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Muscle co contraction

A D Wibawa, N Verdonschot, J P K Halbertsma, J G M Burgerhof, R L Diercks, G J Verkerke
This study focused on comparing muscle activities predicted by the Musculoskeletal Modeling System with EMG from ten healthy subjects who performed normal walking, one-legged forward hopping and side jumping. Eight EMG electrodes measured the activity of eight right leg muscles. Specific thresholds per muscle were applied on the EMG prior comparison. These thresholds were determined by equalizing the duration of EMG to AMS muscle activity. Three graph variables, number of onsets, offsets and hills were used to quantify the level of agreement by using Cohen׳s kappa analysis...
October 6, 2016: Journal of Biomechanics
Yasuhide Yoshitake, Hiroaki Kanehisa, Minoru Shinohara
PURPOSE: The purpose of this study was to determine the modulation of common low-frequency oscillations in pools of motor units across antagonistic muscles due to the difference in the activation level of pools of spinal motor neurons and the presence of neuromuscular fatigue during intended co-contraction. METHODS: Ten healthy young men (21.8 ± 1.5 yr) performed intended steady co-contractions of elbow flexors and extensors at maximal and a submaximal (10% of maximal electromyogram, EMG) effort...
October 6, 2016: Medicine and Science in Sports and Exercise
Justin Parreno, Sneha Raju, Po-Han Wu, Rita A Kandel
Chondrocyte culture as a monolayer for cell number expansion results in dedifferentiation whereby expanded cells acquire contractile features and increased actin polymerization status. This study determined whether the actin polymerization based signaling pathway, myocardin-related transcription factor-a (MRTF-A) is involved in regulating this contractile phenotype. Serial passaging of chondrocytes in monolayer culture to passage 2 resulted in increased gene and protein expression of the contractile molecules alpha-smooth muscle actin, transgelin and vinculin compared to non-passaged, primary cells...
October 14, 2016: Matrix Biology: Journal of the International Society for Matrix Biology
Marco Hagen, Gerrit Schwiertz, Karl B Landorf, Hylton B Menz, George S Murley
The pronators and supinators play a key role in the medio-lateral stability of the ankle joint complex (i.e. talo-crural and subtalar joints). We hypothesized that each shank muscle has a specific activation pattern determined by its anatomical course around the axes of the subtalar and talo-crural joints. A secondary objective was to examine the effect of foot posture on these activation patterns. Forty-nine young adults (25 normal-arched feet, 24 flat-arched feet) performed maximum voluntary isometric contractions against manual resistance in four movement directions: plantarflexion (PF), dorsiflexion (DF), pronation (PRO) and supination (SUP)...
October 6, 2016: Human Movement Science
Bente Rona Jensen, Jesper Sandfeld, Pia Sandfeld Melcher, Katrine Lyders Johansen, Peter Hendriksen, Birgit Juul-Kristensen
BACKGROUND: Generalized Joint Hypermobility (GJH) is associated with increased risk of musculoskeletal joint pain. We investigated neuromuscular performance and muscle activation strategy. METHODS: Girls with GJH and non-GJH (NGJH) performed isometric knee flexions (90°,110°,130°), and extensions (90°) at 20 % Maximum Voluntary Contraction, and explosive isometric knee flexions while sitting. EMG was recorded from knee flexor and extensor muscles. RESULTS: Early rate of torque development was 53 % faster for GJH...
October 3, 2016: BMC Musculoskeletal Disorders
Hannah E Westlake, Louise R Page
Staurozoan cnidarians display an unusual combination of polyp and medusa characteristics and their morphology may be informative about the evolutionary origin of medusae. We studied neuromuscular morphology of two staurozoans, Haliclystus 'sanjuanensis' and Manania handi, using whole mount immunohistochemistry with antibodies against FMRFamide and α-tubulin to label neurons and phalloidin to label muscles. All muscles appeared to lack striations. Longitudinal interradial muscles are probable homologues of stalk muscles in scyphopolyps, but in adult staurozoans they are elaborated to inwardly flex marginal lobes of the calyx during prey capture; these muscles are pennate in M...
October 2, 2016: Journal of Morphology
Jie Xiang, Hui Wang, Chengbang Ma, Mei Zhou, Yuxin Wu, Lei Wang, Shaodong Guo, Tianbao Chen, Chris Shaw
Bradykinin-related peptides (BRPs) are one of the most extensively studied frog secretions-derived peptide families identified from many amphibian species. The diverse primary structures of BRPs have been proven essential for providing valuable information in understanding basic mechanisms associated with drug modification. Here, we isolated, identified and characterized a dodeca-BRP (RAP-L1, T6-BK), with primary structure RAPLPPGFTPFR, from the skin secretions of Chinese large odorous frogs, Odorrana livida...
2016: Toxins
Charlotte Apps, Thorsten Sterzing, Thomas O'Brien, Mark Lake
Unstable shoes (US) continually perturb gait which can train the lower limb musculature, but muscle co-contraction and potential joint stiffness strategies are not well understood. A shoe with a randomly perturbing midsole (IM) may enhance these adaptations. This study compares ankle and knee joint stiffness, and ankle muscle co-contraction during walking and running in US, IM and a control shoe in 18 healthy females. Ground reaction forces, three-dimensional kinematics and electromyography of the gastrocnemius medialis and tibialis anterior were recorded...
September 20, 2016: Journal of Electromyography and Kinesiology
Juliette Ropars, Mathieu Lempereur, Sylvain Brochard, Carole Vuillerot, Vincent Tiffreau, Jean-Marie Cuisset, Yann Péréon, Fabien Leboeuf, Raphaël Gross, Ludovic Delporte, Yannick Delpierre
OBJECTIVE: The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD). MATERIALS/PATIENTS AND METHODS: Dynamic surface electromyography recordings (EMGs) of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF), vastus lateralis (VL), medial hamstrings (HS), tibialis anterior (TA) and gastrocnemius soleus (GAS) muscles was recorded and analyzed quantitatively and qualitatively...
September 2016: Annals of Physical and Rehabilitation Medicine
Céline Coffineau, Annabelle Couillandre, Jean Chapus, Nicolas Lampire
OBJECTIVE: During rehabilitation of hemiparetic patients, physiotherapists face a discrepancy between motor skills during analytical exercises and functional abilities observed during gait. A muscle recruitment difference in the two situations could explain this gap. Among pathologic motricity manifestations observed in hemiparetic patients (Gracies 2005), exist the spastic co contraction phenomenon that presently concerned our work. Indeed, the main objective of this study was to compare co-contractions in hemiparetic subjects between an analytical exercise modality and a functional exercise modality, i...
September 2016: Annals of Physical and Rehabilitation Medicine
Jean-Philippe Ehny, Yoshimasa Sagawa, Laurent Tatu, Ludivine Chamard, Bernard Parratte, Pierre Decavel
OBJECTIVE: Hereditary spastic paraplegia (HSP) designates a rare genetic disorder characterized by the existence of a pyramidal syndrome and/or paresis of the lower limbs, resulting in locomotor disorders. The objective of this study was to investigate the HSP patients walking characteristics during a comfortable walking speed, to determinate the most deleterious impairments and their evolutivity during a prolonged standardized walk. A second goal was to study the co-contraction of targeted muscles during these two walking conditions...
September 2016: Annals of Physical and Rehabilitation Medicine
Zbidi Sana, Badrane Zinoubi, Omar Hammouda, Henry Vandewalle, Virgile Serrau, Tarak Driss
BACKGROUND: The effects of a six-week maximal voluntary isometric co-contraction (MIVCC) training program of the elbow flexor and extensor muscles on maximal and explosive muscle strength have been studied. METHODS: Ten active men underwent 6-week MIVCC. Maximal rate of force development (MRFD) of the elbow flexor (MRFDflex) and extensor (MRFDext) were measured in addition to maximal voluntary contraction (MVC) of these muscles (MVCflex and MVCext) before (T0), after 4-week (T1) and 6-week (T2) MIVCC training program...
September 14, 2016: Journal of Sports Medicine and Physical Fitness
Michael Habeck, Elmira Tokhtaeva, Yotam Nadav, Efrat Ben Zeev, Sean P Ferris, Randal J Kaufman, Elizabeta Bab-Dinitz, Jack H Kaplan, Laura A Dada, Zvi Farfel, Daniel M Tal, Adriana Katz, George Sachs, Olga Vagin, Steven J D Karlish
The Na,K-ATPase 2 subunit plays a key role in cardiac muscle contraction by regulating intracellular Ca2+ while α1 has a more conventional role of maintaining ion homeostasis. The β subunit differentially regulates maturation, trafficking and activity of α-β heterodimers. It is not known whether the distinct role of α2 in heart is related to selective assembly with a particular one of the three β isoforms. We show here by immunofluorescence and co-immunoprecipitation that α2 is preferentially expressed with β2 in T-tubules of cardiac myocytes, forming α2β2 heterodimers...
September 13, 2016: Journal of Biological Chemistry
Juliette Ropars, Mathieu Lempereur, Carole Vuillerot, Vincent Tiffreau, Sylviane Peudenier, Jean-Marie Cuisset, Yann Pereon, Fabien Leboeuf, Ludovic Delporte, Yannick Delpierre, Raphaël Gross, Sylvain Brochard
The aim of this prospective study was to investigate changes in muscle activity during gait in children with Duchenne muscular Dystrophy (DMD). Dynamic surface electromyography recordings (EMGs) of 16 children with DMD and pathological gait were compared with those of 15 control children. The activity of the rectus femoris (RF), vastus lateralis (VL), medial hamstrings (HS), tibialis anterior (TA) and gastrocnemius soleus (GAS) muscles was recorded and analysed quantitatively and qualitatively. The overall muscle activity in the children with DMD was significantly different from that of the control group...
2016: PloS One
Nancy K Drew, Nicholas E Johnsen, Jason Q Core, Anna Grosberg
In a properly contracting cardiac muscle, many different constructs are organized into an intricate architecture. While it has been observed that this organization is altered in pathological conditions, the relationship between length-scales and architecture has not been properly explored. In this work, we utilize a variety of architecture metrics to quantify organization and consistency of single constructs over multiple scales as well as correlation of organization of multiple constructs. Specifically, as the best way to characterize cardiac tissues, we chose the orientational and co-orientational order parameters...
September 12, 2016: Journal of Biomechanical Engineering
Ahmed Handhle, Chloe E Ormonde, N Lowri Thomas, Catherine Bralesford, Alan J Williams, F Anthony Lai, Spyros Zissimopoulos
Cardiac muscle contraction requires sarcoplasmic reticulum (SR) Ca(2+) release mediated by the quaternary complex comprising the ryanodine receptor (RyR2), calsequestrin (CSQ2), junctin and triadin. Here, we demonstrate that a direct interaction exists between RyR2 and CSQ2. Topologically, CSQ2 binding occurs at the first luminal loop of RyR2. Co-expression of RyR2 and CSQ2 in a human cell line devoid of the other quaternary complex proteins results in altered Ca(2+) release dynamics compared to cells expressing RyR2 only...
September 8, 2016: Journal of Cell Science
Andrew J Ghio
Over several decades, asthma has evolved from being recognized as a single disease to include a diverse group of phenotypes with dissimilar natural histories, pathophysiologies, responses to treatment, and distinctive molecular pathways. With the application of Occam's razor to asthma, it is proposed that there is one cause underlying the numerous phenotypes of this disease and that the responsible molecular pathway is a deficiency of iron in the lung tissues. This deficiency can be either absolute (e.g. asthma in the neonate and during both pregnancy and menstruation) or functional (e...
October 2016: Biometals: An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine
Peter C Fino, Maury A Nussbaum, Per Gunnar Brolinson
Two experiments compared multiple methods of estimating postural stability entropy to address: 1) if postural complexity differences exist between concussed and healthy athletes immediately following return-to-play; 2) which methods best detect such differences; and 3) what is an appropriate interpretation of such differences. First, center of pressure (COP) data were collected from six concussed athletes over the six weeks immediately following their concussion and from 24 healthy athletes. Second, 25 healthy non-athletes performed four quiet standing tasks: normal, co-contracting their lower extremity muscles, performing a cognitive arithmetic task, and voluntarily manipulating their sway...
August 26, 2016: Gait & Posture
Yoichi Ajiro, Tsuyoshi Shiga, Morio Shoda, Nobuhisa Hagiwara
An important step in diagnosing myopotential oversensing is to confirm its reproducibility using specific provocation maneuvers. Although most maneuvers involve the co-contraction of many muscles, no attempt has been made to assess relevant muscle activities by electromyography. We describe a case with an implantable cardioverter defibrillator (ICD) whose myopotential oversensing was provoked by simultaneous straining and leftward twisting. Simultaneous recordings from real-time ICD telemetry and myopotentials of the rectus abdominis, oblique abdominis, and diaphragm on electromyography during the provocation maneuvers were conducted...
August 30, 2016: Heart and Vessels
Stephen J Preece, Richard K Jones, Christopher A Brown, Timothy W Cacciatore, Anthony K P Jones
BACKGROUND: Both increased knee muscle co-contraction and alterations in central pain processing have been suggested to play a role in knee osteoarthritis pain. However, current interventions do not target either of these mechanisms. The Alexander Technique provides neuromuscular re-education and may also influence anticipation of pain. This study therefore sought to investigate the potential clinical effectiveness of the AT intervention in the management of knee osteoarthritis and also to identify a possible mechanism of action...
2016: BMC Musculoskeletal Disorders
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