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https://www.readbyqxmd.com/read/28649196/estimation-of-time-varying-intrinsic-and-reflex-dynamic-joint-stiffness-during-movement-application-to-the-ankle-joint
#1
Diego L Guarín, Robert E Kearney
Dynamic joint stiffness determines the relation between joint position and torque, and plays a vital role in the control of posture and movement. Dynamic joint stiffness can be quantified during quasi-stationary conditions using disturbance experiments, where small position perturbations are applied to the joint and the torque response is recorded. Dynamic joint stiffness is composed of intrinsic and reflex mechanisms that act and change together, so that nonlinear, mathematical models and specialized system identification techniques are necessary to estimate their relative contributions to overall joint stiffness...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28647869/muscular-viscoelastic-characteristics-of-athletes-participating-in-the-european-master-indoor-athletics-championship
#2
Marco Gervasi, Davide Sisti, Stefano Amatori, Marco Andreazza, Piero Benelli, Piero Sestili, Marco Bruno Luigi Rocchi, Anna Rita Calavalle
PURPOSE: To investigate how the viscoelastic characteristics of muscles (non-neural tone, elasticity and stiffness) vary as a function of age and gender in a sample of track and field master athletes. To compare these findings with data on related sedentary subjects in literature. METHODS: A total of 390 athletes (aged 35-99) were assessed during the European Master Athletics Indoor Championship 2016. A non-invasive measurement device called MyotonPro was used to measure tone, stiffness, and elasticity in the biceps brachii and rectus femoris muscles at rest...
June 24, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28647867/the-effects-of-4-weeks-stretching-training-to-the-point-of-pain-on-flexibility-and-muscle-tendon-unit-properties
#3
Pornpimol Muanjai, David A Jones, Mantas Mickevicius, Danguole Satkunskiene, Audrius Snieckus, Renata Rutkauskaite, Dalia Mickeviciene, Sigitas Kamandulis
PURPOSE: The purpose of this study was to compare the benefits and possible problems of 4 weeks stretching when taken to the point of pain (POP) and to the point of discomfort (POD). METHODS: Twenty-six physically active women (20 ± 1.1 years) took part in group-based stretching classes of the hamstring muscles, 4 times per week for 4 weeks, one group one stretching to POD, the other to POP. Passive stiffness, joint range of motion (ROM), maximal isometric torque and concentric knee flexion torque, were measured before training and 2 days after the last training session...
June 24, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28642262/arterial-stiffness-induces-remodeling-phenotypes-in-pulmonary-artery-smooth-muscle-cells-via-yap-taz-mediated-repression-of-cyclooxygenase-2
#4
Paul B Dieffenbach, Christina Mallarino Haeger, Anna Maria F Coronata, Kyoung Moo Choi, Xaralabos Varelas, Daniel J Tschumperlin, Laura E Fredenburgh
Pulmonary arterial stiffness is an independent risk factor for mortality in pulmonary hypertension (PH), and plays a critical role in PH pathophysiology. We have recently demonstrated arterial stiffening early in experimental PH, along with evidence for a mechanobiologic feedback loop by which arterial stiffening promotes further cellular remodeling behaviors. Cyclooxygenase-2 (COX-2) and prostaglandin signaling have been implicated in stiffness-mediated regulation, with prostaglandin activity inversely correlated to matrix stiffness and remodeling behaviors in vitro, as well as to disease progression in rodent PH models...
June 22, 2017: American Journal of Physiology. Lung Cellular and Molecular Physiology
https://www.readbyqxmd.com/read/28637823/titin-force-enhancement-following-active-stretch-of-skinned-skeletal-muscle-fibres
#5
Krysta Powers, Venus Joumaa, Azim Jinha, Eng Kuan Moo, Ian Curtis Smith, Kiisa Nishikawa, Walter Herzog
In actively stretched skeletal muscle sarcomeres, titin-based force is enhanced, increasing the stiffness of active sarcomeres. Titin force enhancement in sarcomeres is vastly reduced in mdm, a genetic mutation with a deletion in titin. Whether loss of titin force enhancement is associated with compensatory mechanisms at higher structural levels of organization, such as single fibres or entire muscles, is unclear. The aim of this study was to determine whether mechanical deficiencies in titin force enhancement are also observed at the fibre level, and whether mechanisms compensate for the loss of titin force enhancement...
June 21, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28633035/economy-and-endurance-in-human-evolution
#6
REVIEW
Herman Pontzer
The evolutionary pressures shaping humans' unique bipedal locomotion have been a focus of research since Darwin, but the origins of humans' economical walking gait and endurance running capabilities remain unclear. Here, I review the anatomical and physiological determinants of locomotor economy (e.g., limb length and posture) and endurance (e.g., muscle volume and fiber type) and investigate their development in the hominin fossil record. The earliest hominins were bipedal but retained ape-like features in the hind limb that would have limited their walking economy compared to living humans...
June 19, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28628370/multiple-joint-exercises-using-elastic-resistance-bands-vs-conventional-resistance-training-equipment-a-cross-over-study
#7
Vegard M Iversen, Paul Jarle Mork, Ottar Vasseljen, Ronny Bergquist, Marius S Fimland
Previous studies indicate that elastic resistance bands (ERB) can be a viable option to conventional resistance-training equipment (CRE) during single-joint resistance exercises, but their efficacy has not been established for several commonly used multiple-joint resistance exercises. Thus, we compared muscular activation levels in four popular multiple-joint exercises performed with ERB (TheraBand(®)) vs. CRE (Olympic barbell or cable pulley machines). In a cross-over design, men and women (n = 29) performed squats, stiff-legged deadlifts, unilateral rows and lateral pulldown using both modalities...
June 19, 2017: European Journal of Sport Science
https://www.readbyqxmd.com/read/28626322/the-effect-of-age-on-hamstring-passive-properties-after-a-10-week-stretch-training
#8
Thomas Haab, Georg Wydra
[Purpose] Degenerative changes take place in the musculoskeletal system of elderly people, resulting in a reduced range of motion. For this reason, stretch training is recommended for elderly individuals. To date, there have been no studies of the adaptations of the passive properties of muscles following long-term stretch training. The aim of this study is to investigate the hamstring elasticity of elderly people following a 10-week stretch training and compare the results to a younger cohort. [Subjects and Methods] The experimental groups consisted of 15 younger (24...
June 2017: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28626302/the-immediate-effect-of-diaphragm-taping-with-breathing-exercise-on-muscle-tone-and-stiffness-of-respiratory-muscles-and-spo2-in-stroke-patient
#9
Joong-San Wang, Kyun-Hee Cho, Shin-Jun Park
[Purpose] This study aimed to examine the immediate effects of diaphragm taping with breathing exercise on the tone and stiffness in the respiratory muscles of patient with stroke. [Subjects and Methods] A total of 28 subjects, 14 in the diaphragm taping with breathing exercise group and 14 in the breathing exercise group, were administered respective intervention methods. Subsequently, the muscle tone and stiffness in upper trapezius, scalene, external oblique abdominal and ractus abdominis muscle of both the respiratory muscles were measured...
June 2017: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28624851/acute-effects-of-constant-torque-and-constant-angle-stretching-on-the-muscle-and-tendon-tissue-properties
#10
Andreas Konrad, Francesco Budini, Markus Tilp
PURPOSE: Static stretching induces acute structural changes of the muscle-tendon unit (MTU) that are related to the intensity or duration of stretching. It has been reported that stretching with a constant torque (CT) leads to greater joint range of motion changes than stretching with a constant angle (CA). Whether or not this difference is due to different structural changes of the MTUs of the lower leg and ankle plantar flexors is not known. Therefore, the purpose of this study was to compare the acute effects of single CA and CT stretching on various muscle and tendon mechanical properties...
June 17, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28616397/development-and-use-of-a-non-biomaterial-model-for-hands-on-training-of-endoscopic-procedures
#11
Hiroki Sato, Ken-Ichi Mizuno, Yuichi Sato, Satoru Hashimoto, Kazunao Hayashi, Satoshi Ikarashi, Yutaka Honda, Junji Yokoyama, Shuji Terai
BACKGROUND: Endoscopic submucosal dissection (ESD) and peroral endoscopic myotomy (POEM) are recently developed techniques that have the potential to significantly improve clinical outcomes. However, training opportunities on these techniques remain limited. To address this issue, we developed a novel ex-vivo ESD/POEM training model. Our aim in this paper is to describe the model and provide preliminary evidence of promising feasibility to improve access to ESD/POEM training. METHODS: The model was developed using polyvinyl alcohol hydrogel, which can easily be modified to reproduce the stiffness of the different intestinal layers, namely the mucosa, submucosa, and muscle layer...
April 2017: Annals of Translational Medicine
https://www.readbyqxmd.com/read/28607132/impaired-muscle-oxygenation-and-elevated-exercise-blood-pressure-in-hypertensive-patients-links-with-vascular-stiffness
#12
Konstantina Dipla, Areti Triantafyllou, Nikolaos Koletsos, Stavros Papadopoulos, Vasileios Sachpekidis, Ioannis S Vrabas, Eugenia Gkaliagkousi, Andreas Zafeiridis, Stella Douma
This study examined in vivo (1) skeletal muscle oxygenation and microvascular function, at rest and during handgrip exercise, and (2) their association with macrovascular function and exercise blood pressure (BP), in newly diagnosed, never-treated patients with hypertension and normotensive individuals. Ninety-one individuals (51 hypertensives and 40 normotensives) underwent office and 24-hour ambulatory BP, arterial stiffness, and central aortic BP assessment, followed by a 5-minute arterial occlusion and a 3-minute submaximal handgrip exercise...
June 12, 2017: Hypertension
https://www.readbyqxmd.com/read/28600654/functions-of-the-subregions-of-the-infraspinatus-during-lateral-rotation
#13
Yoshiki Kuwahara, Takuma Yuri, Hiromi Fujii, Yoshiro Kiyoshige
PURPOSE: Although recent morphological studies have revealed that the infraspinatus muscle is subdivided, the functions of the subregions remain unknown. The aim of this study is to investigate the functions of the infraspinatus subregions during lateral rotation using real-time tissue elastography (RTE). METHODS: Ten young male volunteers participated in the study. In addition to the infraspinatus subregions, the teres minor and two of six subregions of the supraspinatus determined by Kim were examined...
June 9, 2017: Surgical and Radiologic Anatomy: SRA
https://www.readbyqxmd.com/read/28593004/influence-of-subjects-characteristics-and-technical-variables-on-muscle-stiffness-measured-by-shear-wave-elastosonography
#14
Chandra Bortolotto, Luca Lungarotti, Ilaria Fiorina, Michela Zacchino, Ferdinando Draghi, Fabrizio Calliada
PURPOSE: The aim of this study is to quantitatively assess lower limbs muscle elasticity in a court of healthy subjects and to evaluate the influence of technical variables (e.g., diameter of the ROI-region of interest) and examined subjects' characteristics (e.g., sex, levels of physical activity, side evaluated) on muscle stiffness. MATERIALS AND METHODS: 54 healthy subjects (48 men, 6 women) were evaluated for a total of 108 lower limbs. Shear wave elastography was performed with a multifrequency linear probe (15-4 MHz)...
June 2017: Journal of Ultrasound
https://www.readbyqxmd.com/read/28588472/key-insights-into-hand-biomechanics-human-grip-stiffness-can-be-decoupled-from-force-by-cocontraction-and-predicted-from-electromyography
#15
Hannes Höppner, Maximilian Große-Dunker, Georg Stillfried, Justin Bayer, Patrick van der Smagt
We investigate the relation between grip force and grip stiffness for the human hand with and without voluntary cocontraction. Apart from gaining biomechanical insight, this issue is particularly relevant for variable-stiffness robotic systems, which can independently control the two parameters, but for which no clear methods exist to design or efficiently exploit them. Subjects were asked in one task to produce different levels of force, and stiffness was measured. As expected, this task reveals a linear coupling between force and stiffness...
2017: Frontiers in Neurorobotics
https://www.readbyqxmd.com/read/28587976/mechanosensing-of-matrix-by-stem-cells-from-contractility-and-matrix-heterogeneity-to-cardiogenesis-and-muscle-stem-cells
#16
REVIEW
Lucas Smith, Sangkyun Cho, Dennis E Discher
Stem cells are particularly 'plastic' cell types that are induced by various cues to become specialized, tissue-functional lineages by switching on the expression of specific gene programs. Matrix stiffness is among the cues that multiple stem cell types can sense and respond to. This seminar-style review focuses on mechanosensing of matrix elasticity in the differentiation or early maturation of a few illustrative stem cell types, with an intended audience of biologists and physical scientists. Contractile forces applied by a cell's acto-myosin cytoskeleton are often resisted by the extracellular matrix and transduced through adhesions and the cytoskeleton ultimately into the nucleus to modulate gene expression...
June 3, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/28586712/ultrasound-shear-wave-elastography-in-the-assessment-of-passive-biceps-brachii-muscle-stiffness-influences-of-sex-and-elbow-position
#17
Johnson Chen, Michael O'Dell, Wen He, Li-Juan Du, Pai-Chi Li, Jing Gao
OBJECTIVE: To assess differences in biceps brachii muscle (BBM) stiffness as evaluated by ultrasound shear wave elastography (SWE). METHODS: The passive stiffness of the BBM was quantified with shear wave velocity (SWV) measurements obtained from 10 healthy volunteers (5 men and 5 women, mean age 50years, age range 42-63 years) with the elbow at full extension and 30° flexion in this IRB-approved study. Potential differences between two depths within the muscle, two elbow positions, the two arms, and sexes were assessed by using two-tailed t-test...
May 31, 2017: Clinical Imaging
https://www.readbyqxmd.com/read/28579954/linear-parameter-varying-identification-of-dynamic-joint-stiffness-during-time-varying-voluntary-contractions
#18
Mahsa A Golkar, Ehsan Sobhani Tehrani, Robert E Kearney
Dynamic joint stiffness is a dynamic, nonlinear relationship between the position of a joint and the torque acting about it, which can be used to describe the biomechanics of the joint and associated limb(s). This paper models and quantifies changes in ankle dynamic stiffness and its individual elements, intrinsic and reflex stiffness, in healthy human subjects during isometric, time-varying (TV) contractions of the ankle plantarflexor muscles. A subspace, linear parameter varying, parallel-cascade (LPV-PC) algorithm was used to identify the model from measured input position perturbations and output torque data using voluntary torque as the LPV scheduling variable (SV)...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28577155/rbm20-a-potential-target-for-treatment-of-cardiomyopathy-via-titin-isoform-switching
#19
REVIEW
Wei Guo, Mingming Sun
Cardiomyopathy, also known as heart muscle disease, is an unfavorable condition leading to alterations in myocardial contraction and/or impaired ability of ventricular filling. The onset and development of cardiomyopathy have not currently been well defined. Titin is a giant multifunctional sarcomeric filament protein that provides passive stiffness to cardiomyocytes and has been implicated to play an important role in the origin and development of cardiomyopathy and heart failure. Titin-based passive stiffness can be mainly adjusted by isoform switching and post-translational modifications in the spring regions...
June 2, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28574727/development-of-the-rheumatoid-arthritis-symptom-questionnaire-rasq-a-patient-reported-outcome-scale-for-measuring-symptoms-of-rheumatoid-arthritis
#20
Benjamin Banderas, Martha Skup, Alan L Shields, Iyar Mazar, Arijit Ganguli
BACKGROUND: Rheumatoid arthritis (RA), a chronic, progressive inflammatory, autoimmune disease, can substantially reduce health-related quality of life (HRQoL) and lead to severe disability and early mortality. Patient-reported outcome (PRO) instruments are used to assess the patient experience of RA symptoms and impacts, and can capture RA treatment effects. To address limitations in existing PRO instruments, this research aimed to establish the content validity of a new instrument, the Rheumatoid Arthritis Symptom Questionnaire (RASQ), to assess the signs and symptoms of RA...
June 2, 2017: Current Medical Research and Opinion
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