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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 Apr 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

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

J Shoulder Elbow Surg 2020 Jun 12;29(6):e245-e251. Epub 2020 Feb 12.

Division of Sports Medicine and Department of Orthopaedic Surgery, Saitama Medical University, Saitama, Japan.

Background: Medial elbow injuries are common in baseball pitchers. This study investigated the reliability of medial elbow elastography measurement and the characteristics of the medial elbow stabilizers.

Methods: Medial elbow joint space gapping and the strain ratios of the ulnar collateral ligament (UCL) and the forearm flexor-pronator muscle (FPM) were measured at rest and during gripping in 29 healthy college students. Read More

Gait Posture 2020 03 7;77:83-88. Epub 2020 Jan 7.

Queensland Children's Motion Analysis Service, Children's Health Queensland Hospital and Health Service, Brisbane, Australia; Gold Coast Orthopaedic Research and Education Alliance, Menzies Health Institute Queensland, Gold Coast, Australia.

Introduction/aim: Flip-flops are a popular choice of footwear for children. However, their inherent design provides minimal support to the foot and ankle and has been suggested to increase the work performed by muscle and tendon structures, potentially predisposing them to injury. Therefore, the aim of this study was to compare the length change behaviour of the medial gastrocnemius (MG) muscle fascicles and muscle tendon unit (MTU) and their mechanical function at the ankle and subtalar joints in children during walking with and without flip-flop. Read More

Magn Reson Med 2020 07 11;84(1):142-156. Epub 2019 Dec 11.

Muscle Imaging and Modeling Lab, Department of Radiology, UC San Diego, San Diego, California.

Purpose: This study implements a compressed sensing (CS) 3-directional velocity encoded phase contrast (VE-PC) imaging for studying skeletal muscle kinematics within 40 s.

Methods: Independent variable density random sampling in the phase encoding direction for each temporal frame was implemented for various combinations of CS-factors and views per segment. CS reconstruction was performed for the combined multicoil, temporal datasets using temporal Fourier transform followed by temporal principal component analysis sparsifying transformations. Read More

Undersea Hyperb Med 2019 Sep - Dec - Fourth Quarter;46(5):647-654

Department of Orthopaedic Surgery, Tokyo Medical and Dental University.

Introduction: The effects of hyperbaric oxygen (HBO2) therapy on sprains, ligament injuries, and muscle strains have been reported in several animal studies. In a dog model of compartment syndrome and in a rat contused skeletal muscle injury model, the significant effects of HBO2 therapy on the reduction of edema and muscle necrosis have been reported. In basic research HBO2 therapy stimulated fibroblast activity to improve the healing process. Read More

Surg Radiol Anat 2020 Jan 5;42(1):63-67. Epub 2019 Sep 5.

Department of Maxillofacial Surgery, Public Assistance Hospital,, University Hospital Center Conception, Marseille, France.

Purpose: Since prehistory, changes of the facial skeleton have been related to the modification of diet. More recent studies have shown changes in the morphology of the mandible and maxilla due to variations of strain during mastication. The temporal muscle (TM) is a strong masticatory muscle, with its insertions extending through the temporal fossa. Read More

Clin Biomech (Bristol, Avon) 2019 10 13;69:115-119. Epub 2019 Jul 13.

School of Health Sciences and Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal.

Background: Impact of prior injury on myoelectrical activity of the hamstrings during isokinetic eccentric contractions has received increased literature attention. This cross-sectional study aimed to assess neuromuscular adaptations, namely proprioception, core stability, muscle strength, extensibility and activity, in football players with history of hamstring strain injury.

Methods: Seventeen players, 10 with history of hamstring injury and 7 without prior injury underwent isokinetic strength testing, eccentric knee extension at 30 and 120°/s. Read More

Orbit 2020 Jun 11;39(3):160-164. Epub 2019 Jul 11.

Ophthalmology Department, Gazi Yasargil Training and Research Hospital, Diyarbakir, Turkey.

: To evaluate the affected extraocular muscles (EOMs) of patients with Graves' ophthalmopathy (GO) using real-time ultrasound elastography (UE) and to compare these results with those of healthy subjects.: This prospective, comparative case series included 70 eyes of 35 patients with moderate-to-severe GO with type 2 orbitopathy (myogenic variant) according to their computed tomography (CT) scans. Forty-six eyes of 23 healthy subjects were evaluated as the control group. Read More

Prog Brain Res 2019 20;248:93-102. Epub 2019 May 20.

Stein Eye Institute and Departments of Ophthalmology and Neurology, University of California, Los Angeles, CA, United States. Electronic address:

The ocular motor plant, consisting of the globe, extraocular muscles (EOMs), and connective tissue suspension, constitutes an intricate and non-linear actuator of eye movements. The pulley system of the rectus EOMs constitutes a non-linear inner gimbal actuated by the orbital layers of these EOMs that renders the sequence of ocular rotations effectively commutative to the central controller, and can be rotated by the outer gimbal driven by the oblique EOMs. Optic nerve (ON) length is insufficient to permit large angle adduction without tethering by the ON and sheath, creating at and beyond this threshold a large additional load on the medial rectus muscle. Read More

Sports Biomech 2019 Jun 24:1-14. Epub 2019 Jun 24.

a Department of Life Science , University of Tokyo , Tokyo , Japan.

The purpose of present study was to investigate site differences in the effects of strain rate on tendon properties between knee extensors and plantar flexors. Elongation of tendon structures (L) in vastus lateralis and medial gastrocnemius muscles was measured by ultrasonography while participants performed ramp and ballistic contractions to their voluntary maximum, followed by ramp and sudden relaxation. The relationship between muscle force (Fm) and L was fit to linear regression, the slope of which was defined as stiffness of tendon structures. Read More

Phys Ther Sport 2019 Sep 5;39:8-15. Epub 2019 Jun 5.

University of Nevada, Las Vegas, United States. Electronic address:

Objectives: The purpose of the current study was to compare injury and running history among current and former runners who consider themselves either injured or uninjured.

Design: Cross-sectional survey.

Setting: Online survey, available to any individuals over the age of 18 who currently run (runners) or who once ran regularly but are no longer running (former runners). Read More

JBJS Case Connect 2019 Apr-Jun;9(2):e0189

Hansjörg Wyss Department of Plastic Surgery, New York University Langone Health, New York, New York.

Case: A 32-year-old right-handed surgeon presented with a history of intermittent pain at the right medial epicondyle, a mild Tinel's sign, and dysesthesia in the ulnar nerve distribution. Dynamic ultrasound demonstrated a hypertrophic anconeus epitrochlearis bilaterally, and chronic irritation of the ulnar nerve. Anterior release with myectomy of the accessory muscle was performed. Read More