respectively ( P < 0.05, deep vs. superficial). The deviation of the shortening direction from the fiber direction was due primarily to the lower angle of elevation of the shortening direction over the axial plane than that of the fiber direction. It is concluded that three-dimensional analyses of strain interpreted with respect to the fiber architecture are necessary to characterize skeletal muscle contraction in vivo. The deviation of the principal shortening direction from the fiber direction may relate to intramuscle variations in fiber length and pennation angle.

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Plantar Flexor Muscle Architecture Changes as a Result of Eccentric Exercise in Patients With Achilles Tendinosis

Foot & Ankle Specialist ◽

10.1177/1938640014539812 ◽

2014 ◽

Vol 7 (6) ◽

pp. 460-465 ◽

Cited By ~ 1

Author(s):

Matthew T. Crill ◽

Gregory Berlet ◽

Christopher Hyer

Keyword(s):

Case Series ◽

Muscle Architecture ◽

Medial Gastrocnemius ◽

Eccentric Training ◽

Plantar Flexors ◽

Flexor Muscle ◽

Fascicle Length ◽

Achilles Tendinosis ◽

Muscle Fascicle ◽

Maximal Load

Eccentric training for Achilles tendinosis (AT) has been reported to significantly improve patient symptoms. There has been no biomechanical explanation on the mechanism for specific rehabilitation technique. The purpose of this study was to determine changes in muscle architecture that occurred as a result of Achilles tendinosis injury and a subsequent eccentric rehabilitation program. Twenty-five patients (age, 53.3 ± 17.5 years) diagnosed with AT participated in 6 weeks of rehabilitation. Specific exercises for the ankle plantar flexors consisted of maximal load eccentric muscle action using 3 sets of 15 repetitions. Patients also completed a protocol for AT, which consisting of traditional rehabilitation. Medial gastrocnemius (GM) and lateral gastrocnemius (GL) muscle fascicle length and thickness were measured with ultrasound at 2-week intervals from initial treatment day to the end of 6 weeks of rehabilitation. Medial gastrocnemius fascicle length increased (45.1 ± 10.5 mm to 51.4 ± 10.5 mm; P = .22) between the initial day of rehabilitation and after 6 weeks of rehabilitation. But, GM thickness (16.3 ± 3.5 mm to 16.8 ± 2.0 mm), GL fascicle length (47.2 ± 10.0 mm to 47.1 ± 7.4 mm), and GL thickness (14.9 ± 5.2 mm to 14.4 ± 2.7 mm) did not change as a result of rehabilitation. A 6-week eccentric-biased exercise increased the GM muscle fascicle length by 12%, but GM thickness, GL fascicle length, and GL thickness did not change as a result of rehabilitation. Eccentric training for the treatment of AT is well recognized, but the mechanism of action has not been previously reported. A 6-week eccentric training protocol increased the GM muscle fascicle length by 12%, and this correlated with improvement in a validated patient outcome scoring system. Further study is warranted to determine a predictive relationship between improvement of GM fascicle length and outcome scores. Levels of Evidence: Therapeutic, Level IV: Case series

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A comparison of two Hill-type skeletal muscle models on the construction of medial gastrocnemius length-tension curves in humans in vivo

Journal of Applied Physiology ◽

10.1152/japplphysiol.00070.2012 ◽

2012 ◽

Vol 113 (1) ◽

pp. 90-96 ◽

Cited By ~ 17

Author(s):

B. W. Hoffman ◽

G. A. Lichtwark ◽

T. J. Carroll ◽

A. G. Cresswell

Keyword(s):

Medial Gastrocnemius ◽

Passive Tension ◽

Fascicle Length ◽

Good Reliability ◽

Length Relationship ◽

Animal Data ◽

Tension Curves ◽

Resting Muscle ◽

Heel Lift

Human length-tension curves are traditionally constructed using a model that assumes passive tension does not change during contraction ( model A) even though the animal literature suggests that passive tension can decrease ( model B). The study's aims were threefold: 1) measure differences in human medial gastrocnemius length-tension curves using model A vs. model B, 2) test the reliability of ultrasound constructed length-tension curves, and 3) test the robustness of fascicle length-generated length-tension curves to variations between the angle and fascicle length relationship. An isokinetic dynamometer manipulated and measured ankle angle while ultrasound was used to measure medial gastrocnemius fascicle length. Supramaximal tibial nerve stimulation was used to evoke resting muscle twitches. Length-tension curves were constructed using model A {angle-torque [A-T(A)], length-torque [L-T(A)]} or model B {length-torque [L-T(B)]} in three conditions: baseline, heel-lift (where the muscle was shortened at each angle), and baseline repeated 2 h later (+2 h). Length-tension curves constructed from model B differed from those produced via model A, indicated by a significant increase in maximum torque (≈23%) when using L-T(B) vs. L-T(A). No parameter measured was different between baseline and +2 h for any method, indicating good reliability when using ultrasound. Length-tension curves were unaffected by the heel-lift condition when using L-T(A) or L-T(B) but were affected when using A-T(A). Since the muscle model used significantly alters human length-tension curves, and given animal data indicate model B to be more accurate when passive tension is present, we recommend that model B should be used when constructing medial gastrocnemius length-tension curves in humans in vivo.

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Progress of Age-Related Changes in Properties of Motor Units in the Gastrocnemius Muscle of Rats

Journal of Neurophysiology ◽

10.1152/jn.00947.2003 ◽

2004 ◽

Vol 92 (3) ◽

pp. 1357-1365 ◽

Cited By ~ 21

Author(s):

Miho Sugiura ◽

Kenro Kanda

Keyword(s):

Gastrocnemius Muscle ◽

Muscle Tension ◽

Muscle Fibers ◽

Motor Units ◽

Medial Gastrocnemius ◽

Motor Nucleus ◽

Twitch Contraction ◽

Age Related ◽

Old Rats ◽

Whole Muscle

The mechanical properties of individual motor units in the medial gastrocnemius muscle, as well as the whole muscle properties and innervating motor nucleus, were investigated in dietary-restricted, male Fischer 344/DuCrj rats at ages of 4, 7, 12, 21/22, 27, 31, and 36 mo. The tetanic tension of the type S units continuously increased until the age of 36 mo. Those of type FF and FR units declined from 21/22 to 27 mo of age but did not change further while the whole muscle tension decreased greatly. The atrophy of muscle fibers, the decline in motoneuron number and axonal conduction velocity, and the decrease in the posttetanic potentiation of twitch contraction of motor units seemed to start after 21/22 mo of age and were accelerated with advancing age. Prolongation of twitch contraction time was evident for only type S and FR units in 36-mo-old rats. The fatigue index was greatly increased for type FF units in 36-mo-old rats. These findings indicated that the progress of changes in various properties occurring in the senescent muscle was different in terms of their time course and degree and also dependent on the types of motor unit. The atrophy and decrease in specific tension of muscle fibers affected the decline in tension output of motor units. This was effectively compensated for by the capture of denervated muscle fibers over time.

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