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Eur J Appl Physiol 2022 May 6. Epub 2022 May 6.

Faculty of Sport and Health Sciences, Neuromuscular Research Centre, University of Jyväskylä, Viveca 227, Rautpohjankatu 8, 40700, Jyväskylä, Finland.

Purpose: Measurement of medial gastrocnemius (MG) tendon length using ultrasonography (US) requires the muscle-tendon junction (MTJ) to be located. Previously, the MG MTJ has been tracked from different proximo-distal locations near the MTJ, which could influence estimates of tendon length change due to the different characteristics of the aponeurosis and tendon. We used US to evaluate the effect of tracking point location on MG MTJ displacement during maximal and submaximal (10, 20 and 30% of the non-injured maximal) isometric plantar flexion contractions. Read More

Insights Imaging 2022 Apr 5;13(1):67. Epub 2022 Apr 5.

School of Clinical Sciences, Queensland University of Technology, Gardens Point Campus, 2 George St, Brisbane, QLD, 4000, Australia.

Background: Post-stroke muscle stiffness is a major challenge in the rehabilitation of stroke survivors, with no gold standard in clinical assessment. Muscle stiffness is typically evaluated by the Modified Ashworth Scale or the Tardieu Scale; however, these can have low reliability and sensitivity. Ultrasound elastography is an advanced imaging technology that can quantitatively measure the stiffness of a tissue and has been shown to have good construct validity when compared to clinically assessed muscle stiffness and functional motor recovery. Read More

Sci Rep 2022 02 1;12(1):1702. Epub 2022 Feb 1.

Sports Science Laboratory, Wako University, Machida, Tokyo, Japan.

The purpose of this study was to compare the mechanical properties of muscles and tendon structures for plantar flexor muscles at various strain rates and jump performances using single joint between middle-aged and young men in order to clarify the mechanisms of age-related decline in power output during vertical jump of middle-aged people previously reported. Passive muscle stiffness of the medial gastrocnemius muscle was determined based on passive muscle force and fascicle length during passive stretching at four angular velocities. Active muscle stiffness was calculated based on changes in muscle force and fascicle length during stretching at five angular velocities after submaximal isometric contractions. Read More

J Bodyw Mov Ther 2021 10 17;28:463-469. Epub 2021 Jun 17.

Department of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Universidad Rey Juan Carlos, Madrid, Spain.

Objective: To investigate the reliability and discriminative validity of real-time ultrasound elastography (RTE) measures of soft-tissue elasticity after calf muscle tear.

Design: Cross-sectional, intra/inter-examiner reliability and comparative validity study.

Setting: Department of Physical Therapy. Read More

Eur J Appl Physiol 2022 Feb 2;122(2):357-369. Epub 2021 Nov 2.

School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.

Purpose: Cortical mechanisms may contribute to weakness in participants with previous hamstring strain injury. This study aims to examine intra-cortical inhibition (SICI) and corticospinal excitability in previously injured participants.

Methods: In this cross-sectional study, TMS was used to examine SICI, silent period, silent period: MEP ratios and area under the stimulus response curve in the biceps femoris and medial hamstrings. Read More

J Bodyw Mov Ther 2021 Jul 19;27:493-499. Epub 2021 May 19.

Faculty of Health and Medical Care, Saitama Medical University, 981, Kawakado, Moroyama, Saitama, Japan.

Introduction: Hamstring strain often occurs at the end of a match or during practice in sports activities. The gluteus maximus muscle is an important muscle for hip extension along with the hamstring. Gluteus maximus muscle dysfunction may be involved in the occurrence of hamstring strain. Read More

Tokai J Exp Clin Med 2021 Jul 20;46(2):83-88. Epub 2021 Jul 20.

Department of Rehabilitation Medicine, Tokai University Hachioji Hospital, Ishikawa-machi, Hachioji, Tokyo 192-0032, Japan.

We examined the biceps brachii and the medial head of the gastrocnemius muscles on the affected side of two patients with post-stroke spasticity. Sonoelastography was used to evaluate the changes in spastic muscles before treatment; and 2, 4, 8 and 12 weeks after treatment with botulinum toxin Type A. Modified Ashworth scale (MAS), and the passive range of motion of the elbow and the ankle joints, before and after the treatment, were also evaluated. Read More

Life (Basel) 2021 Jun 17;11(6). Epub 2021 Jun 17.

School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China.

This study aims to explore whether gender differences exist in the architectural and mechanical properties of the medial gastrocnemius-Achilles tendon unit (gMTU) in vivo. Thirty-six healthy male and female adults without training experience and regular exercise habits were recruited. The architectural and mechanical properties of the gMTU were measured via an ultrasonography system and MyotonPRO, respectively. Read More

Gait Posture 2021 07 21;88:138-145. Epub 2021 May 21.

Athletic Training Program, School of Exercise and Rehabilitation Sciences, University of Toledo, Toledo, OH, USA. Electronic address:

Background: While traditionally viewed as a beneficial adaptation to preserve stability in the presence of knee pathology, excessive muscle co-activation may be detrimental for joint health when extrapolated to repetitive movement patterns over time. Lesser hamstrings strength relative to the quadriceps (low H:Q strength ratio) may influence neuromuscular patterns about the knee, as it is reported to increase risk for lower extremity injury among healthy females.

Research Question: Does the relationship between H:Q strength ratio and H:Q co-activation differ between sexes during walking and jogging?

Methods: We used a descriptive laboratory study to assess hamstrings and quadriceps strength and muscle activity patterns during the loading response of treadmill walking gait (1. Read More

Am J Sports Med 2021 06 19;49(7):1847-1853. Epub 2021 Apr 19.

University of Cologne, Faculty of Medicine, Cologne, Germany.

Background: Double-row (DR) and transosseous-equivalent (TOE) techniques for rotator cuff repair offer more stability and promote better tendon healing compared with single-row (SR) repairs and are preferred by many surgeons. However, they can lead to more disastrous retear patterns with failure at the medial anchor row or the musculotendinous junction. The biomechanics of medial cuff failure have not been thoroughly investigated thus far. Read More

Scand J Med Sci Sports 2021 Jul 11;31(7):1471-1480. Epub 2021 Apr 11.

Institute for Biomechanics and Orthopaedics, German Sport University Cologne, Cologne, Germany.

The compliant nature of distal limb muscle-tendon units is traditionally considered suboptimal in explosive movements when positive joint work is required. However, during accelerative running, ankle joint net mechanical work is positive. Therefore, this study aims to investigate how plantar flexor muscle-tendon behavior is modulated during fast accelerations. Read More

Biomed Res Int 2021 9;2021:8899699. Epub 2021 Feb 9.

Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden.

The characterization of the passive mechanical properties of the human triceps surae musculotendinous unit is important for gaining a deeper understanding of the interactive responses of the tendon and muscle tissues to loading during passive stretching. This study sought to quantify a comprehensive set of passive muscle-tendon properties such as slack length, stiffness, and the stress-strain relationship using a combination of ultrasound imaging and a three-dimensional motion capture system in healthy adults. By measuring tendon length, the cross-section areas of the Achilles tendon subcompartments (i. Read More

BMJ Case Rep 2021 Jan 19;14(1). Epub 2021 Jan 19.

Department of Interventional Radiology, Avera McKennan Hospital and University Health Center, Sioux Falls, South Dakota, USA.

A 26-year-old man presented with a 4-week history of right lower quadrant abdominal pain which was managed conservatively at home with ibuprofen. Three days later, he presented to the emergency department with worsening pain and swelling following an episode of coughing and slipping in the bathroom. Following his admission, CT angiography showed an active bleed into a 4. Read More

J Appl Physiol (1985) 2021 04 7;130(4):941-951. Epub 2021 Jan 7.

Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts.

Skeletal muscle has fiber architectures ranging from simple to complex, alongside variations in fiber-type and neuro-anatomical compartmentalization. However, the functional implications of muscle subdivision into discrete functional units remain poorly understood. The rat medial gastrocnemius has well-characterized regions with distinct architectures and fiber type composition. Read More

J Ultrasound 2021 Jun 5;24(2):201-203. Epub 2021 Jan 5.

Diagnostic Imaging Department, Centro Medico Inacqua, Piacenza, Italy.

The medial gastrocnemius is the most commonly injured muscle in the calf, and while traumatic lesions of the medial gastrocnemius are frequently described in the medical literature and clinical and sonographic diagnoses are easy, those of the soleus are less easily recognisable clinically or by sonography. We present a case of traumatic lesions of the medial gastrocnemius, diagnosed clinically and with ultrasound, while MRI also detected two lesions of the soleus. The case presented and the review of the literature highlight how clinical and ultrasound examinations can lead to misunderstandings about traumatic injury to the soleus. Read More

Invest Ophthalmol Vis Sci 2021 01;62(1)

Stein Eye Institute, University of California, Los Angeles, United States.

Purpose: In order to clarify the role of the optic nerve (ON) as a load on ocular rotation, we developed a finite element model (FEM) of incremental adduction induced by active contractility of extraocular muscles (EOMs), with and without tethering by the ON.

Methods: Three-dimensional (3-D) horizontal rectus EOM geometries were obtained from magnetic resonance imaging of five healthy adults, and measured constitutive tissue properties were used. Active and passive strain energies of EOMs were defined using ABAQUS (Dassault Systemes) software. Read More

Front Physiol 2020 3;11:600590. Epub 2020 Dec 3.

Department of Radiology, University of California, San Diego, San Diego, CA, United States.

3D strain or strain rate tensor mapping comprehensively captures regional muscle deformation. While compressive strain along the muscle fiber is a potential measure of the force generated, radial strains in the fiber cross-section may provide information on the material properties of the extracellular matrix. Additionally, shear strain may potentially inform on the shearing of the extracellular matrix; the latter has been hypothesized as the mechanism of lateral transmission of force. Read More

Phys Ther Sport 2021 Jan 25;47:134-139. Epub 2020 Nov 25.

Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine Department, Rey Juan Carlos University, Madrid, Spain; Faculty of Health Sciences, Rey Juan Carlos University, Madrid, Spain.

Objective: To study postural control and muscle activity during the limit of stability test (LOS) in subjects with chronic ankle instability.

Design: Observational study.

Setting: University laboratory. Read More

J Hand Surg Asian Pac Vol 2020 Dec;25(4):393-401

Department of Orthopaedic Surgery, Royal Wolverhampton NHS Trust, Wolverhampton, UK.

Cubital tunnel syndrome is the second most common nerve compression syndrome seen in the upper limb. Paresthesia and weakness are the two most common presentations in the hand. If left untreated, compression can lead to irreversible nerve damage, resulting in a loss of function of the forearm and hand. Read More

Physiol Rep 2020 10;8(19):e14583

Faculty of Physical Education, Kokushikan University, Tokyo, Japan.

The aim of the present study was to compare the mechanical properties of muscles and tendons at high strain rates between sprinters and untrained men. Fifteen sprinters and 18 untrained men participated in this study. Active muscle stiffness of the medial gastrocnemius muscle was calculated according to changes in the estimated muscle force and fascicle length during fast stretching at five different angular velocities (100, 200, 300, 500, and 600 deg·s ) after submaximal isometric contractions. Read More

Physiol Rep 2020 10;8(19):e14580

VasoActive Research Group, School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia.

Impairments in skeletal muscle microvascular function are frequently reported in patients with various cardiometabolic conditions for which older age is a risk factor. Whether aging per se predisposes the skeletal muscle to microvascular dysfunction is unclear. We used contrast-enhanced ultrasound (CEU) to compare skeletal muscle microvascular perfusion responses to cuff occlusion and leg exercise between healthy young (n = 12, 26 ± 3 years) and older (n = 12, 68 ± 7 years) adults. Read More

Front Physiol 2020 31;11:813. Epub 2020 Aug 31.

Department of Mathematics, Simon Fraser University, Burnaby, BC, Canada.

During contraction the energy of muscle tissue increases due to energy from the hydrolysis of ATP. This energy is distributed across the tissue as strain-energy potentials in the contractile elements, strain-energy potential from the 3D deformation of the base-material tissue (containing cellular and extracellular matrix effects), energy related to changes in the muscle's nearly incompressible volume and external work done at the muscle surface. Thus, energy is redistributed through the muscle's tissue as it contracts, with only a component of this energy being used to do mechanical work and develop forces in the muscle's longitudinal direction. Read More

Scand J Med Sci Sports 2021 Jan 27;31(1):193-204. Epub 2020 Sep 27.

Department of Kinesiology, University of Virginia, Charlottesville, VA, USA.

Our purpose was to analyze the effects of 4 weeks of visual gait biofeedback (GBF) and impairment-based rehabilitation on gait biomechanics and patient-reported outcomes (PROs) in individuals with chronic ankle instability (CAI). Twenty-seven individuals with CAI participated in this randomized controlled trial (14 received no biofeedback (NBF), 13 received GBF). Both groups received 8 sessions of impairment-based rehabilitation. Read More

J Biomech 2020 08 15;109:109955. Epub 2020 Jul 15.

Department of Mechatronics and Electronic Engineering, Konkuk University Glocal Campus, Chungcheongbuk-do, Republic of Korea. Electronic address:

Accurate knowledge of extraocular muscle (EOM) tension is important for the diagnosis of and surgical planning for strabismus, such as choosing which eye to operate or determining the amount of muscle displacement. Previous evaluations of passive EOM tension have relied extensively on the experience and skill of ophthalmic surgeons, who generally perform such evaluations by gripping the eyeball and then pushing and pulling it. This methodology, named the forced duction test, has the significant limitation that the tension is felt subjectively via the forceps, with the results therefore not being quantifiable. Read More

Clin Anat 2021 Oct 2;34(7):991-1001. Epub 2020 Sep 2.

Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan.

Introduction: Strains of the soleus are widely found both in amateur and professional athletes. For their accurate regional diagnoses, understanding the anatomy of the spatial relationship between muscular fibers and tendinous structures is important because their interfaces are susceptible sites to muscle strains. Therefore, this study evaluated the precise architecture of the soleus. Read More

Jpn J Radiol 2020 Nov 7;38(11):1028-1035. Epub 2020 Jul 7.

Faculty of Medicine, Endocrinology and Metabolism Department, Kirikkale University, Kirikkale, Turkey.

Purpose: The purpose of this study was to describe the elastic properties of the medial rectus muscle and optic nerve in Graves' patients without clinically apparent ophthalmopathy using strain elastography (SE) and shear wave elastography (SWE) and to determine whether these elastic properties could be used to aid in the diagnosis of the medial rectus muscle or optic nerve involvement.

Materials And Methods: Thirty participants diagnosed with Graves' disease without ophthalmopathy and 30 healthy volunteers (control group) were prospectively examined between November 2018 and August 2019. SE and SWE findings in both groups were compared using the χ test and the independent samples t test. Read More

Eur J Transl Myol 2020 Apr 1;30(1):8935. Epub 2020 Apr 1.

Department of Radiology, University of California San Diego, San Diego, CA, USA.

Age- and disuse- related loss of muscle force is disproportionately larger than the loss of muscle mass. Earlier studies reported that comparing concentric and eccentric contractions, there is a significant age-related decrease in force only in concentric contractions. Magnetic Resonance Imaging enables mapping of muscle deformation and has been used to study isometric but not eccentric contractions. Read More

Am J Sports Med 2020 07 2;48(9):2287-2294. Epub 2020 Jun 2.

Bellin Health Titletown Sports Medicine and Orthopedics, Green Bay, Wisconsin, USA.

Background: Lower extremity injuries are the most common injuries in professional sports and carry a high burden to players and teams in the National Football League (NFL). Injury prevention strategies can be refined by a foundational understanding of the occurrence and effect of these injuries on NFL players.

Purpose: To determine the incidence of specific lower extremity injuries sustained by NFL players across 4 NFL seasons. Read More

Front Physiol 2020 20;11:143. Epub 2020 Mar 20.

Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University, Bedford, MA, United States.

Contractions of skeletal muscles to generate movement involve dynamic changes in contractile and elastic tissue strains that likely interact to influence the force and work of a muscle. However, studies of the dynamics of skeletal muscle and tendon strains remain largely limited to bipedal animals, and rarely cover the broad spectra of movement requirements met by muscles that operate as motors, struts, or brakes across the various gaits that animals commonly use and conditions they encounter. Using high-speed bi-planar fluoromicrometry, we analyze strains within the rat medial gastrocnemius (MG) across a range of gait and slope conditions. Read More

J Theor Biol 2020 06 19;495:110251. Epub 2020 Mar 19.

Department of Mechanical Engineering, Faculty of Engineering, University of Alberta, Edmonton, T6G 1H9 AB, Canada.

Muscle is typically modelled using a lump sum idealization, scaling a single fascicle to represent the entire muscle. However, fascicles within a muscle have unique orientations, which could result in forces exerted not only in the axis running along the tendon, but also the two perpendicular axes, describing the muscle's width and depth. The purpose of this research was to develop a geometric-based model of the soleus, medial gastrocnemius, and lateral gastrocnemius as distributed force systems which can predict three-dimensional forces. Read More