WorldWideScience

Sample records for striated muscle activator

  1. Striated Muscle Function, Regeneration, and Repair

    Science.gov (United States)

    Shadrin, I.Y.; Khodabukus, A.; Bursac, N.

    2016-01-01

    As the only striated muscle tissues in the body, skeletal and cardiac muscle share numerous structural and functional characteristics, while exhibiting vastly different size and regenerative potential. Healthy skeletal muscle harbors a robust regenerative response that becomes inadequate after large muscle loss or in degenerative pathologies and aging. In contrast, the mammalian heart loses its regenerative capacity shortly after birth, leaving it susceptible to permanent damage by acute injury or chronic disease. In this review, we compare and contrast the physiology and regenerative potential of native skeletal and cardiac muscles, mechanisms underlying striated muscle dysfunction, and bioengineering strategies to treat muscle disorders. We focus on different sources for cellular therapy, biomaterials to augment the endogenous regenerative response, and progress in engineering and application of mature striated muscle tissues in vitro and in vivo. Finally, we discuss the challenges and perspectives in translating muscle bioengineering strategies to clinical practice. PMID:27271751

  2. Effects of different activity and inactivity paradigms on myosin heavy chain gene expression in striated muscle

    Science.gov (United States)

    Baldwin, K. M.; Haddad, F.

    2001-01-01

    The goal of this mini-review is to summarize findings concerning the role that different models of muscular activity and inactivity play in altering gene expression of the myosin heavy chain (MHC) family of motor proteins in mammalian cardiac and skeletal muscle. This was done in the context of examining parallel findings concerning the role that thyroid hormone (T(3), 3,5,3'-triiodothyronine) plays in MHC expression. Findings show that both cardiac and skeletal muscles of experimental animals are initially undifferentiated at birth and then undergo a marked level of growth and differentiation in attaining the adult MHC phenotype in a T(3)/activity level-dependent fashion. Cardiac MHC expression in small mammals is highly sensitive to thyroid deficiency, diabetes, energy deprivation, and hypertension; each of these interventions induces upregulation of the beta-MHC isoform, which functions to economize circulatory function in the face of altered energy demand. In skeletal muscle, hyperthyroidism, as well as interventions that unload or reduce the weight-bearing activity of the muscle, causes slow to fast MHC conversions. Fast to slow conversions, however, are seen under hypothyroidism or when the muscles either become chronically overloaded or subjected to intermittent loading as occurs during resistance training and endurance exercise. The regulation of MHC gene expression by T(3) or mechanical stimuli appears to be strongly regulated by transcriptional events, based on recent findings on transgenic models and animals transfected with promoter-reporter constructs. However, the mechanisms by which T(3) and mechanical stimuli exert their control on transcriptional processes appear to be different. Additional findings show that individual skeletal muscle fibers have the genetic machinery to express simultaneously all of the adult MHCs, e.g., slow type I and fast IIa, IIx, and IIb, in unique combinations under certain experimental conditions. This degree of

  3. Dynamic Regulation of Sarcomeric Actin Filaments in Striated Muscle

    OpenAIRE

    Ono, Shoichiro

    2010-01-01

    In striated muscle, the actin cytoskeleton is differentiated into myofibrils. Actin and myosin filaments are organized in sarcomeres and specialized for producing contractile forces. Regular arrangement of actin filaments with uniform length and polarity is critical for the contractile function. However, the mechanisms of assembly and maintenance of sarcomeric actin filaments in striated muscle are not completely understood. Live imaging of actin in striated muscle has revealed that actin sub...

  4. Contracture of Slow Striated Muscle during Calcium Deprivation

    Science.gov (United States)

    Irwin, Richard L.; Hein, Manfred M.

    1963-01-01

    When deprived of calcium the slow striated muscle fibers of the frog develop reversible contractures in either hypertonic or isotonic solutions. While calcium deprivation continues because of a flowing calcium-free solution the muscles relax slowly and completely. Restoration of calcium during contracture relaxes the muscle promptly to initial tension. When relaxed during calcium lack the return of calcium does not change tension and the muscle stays relaxed. When contractures are induced by solutions containing small amounts of calcium relaxation does not occur or requires several hours. The rate of tension development depends upon the rate at which calcium moves outward since the contractures develop slower in low concentrations of calcium and are absent or greatly slowed in a stagnant calcium-free solution. Withdrawal of calcium prevents the contractile responses to ACh, KCl, or electrical stimulation through the nerve. Muscles return to their original excitability after calcium is restored. Origin of the contractures is unrelated to nerve activity since they are maximal during transmission failure from calcium lack, occur in denervated muscles, and are not blocked by high concentrations of d-tubocurarine, procaine, or atropine. The experiments also indicate that the contractures do not originate from repetitive activity of muscle membranes. The findings are most simply explained by relating the outward movement of calcium as a link for initiating contraction in slow type striated muscle. PMID:14065284

  5. Systems Biology Approaches to Discerning Striated Muscle Pathologies

    OpenAIRE

    Mukund, Kavitha

    2016-01-01

    The human muscular system represents nearly 75% of the body mass and encompasses two major muscle forms- striated and smooth. Striated muscle, composed broadly of myofibers, accompanying membrane systems, cytoskeletal networks together with the metabolic and regulatory machinery, have revealed complexities in composition, structure and function. A disruption to any component within this complex system of interactions lead to disorders of the muscle, typically characterized by muscle fiber los...

  6. Poorly Understood Aspects of Striated Muscle Contraction

    Directory of Open Access Journals (Sweden)

    Alf Månsson

    2015-01-01

    Full Text Available Muscle contraction results from cyclic interactions between the contractile proteins myosin and actin, driven by the turnover of adenosine triphosphate (ATP. Despite intense studies, several molecular events in the contraction process are poorly understood, including the relationship between force-generation and phosphate-release in the ATP-turnover. Different aspects of the force-generating transition are reflected in the changes in tension development by muscle cells, myofibrils and single molecules upon changes in temperature, altered phosphate concentration, or length perturbations. It has been notoriously difficult to explain all these events within a given theoretical framework and to unequivocally correlate observed events with the atomic structures of the myosin motor. Other incompletely understood issues include the role of the two heads of myosin II and structural changes in the actin filaments as well as the importance of the three-dimensional order. We here review these issues in relation to controversies regarding basic physiological properties of striated muscle. We also briefly consider actomyosin mutation effects in cardiac and skeletal muscle function and the possibility to treat these defects by drugs.

  7. Expression of various sarcomeric tropomyosin isoforms in equine striated muscles

    Directory of Open Access Journals (Sweden)

    Syamalima Dube

    2017-06-01

    Full Text Available In order to better understand the training and athletic activity of horses, we must have complete understanding of the isoform diversity of various myofibrillar protein genes like tropomyosin. Tropomyosin (TPM, a coiled-coil dimeric protein, is a component of thin filament in striated muscles. In mammals, four TPM genes (TPM1, TPM2, TPM3, and TPM4 generate a multitude of TPM isoforms via alternate splicing and/or using different promoters. Unfortunately, our knowledge of TPM isoform diversity in the horse is very limited. Hence, we undertook a comprehensive exploratory study of various TPM isoforms from horse heart and skeletal muscle. We have cloned and sequenced two sarcomeric isoforms of the TPM1 gene called TPM1α and TPM1κ, one sarcomeric isoform of the TPM2 and one of the TPM3 gene, TPM2α and TPM3α respectively. By qRT-PCR using both relative expression and copy number, we have shown that TPM1α expression compared to TPM1κ is very high in heart. On the other hand, the expression of TPM1α is higher in skeletal muscle compared to heart. Further, the expression of TPM2α and TPM3α are higher in skeletal muscle compared to heart. Using western blot analyses with CH1 monoclonal antibody we have shown the high expression levels of sarcomeric TPM proteins in cardiac and skeletal muscle. Due to the paucity of isoform specific antibodies we cannot specifically detect the expression of TPM1κ in horse striated muscle. To the best of our knowledge this is the very first report on the characterization of sarcmeric TPMs in horse striated muscle.

  8. Neurohypophyseal hormones: novel actors of striated muscle development and homeostasis

    Directory of Open Access Journals (Sweden)

    Alessandra Costa

    2014-09-01

    Full Text Available Since the 1980's, novel functional roles of the neurohypophyseal hormones vasopressin and oxytocin have emerged. Several studies have investigated the effects of these two neurohormones on striated muscle tissues, both in vitro and in vivo. The effects of vasopressin on skeletal myogenic cells, developing muscle and muscle homeostasis have been documented. Oxytocin appears to have a greater influence on cardiomyocite differentiation and heart homeostasis. This review summarizes the studies on these novel roles of the two neurohypophyseal hormones, and open the possibility of new therapeutic approaches for diseases affecting striated muscle.

  9. Standardization of metachromatic staining method of myofibrillar ATPase activity of myosin to skeletal striated muscle of mules and donkeys

    Directory of Open Access Journals (Sweden)

    Flora H.F. D'Angelis

    2014-09-01

    Full Text Available This study aims at standardizing the pre-incubation and incubation pH and temperature used in the metachromatic staining method of myofibrillar ATPase activity of myosin (mATPase used for asses and mules. Twenty four donkeys and 10 mules, seven females and three males, were used in the study. From each animal, fragments from the Gluteus medius muscle were collected and percutaneous muscle biopsy was performed using a 6.0-mm Bergström-type needle. In addition to the metachromatic staining method of mATPase, the technique of nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR was also performed to confirm the histochemical data. The histochemical result of mATPase for acidic pre-incubation (pH=4.50 and alkaline incubation (pH=10.50, at a temperature of 37ºC, yielded the best differentiation of fibers stained with toluidine blue. Muscle fibers were identified according to the following colors: type I (oxidative, light blue, type IIA (oxidative-glycolytic, intermediate blue and type IIX (glycolytic, dark blue. There are no reports in the literature regarding the characterization and distribution of different types of muscle fibers used by donkeys and mules when performing traction work, cargo transportation, endurance sports (horseback riding and marching competitions. Therefore, this study is the first report on the standardization of the mATPase technique for donkeys and mules.

  10. Autoradiographic analysis of protein regeneration in striated skeleton muscle

    International Nuclear Information System (INIS)

    Dadoune, J.P.

    1977-01-01

    An autoradiographic study was conducted of protein regeneration in striated muscles aimed at clarifying the contradictions in the literature: while some authors hold that the regeneration rate is identical for all types of myofibril proteins and the myofibril is thus regenerated as a whole, others claim that the regeneration rate differs depending on the type of the myofibril protein. Tritium-labelled leucine incorporation experiments showed the existence of at least 2 pools of newly formed proteins in striated muscles in both adult and young animals. One pool is regenerated in 1 to 2 weeks, the other roughly in a month. The regeneration of proteins is initially more significant in red fibres; thus the rate of myofibril protein regeneration is not uniform. In adult animals regeneration seems to be slower in filaments than in the sarcoplasm and in the mitochondria. (A.K.)

  11. Ultrastructure of striated muscle fibers in the middle third of the human esophagus

    OpenAIRE

    Faussone-Pellegrini, M.S; Cortesini, C.

    1986-01-01

    Striated muscle fibers and .their spatial relationship to smooth muscle cells have been studied in the middle third of human esophagus. Biopsies were obtained from 3 patients during surgery. In both the circular and longitudinal layers, the muscle coat of this transition zone was composed of fascicles of uniform dimensioi~ (100-200 pm of diameter); some of these bundles were made up of striated muscle fibers, others were pure bundles of smooth muscle cells and ...

  12. The homeobox gene Msx in development and transdifferentiation of jellyfish striated muscle.

    Science.gov (United States)

    Galle, Sabina; Yanze, Nathalie; Seipel, Katja

    2005-01-01

    Bilaterian Msx homeobox genes are generally expressed in areas of cell proliferation and in association with multipotent progenitor cells. Likewise, jellyfish Msx is expressed in progenitor cells of the developing entocodon, a cell layer giving rise to the striated and smooth muscles of the medusa. However, in contrast to the bilaterian homologs, Msx gene expression is maintained at high levels in the differentiated striated muscle of the medusa in vivo and in vitro. This tissue exhibits reprogramming competence. Upon induction, the Msx gene is immediately switched off in the isolated striated muscle undergoing transdifferentiation, to be upregulated again in the emerging smooth muscle cells which, in a stem cell like manner, undergo quantal cell divisions producing two cell types, a proliferating smooth muscle cell and a differentiating nerve cell. This study indicates that the Msx protein may be a key component of the reprogramming machinery responsible for the extraordinary transdifferentation and regeneration potential of striated muscle in the hydrozoan jellyfish.

  13. In vivo functional and morphological characterization of bone and striated muscle microcirculation in NSG mice.

    Directory of Open Access Journals (Sweden)

    Haider Mussawy

    Full Text Available Organ-specific microcirculation plays a central role in tumor growth, tumor cell homing, tissue engineering, and wound healing. Mouse models are widely used to study these processes; however, these mouse strains often possess unique microhemodynamic parameters, making it difficult to directly compare experiments. The full functional characterization of bone and striated muscle microcirculatory parameters in non-obese diabetic-severe combined immunodeficiency/y-chain; NOD-Prkds IL2rg (NSG mice has not yet been reported. Here, we established either a dorsal skinfold chamber or femur window in NSG mice (n = 23, allowing direct analysis of microcirculatory parameters in vivo by intravital fluorescence microscopy at 7, 14, 21, and 28 days after chamber preparation. Organ-specific differences were observed. Bone had a significantly lower vessel density but a higher vessel diameter than striated muscle. Bone also showed higher effective vascular permeability than striated muscle. The centerline velocity values were similar in the femur window and dorsal skinfold chamber, with a higher volumetric blood flow in bone. Interestingly, bone and striated muscle showed similar tissue perfusion rates. Knowledge of physiological microhemodynamic values of bone and striated muscle in NSG mice makes it possible to analyze pathophysiological processes at these anatomic sites, such as tumor growth, tumor metastasis, and tumor microcirculation, as well as the response to therapeutic agents.

  14. VAPB/ALS8 MSP ligands regulate striated muscle energy metabolism critical for adult survival in caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Sung Min Han

    Full Text Available Mutations in VAPB/ALS8 are associated with amyotrophic lateral sclerosis (ALS and spinal muscular atrophy (SMA, two motor neuron diseases that often include alterations in energy metabolism. We have shown that C. elegans and Drosophila neurons secrete a cleavage product of VAPB, the N-terminal major sperm protein domain (vMSP. Secreted vMSPs signal through Roundabout and Lar-like receptors expressed on striated muscle. The muscle signaling pathway localizes mitochondria to myofilaments, alters their fission/fusion balance, and promotes energy production. Here, we show that neuronal loss of the C. elegans VAPB homolog triggers metabolic alterations that appear to compensate for muscle mitochondrial dysfunction. When vMSP levels drop, cytoskeletal or mitochondrial abnormalities in muscle induce elevated DAF-16, the Forkhead Box O (FoxO homolog, transcription factor activity. DAF-16 promotes muscle triacylglycerol accumulation, increases ATP levels in adults, and extends lifespan, despite reduced muscle mitochondria electron transport chain activity. Finally, Vapb knock-out mice exhibit abnormal muscular triacylglycerol levels and FoxO target gene transcriptional responses to fasting and refeeding. Our data indicate that impaired vMSP signaling to striated muscle alters FoxO activity, which affects energy metabolism. Abnormalities in energy metabolism of ALS patients may thus constitute a compensatory mechanism counterbalancing skeletal muscle mitochondrial dysfunction.

  15. Cannabinoid CB1 Receptors Are Localized in Striated Muscle Mitochondria and Regulate Mitochondrial Respiration

    Directory of Open Access Journals (Sweden)

    Juan Mendizabal-Zubiaga

    2016-10-01

    Full Text Available The cannabinoid type 1 (CB1 receptor is widely distributed in the brain and peripheral organs where it regulates cellular functions and metabolism. In the brain, CB1 is mainly localized on presynaptic axon terminals but is also found on mitochondria (mtCB1, where it regulates cellular respiration and energy production. Likewise, CB1 is localized on muscle mitochondria, but very little is known about it. The aim of this study was to further investigate in detail the distribution and functional role of mtCB1 in three different striated muscles. Immunoelectron microscopy for CB1 was used in skeletal muscles (gastrocnemius and rectus abdominis and myocardium from wild-type and CB1-KO mice. Functional assessments were performed in mitochondria purified from the heart of the mice and the mitochondrial oxygen consumption upon application of different acute delta-9-tetrahidrocannabinol (Δ9-THC concentrations (100 nM or 200 nM was monitored. About 26% of the mitochondrial profiles in gastrocnemius, 22% in the rectus abdominis and 17% in the myocardium expressed CB1. Furthermore, the proportion of mtCB1 versus total CB1 immunoparticles was about 60% in the gastrocnemius, 55% in the rectus abdominis and 78% in the myocardium. Importantly, the CB1 immunolabeling pattern disappeared in muscles of CB1-KO mice. Functionally, acute 100 nM or 200 nM THC treatment specifically decreased mitochondria coupled respiration between 12% and 15% in wild-type isolated mitochondria of myocardial muscles but no significant difference was noticed between THC treated and vehicle in mitochondria isolated from CB1-KO heart. Furthermore, gene expression of key enzymes involved in pyruvate synthesis, tricarboxylic acid (TCA cycle and mitochondrial respiratory chain was evaluated in the striated muscle of CB1-WT and CB1-KO. CB1-KO showed an increase in the gene expression of Eno3, Pkm2, and Pdha1, suggesting an increased production of pyruvate. In contrast, no significant

  16. Morphology of lesions in striated muscle fibres from the beige mouse

    DEFF Research Database (Denmark)

    Kirkeby, S

    1982-01-01

    Lesions in striated muscle fibres from the beige mouse are described at both the light- and electronmicroscopical levels. The muscles have two types of lesions, one is well defined cores in the fibres and the other is diffusely enlarged intermyofibrillar spaces (IMS). The cores can be filled...... with membrane-like structures or a fluffy unstructured material. In the areas with enlarged IMS comparatively few organelles are present and the muscle fibres seem to be fragmented....

  17. Esophageal striated muscle contractions in patients with Chagas' disease and idiopathic achalasia

    Directory of Open Access Journals (Sweden)

    R.O. Dantas

    2002-06-01

    Full Text Available Chagas' disease causes degeneration and reduction of the number of intrinsic neurons of the esophageal myenteric plexus, with consequent absent or partial lower esophageal sphincter relaxation and loss of peristalsis in the esophageal body. The impairment of esophageal motility is seen mainly in the distal smooth muscle region. There is no study about esophageal striated muscle contractions in the disease. In 81 patients with heartburn (44 with esophagitis taken as controls, 51 patients with Chagas' disease (21 with esophageal dilatation and 18 patients with idiopathic achalasia (11 with esophageal dilatation we studied the amplitude, duration and area under the curve of esophageal proximal contractions. Using the manometric method and a continuous perfusion system we measured the esophageal striated muscle contractions 2 to 3 cm below the upper esophageal sphincter after swallows of a 5-ml bolus of water. There was no significant difference in striated muscle contractions between patients with heartburn and esophagitis and patients with heartburn without esophagitis. There was also no significant difference between patients with heartburn younger or older than 50 years or between men and women or in esophageal striated muscle contractions between patients with heartburn and Chagas' disease. The esophageal proximal amplitude of contractions was lower in patients with idiopathic achalasia than in patients with heartburn. In patients with Chagas' disease there was no significant difference between patients with esophageal dilatation and patients with normal esophageal diameter. Esophageal striated muscle contractions in patients with Chagas' disease have the same amplitude and duration as seen in patients with heartburn. Patients with idiopathic achalasia have a lower amplitude of contraction than patients with heartburn.

  18. Striated Muscle as Implantation Site for Transplanted Pancreatic Islets

    Directory of Open Access Journals (Sweden)

    Daniel Espes

    2011-01-01

    Full Text Available Islet transplantation is an attractive treatment for selected patients with brittle type 1 diabetes. In the clinical setting, intraportal transplantation predominates. However, due to extensive early islet cell death, the quantity of islets needed to restore glucose homeostasis requires in general a minimum of two donors. Moreover, the deterioration of islet function over time results in few insulin-independent patients after five-year followup. Specific obstacles to the success of islet transplantation include site-specific concerns for the liver such as the instant blood mediated inflammatory reaction, islet lipotoxicity, low oxygen tension, and poor revascularization, impediments that have led to the developing interest for alternative implantation sites over recent years. Within preclinical settings, several alternative sites have now been investigated and proven favorable in various aspects. Muscle is considered a very promising site and has physiologically properties and technical advantages that could make it optimal for islet transplantation.

  19. The Popeye Domain Containing Genes and Their Function in Striated Muscle

    Science.gov (United States)

    Schindler, Roland F. R.; Scotton, Chiara; French, Vanessa; Ferlini, Alessandra; Brand, Thomas

    2016-01-01

    The Popeye domain containing (POPDC) genes encode a novel class of cAMP effector proteins, which are abundantly expressed in heart and skeletal muscle. Here, we will review their role in striated muscle as deduced from work in cell and animal models and the recent analysis of patients carrying a missense mutation in POPDC1. Evidence suggests that POPDC proteins control membrane trafficking of interacting proteins. Furthermore, we will discuss the current catalogue of established protein-protein interactions. In recent years, the number of POPDC-interacting proteins has been rising and currently includes ion channels (TREK-1), sarcolemma-associated proteins serving functions in mechanical stability (dystrophin), compartmentalization (caveolin 3), scaffolding (ZO-1), trafficking (NDRG4, VAMP2/3) and repair (dysferlin) or acting as a guanine nucleotide exchange factor for Rho-family GTPases (GEFT). Recent evidence suggests that POPDC proteins might also control the cellular level of the nuclear proto-oncoprotein c-Myc. These data suggest that this family of cAMP-binding proteins probably serves multiple roles in striated muscle. PMID:27347491

  20. Application of 31P-NMR spectroscopy to the study of striated muscle metabolism

    International Nuclear Information System (INIS)

    Meyer, R.A.; Kushmerick, M.J.; Brown, T.R.

    1982-01-01

    This review presents the principles and limitations of phosphorus nuclear magnetic resonance ( 31 P-NMR) spectroscopy as applied to the study of striated muscle metabolism. Application of the techniques discussed include noninvasive measurement of high-energy phosphate, intracellular pH, intracellular free Mg 2+ , and metabolite compartmentation. In perfused cat biceps (fast-twitch) muscles, but not in soleus (slow-twitch), NMR spectra indicate a substantially lower (1 mM) free inorganic phosphate level than when measured chemically (6 mM). In addition, saturation and inversion spin-transfer methods that enable direct measurement of the unidirectional fluxes through creatine kinase are described. In perfused cat biceps muscle, results suggest that this enzyme and its substrates are in simple chemical equilibrium

  1. Architecture of vagal motor units controlling striated muscle of esophagus: peripheral elements patterning peristalsis?

    Science.gov (United States)

    Powley, Terry L; Mittal, Ravinder K; Baronowsky, Elizabeth A; Hudson, Cherie N; Martin, Felecia N; McAdams, Jennifer L; Mason, Jacqueline K; Phillips, Robert J

    2013-12-01

    Little is known about the architecture of the vagal motor units that control esophageal striated muscle, in spite of the fact that these units are necessary, and responsible, for peristalsis. The present experiment was designed to characterize the motor neuron projection fields and terminal arbors forming esophageal motor units. Nucleus ambiguus compact formation neurons of the rat were labeled by bilateral intracranial injections of the anterograde tracer dextran biotin. After tracer transport, thoracic and abdominal esophagi were removed and prepared as whole mounts of muscle wall without mucosa or submucosa. Labeled terminal arbors of individual vagal motor neurons (n=78) in the esophageal wall were inventoried, digitized and analyzed morphometrically. The size of individual vagal motor units innervating striated muscle, throughout thoracic and abdominal esophagus, averaged 52 endplates per motor neuron, a value indicative of fine motor control. A majority (77%) of the motor terminal arbors also issued one or more collateral branches that contacted neurons, including nitric oxide synthase-positive neurons, of local myenteric ganglia. Individual motor neuron terminal arbors co-innervated, or supplied endplates in tandem to, both longitudinal and circular muscle fibers in roughly similar proportions (i.e., two endplates to longitudinal for every three endplates to circular fibers). Both the observation that vagal motor unit collaterals project to myenteric ganglia and the fact that individual motor units co-innervate longitudinal and circular muscle layers are consistent with the hypothesis that elements contributing to peristaltic programming inhere, or are "hardwired," in the peripheral architecture of esophageal motor units. © 2013.

  2. Revealing t-tubules in striated muscle with new optical super-resolution microscopy techniques

    Directory of Open Access Journals (Sweden)

    Isuru D. Jayasinghe

    2014-12-01

    Full Text Available The t-tubular system plays a central role in the synchronisation of calcium signalling and excitation-contraction coupling in most striated muscle cells. Light microscopy has been used for imaging t-tubules for well over 100 years and together with electron microscopy (EM, has revealed the three-dimensional complexities of the t-system topology within cardiomyocytes and skeletal muscle fibres from a range of species. The emerging super-resolution single molecule localisation microscopy (SMLM techniques are offering a near 10-fold improvement over the resolution of conventional fluorescence light microscopy methods, with the ability to spectrally resolve nanometre scale distributions of multiple molecular targets. In conjunction with the next generation of electron microscopy, SMLM has allowed the visualisation and quantification of intricate t-tubule morphologies within large areas of muscle cells at an unprecedented level of detail. In this paper, we review recent advancements in the t-tubule structural biology with the utility of various microscopy techniques. We outline the technical considerations in adapting SMLM to study t-tubules and its potential to further our understanding of the molecular processes that underlie the sub-micron scale structural alterations observed in a range of muscle pathologies.

  3. Chaperones and the Proteasome System: Regulating the Construction and Demolition of Striated Muscle

    Directory of Open Access Journals (Sweden)

    Casey Carlisle

    2017-12-01

    Full Text Available Protein folding factors (chaperones are required for many diverse cellular functions. In striated muscle, chaperones are required for contractile protein function, as well as the larger scale assembly of the basic unit of muscle, the sarcomere. The sarcomere is complex and composed of hundreds of proteins and the number of proteins and processes recognized to be regulated by chaperones has increased dramatically over the past decade. Research in the past ten years has begun to discover and characterize the chaperones involved in the assembly of the sarcomere at a rapid rate. Because of the dynamic nature of muscle, wear and tear damage is inevitable. Several systems, including chaperones and the ubiquitin proteasome system (UPS, have evolved to regulate protein turnover. Much of our knowledge of muscle development focuses on the formation of the sarcomere but recent work has begun to elucidate the requirement and role of chaperones and the UPS in sarcomere maintenance and disease. This review will cover the roles of chaperones in sarcomere assembly, the importance of chaperone homeostasis and the cooperation of chaperones and the UPS in sarcomere integrity and disease.

  4. The Intriguing Dual Lattices of the Myosin Filaments in Vertebrate Striated Muscles: Evolution and Advantage

    Directory of Open Access Journals (Sweden)

    Pradeep K. Luther

    2014-12-01

    Full Text Available Myosin filaments in vertebrate striated muscle have a long roughly cylindrical backbone with cross-bridge projections on the surfaces of both halves except for a short central bare zone. In the middle of this central region the filaments are cross-linked by the M-band which holds them in a well-defined hexagonal lattice in the muscle A-band. During muscular contraction the M-band-defined rotation of the myosin filaments around their long axes influences the interactions that the cross-bridges can make with the neighbouring actin filaments. We can visualise this filament rotation by electron microscopy of thin cross-sections in the bare-region immediately adjacent to the M-band where the filament profiles are distinctly triangular. In the muscles of teleost fishes, the thick filament triangular profiles have a single orientation giving what we call the simple lattice. In other vertebrates, for example all the tetrapods, the thick filaments have one of two orientations where the triangles point in opposite directions (they are rotated by 60° or 180° according to set rules. Such a distribution cannot be developed in an ordered fashion across a large 2D lattice, but there are small domains of superlattice such that the next-nearest neighbouring thick filaments often have the same orientation. We believe that this difference in the lattice forms can lead to different contractile behaviours. Here we provide a historical review, and when appropriate cite recent work related to the emergence of the simple and superlattice forms by examining the muscles of several species ranging back to primitive vertebrates and we discuss the functional differences that the two lattice forms may have.

  5. (−)-EPICATECHIN IMPROVES MITOCHONDRIAL RELATED PROTEIN LEVELS AND AMELIORATES OXIDATIVE STRESS IN DYSTROPHIC DELTA SARCOGLYCAN NULL MOUSE STRIATED MUSCLE

    Science.gov (United States)

    Ramirez-Sanchez, Israel; De los Santos, Sergio; Gonzalez-Basurto, Silvia; Canto, Patricia; Mendoza-Lorenzo, Patricia; Palma-Flores, Carlos; Ceballos-Reyes, Guillermo; Villarreal, Francisco; Zentella-Dehesa, Alejandro; Coral-Vazquez, Ramon

    2014-01-01

    Muscular dystrophies (MD) are a group of heterogeneous genetic disorders characterized by progressive striated muscle wasting and degeneration. Although the genetic basis for many of these disorders has been identified, the exact mechanism for disease pathogenesis remains unclear. The presence of oxidative stress (OS) is known to contribute to the pathophysiology and severity of the MD. Mitochondrial dysfunction is observed in MD and likely represents an important determinant of increased OS. Experimental antioxidant therapies have been implemented with the aim of protecting against disease progression, but results from clinical trials have been disappointing. In this study, we explored the capacity of the cacao flavonoid (−)-epicatechin (Epi) to mitigate OS by acting as a positive regulator of mitochondrial structure/function endpoints and redox balance control systems in skeletal and cardiac muscles of dystrophic, δ-sarcoglycan (δ-SG) null mice. Wild type or δ-SG null 2.5 month old male mice were treated via oral gavage with either water (control animals) or Epi (1 mg/kg, twice/day) for 2 weeks. Results evidence a significant normalization of total protein carbonylation, recovery of reduced/oxidized glutathione (GSH/GSSG ratio) and enhanced superoxide dismutase 2, catalase and citrate synthase activities with Epi treatment. These effects were accompanied by increases in protein levels for thiolredoxin, glutathione peroxidase, superoxide dismutase 2, catalase and mitochondrial endpoints. Furthermore, we evidence decreases in heart and skeletal muscle fibrosis, accompanied with an improvement in skeletal muscle function with treatment. These results warrant the further investigation of Epi as a potential therapeutic agent to mitigate MD associated muscle degeneration. PMID:25284161

  6. The ‘Goldilocks Zone’ from a redox perspective - Adaptive versus deleterious responses to oxidative stress in striated muscle

    Directory of Open Access Journals (Sweden)

    Rick J Alleman

    2014-09-01

    Full Text Available Consequences of oxidative stress may be beneficial or detrimental in physiological systems. An organ system’s position on the ‘hormetic curve’ is governed by the source and temporality of reactive oxygen species (ROS production, proximity of ROS to moieties most susceptible to damage, and the capacity of the endogenous cellular ROS scavenging mechanisms. Most importantly, the resilience of the tissue (the capacity to recover from damage is a decisive factor, and this is reflected in the disparate response to ROS in cardiac and skeletal muscle. In myocytes, a high oxidative capacity invariably results in a significant ROS burden which in homeostasis, is rapidly neutralized by the robust antioxidant network. The up-regulation of key pathways in the antioxidant network is a central component of the hormetic response to ROS. Despite such adaptations, persistent oxidative stress over an extended time-frame (e.g. months to years inevitably leads to cumulative damages, maladaptation and ultimately the pathogenesis of chronic diseases. Indeed, persistent oxidative stress in heart and skeletal muscle has been repeatedly demonstrated to have causal roles in the etiology of heart disease and insulin resistance, respectively. Deciphering the mechanisms that underlie the divergence between adaptive and maladaptive responses to oxidative stress remains an active area of research for basic scientists and clinicians alike, as this would undoubtedly lead to novel therapeutic approaches. Here, we provide an overview of major types of ROS in striated muscle and the divergent adaptations that occur in response to them. Emphasis is placed on highlighting newly uncovered areas of research on this topic, with particular focus on the mitochondria, and the diverging roles that ROS play in muscle health (e.g., exercise or preconditioning and disease (e.g., cardiomyopathy, ischemia, metabolic syndrome.

  7. Increased hypoxia-inducible factor-1α in striated muscle of tumor-bearing mice.

    Science.gov (United States)

    Devine, Raymond D; Bicer, Sabahattin; Reiser, Peter J; Wold, Loren E

    2017-06-01

    that occur during cancer cachexia. NEW & NOTEWORTHY We used proteomics and metadata analysis software to identify contributors to metabolic changes in striated muscle during cancer cachexia. We found increased expression of hypoxia-inducible factor-1α in the heart and skeletal muscle, suggesting a potential target for the therapeutic treatment of cancer cachexia. Copyright © 2017 the American Physiological Society.

  8. Contracture Coupling of Slow Striated Muscle in Non-Ionic Solutions and Replacement of Calcium, Sodium, and Potassium

    Science.gov (United States)

    Irwin, Richard L.; Hein, Manfred M.

    1964-01-01

    The development of contracture related to changes of ionic environment (ionic contracture coupling) has been studied in the slowly responding fibers of frog skeletal muscle. When deprived of external ions for 30 minutes by use of solutions of sucrose, mannitol, or glucose, the slow skeletal muscle fibers, but not the fast, develop pronounced and easily reversible contractures. Partial replacement of the non-ionic substance with calcium or sodium reduces the development of the contractures but replacement by potassium does not. The concentration of calcium necessary to prevent contracture induced by a non-ionic solution is greater than that needed to maintain relaxation in ionic solutions. To suppress the non-ionic-induced contractures to the same extent as does calcium requires several fold higher concentrations of sodium. Two types of ionic contracture coupling occur in slow type striated muscle fibers: (a) a calcium deprivation type which develops maximally at full physiological concentration of external sodium, shows a flow rate dependency for the calcium-depriving fluid, and is lessened when the sodium concentration is decreased by replacement with sucrose; (b) a sodium deprivation type which occurs maximally without external sodium, is lessened by increasing the sodium concentration, and has no flow rate dependency for ion deprivation. Both types of contracture are largely prevented by the presence of sufficient calcium. There thus seem to be calcium- and sodium-linked processes at work in the ionic contracture coupling of slow striated muscle. PMID:14127603

  9. Impact of a nickel-reduced stainless steel implant on striated muscle microcirculation: a comparative in vivo study.

    Science.gov (United States)

    Kraft, C N; Burian, B; Perlick, L; Wimmer, M A; Wallny, T; Schmitt, O; Diedrich, O

    2001-12-05

    The impairment of skeletal muscle microcirculation by a biomaterial may have profound consequences. With moderately good physical and corrosion characteristics, implant-quality stainless steel is particularly popular in orthopedic surgery. However, due to the presence of a considerable amount of nickel in the alloy, concern has been voiced in respect to local tissue responses. More recently a stainless steel alloy with a significant reduction of nickel has become commercially available. We, therefore, studied in vivo nutritive perfusion and leukocytic response of striated muscle to this nickel-reduced alloy, and compared these results with those of the materials conventional stainless steel and titanium. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, we could demonstrate that reduction of the nickel quantity in a stainless steel implant has a positive effect on local microvascular parameters. Although the implantation of a conventional stainless steel sample led to a distinct and persistent activation of leukocytes combined with disruption of the microvascular endothelial integrity, marked leukocyte extravasation, and considerable venular dilation, animals with a nickel-reduced stainless steel implant showed only a moderate increase of these parameters, with a clear tendency of recuperation. Titanium implants merely caused a transient increase of leukocyte-endothelial cell interaction within the first 120 min, and no significant change in macromolecular leakage, leukocyte extravasation, or venular diameter. Pending biomechanical and corrosion testing, nickel-reduced stainless steel may be a viable alternative to conventional implant-quality stainless steel for biomedical applications. Concerning tolerance by the local vascular system, titanium currently remains unsurpassed. Copyright 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 404-412, 2001

  10. Contrasting effects of strabismic amblyopia on metabolic activity in superficial and deep layers of striate cortex.

    Science.gov (United States)

    Adams, Daniel L; Economides, John R; Horton, Jonathan C

    2015-05-01

    To probe the mechanism of visual suppression, we have raised macaques with strabismus by disinserting the medial rectus muscle in each eye at 1 mo of age. Typically, this operation produces a comitant, alternating exotropia with normal acuity in each eye. Here we describe an unusual occurrence: the development of severe amblyopia in one eye of a monkey after induction of exotropia. Shortly after surgery, the animal demonstrated a strong fixation preference for the left eye, with apparent suppression of the right eye. Later, behavioral testing showed inability to track or to saccade to targets with the right eye. With the left eye occluded, the animal demonstrated no visually guided behavior. Optokinetic nystagmus was absent in the right eye. Metabolic activity in striate cortex was assessed by processing the tissue for cytochrome oxidase (CO). Amblyopia caused loss of CO in one eye's rows of patches, presumably those serving the blind eye. Layers 4A and 4B showed columns of reduced CO, in register with pale rows of patches in layer 2/3. Layers 4C, 5, and 6 also showed columns of CO activity, but remarkably, comparison with more superficial layers showed a reversal in contrast. In other words, pale CO staining in layers 2/3, 4A, and 4B was aligned with dark CO staining in layers 4C, 5, and 6. No experimental intervention or deprivation paradigm has been reported previously to produce opposite effects on metabolic activity in layers 2/3, 4A, and 4B vs. layers 4C, 5, and 6 within a given eye's columns. Copyright © 2015 the American Physiological Society.

  11. Metabolic activity in striate and extrastriate cortex in the hooded rat: contralateral and ipsilateral eye input

    International Nuclear Information System (INIS)

    Thurlow, G.A.; Cooper, R.M.

    1988-01-01

    The extent of changes in glucose metabolism resulting from ipsilateral and contralateral eye activity in the posterior cortex of the hooded rat was demonstrated by means of the C-14 2-deoxyglucose autoradiographic technique. By stimulating one eye with square wave gratings and eliminating efferent activation from the other by means of enucleation or intraocular TTX injection, differences between ipsilaterally and contralaterally based visual activity in the two hemispheres were maximized. Carbon-14 levels in layer IV of autoradiographs of coronal sections were measured and combined across sections to form right and left matrices of posterior cortex metabolic activity. A difference matrix, formed by subtracting the metabolic activity matrix of cortex contralateral to the stimulated eye from the ipsilateral depressed matrix, emphasized those parts of the visual cortex that received monocular visual input. The demarcation of striate cortex by means of cholinesterase stain and the examination of autoradiographs from sections cut tangential to the cortical surface aided in the interpretation of the difference matrices. In striate cortex, differences were maximal in the medial monocular portion, and the lateral or binocular portion was shown to be divided metabolically into a far lateral contralaterally dominant strip along the cortical representation of the vertical meridian, and a more medial region of patches of more or less contralaterally dominant binocular input. Lateral peristriate differences were less than those of striate cortex, and regions of greater and lesser monocular input could be distinguished. We did not detect differences between the two hemispheres in either anterior or medial peristriate areas

  12. Healthy and diseased striated muscle studied by analytical scanning electron microscopy with special reference to fibre type

    International Nuclear Information System (INIS)

    Wroblewski, R.

    1982-01-01

    X-ray microanalytical investigations of striated muscles in the scanning electron microscope are reviewed. The main part of the studies was performed on cryosections cut with a conventional cryostat operating at -20 degrees C to -40 degrees C. The preparation procedure including different types of attachment of the sections to the specimen holder is described in detail. The elemental changes in muscle are related to the muscle fibre type as demonstrated by histochemical methods or to histochemically demonstrated inclusions in diseased muscles. This is of great importance, because muscle disorders are often characterised by selective involvement of different muscle fibre types. The preparation methods of muscle for analytical scanning electron microscopy and the obtained results are compared with studies performed on thin cryo and epoxy sections, analysed in the transmission and scanning-transmission electron microscope. It is evident that X-ray microanalysis performed on thick cryosections provide a quick survey of the elemental composition of whole cells, and should be followed in interesting cases by close examination on the organelle level studied in thin cryosections in the transmission and scanning-transmission electron microscope

  13. Myostatin, a profibrotic factor and the main inhibitor of striated muscle mass, is present in the penile and vascular smooth muscle.

    Science.gov (United States)

    Kovanecz, I; Masouminia, M; Gelfand, R; Vernet, D; Rajfer, J; Gonzalez-Cadavid, N F

    2017-09-01

    Myostatin is present in striated myofibers but, except for myometrial cells, has not been reported within smooth muscle cells (SMC). We investigated in the rat whether myostatin is present in SMC within the penis and the vascular wall and, if so, whether it is transcriptionally expressed and associated with the loss of corporal SMC occurring in certain forms of erectile dysfunction (ED). Myostatin protein was detected by immunohistochemistry/fluorescence and western blots in the perineal striated muscles, and also in the SMC of the penile corpora, arteries and veins, and aorta. Myostatin was found in corporal SMC cultures, and its transcriptional expression (and its receptor) was shown there by DNA microarrays. Myostatin protein was measured by western blots in the penile shaft of rats subjected to bilateral cavernosal nerve resection (BCNR), that were left untreated, or treated (45 days) with muscle-derived stem cells (MDSC), or concurrent daily low-dose sildenafil. Myostatin was not increased by BCNR (compared with sham operated animals), but over expressed after treatment with MDSC. This was reduced by concurrent sildenafil. The presence of myostatin in corporal and vascular SMC, and its overexpression in the corpora by MDSC therapy, may have relevance for the stem cell treatment of corporal fibrosis and ED.

  14. A novel conserved isoform of the ubiquitin ligase UFD2a/UBE4B is expressed exclusively in mature striated muscle cells.

    Directory of Open Access Journals (Sweden)

    Andrew L Mammen

    Full Text Available Yeast Ufd2p was the first identified E4 multiubiquitin chain assembly factor. Its vertebrate homologues later referred to as UFD2a, UBE4B or E4B were also shown to have E3 ubiquitin ligase activity. UFD2a function in the brain has been well established in vivo, and in vitro studies have shown that its activity is essential for proper condensation and segregation of chromosomes during mitosis. Here we show that 2 alternative splice forms of UFD2a, UFD2a-7 and -7/7a, are expressed sequentially during myoblast differentiation of C2C12 cell cultures and during cardiotoxin-induced regeneration of skeletal muscle in mice. UFD2a-7 contains an alternate exon 7, and UFD2a-7/7a, the larger of the 2 isoforms, contains an additional novel exon 7a. Analysis of protein or mRNA expression in mice and zebrafish revealed that a similar pattern of isoform switching occurs during developmental myogenesis of cardiac and skeletal muscle. In vertebrates (humans, rodents, zebrafish, UFD2a-7/7a is expressed only in mature striated muscle. This unique tissue specificity is further validated by the conserved presence of 2 muscle-specific splicing regulatory motifs located in the 3' introns of exons 7 and 7a. UFD2a interacts with VCP/p97, an AAA-type ATPase implicated in processes whose functions appear to be regulated, in part, through their interaction with one or more of 15 previously identified cofactors. UFD2a-7/7a did not interact with VCP/p97 in yeast 2-hybrid experiments, which may allow the ATPase to bind cofactors that facilitate its muscle-specific functions. We conclude that the regulated expression of these UFD2a isoforms most likely imparts divergent functions that are important for myogenisis.

  15. The giant protein titin regulates the length of the striated muscle thick filament.

    Science.gov (United States)

    Tonino, Paola; Kiss, Balazs; Strom, Josh; Methawasin, Mei; Smith, John E; Kolb, Justin; Labeit, Siegfried; Granzier, Henk

    2017-10-19

    The contractile machinery of heart and skeletal muscles has as an essential component the thick filament, comprised of the molecular motor myosin. The thick filament is of a precisely controlled length, defining thereby the force level that muscles generate and how this force varies with muscle length. It has been speculated that the mechanism by which thick filament length is controlled involves the giant protein titin, but no conclusive support for this hypothesis exists. Here we show that in a mouse model in which we deleted two of titin's C-zone super-repeats, thick filament length is reduced in cardiac and skeletal muscles. In addition, functional studies reveal reduced force generation and a dilated cardiomyopathy (DCM) phenotype. Thus, regulation of thick filament length depends on titin and is critical for maintaining muscle health.

  16. Striated muscle fiber size, composition and capillary density in diabetes in relation to neuropathy and muscle strength

    DEFF Research Database (Denmark)

    Andreassen, Christer Swan; Jensen, Jacob Malte; Jakobsen, Johannes

    2014-01-01

    study was to evaluate histologic properties and capillarization of diabetic skeletal muscle in relation to DPN and muscle strength. METHODS: Twenty type 1 and 20 type 2 diabetic (T1D and T2D, respectively) patients underwent biopsy of the gastrocnemic muscle, isokinetic dynamometry at the ankle...... between muscle fiber diameter, muscle fiber type distribution, or capillary density and degree of neuropathy or muscle strength for either patient group. Muscle fiber diameter and the proportion of Type II fibers were greater for T1D patients than both T2D patients and controls. The T2D patients had fewer...

  17. Esterases in striated muscle from mice with the Chediak-Higashi syndrome

    DEFF Research Database (Denmark)

    Kirkeby, S; Moe, D

    1981-01-01

    In this paper a localized strong reaction for non-specific esterase forming cylindric structures is described within skeletal muscle fibres from the beige mouse. It seems from zymograms and protein electrophoresis that this esterase is membrane bound, highly reactive and present in rather small...

  18. New kids on the block: The Popeye domain containing (POPDC) protein family acting as a novel class of cAMP effector proteins in striated muscle.

    Science.gov (United States)

    Brand, Thomas; Schindler, Roland

    2017-12-01

    The cyclic 3',5'-adenosine monophosphate (cAMP) signalling pathway constitutes an ancient signal transduction pathway present in prokaryotes and eukaryotes. Previously, it was thought that in eukaryotes three effector proteins mediate cAMP signalling, namely protein kinase A (PKA), exchange factor directly activated by cAMP (EPAC) and the cyclic-nucleotide gated channels. However, recently a novel family of cAMP effector proteins emerged and was termed the Popeye domain containing (POPDC) family, which consists of three members POPDC1, POPDC2 and POPDC3. POPDC proteins are transmembrane proteins, which are abundantly present in striated and smooth muscle cells. POPDC proteins bind cAMP with high affinity comparable to PKA. Presently, their biochemical activity is poorly understood. However, mutational analysis in animal models as well as the disease phenotype observed in patients carrying missense mutations suggests that POPDC proteins are acting by modulating membrane trafficking of interacting proteins. In this review, we will describe the current knowledge about this gene family and also outline the apparent gaps in our understanding of their role in cAMP signalling and beyond. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Seasonal changes in isoform composition of giant proteins of thick and thin filaments and titin (connectin) phosphorylation level in striated muscles of bears (Ursidae, Mammalia).

    Science.gov (United States)

    Salmov, N N; Vikhlyantsev, I M; Ulanova, A D; Gritsyna, Yu V; Bobylev, A G; Saveljev, A P; Makariushchenko, V V; Maksudov, G Yu; Podlubnaya, Z A

    2015-03-01

    Seasonal changes in the isoform composition of thick and thin filament proteins (titin, myosin heavy chains (MyHCs), nebulin), as well as in the phosphorylation level of titin in striated muscles of brown bear (Ursus arctos) and hibernating Himalayan black bear (Ursus thibetanus ussuricus) were studied. We found that the changes that lead to skeletal muscle atrophy in bears during hibernation are not accompanied by a decrease in the content of nebulin and intact titin-1 (T1) isoforms. However, a decrease (2.1-3.4-fold) in the content of T2 fragments of titin was observed in bear skeletal muscles (m. gastrocnemius, m. longissimus dorsi, m. biceps) during hibernation. The content of the stiffer N2B titin isoform was observed to increase relative to the content of its more compliant N2BA isoform in the left ventricles of hibernating bears. At the same time, in spite of the absence of decrease in the total content of T1 in the myocardium of hibernating brown bear, the content of T2 fragments decreased ~1.6-fold. The level of titin phosphorylation only slightly increased in the cardiac muscle of hibernating brown bear. In the skeletal muscles of brown bear, the level of titin phosphorylation did not vary between seasons. However, changes in the composition of MyHCs aimed at increasing the content of slow (I) and decreasing the content of fast (IIa) isoforms of this protein during hibernation of brown bear were detected. Content of MyHCs I and IIa in the skeletal muscles of hibernating Himalayan black bear corresponded to that in the skeletal muscles of hibernating brown bear.

  20. Microvascular response of striated muscle to metal debris. A comparative in vivo study with titanium and stainless steel.

    Science.gov (United States)

    Kraft, C N; Diedrich, O; Burian, B; Schmitt, O; Wimmer, M A

    2003-01-01

    Wear products of metal implants are known to induce biological events which may have profound consequences for the microcirculation of skeletal muscle. Using the skinfold chamber model and intravital microscopy we assessed microcirculatory parameters in skeletal muscle after confrontation with titanium and stainless-steel wear debris, comparing the results with those of bulk materials. Implantation of stainless-steel bulk and debris led to a distinct activation of leukocytes combined with a disruption of the microvascular endothelial integrity and massive leukocyte extravasation. While animals with bulk stainless steel showed a tendency to recuperation, stainless-steel wear debris induced such severe inflammation and massive oedema that the microcirculation broke down within 24 hours after implantation. Titanium bulk caused only a transient increase in leukocyte-endothelial cell interaction within the first 120 minutes and no significant change in macromolecular leakage, leukocyte extravasation or venular diameter. Titanium wear debris produced a markedly lower inflammatory reaction than stainless-steel bulk, indicating that a general benefit of bulk versus debris could not be claimed. Depending on its constituents, wear debris is capable of eliciting acute inflammation which may result in endothelial damage and subsequent failure of microperfusion. Our results indicate that not only the bulk properties of orthopaedic implants but also the microcirculatory implications of inevitable wear debris play a pivotal role in determining the biocompatibility of an implant.

  1. [Post-traumatic reconnection of the cervical spinal cord with skeletal striated muscles. Study in adult rats and marmosets].

    Science.gov (United States)

    Horvat, J C; Affane-Boulaid, F; Baillet-Derbin, C; Davarpanah, Y; Destombes, J; Duchossoy, Y; Emery, E; Kassar-Duchossoy, L; Mira, J C; Moissonnier, P; Pécot-Dechavassine, M; Reviron, T; Rhrich-Haddout, F; Tadié, M; Ye, J H

    1997-01-01

    In an attempt at repairing the injured spinal cord of adult mammals (rat, dog and marmoset) and its damaged muscular connections, we are currently using: 1) peripheral nerve autografts (PNG), containing Schwann cells, to trigger and direct axonal regrowth from host and/or transplanted motoneurons towards denervated muscular targets; 2) foetal spinal cord transplants to replace lost neurons. In adult rats and marmosets, a PNG bridge was used to joint the injured cervical spinal cord to a denervated skeletal muscle (longissimus atlantis [rat] or biceps brachii [rat and marmoset]). The spinal lesion was obtained by the implantation procedure of the PNG. After a post-operative delay ranging from 2 to 22 months, the animals were checked electrophysiologically for functional muscular reconnection and processed for a morphological study including retrograde axonal tracing (HRP, Fast Blue, True Blue), histochemistry (AChE, ATPase), immunocytochemistry (ChAT) and EM. It was thus demonstrated that host motoneurons of the cervical enlargement could extend axons all the way through the PNG bridge as: a) in anaesthetized animals, contraction of the reconnected muscle could be obtained by electrical stimulation of the grafted nerve; b) the retrograde axonal tracing studies indicated that a great number of host cervical neurons extended axons into the PNG bridge up to the muscle; c) many of them were assumed to be motoneurons (double labelling with True Blue and an antibody against ChAT); and even alpha-motoneurons (type C axosomatic synapses in HRP labelled neurons seen in EM in the rat); d) numerous ectopic endplates were seen around the intramuscular tip of the PNG. In larger (cavitation) spinal lesions (rat), foetal motoneurons contained in E14 spinal cord transplants could similarly grow axons through PNG bridges up to the reconnected muscle. Taking all these data into account, it can be concluded that neural transplants are interesting tools for evaluating both the

  2. Multi-tasking role of the mechanosensing protein Ankrd2 in the signaling network of striated muscle.

    Directory of Open Access Journals (Sweden)

    Anna Belgrano

    Full Text Available Ankrd2 (also known as Arpp together with Ankrd1/CARP and DARP are members of the MARP mechanosensing proteins that form a complex with titin (N2A/calpain 3 protease/myopalladin. In muscle, Ankrd2 is located in the I-band of the sarcomere and moves to the nucleus of adjacent myofibers on muscle injury. In myoblasts it is predominantly in the nucleus and on differentiation shifts from the nucleus to the cytoplasm. In agreement with its role as a sensor it interacts both with sarcomeric proteins and transcription factors.Expression profiling of endogenous Ankrd2 silenced in human myotubes was undertaken to elucidate its role as an intermediary in cell signaling pathways. Silencing Ankrd2 expression altered the expression of genes involved in both intercellular communication (cytokine-cytokine receptor interaction, endocytosis, focal adhesion, tight junction, gap junction and regulation of the actin cytoskeleton and intracellular communication (calcium, insulin, MAPK, p53, TGF-β and Wnt signaling. The significance of Ankrd2 in cell signaling was strengthened by the fact that we were able to show for the first time that Nkx2.5 and p53 are upstream effectors of the Ankrd2 gene and that Ankrd1/CARP, another MARP member, can modulate the transcriptional ability of MyoD on the Ankrd2 promoter. Another novel finding was the interaction between Ankrd2 and proteins with PDZ and SH3 domains, further supporting its role in signaling. It is noteworthy that we demonstrated that transcription factors PAX6, LHX2, NFIL3 and MECP2, were able to bind both the Ankrd2 protein and its promoter indicating the presence of a regulatory feedback loop mechanism.In conclusion we demonstrate that Ankrd2 is a potent regulator in muscle cells affecting a multitude of pathways and processes.

  3. Methylmercury intoxication and histochemical demonstration of NADPH-diaphorase activity in the striate cortex of adult cats

    Directory of Open Access Journals (Sweden)

    R.B. Oliveira

    1998-09-01

    Full Text Available The effects of methylmercury (MeHg on histochemical demonstration of the NADPH-diaphorase (NADPH-d activity in the striate cortex were studied in 4 adult cats. Two animals were used as control. The contaminated animals received 50 ml milk containing 0.42 µg MeHg and 100 g fish containing 0.03 µg MeHg daily for 2 months. The level of MeHg in area 17 of intoxicated animals was 3.2 µg/g wet weight brain tissue. Two cats were perfused 24 h after the last dose (group 1 and the other animals were perfused 6 months later (group 2. After microtomy, sections were processed for NADPHd histochemistry procedures using the malic enzyme method. Dendritic branch counts were performed from camera lucida drawings for control and intoxicated animals (N = 80. Average, standard deviation and Student t-test were calculated for each data group. The concentrations of mercury (Hg in milk, fish and brain tissue were measured by acid digestion of samples, followed by reduction of total Hg in the digested sample to metallic Hg using stannous chloride followed by atomic fluorescence analysis. Only group 2 revealed a reduction of the neuropil enzyme activity and morphometric analysis showed a reduction in dendritic field area and in the number of distal dendrite branches of the NADPHd neurons in the white matter (P<0.05. These results suggest that NADPHd neurons in the white matter are more vulnerable to the long-term effects of MeHg than NADPHd neurons in the gray matter.

  4. Suppression of metabolic activity caused by infantile strabismus and strabismic amblyopia in striate visual cortex of macaque monkeys.

    Science.gov (United States)

    Wong, Agnes M F; Burkhalter, Andreas; Tychsen, Lawrence

    2005-02-01

    Suppression is a major sensorial abnormality in humans and monkeys with infantile strabismus. We previously reported evidence of metabolic suppression in the visual cortex of strabismic macaques, using the mitochondrial enzyme cytochrome oxidase as an anatomic label. The purpose of this study was to further elucidate alterations in cortical metabolic activity, with or without amblyopia. Six macaque monkeys were used in the experiments (four strabismic and two control). Three of the strabismic monkeys had naturally occurring, infantile strabismus (two esotropic, one exotropic). The fourth strabismic monkey had infantile microesotropia induced by alternating monocular occlusion in the first months of life. Ocular motor behaviors and visual acuity were tested after infancy in each animal, and development of stereopsis was recorded during infancy in one strabismic and one control monkey. Ocular dominance columns (ODCs) of the striate visual cortex (area V1) were labeled using cytochrome oxidase (CO) histochemistry alone, or CO in conjunction with an anterograde tracer ([H 3 ]proline or WGA-HRP) injected into one eye. Each of the strabismic monkeys showed inequalities of metabolic activity in ODCs of opposite ocularity, visible as rows of lighter CO staining, corresponding to ODCs of lower metabolic activity, alternating with rows of darker CO staining, corresponding to ODCs of higher metabolic activity. In monkeys who had infantile strabismus and unilateral amblyopia, lower metabolic activity was found in (suppressed) ODCs driven by the nondominant eye in each hemisphere. In monkeys who had infantile esotropia and alternating fixation (no amblyopia), metabolic activity was lower in ODCs driven by the ipsilateral eye in each hemisphere. The suppression included a monocular core zone at the center of ODCs and binocular border zones at the boundaries of ODCs. This suppression was not evident in the monocular lamina of the LGN, indicating an intracortical rather than

  5. Striated muscle microvascular response to silver implants: A comparative in vivo study with titanium and stainless steel.

    Science.gov (United States)

    Kraft, C N; Hansis, M; Arens, S; Menger, M D; Vollmar, B

    2000-02-01

    Local microvascular perfusion is the primary line of defense of tissue against microorganisms and plays a considerable role in reparative processes. The impairment of the microcirculation by a biomaterial may therefore have profound consequences. Silver is known to have excellent antimicrobial activity and, although regional and systemic toxic effects have been described, silver is regularly discussed as an implant material in bone surgery. Because little is known about the influence of silver implants on the adjacent host tissue microvasculature, we studied in vivo nutritive perfusion and leukocytic response, and compared these results with those of the conventionally used materials titanium and stainless steel. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, the implantation of a commercially pure silver sample led to a distinct and persistent activation of leukocytes combined with a marked disruption of the microvascular endothelial integrity, massive leukocyte extravasation, and considerable venular dilation. Whereas animals with stainless-steel implants showed a moderate increase in these parameters with a tendency to recuperate, titanium implants caused only a transient increase of leukocyte-endothelial cell interaction within the first 120 min and no significant change in macromolecular leakage, leukocyte extravasation and venular diameter. After 3 days, five of six preparations with silver samples showed severe inflammation and massive edema. Thus, the use of silver as an implant material should be critically judged despite its bactericidal properties. The implant material titanium seems to be well tolerated by the local vascular system and currently represents the golden standard. Copyright 2000 John Wiley & Sons, Inc.

  6. The alterations in adenosine nucleotides and lactic acid in striated muscles of rats during Rigor mortis following death with drowning or cervical dislocation.

    Science.gov (United States)

    Pençe, Halime Hanim; Pençe, Sadrettin; Kurtul, Naciye; Yilmaz, Necat; Kocoglu, Hasan; Bakan, Ebubekir

    2003-01-01

    In this study, adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and lactic acid in the muscles of masseter, triceps, and quadriceps obtained from right and left sides of Spraque-Dawley rats following death were investigated. The samples were taken immediately and 120 minutes after death occurred. The rats were killed either by cervical dislocation or drowning. ATP concentrations in the muscles of masseter, triceps, and quadriceps were lower in samples obtained 120 minutes after death than in those obtained immediately after death. ADP, AMP, and lactic acid concentrations in these muscles were higher in samples obtained 120 minutes after death than those obtained immediately after death. A positive linear correlation was determined between ATP and ADP concentrations in quadriceps muscles of the rats killed with cervical dislocation and in triceps muscles of the rats killed with drowning. When rats killed with cervical dislocation and with drowning were compared, ADP, AMP, and lactic acid concentrations were lower in the former than in the latter for both times (immediately and 120 minutes after death occurred). In the case of drowning, ATP is consumed faster because of hard exercise or severe physical activity, resulting in a faster rigor mortis. Higher lactic acid levels were determined in muscles of the rats killed with drowning than the other group. In the control and electric shock rats, ATP decreased in different levels in the three different muscle types mentioned above in control group, being much decline in masseter and then in quadriceps. This may be caused by lower mass and less glycogen storage of masseter. No different ATP levels were measured in drowning group with respect to the muscle type possibly because of the severe activity of triceps and quadriceps and because of smaller mass of masseter. One can conclude that the occurrence of rigor mortis is closely related to the mode of death.

  7. A muscle model for hybrid muscle activation

    Directory of Open Access Journals (Sweden)

    Klauer Christian

    2015-09-01

    Full Text Available To develop model-based control strategies for Functional Electrical Stimulation (FES in order to support weak voluntary muscle contractions, a hybrid model for describing joint motions induced by concurrent voluntary-and FES induced muscle activation is proposed. It is based on a Hammerstein model – as commonly used in feedback controlled FES – and exemplarily applied to describe the shoulder abduction joint angle. Main component of a Hammerstein muscle model is usually a static input nonlinearity depending on the stimulation intensity. To additionally incorporate voluntary contributions, we extended the static non-linearity by a second input describing the intensity of the voluntary contribution that is estimated by electromyography (EMG measurements – even during active FES. An Artificial Neural Network (ANN is used to describe the static input non-linearity. The output of the ANN drives a second-order linear dynamical system that describes the combined muscle activation and joint angle dynamics. The tunable parameters are adapted to the individual subject by a system identification approach using previously recorded I/O-data. The model has been validated in two healthy subjects yielding RMS values for the joint angle error of 3.56° and 3.44°, respectively.

  8. Fiber types in the striated urethral and anal sphincters

    DEFF Research Database (Denmark)

    Schrøder, H D; Reske-Nielsen, E

    1983-01-01

    Seven normal human striated urethral and anal sphincters obtained by autopsy were examined using histochemical techniques. In both the urethral sphincter and the subcutaneous (s.c.) and superficial part of the anal sphincter a characteristic pattern with two populations of muscle fibers, abundant...

  9. Validity of Estimation of Pelvic Floor Muscle Activity from Transperineal Ultrasound Imaging in Men.

    Directory of Open Access Journals (Sweden)

    Ryan E Stafford

    Full Text Available To investigate the relationship between displacement of pelvic floor landmarks observed with transperineal ultrasound imaging and electromyography of the muscles hypothesised to cause the displacements.Three healthy men participated in this study, which included ultrasound imaging of the mid-urethra, urethra-vesical junction, ano-rectal junction and bulb of the penis. Fine-wire electromyography electrodes were inserted into the puborectalis and bulbocavernosus muscles and a transurethral catheter electrode recorded striated urethral sphincter electromyography. A nasogastric sensor recorded intra-abdominal pressure. Tasks included submaximal and maximal voluntary contractions, and Valsalva. The relationship between each of the parameters measured from ultrasound images and electromyography or intra-abdominal pressure amplitudes was described with nonlinear regression.Strong, non-linear relationships were calculated for each predicted landmark/muscle pair for submaximal contractions (R2-0.87-0.95. The relationships between mid-urethral displacement and striated urethral sphincter electromyography, and bulb of the penis displacement and bulbocavernosus electromyography were strong during maximal contractions (R2-0.74-0.88. Increased intra-abdominal pressure prevented shortening of puborectalis, which resulted in weak relationships between electromyography and anorectal and urethravesical junction displacement during all tasks.Displacement of landmarks in transperineal ultrasound imaging provides meaningful measures of activation of individual pelvic floor muscles in men during voluntary contractions. This method may aid assessment of muscle function or feedback for training.

  10. UNC-89 (obscurin) binds to MEL-26, a BTB-domain protein, and affects the function of MEI-1 (katanin) in striated muscle of Caenorhabditis elegans.

    Science.gov (United States)

    Wilson, Kristy J; Qadota, Hiroshi; Mains, Paul E; Benian, Guy M

    2012-07-01

    The ubiquitin proteasome system is involved in degradation of old or damaged sarcomeric proteins. Most E3 ubiquitin ligases are associated with cullins, which function as scaffolds for assembly of the protein degradation machinery. Cullin 3 uses an adaptor to link to substrates; in Caenorhabditis elegans, one of these adaptors is the BTB-domain protein MEL-26 (maternal effect lethal). Here we show that MEL-26 interacts with the giant sarcomeric protein UNC-89 (obscurin). MEL-26 and UNC-89 partially colocalize at sarcomeric M-lines. Loss of function or gain of function of mel-26 results in disorganization of myosin thick filaments similar to that found in unc-89 mutants. It had been reported that in early C. elegans embryos, a target of the CUL-3/MEL-26 ubiquitylation complex is the microtubule-severing enzyme katanin (MEI-1). Loss of function or gain of function of mei-1 also results in disorganization of thick filaments similar to unc-89 mutants. Genetic data indicate that at least some of the mel-26 loss-of-function phenotype in muscle can be attributed to increased microtubule-severing activity of MEI-1. The level of MEI-1 protein is reduced in an unc-89 mutant, suggesting that the normal role of UNC-89 is to inhibit the CUL-3/MEL-26 complex toward MEI-1.

  11. The Time Course of the Loss and Recovery of Contracture Ability in Frog Striated Muscle Following Exposure to Ca-Free Solutions

    Science.gov (United States)

    Milligan, J. V.

    1965-01-01

    Using area under the contracture curve to quantitate contractures, the diffusion coefficient of calcium ions within the frog toe muscle during washout in a calcium-free solution and subsequent recovery after reintroduction of calcium to the bathing solution was calculated to be about 2 x 10-6 cm2/sec. The diffusion coefficient measured during washout was found to be independent of temperature or initial calcium ion concentration. During recovery it was found to decrease if the temperature was lowered. This was likely due to the repolarization occurring after the depolarizing effect of the calcium-free solution. The relation between contracture area and [Ca]o was found to be useful over a wider range than that between maximum tension and [Ca]o. The normalized contracture areas were larger at lower calcium concentrations if the contractures were produced with cold potassium solutions or if NO3 replaced Cl in the bathing solutions. Decreasing the potassium concentration of the contracture solution to 50 mM from 115 mM did not change the relation between [Ca]o and the normalized area. If the K concentration of the bathing solution was increased, the areas were decreased at lower concentrations of Ca. PMID:14324991

  12. Physical activity counteracts tumor cell growth in colon carcinoma C26-injected muscles: an interim report

    Directory of Open Access Journals (Sweden)

    Charlotte Hiroux

    2016-06-01

    Full Text Available Skeletal muscle tissue is a rare site of tumor metastasis but is the main target of the degenerative processes occurring in cancer-associated cachexia syndrome. Beneficial effects of physical activity in counteracting cancer-related muscle wasting have been described in the last decades. Recently it has been shown that, in tumor xeno-transplanted mouse models, physical activity is able to directly affect tumor growth by modulating inflammatory responses in the tumor mass microenvironment. Here, we investigated the effect of physical activity on tumor cell growth in colon carcinoma C26 cells injected tibialis anterior muscles of BALB/c mice. Histological analyses revealed that 4 days of voluntary wheel running significantly counteracts tumor cell growth in C26-injected muscles compared to the non-injected sedentary controls. Since striated skeletal muscle tissue is the site of voluntary contraction, our results confirm that physical activity can also directly counteract tumor cell growth in a metabolically active tissue that is usually not a target for metastasis.

  13. Muscle cooling delays activation of the muscle metaboreflex in humans.

    Science.gov (United States)

    Ray, C A; Hume, K M; Gracey, K H; Mahoney, E T

    1997-11-01

    Elevation of muscle temperature has been shown to increase muscle sympathetic nerve activity (MSNA) during isometric exercise in humans. The purpose of the present study was to evaluate the effect of muscle cooling on MSNA responses during exercise. Eight subjects performed ischemic isometric handgrip at 30% of maximal voluntary contraction to fatigue followed by 2 min of postexercise muscle ischemia (PEMI), with and without local cooling of the forearm. Local cooling of the forearm decreased forearm muscle temperature from 31.8 +/- 0.4 to 23.1 +/- 0.8 degrees C (P = 0.001). Time to fatigue was not different during the control and cold trials (156 +/- 11 and 154 +/- 5 s, respectively). Arterial pressures and heart rate were not significantly affected by muscle cooling during exercise, although heart rate tended to be higher during the second minute of exercise (P = 0.053) during muscle cooling. Exercise-induced increases in MSNA were delayed during handgrip with local cooling compared with control. However, MSNA responses at fatigue and PEMI were not different between the two conditions. These findings suggest that muscle cooling delayed the activation of the muscle metaboreflex during ischemic isometric exercise but did not prevent its full expression during fatiguing contraction. These results support the concept that muscle temperature can play a role in the regulation of MSNA during exercise.

  14. Activation of respiratory muscles during respiratory muscle training.

    Science.gov (United States)

    Walterspacher, Stephan; Pietsch, Fabian; Walker, David Johannes; Röcker, Kai; Kabitz, Hans-Joachim

    2018-01-01

    It is unknown which respiratory muscles are mainly activated by respiratory muscle training. This study evaluated Inspiratory Pressure Threshold Loading (IPTL), Inspiratory Flow Resistive Loading (IFRL) and Voluntary Isocapnic Hyperpnea (VIH) with regard to electromyographic (EMG) activation of the sternocleidomastoid muscle (SCM), parasternal muscles (PARA) and the diaphragm (DIA) in randomized order. Surface EMG were analyzed at the end of each training session and normalized using the peak EMG recorded during maximum inspiratory maneuvers (Sniff nasal pressure: SnPna, maximal inspiratory mouth occlusion pressure: PImax). 41 healthy participants were included. Maximal activation was achieved for SCM by SnPna; the PImax activated predominantly PARA and DIA. Activations of SCM and PARA were higher in IPTL and VIH than for IFRL (p<0.05). DIA was higher applying IPTL compared to IFRL or VIH (p<0.05). IPTL, IFRL and VIH differ in activation of inspiratory respiratory muscles. Whereas all methods mainly stimulate accessory respiratory muscles, diaphragm activation was predominant in IPTL. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Muscle activity characterization by laser Doppler Myography

    Science.gov (United States)

    Scalise, Lorenzo; Casaccia, Sara; Marchionni, Paolo; Ercoli, Ilaria; Primo Tomasini, Enrico

    2013-09-01

    Electromiography (EMG) is the gold-standard technique used for the evaluation of muscle activity. This technique is used in biomechanics, sport medicine, neurology and rehabilitation therapy and it provides the electrical activity produced by skeletal muscles. Among the parameters measured with EMG, two very important quantities are: signal amplitude and duration of muscle contraction, muscle fatigue and maximum muscle power. Recently, a new measurement procedure, named Laser Doppler Myography (LDMi), for the non contact assessment of muscle activity has been proposed to measure the vibro-mechanical behaviour of the muscle. The aim of this study is to present the LDMi technique and to evaluate its capacity to measure some characteristic features proper of the muscle. In this paper LDMi is compared with standard superficial EMG (sEMG) requiring the application of sensors on the skin of each patient. sEMG and LDMi signals have been simultaneously acquired and processed to test correlations. Three parameters has been analyzed to compare these techniques: Muscle activation timing, signal amplitude and muscle fatigue. LDMi appears to be a reliable and promising measurement technique allowing the measurements without contact with the patient skin.

  16. Muscle activity characterization by laser Doppler Myography

    International Nuclear Information System (INIS)

    Scalise, Lorenzo; Casaccia, Sara; Marchionni, Paolo; Ercoli, Ilaria; Tomasini, Enrico Primo

    2013-01-01

    Electromiography (EMG) is the gold-standard technique used for the evaluation of muscle activity. This technique is used in biomechanics, sport medicine, neurology and rehabilitation therapy and it provides the electrical activity produced by skeletal muscles. Among the parameters measured with EMG, two very important quantities are: signal amplitude and duration of muscle contraction, muscle fatigue and maximum muscle power. Recently, a new measurement procedure, named Laser Doppler Myography (LDMi), for the non contact assessment of muscle activity has been proposed to measure the vibro-mechanical behaviour of the muscle. The aim of this study is to present the LDMi technique and to evaluate its capacity to measure some characteristic features proper of the muscle. In this paper LDMi is compared with standard superficial EMG (sEMG) requiring the application of sensors on the skin of each patient. sEMG and LDMi signals have been simultaneously acquired and processed to test correlations. Three parameters has been analyzed to compare these techniques: Muscle activation timing, signal amplitude and muscle fatigue. LDMi appears to be a reliable and promising measurement technique allowing the measurements without contact with the patient skin

  17. Muscle activation patterns in posttraumatic neck pain

    NARCIS (Netherlands)

    Nederhand, Marcus Johannes

    2003-01-01

    As an important consequence of our research, we question the relevance of the criteria of the WAD injury severity classification system. We showed that the musculoskeletal signs in WAD grade II are not characterized by muscle spasm, (i.e. increase of muscle activity), but rather by a decrease in

  18. Core Muscle Activation in Suspension Training Exercises.

    Science.gov (United States)

    Cugliari, Giovanni; Boccia, Gennaro

    2017-02-01

    A quantitative observational laboratory study was conducted to characterize and classify core training exercises executed in a suspension modality on the base of muscle activation. In a prospective single-group repeated measures design, seventeen active male participants performed four suspension exercises typically associated with core training (roll-out, bodysaw, pike and knee-tuck). Surface electromyographic signals were recorded from lower and upper parts of rectus abdominis, external oblique, internal oblique, lower and upper parts of erector spinae muscles using concentric bipolar electrodes. The average rectified values of electromyographic signals were normalized with respect to individual maximum voluntary isometric contraction of each muscle. Roll-out exercise showed the highest activation of rectus abdominis and oblique muscles compared to the other exercises. The rectus abdominis and external oblique reached an activation higher than 60% of the maximal voluntary contraction (or very close to that threshold, 55%) in roll-out and bodysaw exercises. Findings from this study allow the selection of suspension core training exercises on the basis of quantitative information about the activation of muscles of interest. Roll-out and bodysaw exercises can be considered as suitable for strength training of rectus abdominis and external oblique muscles.

  19. Muscle as a “Mediator“ of Systemic Metabolism

    Science.gov (United States)

    Baskin, Kedryn K.; Winders, Benjamin R.; Olson, Eric N.

    2015-01-01

    Skeletal and cardiac muscles play key roles in the regulation of systemic energy homeostasis and display remarkable plasticity in their metabolic responses to caloric availability and physical activity. In this Perspective we discuss recent studies highlighting transcriptional mechanisms that govern systemic metabolism by striated muscles. We focus on the participation of the Mediator complex in this process, and suggest that tissue-specific regulation of Mediator subunits impacts metabolic homeostasis. PMID:25651178

  20. Muscle Contraction.

    Science.gov (United States)

    Sweeney, H Lee; Hammers, David W

    2018-02-01

    SUMMARYMuscle cells are designed to generate force and movement. There are three types of mammalian muscles-skeletal, cardiac, and smooth. Skeletal muscles are attached to bones and move them relative to each other. Cardiac muscle comprises the heart, which pumps blood through the vasculature. Skeletal and cardiac muscles are known as striated muscles, because the filaments of actin and myosin that power their contraction are organized into repeating arrays, called sarcomeres, that have a striated microscopic appearance. Smooth muscle does not contain sarcomeres but uses the contraction of filaments of actin and myosin to constrict blood vessels and move the contents of hollow organs in the body. Here, we review the principal molecular organization of the three types of muscle and their contractile regulation through signaling mechanisms and discuss their major structural and functional similarities that hint at the possible evolutionary relationships between the cell types. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

  1. Overview of the Muscle Cytoskeleton

    Science.gov (United States)

    Henderson, Christine A.; Gomez, Christopher G.; Novak, Stefanie M.; Mi-Mi, Lei; Gregorio, Carol C.

    2018-01-01

    Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments. The costamere, on the other hand, tethers the sarcomere to the cell membrane. Unique structures like the intercalated disc in cardiac muscle and the myotendinous junction in skeletal muscle help synchronize and transmit force. Intense investigation has been done on many of the proteins that make up these cytoskeletal assemblies. Yet the details of their function and how they interconnect have just started to be elucidated. A vast number of human myopathies are contributed to mutations in muscle proteins; thus understanding their basic function provides a mechanistic understanding of muscle disorders. In this review, we highlight the components of striated muscle with respect to their interactions, signaling pathways, functions, and connections to disease. PMID:28640448

  2. Interstitial cells of Cajal in the striated musculature of the mouse esophagus

    DEFF Research Database (Denmark)

    Rumessen, J J; de Kerchove d'Exaerde, A; Mignon, S

    2001-01-01

    . Sections and whole-mounts were studied by immunohistochemistry. KitW-lacZ transgenic mice, which carry the lacZ reporter gene inserted in place of the first exon of the Kit gene, were processed for Xgal histochemistry, for quantitative analysis and for ultrastructural studies. Spindle-shaped ICC were...... scarce in both muscle layers of the thoracic esophagus, while their number increased steeply toward the cardia in the striated portion of the intraabdominal esophagus. They did not form networks and had no relationship with intrinsic myenteric ganglia and motor end-plates. They were often close to nerve...... between striated muscle cells in the mouse esophagus. They are close to nerves with defined neurochemical coding and could possibly represent specialized esophageal spindle proprioceptors....

  3. Muscle activity in sprinting: a review.

    Science.gov (United States)

    Howard, Róisín M; Conway, Richard; Harrison, Andrew J

    2018-03-01

    The use of electromyography (EMG) is widely recognised as a valuable tool for enhancing the understanding of performance drivers and potential injury risk in sprinting. The timings of muscle activations relative to running gait cycle phases and the technology used to obtain muscle activation data during sprinting are of particular interest to scientists and coaches. This review examined the main muscles being analysed by surface EMG (sEMG), their activations and timing, and the technologies used to gather sEMG during sprinting. Electronic databases were searched using 'Electromyography' OR 'EMG' AND 'running' OR 'sprinting'. Based on inclusion criteria, 18 articles were selected for review. While sEMG is widely used in biomechanics, relatively few studies have used sEMG in sprinting due to system constraints. The results demonstrated a focus on the leg muscles, with over 70% of the muscles analysed in the upper leg. This is consistent with the use of tethered and data logging EMG systems and many sprints being performed on treadmills. Through the recent advances in wireless EMG technology, an increase in the studies on high velocity movements such as sprinting is expected and this should allow practitioners to perform the analysis in an ecologically valid environment.

  4. Does mental exertion alter maximal muscle activation?

    Directory of Open Access Journals (Sweden)

    Vianney eRozand

    2014-09-01

    Full Text Available Mental exertion is known to impair endurance performance, but its effects on neuromuscular function remain unclear. The purpose of this study was to test the hypothesis that mental exertion reduces torque and muscle activation during intermittent maximal voluntary contractions of the knee extensors. Ten subjects performed in a randomized order three separate mental exertion conditions lasting 27 minutes each: i high mental exertion (incongruent Stroop task, ii moderate mental exertion (congruent Stroop task, iii low mental exertion (watching a movie. In each condition, mental exertion was combined with ten intermittent maximal voluntary contractions of the knee extensor muscles (one maximal voluntary contraction every 3 minutes. Neuromuscular function was assessed using electrical nerve stimulation. Maximal voluntary torque, maximal muscle activation and other neuromuscular parameters were similar across mental exertion conditions and did not change over time. These findings suggest that mental exertion does not affect neuromuscular function during intermittent maximal voluntary contractions of the knee extensors.

  5. Effect of altering starting length and activation timing of muscle on fiber strain and muscle damage.

    Science.gov (United States)

    Butterfield, Timothy A; Herzog, Walter

    2006-05-01

    Muscle strain injuries are some of the most frequent injuries in sports and command a great deal of attention in an effort to understand their etiology. These injuries may be the culmination of a series of subcellular events accumulated through repetitive lengthening (eccentric) contractions during exercise, and they may be influenced by a variety of variables including fiber strain magnitude, peak joint torque, and starting muscle length. To assess the influence of these variables on muscle injury magnitude in vivo, we measured fiber dynamics and joint torque production during repeated stretch-shortening cycles in the rabbit tibialis anterior muscle, at short and long muscle lengths, while varying the timing of activation before muscle stretch. We found that a muscle subjected to repeated stretch-shortening cycles of constant muscle-tendon unit excursion exhibits significantly different joint torque and fiber strains when the timing of activation or starting muscle length is changed. In particular, measures of fiber strain and muscle injury were significantly increased by altering activation timing and increasing the starting length of the muscle. However, we observed differential effects on peak joint torque during the cyclic stretch-shortening exercise, as increasing the starting length of the muscle did not increase torque production. We conclude that altering activation timing and muscle length before stretch may influence muscle injury by significantly increasing fiber strain magnitude and that fiber dynamics is a more important variable than muscle-tendon unit dynamics and torque production in influencing the magnitude of muscle injury.

  6. Activation of Selected Core Muscles during Pressing

    Directory of Open Access Journals (Sweden)

    Thomas W. Nesser

    2015-10-01

    Full Text Available Introduction: Unstable surface training is often used to activate core musculature during resistance training. Unfortunately, unstable surface training is risky and leads to detraining. Purpose: The purpose of this study was to determine core muscle activation during stable surface ground-based lifts. Methods: Fourteen recreational trained and former NCAA DI athletes (weight 84.2 ± 13.3 kg; height 176.0 ± 9.5 cm; age 20.9 ± 2.0 years volunteered for participation. Subjects completed two ground-based lifts: overhead press and push-press. Surface EMG was recorded from 4 muscles on the right side of the body (Rectus Abdominus (RA, External Oblique (EO, Transverse Abdominus (TA, and Erector Spinae (ES. Results: Paired sample T-tests identified significant muscle activation differences between the overhead press and the push-press included ES and EO. Average and peak EMG for ES was significantly greater in push-press (P<0.01. Anterior displacement of COP was significantly greater in push-press compared to overhead press during the eccentric phase. Conclusion: The push-press was identified as superior in core muscle activation when compared to the overhead pressing exercise. Keywords: torso, stability, weight lifting, resistance training

  7. Mechanomyogram for identifying muscle activity and fatigue.

    Science.gov (United States)

    Yang, Zhao Feng; Kumar, Dinesh Kant; Arjunan, Sridhar Poosapadi

    2009-01-01

    Mechanomyogram is the recording of the acoustic activity associated with the muscle contraction. While discovered nearly a decade ago with the intention of providing an alternate to the surface electromyogram, it has not yet been investigated thoroughly and there are no current applications associated with MMG. This paper reports an experimental study of MMG against force of contraction and muscle fatigue during cyclic contraction. The results indicate that there is a relationship between the intensity of the MMG recording and force of contraction. A change in the intensity of MMG is also observed with the onset of muscle fatigue. However, the inter-subject variation is very large. The results also indicate that the spectrum of the MMG is very inconsistent and not a useful feature of the signal.

  8. Lower extremity muscle activation during baseball pitching.

    Science.gov (United States)

    Campbell, Brian M; Stodden, David F; Nixon, Megan K

    2010-04-01

    The purpose of this study was to investigate muscle activation levels of select lower extremity muscles during the pitching motion. Bilateral surface electromyography data on 5 lower extremity muscles (biceps femoris, rectus femoris, gluteus maximus, vastus medialis, and gastrocnemius) were collected on 11 highly skilled baseball pitchers and compared with individual maximal voluntary isometric contraction (MVIC) data. The pitching motion was divided into 4 distinct phases: phase 1, initiation of pitching motion to maximum stride leg knee height; phase 2, maximum stride leg knee height to stride foot contact (SFC); phase 3, SFC to ball release; and phase 4, ball release to 0.5 seconds after ball release (follow-through). Results indicated that trail leg musculature elicited moderate to high activity levels during phases 2 and 3 (38-172% of MVIC). Muscle activity levels of the stride leg were moderate to high during phases 2-4 (23-170% of MVIC). These data indicate a high demand for lower extremity strength and endurance. Specifically, coaches should incorporate unilateral and bilateral lower extremity exercises for strength improvement or maintenance and to facilitate dynamic stabilization of the lower extremities during the pitching motion.

  9. Bones, Muscles, and Joints: The Musculoskeletal System

    Science.gov (United States)

    ... Skeletal muscles are called striated (pronounced: STRY-ay-ted) because they are made up of fibers that ... blood through your body. When we smile and talk, muscles are helping us communicate, and when we ...

  10. Normalization of cell responses in cat striate cortex

    Science.gov (United States)

    Heeger, D. J.

    1992-01-01

    Simple cells in the striate cortex have been depicted as half-wave-rectified linear operators. Complex cells have been depicted as energy mechanisms, constructed from the squared sum of the outputs of quadrature pairs of linear operators. However, the linear/energy model falls short of a complete explanation of striate cell responses. In this paper, a modified version of the linear/energy model is presented in which striate cells mutually inhibit one another, effectively normalizing their responses with respect to stimulus contrast. This paper reviews experimental measurements of striate cell responses, and shows that the new model explains a significantly larger body of physiological data.

  11. How the condition of occlusal support affects the back muscle force and masticatory muscle activity?

    OpenAIRE

    石岡, 克; 河野, 正司; Ishioka, Masaru; Kohno, Shoji

    2002-01-01

    This study was conducted to determine how the condition of occlusal support affects the back muscle force and masticatory muscle activity. Two groups of subjects were enlisted: sport-trained group and normal group. While electrodes of the electromyography (EMG) were attached to the surface of the masticatory muscles, each subject's back muscle force was recorded during upper body stretching using a back muscle force-measuring device. The task was performed under four different occlusal suppor...

  12. Mimicking muscle activity with electrical stimulation

    Science.gov (United States)

    Johnson, Lise A.; Fuglevand, Andrew J.

    2011-02-01

    Functional electrical stimulation is a rehabilitation technology that can restore some degree of motor function in individuals who have sustained a spinal cord injury or stroke. One way to identify the spatio-temporal patterns of muscle stimulation needed to elicit complex upper limb movements is to use electromyographic (EMG) activity recorded from able-bodied subjects as a template for electrical stimulation. However, this requires a transfer function to convert the recorded (or predicted) EMG signals into an appropriate pattern of electrical stimulation. Here we develop a generalized transfer function that maps EMG activity into a stimulation pattern that modulates muscle output by varying both the pulse frequency and the pulse amplitude. We show that the stimulation patterns produced by this transfer function mimic the active state measured by EMG insofar as they reproduce with good fidelity the complex patterns of joint torque and joint displacement.

  13. Activation of Selected Core Muscles during Pressing

    OpenAIRE

    Thomas W. Nesser; Neil Fleming; Matthew J. Gage

    2015-01-01

    Introduction: Unstable surface training is often used to activate core musculature during resistance training. Unfortunately, unstable surface training is risky and leads to detraining. Purpose: The purpose of this study was to determine core muscle activation during stable surface ground-based lifts. Methods: Fourteen recreational trained and former NCAA DI athletes (weight 84.2 ± 13.3 kg; height 176.0 ± 9.5 cm; age 20.9 ± 2.0 years) volunteered for participation. Subjects completed two grou...

  14. Catechins activate muscle stem cells by Myf5 induction and stimulate muscle regeneration.

    Science.gov (United States)

    Kim, A Rum; Kim, Kyung Min; Byun, Mi Ran; Hwang, Jun-Ha; Park, Jung Il; Oh, Ho Taek; Kim, Hyo Kyeong; Jeong, Mi Gyeong; Hwang, Eun Sook; Hong, Jeong-Ho

    2017-07-22

    Muscle weakness is one of the most common symptoms in aged individuals and increases risk of mortality. Thus, maintenance of muscle mass is important for inhibiting aging. In this study, we investigated the effect of catechins, polyphenol compounds in green tea, on muscle regeneration. We found that (-)-epicatechin gallate (ECG) and (-)-epigallocatechin-3-gallate (EGCG) activate satellite cells by induction of Myf5 transcription factors. For satellite cell activation, Akt kinase was significantly induced after ECG treatment and ECG-induced satellite cell activation was blocked in the presence of Akt inhibitor. ECG also promotes myogenic differentiation through the induction of myogenic markers, including Myogenin and Muscle creatine kinase (MCK), in satellite and C2C12 myoblast cells. Finally, EGCG administration to mice significantly increased muscle fiber size for regeneration. Taken together, the results suggest that catechins stimulate muscle stem cell activation and differentiation for muscle regeneration. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Compensatory muscle activation in patients with glenohumeral cuff tears

    NARCIS (Netherlands)

    Steenbrink, Franciscus

    2010-01-01

    Patients suffering tendon tears in the glenohumeral cuff muscles show activation of muscles which pull the arm downwards during arm elevation tasks. This so-called co-activation deviates from healthy controls and is triggered by pain. Goal of this thesis was to demonstrate that deviating muscle

  16. Distinctive serum miRNA profile in mouse models of striated muscular pathologies.

    Directory of Open Access Journals (Sweden)

    Nicolas Vignier

    Full Text Available Biomarkers are critically important for disease diagnosis and monitoring. In particular, close monitoring of disease evolution is eminently required for the evaluation of therapeutic treatments. Classical monitoring methods in muscular dystrophies are largely based on histological and molecular analyses of muscle biopsies. Such biopsies are invasive and therefore difficult to obtain. The serum protein creatine kinase is a useful biomarker, which is however not specific for a given pathology and correlates poorly with the severity or course of the muscular pathology. The aim of the present study was the systematic evaluation of serum microRNAs (miRNAs as biomarkers in striated muscle pathologies. Mouse models for five striated muscle pathologies were investigated: Duchenne muscular dystrophy (DMD, limb-girdle muscular dystrophy type 2D (LGMD2D, limb-girdle muscular dystrophy type 2C (LGMD2C, Emery-Dreifuss muscular dystrophy (EDMD and hypertrophic cardiomyopathy (HCM. Two-step RT-qPCR methodology was elaborated, using two different RT-qPCR miRNA quantification technologies. We identified miRNA modulation in the serum of all the five mouse models. The most highly dysregulated serum miRNAs were found to be commonly upregulated in DMD, LGMD2D and LGMD2C mouse models, which all exhibit massive destruction of striated muscle tissues. Some of these miRNAs were down rather than upregulated in the EDMD mice, a model without massive myofiber destruction. The dysregulated miRNAs identified in the HCM model were different, with the exception of one dysregulated miRNA common to all pathologies. Importantly, a specific and distinctive circulating miRNA profile was identified for each studied pathological mouse model. The differential expression of a few dysregulated miRNAs in the DMD mice was further evaluated in DMD patients, providing new candidates of circulating miRNA biomarkers for DMD.

  17. Muscle activity pattern dependent pain development and alleviation.

    Science.gov (United States)

    Sjøgaard, Gisela; Søgaard, Karen

    2014-12-01

    Muscle activity is for decades considered to provide health benefits irrespectively of the muscle activity pattern performed and whether it is during e.g. sports, transportation, or occupational work tasks. Accordingly, the international recommendations for public health-promoting physical activity do not distinguish between occupational and leisure time physical activity. However, in this body of literature, attention has not been paid to the extensive documentation on occupational physical activity imposing a risk of impairment of health - in particular musculoskeletal health in terms of muscle pain. Focusing on muscle activity patterns and musculoskeletal health it is pertinent to elucidate the more specific aspects regarding exposure profiles and body regional pain. Static sustained muscle contraction for prolonged periods often occurs in the neck/shoulder area during occupational tasks and may underlie muscle pain development in spite of rather low relative muscle load. Causal mechanisms include a stereotype recruitment of low threshold motor units (activating type 1 muscle fibers) characterized by a lack of temporal as well as spatial variation in recruitment. In contrast during physical activities at leisure and sport the motor recruitment patterns are more dynamic including regularly relatively high muscle forces - also activating type 2 muscles fibers - as well as periods of full relaxation even of the type 1 muscle fibers. Such activity is unrelated to muscle pain development if adequate recovery is granted. However, delayed muscle soreness may develop following intensive eccentric muscle activity (e.g. down-hill skiing) with peak pain levels in thigh muscles 1-2 days after the exercise bout and a total recovery within 1 week. This acute pain profile is in contrast to the chronic muscle pain profile related to repetitive monotonous work tasks. The painful muscles show adverse functional, morphological, hormonal, as well as metabolic characteristics. Of

  18. Differences in muscle pain and plasma creatine kinase activity after ...

    African Journals Online (AJOL)

    encephalopathy,18 and the decrement in muscle power associated with muscle damage.6 ... A high degree of intra-individual variability in plasma. CK activity was ..... 21. Komi PV. Stretch-shortening cycle exercise: a powerful model to study.

  19. Inhibition of muscle spindle afferent activity during masseter muscle fatigue in the rat.

    Science.gov (United States)

    Brunetti, Orazio; Della Torre, Giovannella; Lucchi, Maria Luisa; Chiocchetti, Roberto; Bortolami, Ruggero; Pettorossi, Vito Enrico

    2003-09-01

    The influence of muscle fatigue on the jaw-closing muscle spindle activity has been investigated by analyzing: (1) the field potentials evoked in the trigeminal motor nucleus (Vmot) by trigeminal mesencephalic nucleus (Vmes) stimulation, (2) the orthodromic and antidromic responses evoked in the Vmes by stimulation of the peripheral and central axons of the muscle proprioceptive afferents, and (3) the extracellular unitary discharge of masseter muscle spindles recorded in the Vmes. The masseter muscle was fatigued by prolonged tetanic masseter nerve electrical stimulation. Pre- and postsynaptic components of the potentials evoked in the Vmot showed a significant reduction in amplitude following muscle fatigue. Orthodromic and antidromic potentials recorded in the Vmes also showed a similar amplitude decrease. Furthermore, muscle fatigue caused a decrease of the discharge frequency of masseter muscle spindle afferents in most of the examined units. The inhibition of the potential amplitude and discharge frequency was strictly correlated with the extent of muscle fatigue and was mediated by the group III and IV afferent muscle fibers activated by fatigue. In fact, the inhibitory effect was abolished by capsaicin injection in the masseter muscle that provokes selective degeneration of small afferent muscle fibers containing neurokinins. We concluded that fatigue signals originating from the muscle and traveling through capsaicin-sensitive fibers are able to diminish the proprioceptive input by a central presynaptic influence. In the second part of the study, we examined the central projection of the masseter small afferents sensitive to capsaicin at the electron-microscopic level. Fiber degeneration was induced by injecting capsaicin into the masseter muscle. Degenerating terminals were found on the soma and stem process in Vmes and on the dendritic tree of neurons in Vmot. This suggests that small muscle afferents may influence the muscle spindle activity through

  20. Electrically and hybrid-induced muscle activations: effects of muscle size and fiber type

    Directory of Open Access Journals (Sweden)

    Kelly Stratton

    2016-07-01

    Full Text Available The effect of three electrical stimulation (ES frequencies (10, 35, and 50 Hz on two muscle groups with different proportions of fast and slow twitch fibers (abductor pollicis brevis (APB and vastus lateralis (VL was explored. We evaluated the acute muscles’ responses individually and during hybrid activations (ES superimposed by voluntary activations. Surface electromyography (sEMG and force measurements were evaluated as outcomes. Ten healthy adults (mean age: 24.4 ± 2.5 years participated after signing an informed consent form approved by the university Institutional Review Board. Protocols were developed to: 1 compare EMG activities during each frequency for each muscle when generating 25% Maximum Voluntary Contraction (MVC force, and 2 compare EMG activities during each frequency when additional voluntary activation was superimposed over ES-induced 25% MVC to reach 50% and 75% MVC. Empirical mode decomposition (EMD was utilized to separate ES artifacts from voluntary muscle activation. For both muscles, higher stimulation frequency (35 and 50Hz induced higher electrical output detected at 25% of MVC, suggesting more recruitment with higher frequencies. Hybrid activation generated proportionally less electrical activity than ES alone. ES and voluntary activations appear to generate two different modes of muscle recruitment. ES may provoke muscle strength by activating more fatiguing fast acting fibers, but voluntary activation elicits more muscle coordination. Therefore, during the hybrid activation, less electrical activity may be detected due to recruitment of more fatigue-resistant deeper muscle fibers, not reachable by surface EMG.

  1. Muscle activity of leg muscles during unipedal stance on therapy devices with different stability properties.

    Science.gov (United States)

    Wolburg, Thomas; Rapp, Walter; Rieger, Jochen; Horstmann, Thomas

    2016-01-01

    To test the hypotheses that less stable therapy devices require greater muscle activity and that lower leg muscles will have greater increases in muscle activity with less stable therapy devices than upper leg muscles. Cross-sectional laboratory study. Laboratory setting. Twenty-five healthy subjects. Electromyographic activity of four lower (gastrocnemius medialis, soleus, tibialis anterior, peroneus longus) and four upper leg muscles (vastus medialis and lateralis, biceps femoris, semitendinosus) during unipedal quiet barefoot stance on the dominant leg on a flat rigid surface and on five therapy devices with varying stability properties. Muscle activity during unipedal stance differed significantly between therapy devices (P < 0.001). The order from lowest to highest relative muscle activity matched the order from most to least stable therapy device. There was no significant interaction between muscle location (lower versus upper leg) and therapy device (P = 0.985). Magnitudes of additional relative muscle activity for the respective therapy devices differed substantially among lower extremity muscles. The therapy devices offer a progressive increase in training intensity, and thus may be useful for incremental training programs in physiotherapeutic practice and sports training programs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. How is AMPK activity regulated in skeletal muscles during exercise?

    DEFF Research Database (Denmark)

    Jørgensen, Sebastian Beck; Rose, Adam John

    2008-01-01

    AMPK is a metabolic "master" controller activated in skeletal muscle by exercise in a time and intensity dependent manner, and has been implicated in regulating metabolic pathways in muscle during physical exercise. AMPK signaling in skeletal muscle is regulated by several systemic...... and intracellular factors and the regulation of skeletal muscle AMPK in response to exercise is the focus of this review. Specifically, the role of LKB1 and phosphatase PP2C in nucleotide-dependent activation of AMPK, and ionized calcium in CaMKK-dependent activation of AMPK in working muscle is discussed. We also...

  3. Muscle activity pattern dependent pain development and alleviation

    DEFF Research Database (Denmark)

    Sjøgaard, Gisela; Søgaard, Karen

    2014-01-01

    Muscle activity is for decades considered to provide health benefits irrespectively of the muscle activity pattern performed and whether it is during e.g. sports, transportation, or occupational work tasks. Accordingly, the international recommendations for public health-promoting physical activity...... do not distinguish between occupational and leisure time physical activity. However, in this body of literature, attention has not been paid to the extensive documentation on occupational physical activity imposing a risk of impairment of health - in particular musculoskeletal health in terms...... during physical activities at leisure and sport the motor recruitment patterns are more dynamic including regularly relatively high muscle forces - also activating type 2 muscles fibers - as well as periods of full relaxation even of the type 1 muscle fibers. Such activity is unrelated to muscle pain...

  4. Muscle activation during selected strength exercises in women with chronic neck muscle pain

    DEFF Research Database (Denmark)

    Andersen, Lars L; Kjaer, Michael; Andersen, Christoffer H

    2008-01-01

    selected strengthening exercises in women undergoing rehabilitation for chronic neck muscle pain (defined as a clinical diagnosis of trapezius myalgia). SUBJECTS: The subjects were 12 female workers (age=30-60 years) with a clinical diagnosis of trapezius myalgia and a mean baseline pain intensity of 5......BACKGROUND AND PURPOSE: Muscle-specific strength training has previously been shown to be effective in the rehabilitation of chronic neck muscle pain in women. The aim of this study was to determine the level of activation of the neck and shoulder muscles using surface electromyography (EMG) during...... muscle pain. Several of the strength exercises had high activation of neck and shoulder muscles in women with chronic neck pain. These exercises can be used equally in the attempt to achieve a beneficial treatment effect on chronic neck muscle pain....

  5. Intrinsic Hand Muscle Activation for Grasp and Horizontal Transport

    OpenAIRE

    Winges, Sara A.; Kundu, Bornali; Soechting, John F.; Flanders, Martha

    2007-01-01

    During object manipulation, the hand and arm muscles produce internal forces on the object (grasping forces) and forces that result in external translation or rotation of the object in space (transport forces). The present study tested whether the intrinsic hand muscles are actively involved in transport as well as grasping. Intrinsic hand muscle activity increased with increasing demands for grasp stability, but also showed the timing and directional tuning patterns appropriate for actively ...

  6. The origin of activity in the biceps brachii muscle during voluntary contractions of the contralateral elbow flexor muscles

    NARCIS (Netherlands)

    Zijdewind, Inge; Butler, Jane E.; Gandevia, Simon C.; Taylor, Janet L.

    During strong voluntary contractions, activity is not restricted to the target muscles. Other muscles, including contralateral muscles, often contract. We used transcranial magnetic stimulation (TMS) to analyse the origin of these unintended contralateral contractions (termed "associated"

  7. Hip and trunk muscles activity during nordic hamstring exercise

    Science.gov (United States)

    Narouei, Shideh; Imai, Atsushi; Akuzawa, Hiroshi; Hasebe, Kiyotaka; Kaneoka, Koji

    2018-01-01

    The nordic hamstring exercise (NHE) is a dynamic lengthening hamstring exercise that requires trunk and hip muscles activation. Thigh muscles activation, specifically hamstring/quadriceps contractions has been previously examined during NHE. Trunk and hip muscles activity have not been enough studied. The aim of this study was to analyze of hip and trunk muscles activity during NHE. Surface electromyography (EMG) and kinematic data were collected during NHE. Ten healthy men with the age range of 21–36 years performed two sets of two repetitions with downward and upward motions each of NHE. EMG activity of fifteen trunk and hip muscles and knee kinematic data were collected. Muscle activity levels were calculated through repeated measure analysis of variance in downward and upward motions, through Paired t-test between downward and upward motions and gluteus maximus to erector spine activity ratio (Gmax/ES ratio) using Pearson correlation analyses were evaluated. Semitendinosus and biceps femoris muscles activity levels were the greatest in both motions and back extensors and internal oblique muscles activity were greater than other muscles (Phamstrings contractions. It could be important for early assessment of subjects with hamstring injury risk. PMID:29740557

  8. Hip and trunk muscles activity during nordic hamstring exercise.

    Science.gov (United States)

    Narouei, Shideh; Imai, Atsushi; Akuzawa, Hiroshi; Hasebe, Kiyotaka; Kaneoka, Koji

    2018-04-01

    The nordic hamstring exercise (NHE) is a dynamic lengthening hamstring exercise that requires trunk and hip muscles activation. Thigh muscles activation, specifically hamstring/quadriceps contractions has been previously examined during NHE. Trunk and hip muscles activity have not been enough studied. The aim of this study was to analyze of hip and trunk muscles activity during NHE. Surface electromyography (EMG) and kinematic data were collected during NHE. Ten healthy men with the age range of 21-36 years performed two sets of two repetitions with downward and upward motions each of NHE. EMG activity of fifteen trunk and hip muscles and knee kinematic data were collected. Muscle activity levels were calculated through repeated measure analysis of variance in downward and upward motions, through Paired t -test between downward and upward motions and gluteus maximus to erector spine activity ratio (Gmax/ES ratio) using Pearson correlation analyses were evaluated. Semitendinosus and biceps femoris muscles activity levels were the greatest in both motions and back extensors and internal oblique muscles activity were greater than other muscles ( P hamstrings contractions. It could be important for early assessment of subjects with hamstring injury risk.

  9. Pneumatic Muscles Actuated Lower-Limb Orthosis Model Verification with Actual Human Muscle Activation Patterns

    Directory of Open Access Journals (Sweden)

    Dzahir M.A.M

    2017-01-01

    Full Text Available A review study was conducted on existing lower-limb orthosis systems for rehabilitation which implemented pneumatic muscle type of actuators with the aim to clarify the current and on-going research in this field. The implementation of pneumatic artificial muscle will play an important role for the development of the advanced robotic system. In this research a derivation model for the antagonistic mono- and bi-articular muscles using pneumatic artificial muscles of a lower limb orthosis will be verified with actual human’s muscle activities models. A healthy and young male 29 years old subject with height 174cm and weight 68kg was used as a test subject. Two mono-articular muscles Vastus Medialis (VM and Vastus Lateralis (VL were selected to verify the mono-articular muscle models and muscle synergy between anterior muscles. Two biarticular muscles Rectus Femoris (RF and Bicep Femoris (BF were selected to verify the bi-articular muscle models and muscle co-contraction between anterior-posterior muscles. The test was carried out on a treadmill with a speed of 4.0 km/h, which approximately around 1.25 m/s for completing one cycle of walking motion. The data was collected for about one minute on a treadmill and 20 complete cycles of walking motion were successfully recorded. For the evaluations, the mathematical model obtained from the derivation and the actual human muscle activation patterns obtained using the surface electromyography (sEMG system were compared and analysed. The results shown that, high correlation values ranging from 0.83 up to 0.93 were obtained in between the derivation model and the actual human muscle’s model for both mono- and biarticular muscles. As a conclusion, based on the verification with the sEMG muscle activities data and its correlation values, the proposed derivation models of the antagonistic mono- and bi-articular muscles were suitable to simulate and controls the pneumatic muscles actuated lower limb

  10. The influence of experimentally induced pain on shoulder muscle activity

    DEFF Research Database (Denmark)

    Diederichsen, L.P.; Winther, A.; Dyhre-Poulsen, P.

    2009-01-01

    muscles. EMG was recorded before pain, during pain and after pain had subsided and pain intensity was continuously scored on a visual analog scale (VAS). During abduction, experimentally induced pain in the supraspinatus muscle caused a significant decrease in activity of the anterior deltoid, upper......-105A degrees) at a speed of approximately 120A degrees/s, controlled by a metronome. During abduction, electromyographic (EMG) activity was recorded by intramuscular wire electrodes inserted in two deeply located shoulder muscles and by surface-electrodes over six superficially located shoulder...... trapezius and the infraspinatus and an increase in activity of lower trapezius and latissimus dorsi muscles. Following subacromial injection a significantly increased muscle activity was seen in the lower trapezius, the serratus anterior and the latissimus dorsi muscles. In conclusion, this study shows...

  11. Selective activation of neuromuscular compartments within the human trapezius muscle

    DEFF Research Database (Denmark)

    Holtermann, A; Roeleveld, K; Mork, P J

    2009-01-01

    of the human trapezius muscle can be independently activated by voluntary command, indicating neuromuscular compartmentalization of the trapezius muscle. The independent activation of the upper and lower subdivisions of the trapezius is in accordance with the selective innervation by the fine cranial and main...... branch of the accessory nerve to the upper and lower subdivisions. These findings provide new insight into motor control characteristics, learning possibilities, and function of the clinically relevant human trapezius muscle....

  12. Muscle activation patterns when passively stretching spastic lower limb muscles of children with cerebral palsy.

    Directory of Open Access Journals (Sweden)

    Lynn Bar-On

    Full Text Available The definition of spasticity as a velocity-dependent activation of the tonic stretch reflex during a stretch to a passive muscle is the most widely accepted. However, other mechanisms are also thought to contribute to pathological muscle activity and, in patients post-stroke and spinal cord injury can result in different activation patterns. In the lower-limbs of children with spastic cerebral palsy (CP these distinct activation patterns have not yet been thoroughly explored. The aim of the study was to apply an instrumented assessment to quantify different muscle activation patterns in four lower-limb muscles of children with CP. Fifty-four children with CP were included (males/females n = 35/19; 10.8 ± 3.8 yrs; bilateral/unilateral involvement n =  32/22; Gross Motor Functional Classification Score I-IV of whom ten were retested to evaluate intra-rater reliability. With the subject relaxed, single-joint, sagittal-plane movements of the hip, knee, and ankle were performed to stretch the lower-limb muscles at three increasing velocities. Muscle activity and joint motion were synchronously recorded using inertial sensors and electromyography (EMG from the adductors, medial hamstrings, rectus femoris, and gastrocnemius. Muscles were visually categorised into activation patterns using average, normalized root mean square EMG (RMS-EMG compared across increasing position zones and velocities. Based on the visual categorisation, quantitative parameters were defined using stretch-reflex thresholds and normalized RMS-EMG. These parameters were compared between muscles with different activation patterns. All patterns were dominated by high velocity-dependent muscle activation, but in more than half, low velocity-dependent activation was also observed. Muscle activation patterns were found to be both muscle- and subject-specific (p<0.01. The intra-rater reliability of all quantitative parameters was moderate to good. Comparing RMS-EMG between

  13. Effects of muscle activation on shear between human soleus and gastrocnemius muscles.

    Science.gov (United States)

    Finni, T; Cronin, N J; Mayfield, D; Lichtwark, G A; Cresswell, A G

    2017-01-01

    Lateral connections between muscles provide pathways for myofascial force transmission. To elucidate whether these pathways have functional roles in vivo, we examined whether activation could alter the shear between the soleus (SOL) and lateral gastrocnemius (LG) muscles. We hypothesized that selective activation of LG would decrease the stretch-induced shear between LG and SOL. Eleven volunteers underwent a series of knee joint manipulations where plantar flexion force, LG, and SOL muscle fascicle lengths and relative displacement of aponeuroses between the muscles were obtained. Data during a passive full range of motion were recorded, followed by 20° knee extension stretches in both passive conditions and with selective electrical stimulation of LG. During active stretch, plantar flexion force was 22% greater (P stronger (stiffer) connectivity between the two muscles, at least at flexed knee joint angles, which may serve to facilitate myofascial force transmission. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Muscle Atrophy Reversed by Growth Factor Activation of Satellite Cells in a Mouse Muscle Atrophy Model

    DEFF Research Database (Denmark)

    Hauerslev, Simon; Vissing, John; Krag, Thomas O

    2014-01-01

    mechanism that may contribute to the progressive muscle wasting seen in severely affected patients with muscular dystrophy and significant on-going regeneration. This treatment could potentially be applied to many conditions that feature muscle wasting to increase muscle bulk and strength.......Muscular dystrophies comprise a large group of inherited disorders that lead to progressive muscle wasting. We wanted to investigate if targeting satellite cells can enhance muscle regeneration and thus increase muscle mass. We treated mice with hepatocyte growth factor and leukemia inhibitory...... factor under three conditions: normoxia, hypoxia and during myostatin deficiency. We found that hepatocyte growth factor treatment led to activation of the Akt/mTOR/p70S6K protein synthesis pathway, up-regulation of the myognic transcription factors MyoD and myogenin, and subsequently the negative growth...

  15. Muscle triacylglycerol and hormone-sensitive lipase activity in untrained and trained human muscles

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Biba, Taus O; Galbo, Henrik

    2006-01-01

    During exercise, triacylglycerol (TG) is recruited in skeletal muscles. We hypothesized that both muscle hormone-sensitive lipase (HSL) activity and TG recruitment would be higher in trained than in untrained subjects in response to prolonged exercise. Healthy male subjects (26 +/- 1 years, body ...

  16. Fatigue effects on tracking performance and muscle activity

    NARCIS (Netherlands)

    Huysmans, M.A.; Hoozemans, M.J.M.; van der Beek, A.J.; de Looze, M.P.; van Dieen, J.H.

    2008-01-01

    It has been suggested that fatigue affects proprioception and consequently movement accuracy, the effects of which may be counteracted by increased muscle activity. To determine the effects of fatigue on tracking performance and muscle activity in the M. extensor carpi radialis (ECR), 11 female

  17. Activation of plantar flexor muscles is constrained by multiple muscle synergies rather than joint torques.

    Directory of Open Access Journals (Sweden)

    Takahito Suzuki

    Full Text Available Behavioral evidence has suggested that a small number of muscle synergies may be responsible for activating a variety of muscles. Nevertheless, such dimensionality reduction may also be explained using the perspective of alternative hypotheses, such as predictions based on linear combinations of joint torques multiplied by corresponding coefficients. To compare the explanatory capacity of these hypotheses for describing muscle activation, we enrolled 12 male volunteers who performed isometric plantar flexor contractions at 10-100% of maximum effort. During each plantar flexor contraction, the knee extensor muscles were isometrically contracted at 0%, 50%, or 100% of maximum effort. Electromyographic activity was recorded from the vastus lateralis, medial gastrocnemius (MG, lateral gastrocnemius (LG, and soleus muscles and quantified using the average rectified value (ARV. At lower plantar flexion torque, regression analysis identified a clear linear relationship between the MG and soleus ARVs and between the MG and LG ARVs, suggesting the presence of muscle synergy (r2 > 0.65. The contraction of the knee extensor muscles induced a significant change in the slope of this relationship for both pairs of muscles (MG × soleus, P = 0.002; MG × LG, P = 0.006. Similarly, the slope of the linear relationship between the plantar flexion torque and the ARV of the MG or soleus changed significantly with knee extensor contraction (P = 0.031 and P = 0.041, respectively. These results suggest that muscle synergies characterized by non-mechanical constraints are selectively recruited according to whether contraction of the knee extensor muscles is performed simultaneously, which is relatively consistent with the muscle synergy hypothesis.

  18. Masticatory muscle activity during deliberately performed oral tasks

    International Nuclear Information System (INIS)

    Farella, M; Palla, S; Erni, S; Gallo, L M; Michelotti, A

    2008-01-01

    The aim of this study was to investigate masticatory muscle activity during deliberately performed functional and non-functional oral tasks. Electromyographic (EMG) surface activity was recorded unilaterally from the masseter, anterior temporalis and suprahyoid muscles in 11 subjects (5 men, 6 women; age = 34.6 ± 10.8 years), who were accurately instructed to perform 30 different oral tasks under computer guidance using task markers. Data were analyzed by descriptive statistics, repeated measurements analysis of variance (ANOVA) and hierarchical cluster analysis. The maximum EMG amplitude of the masseter and anterior temporalis muscles was more often found during hard chewing tasks than during maximum clenching tasks. The relative contribution of masseter and anterior temporalis changed across the tasks examined (F ≥ 5.2; p ≤ 0.001). The masseter muscle was significantly (p ≤ 0.05) more active than the anterior temporalis muscle during tasks involving incisal biting, jaw protrusion, laterotrusion and jaw cupping, the difference being statistically significant (p ≤ 0.05). The anterior temporalis muscle was significantly (p ≤ 0.01) more active than the masseter muscle during tasks performed in intercuspal position, during tooth grinding, and during hard chewing on the working side. Based upon the relative contribution of the masseter, anterior temporalis, and suprahyoid muscles, the investigated oral tasks could be grouped into six separate clusters. The findings provided further insight into muscle- and task-specific EMG patterns during functional and non-functional oral behaviors

  19. Frequency band analysis of muscle activation during cycling to exhaustion

    Directory of Open Access Journals (Sweden)

    Fernando Diefenthaeler

    2012-04-01

    Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n3p243 Lower limb muscles activation was assessed during cycling to exhaustion using frequency band analysis. Nine cyclists were evaluated in two days. On the first day, cyclists performed a maximal incremental cycling exercise to measure peak power output, which was used on the second day to define the workload for a constant load time to exhaustion cycling exercise (maximal aerobic power output from day 1. Muscle activation of vastus lateralis (VL, long head of biceps femoris (BF, lateral head of gastrocnemius (GL, and tibialis anterior (TA from the right lower limb was recorded during the time to exhaustion cycling exercise. A series of nine band-pass Butterworth digital filters was used to analyze muscle activity amplitude for each band. The overall amplitude of activation and the high and low frequency components were defined to assess the magnitude of fatigue effects on muscle activity via effect sizes. The profile of the overall muscle activation during the test was analyzed using a second order polynomial, and the variability of the overall bands was analyzed by the coefficient of variation for each muscle in each instant of the test. Substantial reduction in the high frequency components of VL and BF activation was observed. The overall and low frequency bands presented trivial to small changes for all muscles. High relationship between the second order polynomial fitting and muscle activity was found (R2 > 0.89 for all muscles. High variability (~25% was found for muscle activation at the four instants of the fatigue test. Changes in the spectral properties of the EMG signal were only substantial when extreme changes in fatigue state were induced.

  20. A three-dimensional muscle activity imaging technique for assessing pelvic muscle function

    Science.gov (United States)

    Zhang, Yingchun; Wang, Dan; Timm, Gerald W.

    2010-11-01

    A novel multi-channel surface electromyography (EMG)-based three-dimensional muscle activity imaging (MAI) technique has been developed by combining the bioelectrical source reconstruction approach and subject-specific finite element modeling approach. Internal muscle activities are modeled by a current density distribution and estimated from the intra-vaginal surface EMG signals with the aid of a weighted minimum norm estimation algorithm. The MAI technique was employed to minimally invasively reconstruct electrical activity in the pelvic floor muscles and urethral sphincter from multi-channel intra-vaginal surface EMG recordings. A series of computer simulations were conducted to evaluate the performance of the present MAI technique. With appropriate numerical modeling and inverse estimation techniques, we have demonstrated the capability of the MAI technique to accurately reconstruct internal muscle activities from surface EMG recordings. This MAI technique combined with traditional EMG signal analysis techniques is being used to study etiologic factors associated with stress urinary incontinence in women by correlating functional status of muscles characterized from the intra-vaginal surface EMG measurements with the specific pelvic muscle groups that generated these signals. The developed MAI technique described herein holds promise for eliminating the need to place needle electrodes into muscles to obtain accurate EMG recordings in some clinical applications.

  1. Muscle Activation during Gait in Children with Duchenne Muscular Dystrophy.

    Science.gov (United States)

    Ropars, Juliette; Lempereur, Mathieu; Vuillerot, Carole; Tiffreau, Vincent; Peudenier, Sylviane; Cuisset, Jean-Marie; Pereon, Yann; Leboeuf, Fabien; Delporte, Ludovic; Delpierre, Yannick; Gross, Raphaël; Brochard, Sylvain

    2016-01-01

    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. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity.

  2. Muscle Activation during Gait in Children with Duchenne Muscular Dystrophy.

    Directory of Open Access Journals (Sweden)

    Juliette Ropars

    Full Text Available 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. Percentage activation amplitudes of RF, HS and TA were greater throughout the gait cycle in the children with DMD and the timing of GAS activity differed from the control children. Significantly greater muscle coactivation was found in the children with DMD. There were no significant differences between sides. Since the motor command is normal in DMD, the hyper-activity and co-contractions likely compensate for gait instability and muscle weakness, however may have negative consequences on the muscles and may increase the energy cost of gait. Simple rehabilitative strategies such as targeted physical therapies may improve stability and thus the pattern of muscle activity.

  3. The influence of experimentally induced pain on shoulder muscle activity

    DEFF Research Database (Denmark)

    Diederichsen, L.P.; Winther, A.; Dyhre-Poulsen, P.

    2009-01-01

    healthy men (range 22-27 years), with no history of shoulder or cervical problems, were included in the study. Pain was induced by 5% hypertonic saline injections into the supraspinatus muscle or subacromially. Seated in a shoulder machine, subjects performed standardized concentric abduction (0A degrees......Muscle function is altered in painful shoulder conditions. However, the influence of shoulder pain on muscle coordination of the shoulder has not been fully clarified. The aim of the present study was to examine the effect of experimentally induced shoulder pain on shoulder muscle function. Eleven...... muscles. EMG was recorded before pain, during pain and after pain had subsided and pain intensity was continuously scored on a visual analog scale (VAS). During abduction, experimentally induced pain in the supraspinatus muscle caused a significant decrease in activity of the anterior deltoid, upper...

  4. Thoracic posture, shoulder muscle activation patterns and isokinetic ...

    African Journals Online (AJOL)

    Background. Shoulder injuries are the most severe injuries in rugby union players, accounting for almost 20% of injuries related to the sport and resulting in lost playing hours. Objective. To profile the thoracic posture, scapular muscle activation patterns and rotator cuff muscle isokinetic strength of semi-professional

  5. Relationship between sleep stages and nocturnal trapezius muscle activity.

    Science.gov (United States)

    Müller, Christian; Nicoletti, Corinne; Omlin, Sarah; Brink, Mark; Läubli, Thomas

    2015-06-01

    Former studies reported a relationship between increased nocturnal low level trapezius muscle activity and neck or shoulder pain but it has not been explored whether trapezius muscle relaxation is related to sleep stages. The goal of the present study was to investigate whether trapezius muscle activity is related to different sleep stages, as measured by polysomnography. Twenty one healthy subjects were measured on four consecutive nights in their homes, whereas the first night served as adaptation night. The measurements included full polysomnography (electroencephalography (EEG), electrooculography (EOG), electromyography (EMG) and electrocardiography (ECG)), as well as surface EMG of the m. trapezius descendens of the dominant arm. Periods with detectable EMG activity of the trapezius muscle lasted on average 1.5% of the length of the nights and only in four nights it lasted longer than 5% of sleeping time. Neither rest time nor the length of periods with higher activity levels of the trapezius muscle did significantly differ between sleep stages. We found no evidence that nocturnal trapezius muscle activity is markedly moderated by the different sleep stages. Thus the results support that EMG measurements of trapezius muscle activity in healthy subjects can be carried out without concurrent polysomnographic recordings. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Redundancy or heterogeneity in the electric activity of the biceps brachii muscle? Added value of PCA-processed multi-channel EMG muscle activation estimates in a parallel-fibered muscle

    NARCIS (Netherlands)

    Staudenmann, D.; Stegeman, D.F.; van Dieen, J.H.

    2013-01-01

    Conventional bipolar EMG provides imprecise muscle activation estimates due to possibly heterogeneous activity within muscles and due to improper alignment of the electrodes with the muscle fibers. Principal component analysis (PCA), applied on multi-channel monopolar EMG yielded substantial

  7. Muscle atrophy reversed by growth factor activation of satellite cells in a mouse muscle atrophy model.

    Directory of Open Access Journals (Sweden)

    Simon Hauerslev

    Full Text Available Muscular dystrophies comprise a large group of inherited disorders that lead to progressive muscle wasting. We wanted to investigate if targeting satellite cells can enhance muscle regeneration and thus increase muscle mass. We treated mice with hepatocyte growth factor and leukemia inhibitory factor under three conditions: normoxia, hypoxia and during myostatin deficiency. We found that hepatocyte growth factor treatment led to activation of the Akt/mTOR/p70S6K protein synthesis pathway, up-regulation of the myognic transcription factors MyoD and myogenin, and subsequently the negative growth control factor, myostatin and atrophy markers MAFbx and MuRF1. Hypoxia-induced atrophy was partially restored by hepatocyte growth factor combined with leukemia inhibitory factor treatment. Dividing satellite cells were three-fold increased in the treatment group compared to control. Finally, we demonstrated that myostatin regulates satellite cell activation and myogenesis in vivo following treatment, consistent with previous findings in vitro. Our results suggest, not only a novel in vivo pharmacological treatment directed specifically at activating the satellite cells, but also a myostatin dependent mechanism that may contribute to the progressive muscle wasting seen in severely affected patients with muscular dystrophy and significant on-going regeneration. This treatment could potentially be applied to many conditions that feature muscle wasting to increase muscle bulk and strength.

  8. Abdominal muscle activity during a standing long jump.

    Science.gov (United States)

    Okubo, Yu; Kaneoka, Koji; Shiina, Itsuo; Tatsumura, Masaki; Miyakawa, Shumpei

    2013-08-01

    Experimental laboratory study. To measure the activation patterns (onset and magnitude) of the abdominal muscles during a standing long jump using wire and surface electromyography. Activation patterns of the abdominal muscles, especially the deep muscles such as the transversus abdominis (TrA), have yet to be examined during full-body movements such as jumping. Thirteen healthy men participated. Wire electrodes were inserted into the TrA with the guidance of ultrasonography, and surface electrodes were attached to the skin overlying the rectus abdominis (RA) and external oblique (EO). Electromyographic signals and video images were recorded while each subject performed a standing long jump. The jump task was divided into 3 phases: preparation, push-off, and float. For each muscle, activation onset relative to the onset of the RA and normalized muscle activation levels (percent maximum voluntary contraction) were analyzed during each phase. Comparisons between muscles and phases were assessed using 2-way analyses of variance. The onset times of the TrA and EO relative to the onset of the RA were -0.13 ? 0.17 seconds and -0.02 ? 0.07 seconds, respectively. Onset of TrA activation was earlier than that of the EO. The activation levels of all 3 muscles were significantly greater during the push-off phase than during the preparation and float phases. Consistent with previously published trunk-perturbation studies in healthy persons, the TrA was activated prior to the RA and EO. Additionally, the highest muscle activation levels were observed during the push-off phase.

  9. Effects of visually demanding near work on trapezius muscle activity.

    Science.gov (United States)

    Zetterberg, C; Forsman, M; Richter, H O

    2013-10-01

    Poor visual ergonomics is associated with visual and neck/shoulder discomfort, but the relation between visual demands and neck/shoulder muscle activity is unclear. The aims of this study were to investigate whether trapezius muscle activity was affected by: (i) eye-lens accommodation; (ii) incongruence between accommodation and convergence; and (iii) presence of neck/shoulder discomfort. Sixty-six participants (33 controls and 33 with neck pain) performed visually demanding near work under four different trial-lens conditions. Results showed that eye-lens accommodation per se did not affect trapezius muscle activity significantly. However, when incongruence between accommodation and convergence was present, a significant positive relationship between eye-lens accommodation and trapezius muscle activity was found. There were no significant group-differences. It was concluded that incongruence between accommodation and convergence is an important factor in the relation between visually demanding near work and trapezius muscle activity. The relatively low demands on accommodation and convergence in the present study imply that visually demanding near work may contribute to increased muscle activity, and over time to the development of near work related neck/shoulder discomfort. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Interpretation of the function of the striate cortex

    Science.gov (United States)

    Garner, Bernardette M.; Paplinski, Andrew P.

    2000-04-01

    Biological neural networks do not require retraining every time objects move in the visual field. Conventional computer neural networks do not share this shift-invariance. The brain compensates for movements in the head, body, eyes and objects by allowing the sensory data to be tracked across the visual field. The neurons in the striate cortex respond to objects moving across the field of vision as is seen in many experiments. It is proposed, that the neurons in the striate cortex allow continuous angle changes needed to compensate for changes in orientation of the head, eyes and the motion of objects in the field of vision. It is hypothesized that the neurons in the striate cortex form a system that allows for the translation, some rotation and scaling of objects and provides a continuity of objects as they move relative to other objects. The neurons in the striate cortex respond to features which are fundamental to sight, such as orientation of lines, direction of motion, color and contrast. The neurons that respond to these features are arranged on the cortex in a way that depends on the features they are responding to and on the area of the retina from which they receive their inputs.

  11. The striated MR nephrogram, not a reflection of pathology

    Energy Technology Data Exchange (ETDEWEB)

    Trout, Andrew T.; Care, Marguerite M.; Towbin, Alexander J. [Cincinnati Children' s Hospital Medical Center, Department of Radiology - MLC 5031, Cincinnati, OH (United States); Zhang, Bin [Cincinnati Children' s Hospital Medical Center, Division of Biostatistics and Epidemiology, Cincinnati, OH (United States)

    2015-10-15

    We have intermittently observed low signal striations in the kidneys on delayed post-contrast MR exams of the spine. While we suspected these striations were due to concentrated gadolinium, the clinical importance of this finding was uncertain. To describe the striated MR nephrogram (low signal striations in the kidney) and assess its clinical relevance. Retrospective review of delayed post-contrast MRIs of the spine (mean: 45 min after contrast administration). The presence of the striated MR nephrogram was correlated with imaging parameters (field strength, time since contrast), and findings (gadolinium in the bladder, inferior vena cava and aorta diameters) and with clinical factors (history of renal disease, laboratory values). Seven hundred seventy-three exams performed on 229 patients, 8.3 ± 5.3 years of age, were reviewed. The striated MR nephrogram was observed in 102/773 examinations (13.2%) and was present on at least one study in 54/229 patients (23.6%). The presence of striations was associated with the specific magnet on which the exam was performed (P < 0.01) but not with magnet field strength. Serum creatinine was minimally lower in patients with striations (0.43 ± 0.12 vs. 0.49 ± 0.18 mg/dL, P = 0.002), but no other clinical or historical data, including time from contrast administration (P = 0.54), fluid status (P = 0.17) and clinical history of renal disease (P = 0.14), were predictive of the presence of striations. The striated MR nephrogram was observed in 13% of delayed post-contrast MR exams of the spine. Precipitating factors are unclear, but the striated nephrogram does not appear to be a marker of clinically apparent renal dysfunction. (orig.)

  12. Muscle activity and inactivity periods during normal daily life.

    Directory of Open Access Journals (Sweden)

    Olli Tikkanen

    Full Text Available Recent findings suggest that not only the lack of physical activity, but also prolonged times of sedentary behaviour where major locomotor muscles are inactive, significantly increase the risk of chronic diseases. The purpose of this study was to provide details of quadriceps and hamstring muscle inactivity and activity during normal daily life of ordinary people. Eighty-four volunteers (44 females, 40 males, 44.1±17.3 years, 172.3±6.1 cm, 70.1±10.2 kg were measured during normal daily life using shorts measuring muscle electromyographic (EMG activity (recording time 11.3±2.0 hours. EMG was normalized to isometric MVC (EMG(MVC during knee flexion and extension, and inactivity threshold of each muscle group was defined as 90% of EMG activity during standing (2.5±1.7% of EMG(MVC. During normal daily life the average EMG amplitude was 4.0±2.6% and average activity burst amplitude was 5.8±3.4% of EMG(MVC (mean duration of 1.4±1.4 s which is below the EMG level required for walking (5 km/h corresponding to EMG level of about 10% of EMG(MVC. Using the proposed individual inactivity threshold, thigh muscles were inactive 67.5±11.9% of the total recording time and the longest inactivity periods lasted for 13.9±7.3 min (2.5-38.3 min. Women had more activity bursts and spent more time at intensities above 40% EMG(MVC than men (p<0.05. In conclusion, during normal daily life the locomotor muscles are inactive about 7.5 hours, and only a small fraction of muscle's maximal voluntary activation capacity is used averaging only 4% of the maximal recruitment of the thigh muscles. Some daily non-exercise activities such as stair climbing produce much higher muscle activity levels than brisk walking, and replacing sitting by standing can considerably increase cumulative daily muscle activity.

  13. Effects of physical activity and inactivity on muscle fatigue

    Directory of Open Access Journals (Sweden)

    Gregory C. Bogdanis

    2012-05-01

    Full Text Available The aim of this review was to examine the mechanisms by which physical activity and inactivity modify muscle fatigue. It is well known that acute or chronic increases in physical activity result in structural, metabolic, hormonal, neural and molecular adaptations that increase the level of force or power that can be sustained by a muscle. These adaptations depend on the type, intensity and volume of the exercise stimulus, but recent studies have highlighted the role of high intensity, short duration exercise as a time-efficient method to achieve both anaerobic and aerobic/endurance type adaptations. The factors that determine the fatigue profile of a muscle during intense exercise include muscle fibre composition, neuromuscular characteristics high energy metabolite stores, buffering capacity, ionic regulation, capillarization and mitochondrial density. Muscle fiber type transformation during exercise training is usually towards the intermediate type IIA at the expense of both type I and type IIx myosin heavy chain isoforms. High intensity training results in increases of both glycolyic and oxidative enzymes, muscle capilarization, improved phosphocreatine resynthesis and regulation of K+, H+ and lactate ions. Decreases of the habitual activity level due to injury or sedentary lifestyle result in partial or even compete reversal of the adaptations due to previous training, manifested by reductions in fibre cross-sectional area, decreased oxidative capacity and capillarization. Complete immobilization due to injury results in markedly decreased force output and fatigue resistance. Muscle unloading reduces electromyographic activity and causes muscle atrophy and significant decreases in capillarization and oxidative enzymes activity. The last part of the review discusses the beneficial effects of intermittent high intensity exercise training in patients with different health conditions to demonstrate the powerful effect exercise on health and well

  14. Muscle activity and kinematics of forefoot and rearfoot strike runners

    Directory of Open Access Journals (Sweden)

    A.N. Ahn

    2014-06-01

    Conclusion: This earlier and longer relative activation of the plantarflexors likely enhances the capacity for the passive structures of the foot and ankle to store elastic energy, and may also enhance the performance of the active muscle by increasing the storage of elastic strain energy in the cross-bridges and activated titin.

  15. Corticospinal contribution to arm muscle activity during human walking

    DEFF Research Database (Denmark)

    Barthélemy, Dorothy; Nielsen, Jens Bo

    2010-01-01

    inhibitory interneurones, the suppression is in all likelihood caused by removal of a corticospinal contribution to the ongoing EMG activity. The data thus suggest that the motor cortex makes an active contribution, through the corticospinal tract, to the ongoing EMG activity in arm muscles during walking....

  16. Effects of experimental muscle pain on muscle activity and co-ordination during static and dynamic motor function.

    Science.gov (United States)

    Graven-Nielsen, T; Svensson, P; Arendt-Nielsen, L

    1997-04-01

    The relation between muscle pain, muscle activity, and muscle co-ordination is still controversial. The present human study investigates the influence of experimental muscle pain on resting, static, and dynamic muscle activity. In the resting and static experiments, the electromyography (EMG) activity and the contraction force of m. tibialis anterior were assessed before and after injection of 0.5 ml hypertonic saline (5%) into the same muscle. In the dynamic experiment, injections of 0.5 ml hypertonic saline (5%) were performed into either m. tibialis anterior (TA) or m. gastrocnemius (GA) and the muscle activity and co-ordination were investigated during gait on a treadmill by EMG recordings from m. TA and m. GA. At rest no evidence of EMG hyperactivity was found during muscle pain. The maximal voluntary contraction (MVC) during muscle pain was significantly lower than the control condition (P Fibromyalgia and Myofascial Pain. Elsevier, Amsterdam, 1993, pp. 311-327.) which predicts increased activity of antagonistic muscle and decreased activity of agonistic muscle during experimental and clinical muscle pain.

  17. Impaired glycogen synthase activity and mitochondrial dysfunction in skeletal muscle

    DEFF Research Database (Denmark)

    Højlund, Kurt; Beck-Nielsen, Henning

    2006-01-01

    Insulin resistance in skeletal muscle is a major hallmark of type 2 diabetes and an early detectable abnormality in the development of this disease. The cellular mechanisms of insulin resistance include impaired insulin-mediated muscle glycogen synthesis and increased intramyocellular lipid content......, whereas impaired insulin activation of muscle glycogen synthase represents a consistent, molecular defect found in both type 2 diabetic and high-risk individuals. Despite several studies of the insulin signaling pathway believed to mediate dephosphorylation and hence activation of glycogen synthase......, the molecular mechanisms responsible for this defect remain unknown. Recently, the use of phospho-specific antibodies in human diabetic muscle has revealed hyperphosphorylation of glycogen synthase at sites not regulated by the classical insulin signaling pathway. In addition, novel approaches such as gene...

  18. Immunocytochemical electron microscopic study and western blot analysis of paramyosin in different invertebrate muscle cell types of the fruit fly Drosophila melanogaster, the earthworm Eisenia foetida, and the snail Helix aspersa.

    Science.gov (United States)

    Royuela, M; García-Anchuelo, R; Arenas, M I; Cervera, M; Fraile, B; Paniagua, R

    1996-04-01

    The presence and distribution pattern of paramyosin have been examined in different invertebrate muscle cell types by means of Western blot analysis and electron microscopy immunogold labelling. The muscles studied were: transversely striated muscle with continuous Z lines (flight muscle from Drosophila melanogaster), transversely striated muscle with discontinuous Z lines (heart muscle from the snail Helix aspersa), obliquely striated body wall muscle from the earthworm Eisenia foetida, and smooth muscles (retractor muscle from the snail and pseudoheart outer muscular layer from the earthworm). Paramyosin-like immunoreactivity was localized in thick filaments of all muscles studied. Immunogold particle density was similar along the whole thick filament length in insect flight muscle but it predominated in filament tips of fusiform thick filaments in both snail heart and earthworm body wall musculature when these filaments were observed in longitudinal sections. In obliquely sectioned thick filaments, immunolabelling was more abundant at the sites where filaments disappeared from the section. These results agree with the notion that paramyosin extended along the whole filament length, but that it can only be immunolabelled when it is not covered by myosin. In all muscles examined, immunolabelling density was lower in cross-sectioned myofilaments than in longitudinally sectioned myofilaments. This suggests that paramyosin does not form a continuous filament. The results of a semiquantitative analysis of paramyosin-like immunoreactivity indicated that it was more abundant in striated than in smooth muscles, and that, within striated muscles, transversely striated muscles contain more paramyosin than obliquely striated muscles.

  19. Scapular kinematics and muscle activities during pushing tasks.

    Science.gov (United States)

    Huang, Chun-Kai; Siu, Ka-Chun; Lien, Hen-Yu; Lee, Yun-Ju; Lin, Yang-Hua

    2013-01-01

    Pushing tasks are functional activities of daily living. However, shoulder complaints exist among workers exposed to regular pushing conditions. It is crucial to investigate the control of shoulder girdles during pushing tasks. The objective of the study was to demonstrate scapular muscle activities and motions on the dominant side during pushing tasks and the relationship between scapular kinematics and muscle activities in different pushing conditions. Thirty healthy adults were recruited to push a four-wheel cart in six pushing conditions. The electromyographic signals of the upper trapezius (UT) and serratus anterior (SA) muscles were recorded. A video-based system was used for measuring the movement of the shoulder girdle and scapular kinematics. Differences in scapular kinematics and muscle activities due to the effects of handle heights and weights of the cart were analyzed using two-way ANOVA with repeated measures. The relationships between scapular kinematics and muscle activities were examined by Pearson's correlation coefficients. The changes in upper trapezius and serratus anterior muscle activities increased significantly with increased pushing weights in the one-step pushing phase. The UT/SA ratio on the dominant side decreases significantly with increased handle heights in the one-step pushing phase. The changes in upward rotation, lateral slide and elevation of the scapula decreased with increased pushing loads in the trunk-forward pushing phase. This study indicated that increased pushing loads result in decreased motions of upward rotation, lateral slide and elevation of the scapula; decreased handle heights result in relatively increased activities of the serratus anterior muscles during pushing tasks.

  20. T2 mapping of muscle activity using ultrafast imaging

    International Nuclear Information System (INIS)

    Tawara, Noriyuki; Nitta, Osamu; Kuruma, Hironobu; Niitsu, Mamoru; Itoh, Akiyoshi

    2011-01-01

    Measuring exercise-induced muscle activity is essential in sports medicine. Previous studies proposed measuring transverse relaxation time (T 2 ) using muscle functional magnetic resonance imaging (mfMRI) to map muscle activity. However, mfMRI uses a spin-echo (SE) sequence that requires several minutes for acquisition. We evaluated the feasibility of T 2 mapping of muscle activity using ultrafast imaging, called fast-acquired mfMRI (fast-mfMRI), to reduce image acquisition time. The current method uses 2 pulse sequences, spin-echo echo-planar imaging (SE-EPI) and true fast imaging with steady precession (TrueFISP). SE-EPI images are used to calculate T 2 , and TrueFISP images are used to obtain morphological information. The functional image is produced by subtracting the image of muscle activity obtained using T 2 at rest from that produced after exercise. Final fast-mfMRI images are produced by fusing the functional images with the morphologic images. Ten subjects repeated ankle plantar flexion 200 times. In the fused images, the areas of activated muscle in the fast-mfMRI and SE-EPI images were identical. The geometric location of the fast-mfMRI did not differ between the morphologic and functional images. Morphological and functional information from fast-mfMRI can be applied to the human trunk, which requires limited scan duration. The difference obtained by subtracting T 2 at rest from T 2 after exercise can be used as a functional image of muscle activity. (author)

  1. Muscle Activity Adaptations to Spinal Tissue Creep in the Presence of Muscle Fatigue

    Science.gov (United States)

    Nougarou, François

    2016-01-01

    Aim The aim of this study was to identify adaptations in muscle activity distribution to spinal tissue creep in presence of muscle fatigue. Methods Twenty-three healthy participants performed a fatigue task before and after 30 minutes of passive spinal tissue deformation in flexion. Right and left erector spinae activity was recorded using large-arrays surface electromyography (EMG). To characterize muscle activity distribution, dispersion was used. During the fatigue task, EMG amplitude root mean square (RMS), median frequency and dispersion in x- and y-axis were compared before and after spinal creep. Results Important fatigue-related changes in EMG median frequency were observed during muscle fatigue. Median frequency values showed a significant main creep effect, with lower median frequency values on the left side under the creep condition (p≤0.0001). A significant main creep effect on RMS values was also observed as RMS values were higher after creep deformation on the right side (p = 0.014); a similar tendency, although not significant, was observed on the left side (p = 0.06). A significant creep effects for x-axis dispersion values was observed, with higher dispersion values following the deformation protocol on the left side (p≤0.001). Regarding y-axis dispersion values, a significant creep x fatigue interaction effect was observed on the left side (p = 0.016); a similar tendency, although not significant, was observed on the right side (p = 0.08). Conclusion Combined muscle fatigue and creep deformation of spinal tissues led to changes in muscle activity amplitude, frequency domain and distribution. PMID:26866911

  2. Nerve–muscle activation by rotating permanent magnet configurations

    Science.gov (United States)

    Nicholson, Graham M.

    2016-01-01

    Key points The standard method of magnetic nerve activation using pulses of high current in coils has drawbacks of high cost, high electrical power (of order 1 kW), and limited repetition rate without liquid cooling.Here we report a new technique for nerve activation using high speed rotation of permanent magnet configurations, generating a sustained sinusoidal electric field using very low power (of order 10 W).A high ratio of the electric field gradient divided by frequency is shown to be the key indicator for nerve activation at high frequencies.Activation of the cane toad sciatic nerve and attached gastrocnemius muscle was observed at frequencies as low as 180 Hz for activation of the muscle directly and 230 Hz for curved nerves, but probably not in straight sections of nerve.These results, employing the first prototype device, suggest the opportunity for a new class of small low‐cost magnetic nerve and/or muscle stimulators. Abstract Conventional pulsed current systems for magnetic neurostimulation are large and expensive and have limited repetition rate because of overheating. Here we report a new technique for nerve activation, namely high‐speed rotation of a configuration of permanent magnets. Analytical solutions of the cable equation are derived for the oscillating electric field generated, which has amplitude proportional to the rotation speed. The prototype device built comprised a configuration of two cylindrical magnets with antiparallel magnetisations, made to rotate by interaction between the magnets’ own magnetic field and three‐phase currents in coils mounted on one side of the device. The electric field in a rectangular bath placed on top of the device was both numerically evaluated and measured. The ratio of the electric field gradient on frequency was approximately 1 V m−2 Hz−1 near the device. An exploratory series of physiological tests was conducted on the sciatic nerve and attached gastrocnemius muscle of the cane toad

  3. Nerve-muscle activation by rotating permanent magnet configurations.

    Science.gov (United States)

    Watterson, Peter A; Nicholson, Graham M

    2016-04-01

    The standard method of magnetic nerve activation using pulses of high current in coils has drawbacks of high cost, high electrical power (of order 1 kW), and limited repetition rate without liquid cooling. Here we report a new technique for nerve activation using high speed rotation of permanent magnet configurations, generating a sustained sinusoidal electric field using very low power (of order 10 W). A high ratio of the electric field gradient divided by frequency is shown to be the key indicator for nerve activation at high frequencies. Activation of the cane toad sciatic nerve and attached gastrocnemius muscle was observed at frequencies as low as 180 Hz for activation of the muscle directly and 230 Hz for curved nerves, but probably not in straight sections of nerve. These results, employing the first prototype device, suggest the opportunity for a new class of small low-cost magnetic nerve and/or muscle stimulators. Conventional pulsed current systems for magnetic neurostimulation are large and expensive and have limited repetition rate because of overheating. Here we report a new technique for nerve activation, namely high-speed rotation of a configuration of permanent magnets. Analytical solutions of the cable equation are derived for the oscillating electric field generated, which has amplitude proportional to the rotation speed. The prototype device built comprised a configuration of two cylindrical magnets with antiparallel magnetisations, made to rotate by interaction between the magnets' own magnetic field and three-phase currents in coils mounted on one side of the device. The electric field in a rectangular bath placed on top of the device was both numerically evaluated and measured. The ratio of the electric field gradient on frequency was approximately 1 V m(-2) Hz(-1) near the device. An exploratory series of physiological tests was conducted on the sciatic nerve and attached gastrocnemius muscle of the cane toad (Bufo marinus). Activation was

  4. The effect of whole body vibration exercise on muscle activation ...

    African Journals Online (AJOL)

    African Journal for Physical Activity and Health Sciences ... The effect of whole body vibration exercise (WBV) on muscle activation has recently been a topic for discussion amongst some researchers. ... Participants then performed two different exercises: standing calf raises and prone bridging, without and with WBV.

  5. Active biofeedback changes the spatial distribution of upper trapezius muscle activity during computer work

    DEFF Research Database (Denmark)

    Samani, Afshin; Holtermann, Andreas; Søgaard, Karen

    2010-01-01

    The aim of this study was to investigate the spatio-temporal effects of advanced biofeedback by inducing active and passive pauses on the trapezius activity pattern using high-density surface electromyography (HD-EMG). Thirteen healthy male subjects performed computer work with superimposed...... benefit of superimposed muscle contraction in relation to the spatial organization of muscle activity during computer work....

  6. Ficus Deltoidea Enhance Glucose Uptake Activity in Cultured Muscle Cells

    International Nuclear Information System (INIS)

    Zainah Adam; Shafii Khamis; Amin Ismail; Muhajir Hamid

    2015-01-01

    Ficus deltoidea or locally known as Mas cotek is one of the common medicinal plants used in Malaysia. Our previous studies showed that this plant have blood glucose lowering effect. Glucose uptake into muscle and adipocytes cells is one of the known mechanisms of blood glucose lowering effect. This study was performed to evaluate the effect of Ficus deltoidea on glucose uptake activity into muscle cells. The cells were incubated with Ficus deltoidea extracts either alone or combination with insulin. Amount of glucose uptake by L6 myotubes was determined using glucose tracer, 2-deoxy-(1- 3 H 1 )-glucose. The results showed that Ficus deltoidea extracts at particular doses enhanced basal or insulin-mediated glucose uptake into muscle cells significantly. Hot aqueous extract enhanced glucose uptake at the low concentration (10 μg/ ml) whereas methanolic extract enhanced glucose uptake at low and high concentrations. Methanolic extract also mimicked insulin activity during enhancing glucose uptake into L^ muscle cells. Glucose uptake activity of Ficus deltoidea could be attributed by the phenolic compound presence in the plant. This study had shown that Ficus deltoidea has the ability to enhance glucose uptake into muscle cells which is partly contributed the antidiabetic activity of this plant. (author)

  7. Force steadiness, muscle activity, and maximal muscle strength in subjects with subacromial impingement syndrome

    DEFF Research Database (Denmark)

    Bandholm, Thomas; Rasmussen, Lars; Aagaard, Per

    2006-01-01

    physically active in spite of shoulder pain and nine healthy matched controls were examined to determine isometric and isokinetic submaximal shoulder-abduction force steadiness at target forces corresponding to 20%, 27.5%, and 35% of the maximal shoulder abductor torque, and maximal shoulder muscle strength......We investigated the effects of the subacromial impingement syndrome (SIS) on shoulder sensory-motor control and maximal shoulder muscle strength. It was hypothesized that both would be impaired due to chronic shoulder pain associated with the syndrome. Nine subjects with unilateral SIS who remained...

  8. A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups

    Science.gov (United States)

    Randolph, Matthew E.; Pavlath, Grace K.

    2015-01-01

    The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease. PMID:26500547

  9. Contributions of central command and muscle feedback to sympathetic nerve activity in contracting human skeletal muscle

    Directory of Open Access Journals (Sweden)

    Daniel eBoulton

    2016-05-01

    Full Text Available During voluntary contractions, muscle sympathetic nerve activity (MSNA to contracting muscles increases in proportion to force but the underlying mechanisms are not clear. To shed light on these mechanisms, particularly the influences of central command and muscle afferent feedback, the present study tested the hypothesis that MSNA is greater during voluntary compared with electrically-evoked contractions. Seven male subjects performed a series of 1-minute isometric dorsiflexion contractions (left leg separated by 2-minute rest periods, alternating between voluntary and electrically-evoked contractions at similar forces (5-10 % of maximum. MSNA was recorded continuously (microneurography from the left peroneal nerve and quantified from cardiac-synchronised, negative-going spikes in the neurogram. Compared with pre-contraction values, MSNA increased by 51 ± 34 % (P 0.05. MSNA analysed at 15-s intervals revealed that this effect of voluntary contraction appeared 15-30 s after contraction onset (P < 0.01, remained elevated until the end of contraction, and disappeared within 15 s after contraction. These findings suggest that central command, and not feedback from contracting muscle, is the primary mechanism responsible for the increase in MSNA to contracting muscle. The time-course of MSNA suggests that there is a longer delay in the onset of this effect compared with its cessation after contraction.

  10. Muscle Activity during Dryland Swimming while Wearing a Triathlon Wetsuit

    Directory of Open Access Journals (Sweden)

    Ciro Agnelli

    2018-01-01

    Full Text Available Background: Triathletes typically wear a wetsuit during the swim portion of an event, but it is not clear if muscle activity is influenced by wearing a wetsuit. Purpose: To investigate if shoulder muscle activity was influenced by wearing a full-sleeve wetsuit vs. no wetsuit during dryland swimming. Methods: Participants (n=10 males; 179.1±13.2 cm; 91.2±7.25 kg; 45.6±10.5 years completed two dry land swimming conditions on a swim ergometer: No Wetsuit (NW and with Wetsuit (W. Electromyography (EMG of four upper extremity muscles was recorded (Noraxon telemetry EMG, 500 Hz during each condition: Trapezius (TRAP, Triceps (TRI, Anterior Deltoid (AD and Posterior Deltoid (PD. Each condition lasted 90 seconds with data collected during the last 60 seconds. Resistance setting was self-selected and remained constant for both conditions. Stroke rate was controlled at 60 strokes per minute by having participants match a metronome. Average (AVG and Root Mean Square (RMS EMG were calculated over 45 seconds and each were compared between conditions using a paired t-test (α=0.05 for each muscle. Results: PD and AD AVG and RMS EMG were each greater (on average 40.0% and 66.8% greater, respectively during W vs. NW (p0.05. Conclusion: The greater PD and AD muscle activity while wearing a wetsuit might affect swimming performance and /or stroke technique on long distance event.

  11. CHANGES IN QUADRICEPS MUSCLE ACTIVITY DURING SUSTAINED RECREATIONAL ALPINE SKIING

    Directory of Open Access Journals (Sweden)

    Josef Kröll

    2011-03-01

    Full Text Available During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing and the last two (POSTskiing runs was measured from the vastus lateralis (VL and rectus femoris (RF using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs

  12. Multivariable Dynamic Ankle Mechanical Impedance With Active Muscles

    Science.gov (United States)

    Lee, Hyunglae; Krebs, Hermano Igo; Hogan, Neville

    2015-01-01

    Multivariable dynamic ankle mechanical impedance in two coupled degrees-of-freedom (DOFs) was quantified when muscles were active. Measurements were performed at five different target activation levels of tibialis anterior and soleus, from 10% to 30% of maximum voluntary contraction (MVC) with increments of 5% MVC. Interestingly, several ankle behaviors characterized in our previous study of the relaxed ankle were observed with muscles active: ankle mechanical impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness; stiffness was greater in the sagittal plane than in the frontal plane at all activation conditions for all subjects; and the coupling between dorsiflexion–plantarflexion and inversion–eversion was small—the two DOF measurements were well explained by a strictly diagonal impedance matrix. In general, ankle stiffness increased linearly with muscle activation in all directions in the 2-D space formed by the sagittal and frontal planes, but more in the sagittal than in the frontal plane, resulting in an accentuated “peanut shape.” This characterization of young healthy subjects’ ankle mechanical impedance with active muscles will serve as a baseline to investigate pathophysiological ankle behaviors of biomechanically and/or neurologically impaired patients. PMID:25203497

  13. Inactivation of the infragranular striate cortex broadens orientation tuning of supragranular visual neurons in the cat.

    Science.gov (United States)

    Allison, J D; Bonds, A B

    1994-01-01

    Intracortical inhibition is believed to enhance the orientation tuning of striate cortical neurons, but the origin of this inhibition is unclear. To examine the possible influence of ascending inhibitory projections from the infragranular layers of striate cortex on the orientation selectivity of neurons in the supragranular layers, we measured the spatiotemporal response properties of 32 supragranular neurons in the cat before, during, and after neural activity in the infragranular layers beneath the recorded cells was inactivated by iontophoretic administration of GABA. During GABA iontophoresis, the orientation tuning bandwidth of 15 (46.9%) supragranular neurons broadened as a result of increases in response amplitude to stimuli oriented about +/- 20 degrees away from the preferred stimulus angle. The mean (+/- SD) baseline orientation tuning bandwidth (half width at half height) of these neurons was 13.08 +/- 2.3 degrees. Their mean tuning bandwidth during inactivation of the infragranular layers increased to 19.59 +/- 2.54 degrees, an increase of 49.7%. The mean percentage increase in orientation tuning bandwidth of the individual neurons was 47.4%. Four neurons exhibited symmetrical changes in their orientation tuning functions, while 11 neurons displayed asymmetrical changes. The change in form of the orientation tuning functions appeared to depend on the relative vertical alignment of the recorded neuron and the infragranular region of inactivation. Neurons located in close vertical register with the inactivated infragranular tissue exhibited symmetric changes in their orientation tuning functions. The neurons exhibiting asymmetric changes in their orientation tuning functions were located just outside the vertical register. Eight of these 11 neurons also demonstrated a mean shift of 6.67 +/- 5.77 degrees in their preferred stimulus orientation. The magnitude of change in the orientation tuning functions increased as the delivery of GABA was prolonged

  14. Scapular muscle activity in a variety of plyometric exercises.

    Science.gov (United States)

    Maenhout, Annelies; Benzoor, Maya; Werin, Maria; Cools, Ann

    2016-04-01

    Plyometric shoulder exercises are commonly used to progress from slow analytical strength training to more demanding high speed power training in the return to play phase after shoulder injury. The aim of this study was first, to investigate scapular muscle activity in plyometric exercises to support exercise selection in practice and second, to enhance understanding of how scapular muscles are recruited during the back and forth movement phase of these exercises. Thirty-two healthy subjects performed 10 plyometric exercises while surface EMG-activity of the scapular muscles (upper (UT), middle (MT) and lower trapezius (LT) and serratus anterior (SA)) was registered. A high speed camera tracked start and end of the back and forth movement. Mean scapular EMG activity during the 10 exercises ranged from 14.50% to 76.26%MVC for UT, from 15.19% to 96.55%MVC for MT, from 13.18% to 94.35%MVC for LT and from 13.50% to 98.50%MVC for SA. Anova for repeated measures showed significant differences in scapular muscle activity between exercises (pPlyometric shoulder exercises require moderate (31-60%MVC) to high (>60%MVC) scapular muscle activity. Highest MT/LT activity was present in prone plyometric external rotation and flexion. Highest SA activity was found in plyometric external rotation and flexion with Xco and plyometric push up on Bosu. Specific exercises can be selected that recruit minimal levels of UT activity (plyometric external rotation and horizontal abduction or plyometric push up on the Bosu. The results of this study support exercise selection for clinical practice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Trunk muscle activity increases with unstable squat movements.

    Science.gov (United States)

    Anderson, Kenneth; Behm, David G

    2005-02-01

    The objective of this study was to determine differences in electromyographic (EMG) activity of the soleus (SOL), vastus lateralis (VL), biceps femoris (BF), abdominal stabilizers (AS), upper lumbar erector spinae (ULES), and lumbo-sacral erector spinae (LSES) muscles while performing squats of varied stability and resistance. Stability was altered by doing the squat movement on a Smith machine, a free squat, and while standing on two balance discs. Fourteen male subjects performed the movements. Activities of the SOL, AS, ULES, and LSES were highest during the unstable squat and lowest with the Smith machine protocol (p squats on unstable surfaces may permit a training adaptation of the trunk muscles responsible for supporting the spinal column (i.e., erector spinae) as well as the muscles most responsible for maintaining posture (i.e., SOL).

  16. Patterns of arm muscle activation involved in octopus reaching movements.

    Science.gov (United States)

    Gutfreund, Y; Flash, T; Fiorito, G; Hochner, B

    1998-08-01

    The extreme flexibility of the octopus arm allows it to perform many different movements, yet octopuses reach toward a target in a stereotyped manner using a basic invariant motor structure: a bend traveling from the base of the arm toward the tip (Gutfreund et al., 1996a). To study the neuronal control of these movements, arm muscle activation [electromyogram (EMG)] was measured together with the kinematics of reaching movements. The traveling bend is associated with a propagating wave of muscle activation, with maximal muscle activation slightly preceding the traveling bend. Tonic activation was occasionally maintained afterward. Correlation of the EMG signals with the kinematic variables (velocities and accelerations) reveals that a significant part of the kinematic variability can be explained by the level of muscle activation. Furthermore, the EMG level measured during the initial stages of movement predicts the peak velocity attained toward the end of the reaching movement. These results suggest that feed-forward motor commands play an important role in the control of movement velocity and that simple adjustment of the excitation levels at the initial stages of the movement can set the velocity profile of the whole movement. A simple model of octopus arm extension is proposed in which the driving force is set initially and is then decreased in proportion to arm diameter at the bend. The model qualitatively reproduces the typical velocity profiles of octopus reaching movements, suggesting a simple control mechanism for bend propagation in the octopus arm.

  17. Molecular mechanism by which AMP-activated protein kinase activation promotes glycogen accumulation in muscle

    DEFF Research Database (Denmark)

    Hunter, Roger W; Treebak, Jonas Thue; Wojtaszewski, Jørgen

    2011-01-01

    AND METHODS We recently generated knock-in mice in which wild-type muscle GS was replaced by a mutant (Arg582Ala) that could not be activated by glucose-6-phosphate (G6P), but possessed full catalytic activity and could still be activated normally by dephosphorylation. Muscles from GS knock-in or transgenic......-insensitive GS knock-in mice, although AICAR-stimulated AMPK activation, glucose transport, and total glucose utilization were normal. CONCLUSIONS We provide genetic evidence that AMPK activation promotes muscle glycogen accumulation by allosteric activation of GS through an increase in glucose uptake...

  18. Effects of pO2 on the activation of skeletal muscle ryanodine receptors by NO: a cautionary note.

    Science.gov (United States)

    Cheong, Eunji; Tumbev, Vassil; Stoyanovsky, Detcho; Salama, Guy

    2005-11-01

    Eu et al., reported that O2 dynamically controls the redox state of 6-8 out of 50 thiols per skeletal ryanodine receptor (RyR1) subunit and thereby tunes the response of Ca2+-release channels to authentic nitric oxide (NO) [J.P. Eu, J. Sun, L. Xu, J.S. Stamler, G. Meissner, The skeletal muscle calcium release channel: coupled O2 sensor and NO signaling functions, Cell 102 (2000) 499-509]. A role for O2 was based on the observation that RyR1 can be activated by submicromolar NO at physiological ( approximately 10 mmHg) but not ambient (approximately 150 mmHg) pO2. At ambient pO2, these critical thiols were oxidized but incubation at low pO2 reset the redox state of these thiols, closed RyR1 channels and made these thiols available for nitrosation by low NO concentrations. Eu et al., postulated the existence of a redox/O2sensor that couples channel activity to NO and pO2 and explained that "the nature of the 'redox/O2 sensor' that couples channel activity to intracellular redox chemistry is a mystery". Here, we re-examined the effect of pO2 on RyR1 and find that incubation of RyR1 at low pO2 did not alter channel activity and NO (0.5-50 microM) failed to activate RyR1 despite a wide range of pO2 pre-incubation conditions. We show that low levels of NO do not activate RyR1, do not reverse the inhibition of RyR1 by calmodulin (CaM) even at physiological pO2. Similarly, the pre-incubation of SR vesicles in low pO2 (for 10-80 min) did not inhibit channel activity or sensitization of RyR1 to NO. We discuss the significance of these findings and propose that caution should be taken when considering a role for pO2 and nitrosation by NO as mechanisms that tune RyRs in striated muscles.

  19. Muscle Activity during Unilateral Vs. Bilateral Battle Rope Exercises

    DEFF Research Database (Denmark)

    Calatayud, J.; Martin, F.; Colado, J. C.

    2015-01-01

    Calatayud, J, Martin, F, Colado, JC, Benitez, JC, Jakobsen, MD, and Andersen, LL. Muscle activity during unilateral vs. bilateral battle rope exercises. J Strength Cond Res 29(10): 2854-2859, 2015High training intensity is important for efficient strength gains. Although battle rope training is m...

  20. Nutritional strategies of physically active subjects with muscle dysmorphia.

    Science.gov (United States)

    Contesini, Nadir; Adami, Fernando; Blake, Márcia de-Toledo; Monteiro, Carlos Bm; Abreu, Luiz C; Valenti, Vitor E; Almeida, Fernando S; Luciano, Alexandre P; Cardoso, Marco A; Benedet, Jucemar; de Assis Guedes de Vasconcelos, Francisco; Leone, Claudio; Frainer, Deivis Elton Schlickmann

    2013-05-26

    The aim of this study was to identify dietary strategies for physically active individuals with muscle dysmorphia based on a systematic literature review. References were included if the study population consisted of adults over 18 years old who were physically active in fitness centers. We identified reports through an electronic search ofScielo, Lilacs and Medline using the following keywords: muscle dysmorphia, vigorexia, distorted body image, and exercise. We found eight articles in Scielo, 17 in Medline and 12 in Lilacs. Among the total number of 37 articles, only 17 were eligible for inclusion in this review. The results indicated that the feeding strategies used by physically active individuals with muscle dysmorphia did not include planning or the supervision of a nutritionist. Diet included high protein and low fat foods and the ingestion of dietary and ergogenic supplements to reduce weight. Physically active subjects with muscle dysmorphia could benefit from the help of nutritional professionals to evaluate energy estimation, guide the diet and its distribution in macronutrient and consider the principle of nutrition to functional recovery of the digestive process, promote liver detoxification, balance and guide to organic adequate intake of supplemental nutrients and other substances.

  1. Changes in Quadriceps Muscle Activity During Sustained Recreational Alpine Skiing

    Science.gov (United States)

    Kröll, Josef; Müller, Erich; Seifert, John G.; Wakeling, James M.

    2011-01-01

    During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing) and the last two (POSTskiing) runs was measured from the vastus lateralis (VL) and rectus femoris (RF) using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination) within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs. Key points The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF. General muscular fatigue, where additional specific fibers have to be recruited due to the reduced power output of other fibers, did not occur. A modified skiing style towards a less functional and hence more uncontrolled skiing technique seems to be a key

  2. Mapping Muscles Activation to Force Perception during Unloading.

    Directory of Open Access Journals (Sweden)

    Simone Toma

    Full Text Available It has been largely proved that while judging a force humans mainly rely on the motor commands produced to interact with that force (i.e., sense of effort. Despite of a large bulk of previous investigations interested in understanding the contributions of the descending and ascending signals in force perception, very few attempts have been made to link a measure of neural output (i.e., EMG to the psychophysical performance. Indeed, the amount of correlation between EMG activity and perceptual decisions can be interpreted as an estimate of the contribution of central signals involved in the sensation of force. In this study we investigated this correlation by measuring the muscular activity of eight arm muscles while participants performed a quasi-isometric force detection task. Here we showed a method to quantitatively describe muscular activity ("muscle-metric function" that was directly comparable to the description of the participants' psychophysical decisions about the stimulus force. We observed that under our experimental conditions, muscle-metric absolute thresholds and the shape of the muscle-metric curves were closely related to those provided by the psychophysics. In fact a global measure of the muscles considered was able to predict approximately 60% of the perceptual decisions total variance. Moreover the inter-subjects differences in psychophysical sensitivity showed high correlation with both participants' muscles sensitivity and participants' joint torques. Overall, our findings gave insights into both the role played by the corticospinal motor commands while performing a force detection task and the influence of the gravitational muscular torque on the estimation of vertical forces.

  3. [Central muscle relaxant activities of 2-methyl-3-aminopropiophenone derivatives].

    Science.gov (United States)

    Kontani, H; Mano, A; Koshiura, R; Yamazaki, M; Shimada, Y; Oshita, M; Morikawa, K; Kato, H; Ito, Y

    1987-02-01

    In this experiment, we synthetized new 2-methyl-3-aminopropiophenone (MP) derivatives, whose structure is known to have central muscle relaxant activities, and quinolizidine and indan . tetralin derivatives derived from MP by cyclization, and we investigated the central muscle relaxant activity. Among the quinolizidine derivatives, there was a very strong central depressant agent, trans (3H, 9aH)-3-(p-chloro) benzoyl-quinolizidine (HSR-740), and among the indan . tetralin derivatives, there was an excitant agents, trans (1H, 2H)-5-methoxy-3, 3-dimethyl-2-piperidinomethyl indan-1-ol (HSR-719). From the results, these derivatives were not considered to be adequate for central muscle relaxant. Among the MP derivatives, (4'-chloro-2'-methoxy-3-piperidino) propiophenone HCl (HSR-733) and (4'-ethyl-2-methyl-3-pyrrolidino) propiophenone HCl (HSR-770) strongly inhibited the cooperative movement in the rotating rod method using mice, and it exerted almost the same depressant activity on the cross extensor reflex using alpha-chloralose anesthetized rats. However, the inhibitory effects of HSR-733 on the anemic decerebrate rigidity and the rigidity induced by intracollicular decerebration in rats were weaker than those of HSR-770 and eperisone. In spinal cats, at a low dose (5 mg/kg, i.v.), HSR-733 depressed monosynaptic and dorsal root reflex potentials as compared with polysynaptic reflex potentials, and inhibitory effects of HSR-733 on these three reflex potentials were more potent than those of eperisone and HSR-770. Although HSR-770 acts on the spinal cord and supraspinal level on which eperisone has been reported to act, HSR-733 may mainly act on the spinal cord. These results indicate that the MP derivative with a 2-methyl group may be suitable as a central muscle relaxant. HSR-770, which has equipotent muscle relaxant activity to eperisone, exerted strong inhibitory effects on oxotremorine-induced tremor and weak inhibitory effects on spontaneous motor activity in the

  4. Influence of muscle groups' activation on proximal femoral growth tendency.

    Science.gov (United States)

    Yadav, Priti; Shefelbine, Sandra J; Pontén, Eva; Gutierrez-Farewik, Elena M

    2017-12-01

    Muscle and joint contact force influence stresses at the proximal growth plate of the femur and thus bone growth, affecting the neck shaft angle (NSA) and femoral anteversion (FA). This study aims to illustrate how different muscle groups' activation during gait affects NSA and FA development in able-bodied children. Subject-specific femur models were developed for three able-bodied children (ages 6, 7, and 11 years) using magnetic resonance images. Contributions of different muscle groups-hip flexors, hip extensors, hip adductors, hip abductors, and knee extensors-to overall hip contact force were computed. Specific growth rate for the growth plate was computed, and the growth was simulated in the principal stress direction at each element in the growth front. The predicted growth indicated decreased NSA and FA (of about [Formula: see text] over a four-month period) for able-bodied children. Hip abductors contributed the most, and hip adductors, the least, to growth rate. All muscles groups contributed to a decrease in predicted NSA ([Formula: see text]0.01[Formula: see text]-0.04[Formula: see text] and FA ([Formula: see text]0.004[Formula: see text]-[Formula: see text]), except hip extensors and hip adductors, which showed a tendency to increase the FA ([Formula: see text]0.004[Formula: see text]-[Formula: see text]). Understanding influences of different muscle groups on long bone growth tendency can help in treatment planning for growing children with affected gait.

  5. Syndrome of Continuous Muscle Fibre Activity

    African Journals Online (AJOL)

    1974-08-10

    Aug 10, 1974 ... A period of electrical silence follows each period of strenuous activity and .... the cell during this period of stimulation. Rises in intra- cellular Na+ .... and brain stem origin, but may be a peripheral manifesta- tion of a similar ...

  6. Muscle Co-activation: Definitions, Mechanisms, and Functions.

    Science.gov (United States)

    Latash, Mark L

    2018-03-28

    The phenomenon of agonist-antagonist muscle co-activation is discussed with respect to its consequences for movement mechanics (such as increasing joint apparent stiffness, facilitating faster movements, and effects on action stability), implication for movement optimization, and involvement of different neurophysiological structures. Effects of co-activation on movement stability are ambiguous and depend on the effector representing a kinematic chain with a fixed origin or free origin. Further, co-activation is discussed within the framework of the equilibrium-point hypothesis and the idea of hierarchical control with spatial referent coordinates. Relations of muscle co-activation to changes in one of the basic commands, the c-command, are discussed and illustrated. A hypothesis is suggested that agonist-antagonist co-activation reflects a deliberate neural control strategy to preserve effector-level control and avoid making it degenerate and facing the necessity to control at the level of signals to individual muscles. This strategy, in particular, allows stabilizing motor actions by co-varied adjustments in spaces of control variables. This hypothesis is able to account for higher levels of co-activation in young healthy persons performing challenging tasks and across various populations with movement impairments.

  7. Lower Extremity Muscle Activity During a Women's Overhand Lacrosse Shot

    Directory of Open Access Journals (Sweden)

    Millard Brianna M.

    2014-07-01

    Full Text Available The purpose of this study was to describe lower extremity muscle activity during the lacrosse shot. Participants (n=5 females, age 22±2 years, body height 162.6±15.2 cm, body mass 63.7±23.6 kg were free from injury and had at least one year of lacrosse experience. The lead leg was instrumented with electromyography (EMG leads to measure muscle activity of the rectus femoris (RF, biceps femoris (BF, tibialis anterior (TA, and medial gastrocnemius (GA. Participants completed five trials of a warm-up speed shot (Slow and a game speed shot (Fast. Video analysis was used to identify the discrete events defining specific movement phases. Full-wave rectified data were averaged per muscle per phase (Crank Back Minor, Crank Back Major, Stick Acceleration, Stick Deceleration. Average EMG per muscle was analyzed using a 4 (Phase x 2 (Speed ANOVA. BF was greater during Fast vs. Slow for all phases (p0.05. RF and GA were each influenced by the interaction of Phase and Speed (p<0.05 with GA being greater during Fast vs. Slow shots during all phases and RF greater during Crank Back Minor and Major as well as Stick Deceleration (p<0.05 but only tended to be greater during Stick Acceleration (p=0.076 for Fast vs. Slow. The greater muscle activity (BF, RF, GA during Fast vs. Slow shots may have been related to a faster approach speed and/or need to create a stiff lower extremity to allow for faster upper extremity movements.

  8. Trunk muscle activation during golf swing: Baseline and threshold.

    Science.gov (United States)

    Silva, Luís; Marta, Sérgio; Vaz, João; Fernandes, Orlando; Castro, Maria António; Pezarat-Correia, Pedro

    2013-10-01

    There is a lack of studies regarding EMG temporal analysis during dynamic and complex motor tasks, such as golf swing. The aim of this study is to analyze the EMG onset during the golf swing, by comparing two different threshold methods. Method A threshold was determined using the baseline activity recorded between two maximum voluntary contraction (MVC). Method B threshold was calculated using the mean EMG activity for 1000ms before the 500ms prior to the start of the Backswing. Two different clubs were also studied. Three-way repeated measures ANOVA was used to compare methods, muscles and clubs. Two-way mixed Intraclass Correlation Coefficient (ICC) with absolute agreement was used to determine the methods reliability. Club type usage showed no influence in onset detection. Rectus abdominis (RA) showed the higher agreement between methods. Erector spinae (ES), on the other hand, showed a very low agreement, that might be related to postural activity before the swing. External oblique (EO) is the first being activated, at 1295ms prior impact. There is a similar activation time between right and left muscles sides, although the right EO showed better agreement between methods than left side. Therefore, the algorithms usage is task- and muscle-dependent. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Activity of upper limb muscles during human walking.

    Science.gov (United States)

    Kuhtz-Buschbeck, Johann P; Jing, Bo

    2012-04-01

    The EMG activity of upper limb muscles during human gait has rarely been studied previously. It was examined in 20 normal volunteers in four conditions: walking on a treadmill (1) with unrestrained natural arm swing (Normal), (2) while volitionally holding the arms still (Held), (3) with the arms immobilized (Bound), and (4) with the arms swinging in phase with the ipsilateral legs, i.e. opposite-to-normal phasing (Anti-Normal). Normal arm swing involved weak rhythmical lengthening and shortening contractions of arm and shoulder muscles. Phasic muscle activity was needed to keep the unrestricted arms still during walking (Held), indicating a passive component of arm swing. An active component, possibly programmed centrally, existed as well, because some EMG signals persisted when the arms were immobilized during walking (Bound). Anti-Normal gait involved stronger EMG activity than Normal walking and was uneconomical. The present results indicate that normal arm swing has both passive and active components. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Increased neck muscle activity and impaired balance among females with whiplash-related chronic neck pain

    DEFF Research Database (Denmark)

    Juul-Kristensen, Birgit; Clausen, Brian; Ris Hansen, Inge

    2013-01-01

    To investigate neck muscle activity and postural control in patients with whiplash-associated disorder compared with healthy controls.......To investigate neck muscle activity and postural control in patients with whiplash-associated disorder compared with healthy controls....

  11. Influence of gravity compensation on muscle activity during reach and retrieval in healthy elderly.

    NARCIS (Netherlands)

    Prange, Grada Berendina; Kallenberg, L.A.C.; Jannink, M.J.A.; Stienen, Arno; van der Kooij, Herman; IJzerman, Maarten Joost; Hermens, Hermanus J.

    2007-01-01

    INTRODUCTION: Arm support like gravity compensation may improve arm movements during stroke rehabilitation. It is unknown how gravity compensation affects muscle activation patterns during reach and retrieval movements. Since muscle activity during reach is represented by a component varying with

  12. Does the habitual mastication side impact jaw muscle activity?

    Science.gov (United States)

    Turcio, Karina Helga Leal; Zuim, Paulo Renato Junqueira; Guiotti, Aimée Maria; Dos Santos, Daniela Micheline; Goiato, Marcelo Coelho; Brandini, Daniela Atili

    2016-07-01

    To compare electrical activity in the anterior temporal and masseter muscles on the habitual (HMS) and non-habitual mastication side (NHMS), during mastication and in the mandibular postural position. In addition, the increase in electrical activity during mastication was assessed for the HMS and NHMS, analysing both working (WSM) and non-working side during mastication (NWSM). A total of 28 healthy women (18-32 years) participated in the study. They were submitted to Kazazoglu's test to identify the HMS. Bioresearch 'Bio EMG' software and bipolar surface electrodes were used in the exams. The exams were conducted in the postural position and during the unilateral mastication of raisins, on both the HMS and NHMS. The working and non-working side on HMS and NHMS were assessed separately. The obtained data were then statistically analysed with SPSS 20.0, using the Paired Samples Test at a significance level of 95%. The differences in the average EMG values between HMS and NHMS were not statistically significant in the postural position (Temporal p=0.2; Masseter p=0.4) or during mastication (Temporal WSM p=0.8; Temporal NWSM p=0.8; Masseter WSM p=0.6; Masseter NWSM p=0.2). Differences in the increase in electrical activity between the masseter and temporal muscles occurred on the working side, on the HMS and NHMS (p=0.0), but not on the non-working side: HMS (p=0.9) and NHMS (p=0.3). The increase in electrical activity was about 35% higher in the masseter than in the temporal muscle. Mastication side preference does not significantly impact electrical activity of the anterior temporal and masseter muscles during mastication or in postural position. Copyright © 2016. Published by Elsevier Ltd.

  13. The influence of temperature on the distribution and intensity of the reaction product in rat muscle fibers obtained with the histochemical method for myosin ATPase

    DEFF Research Database (Denmark)

    Kirkeby, S; Tuxen, A

    1989-01-01

    The influence of temperature in the incubation medium on the localization and intensity of myosin ATPase was investigated in striated muscles from the rat using a conventional histochemical technique. It was found that the enzyme reaction was temperature-dependent since the activity in some fibers...... was raised and in others was depressed by alteration of the incubation temperature. There was no obvious correlation between the temperature sensitivity of ATPase in the muscle fibers and their activity for succinic dehydrogenase. It is proposed that the histochemical method for myosin ATPase can be used...

  14. Perceived loading and muscle activity during hip strengthening exercises

    DEFF Research Database (Denmark)

    Brandt, Mikkel; Jakobsen, Markus Due; Thorborg, Kristian

    2013-01-01

    hip muscle activity during hip abduction and hip adduction exercises using elastic resistance and isotonic machines, using electromyography (EMG). METHODS: EMG activity was recorded from 11 muscles at the hip, thigh and trunk during hip adduction and hip abduction exercises in 16 untrained women......, using elastic resistance and isotonic exercise machines. These recordings were normalized to maximal voluntary contraction (MVC) EMG (nEMG). The exercises were performed at four levels of perceived loading reported using the Borg CR10: light (Borg ≤2), moderate (Borg >2-... (r =0.62±0.54). The abduction exercise performed with elastic resistance displayed significantly higher gluteus medius nEMG recruitment than the in machine exercise. CONCLUSIONS: The results of this study show that the Borg CR10 scale can be a useful tool for estimating intensity levels during...

  15. Effects of flight speed upon muscle activity in hummingbirds.

    Science.gov (United States)

    Tobalske, Bret W; Biewener, Andrew A; Warrick, Douglas R; Hedrick, Tyson L; Powers, Donald R

    2010-07-15

    Hummingbirds have the smallest body size and highest wingbeat frequencies of all flying vertebrates, so they represent one endpoint for evaluating the effects of body size on sustained muscle function and flight performance. Other bird species vary neuromuscular recruitment and contractile behavior to accomplish flight over a wide range of speeds, typically exhibiting a U-shaped curve with maxima at the slowest and fastest flight speeds. To test whether the high wingbeat frequencies and aerodynamically active upstroke of hummingbirds lead to different patterns, we flew rufous hummingbirds (Selasphorus rufus, 3 g body mass, 42 Hz wingbeat frequency) in a variable-speed wind tunnel (0-10 m s(-1)). We measured neuromuscular activity in the pectoralis (PECT) and supracoracoideus (SUPRA) muscles using electromyography (EMG, N=4 birds), and we measured changes in PECT length using sonomicrometry (N=1). Differing markedly from the pattern in other birds, PECT deactivation occurred before the start of downstroke and the SUPRA was deactivated before the start of upstroke. The relative amplitude of EMG signal in the PECT and SUPRA varied according to a U-shaped curve with flight speed; additionally, the onset of SUPRA activity became relatively later in the wingbeat at intermediate flight speeds (4 and 6 m s(-1)). Variation in the relative amplitude of EMG was comparable with that observed in other birds but the timing of muscle activity was different. These data indicate the high wingbeat frequency of hummingbirds limits the time available for flight muscle relaxation before the next half stroke of a wingbeat. Unlike in a previous study that reported single-twitch EMG signals in the PECT of hovering hummingbirds, across all flight speeds we observed 2.9+/-0.8 spikes per contraction in the PECT and 3.8+/-0.8 spikes per contraction in the SUPRA. Muscle strain in the PECT was 10.8+/-0.5%, the lowest reported for a flying bird, and average strain rate was 7.4+/-0.2 muscle

  16. Thick filament mechano-sensing is a calcium-independent regulatory mechanism in skeletal muscle.

    Science.gov (United States)

    Fusi, L; Brunello, E; Yan, Z; Irving, M

    2016-10-31

    Recent X-ray diffraction studies on actively contracting fibres from skeletal muscle showed that the number of myosin motors available to interact with actin-containing thin filaments is controlled by the stress in the myosin-containing thick filaments. Those results suggested that thick filament mechano-sensing might constitute a novel regulatory mechanism in striated muscles that acts independently of the well-known thin filament-mediated calcium signalling pathway. Here we test that hypothesis using probes attached to the myosin regulatory light chain in demembranated muscle fibres. We show that both the extent and kinetics of thick filament activation depend on thick filament stress but are independent of intracellular calcium concentration in the physiological range. These results establish direct control of myosin motors by thick filament mechano-sensing as a general regulatory mechanism in skeletal muscle that is independent of the canonical calcium signalling pathway.

  17. Length and activation dependent variations in muscle shear wave speed

    International Nuclear Information System (INIS)

    Chernak, L A; DeWall, R J; Lee, K S; Thelen, D G

    2013-01-01

    Muscle stiffness is known to vary as a result of a variety of disease states, yet current clinical methods for quantifying muscle stiffness have limitations including cost and availability. We investigated the capability of shear wave elastography (SWE) to measure variations in gastrocnemius shear wave speed induced via active contraction and passive stretch. Ten healthy young adults were tested. Shear wave speeds were measured using a SWE transducer positioned over the medial gastrocnemius at ankle angles ranging from maximum dorsiflexion to maximum plantarflexion. Shear wave speeds were also measured during voluntary plantarflexor contractions at a fixed ankle angle. Average shear wave speed increased significantly from 2.6 to 5.6 m s –1 with passive dorsiflexion and the knee in an extended posture, but did not vary with dorsiflexion when the gastrocnemius was shortened in a flexed knee posture. During active contractions, shear wave speed monotonically varied with the net ankle moment generated, reaching 8.3 m s –1 in the maximally contracted condition. There was a linear correlation between shear wave speed and net ankle moment in both the active and passive conditions; however, the slope of this linear relationship was significantly steeper for the data collected during passive loading conditions. The results show that SWE is a promising approach for quantitatively assessing changes in mechanical muscle loading. However, the differential effect of active and passive loading on shear wave speed makes it important to carefully consider the relevant loading conditions in which to use SWE to characterize in vivo muscle properties. (paper)

  18. Reorganized trunk muscle activity during multidirectional floor perturbations after experimental low back pain

    DEFF Research Database (Denmark)

    Larsen, Lars Henrik; Hirata, Rogerio Pessoto; Graven-Nielsen, Thomas

    2016-01-01

    Low back pain changes the trunk muscle activity after external perturbations but the relationship between pain intensities and distributions and their effect on the trunk muscle activity remains unclear. The effects of unilateral and bilateral experimental low back pain on trunk muscle activity w...

  19. Allergic Interstitial Nephritis Manifesting as a Striated Nephrogram

    Directory of Open Access Journals (Sweden)

    Irfan Moinuddin

    2015-01-01

    Full Text Available Allergic interstitial nephritis (AIN is an underdiagnosed cause of acute kidney injury (AKI. Guidelines suggest that AIN should be suspected in a patient who presents with an elevated serum creatinine and a urinalysis that shows white cells, white cell casts, or eosinophiluria. Drug-induced AIN is suspected if AKI is temporally related to the initiation of a new drug. However, patients with bland sediment and normal urinalysis can also have AIN. Currently, a definitive diagnosis of AIN is made by renal biopsy which is invasive and fraught with risks such as bleeding, infection, and hematoma. Additionally, it is frequently unclear when a kidney biopsy should be undertaken. We describe a biopsy proven case of allergic interstitial nephritis which manifested on contrast enhanced Magnetic Resonance Imaging (MRI as a striated nephrogram. Newer and more stable macrocyclic gadolinium contrast agents have a well-demonstrated safety profile. Additionally, in the presentation of AKI, gadolinium contrast agents are safe to administer in patients who demonstrate good urine output and a downtrending creatinine. We propose that the differential for a striated nephrogram may include AIN. In cases in which the suspicion for AIN is high, this diagnostic consideration may be further characterized by contrast enhanced MRI.

  20. Topography of Striate-Extrastriate Connections in Neonatally Enucleated Rats

    Directory of Open Access Journals (Sweden)

    Robyn J. Laing

    2013-01-01

    Full Text Available It is known that retinal input is necessary for the normal development of striate cortex and its corticocortical connections, but there is little information on the role that retinal input plays in the development of retinotopically organized connections between V1 and surrounding visual areas. In nearly all lateral extrastriate areas, the anatomical and physiological representation of the nasotemporal axis of the visual field mirrors the representation of this axis in V1. To determine whether the mediolateral topography of striate-extrastriate projections is preserved in neonatally enucleated rats, we analyzed the patterns of projections resulting from tracer injections placed at different sites along the mediolateral axis of V1. We found that the correlation between the distance from injection sites to the lateral border of V1 and the distance of the labeling patterns in area 18a was strong in controls and much weaker in enucleates. Data from pairs of injections in the same animal revealed that the separation of area 18a projection fields for a given separation of injection sites was more variable in enucleated than in control rats. Our analysis of single and double tracer injections suggests that neonatal bilateral enucleation weakens, but not completely abolishes, the mediolateral topography in area 18a.

  1. Importance of contraction history on muscle force of porcine urinary bladder smooth muscle.

    Science.gov (United States)

    Menzel, Robin; Böl, Markus; Siebert, Tobias

    2017-02-01

    The purpose of this study was to provide a comprehensive dataset of porcine urinary bladder smooth muscle properties. Particularly, the history dependence of force production, namely force depression (FD) following shortening and force enhancement (FE) following stretch, was analysed. During active micturition, the circumference of the urinary bladder changes enormously. Thus, FD might be an important phenomenon during smooth muscle contraction. Electrically stimulated, intact urinary bladder strips from pigs (n = 10) were suspended in an aerated-filled organ bath, and different isometric, isotonic, and isokinetic contraction protocols were performed to determine the force-length and the force-velocity relation. FD and FE were assessed in concentric and eccentric contractions with different ramp lengths and ramp velocities. Bladder smooth muscles exhibit considerable amounts of FD and FE. The amount of FD increased significantly with ramp length, while FE did not change. However, FE and FD were independent of ramp velocity. The results imply that smooth muscle bladder strips exhibit similar muscle properties and history-dependent behaviour compared to striated muscles. The provided dataset of muscle properties is important for bladder modelling as well as for the analyses and interpretation of dynamic bladder filling and voiding.

  2. The Assessment Methods of Laryngeal Muscle Activity in Muscle Tension Dysphonia: A Review

    Science.gov (United States)

    Khoddami, Seyyedeh Maryam; Nakhostin Ansari, Noureddin; Izadi, Farzad; Talebian Moghadam, Saeed

    2013-01-01

    The purpose of this paper is to review the methods used for the assessment of muscular tension dysphonia (MTD). The MTD is a functional voice disorder associated with abnormal laryngeal muscle activity. Various assessment methods are available in the literature to evaluate the laryngeal hyperfunction. The case history, laryngoscopy, and palpation are clinical methods for the assessment of patients with MTD. Radiography and surface electromyography (EMG) are objective methods to provide physiological information about MTD. Recent studies show that surface EMG can be an effective tool for assessing muscular tension in MTD. PMID:24319372

  3. THE NEPHROTOXICITY RISK IN RATS SUBJECTED TO HEAVY MUSCLE ACTIVITY

    Directory of Open Access Journals (Sweden)

    Gülsen Öner

    2009-09-01

    Full Text Available When the body is exposed to insults, the kidneys exhibit adaptive changes termed renal cytoresistance, characterized by cholesterol accumulation in the membranes of the tubule cells. However, heavy muscle activity has not yet been accepted as one of the stressors that could lead to cytoresistance. In order to study the renal functional characteristics of animals exposed to heavy muscle activity, rats were subjected to exhaustive treadmill exercise for 5 days and their data was compared to those of sedentary controls. It was found that in exercised rats, blood lactate, muscle citrate synthase and proximal tubule peroxynitrite levels were all elevated, suggesting the presence of oxidative stress in the proximal tubule segments. However, mean arterial pressure, renal blood flow, glomerular filtration rate, fractional excretion of sodium and potassium, and organic anion excretion remained normal. Despite unchanged blood cholesterol levels, cholesterol loading in the proximal tubule segments, especially the free form, and decreased lactate dehydrogenase release from cytoresistant proximal tubule segments indicated the development of renal cytoresistance. However, this resistance did not seem to have protected the kidneys as expected because organic anion accumulation associated with glycosuria and proteinuria, in addition to the elevated urinary cholesterol levels, all imply the presence of an impaired glomerular permeability and reabsorption in the proximal tubule cells. Therefore, we suggest that in response to heavy muscle activity the tubular secretion may remain intact, although cytoresistance in the proximal tubule cells may affect the tubular reabsorptive functions and basolateral uptake of substances. Thus, this differential sensitivity in the cytoresistance should be taken into account during functional evaluation of the kidneys

  4. Influence of glutamate-evoked pain and sustained elevated muscle activity on blood oxygenation in the human masseter muscle.

    Science.gov (United States)

    Suzuki, Shunichi; Arima, Taro; Kitagawa, Yoshimasa; Svensson, Peter; Castrillon, Eduardo

    2017-12-01

    This study aimed to investigate the effect of glutamate-evoked masseter muscle pain on intramuscular oxygenation during rest and sustained elevated muscle activity (SEMA). Seventeen healthy individuals participated in two sessions in which they were injected with glutamate and saline in random order. Each session was divided into three, 10-min periods. During the first (period 1) and the last (period 3) 10-min periods, participants performed five intercalated 1-min bouts of masseter SEMA with 1-min periods of 'rest'. At onset of the second 10-min period, glutamate (0.5 ml, 1 M; Ajinomoto, Tokyo, Japan) or isotonic saline (0.5 ml; 0.9%) was injected into the masseter muscle and the participants kept the muscle relaxed in a resting position for 10 min (period 2). The hemodynamic characteristics of the masseter muscle were recorded simultaneously during the experiment by a laser blood-oxygenation monitor. The results demonstrated that glutamate injections caused significant levels of self-reported pain in the masseter muscle; however, this nociceptive input did not have robust effects on intramuscular oxygenation during rest or SEMA tasks. Interestingly, these findings suggest an uncoupling between acute nociceptive activity and hemodynamic parameters in both resting and low-level active jaw muscles. Further studies are needed to explore the pathophysiological significance of blood-flow changes for persistent jaw-muscle pain conditions. © 2017 Eur J Oral Sci.

  5. Influence of end-joint methods on magnetization loss in striated helical conductors

    International Nuclear Information System (INIS)

    Kim, Woo Seok; Kim, Yung Il; Choi, Kyeong Dal; Lee, Ji Kwang

    2013-01-01

    To reduce the magnetization loss of a coated conductor, the striation and the transposition have to be accomplished for magnetic decoupling. The loss reduction effect in incomplete as well as complete striated YBCO CCs was reported in previous research. At the case of the incomplete striated sample, the end region of the sample is non-striated. So, it is not jointed with each other. In power applications, the joint is needed because current leads must be connected with HTS coils. In this research, the influence of end-joint methods with copper and superconducting joint on magnetization loss in striated YBCO CC and spiral winding samples are presented and compared with non-striated measured result.

  6. Activation of estrogen response elements is mediated both via estrogen and muscle contractions in rat skeletal muscle myotubes

    DEFF Research Database (Denmark)

    Wiik, A.; Hellsten, Ylva; Berthelson, P.

    2009-01-01

    is ER independent. The muscle contraction-induced transactivation of ERE and increase in ERbeta mRNA were instead found to be MAP kinase (MAPK) dependent. This study demonstrates for the first time that muscle contractions have a similar functional effect as estrogen in skeletal muscle myotubes, causing......The aim of the present study was to investigate the activation of estrogen response elements (EREs) by estrogen and muscle contractions in rat myotubes in culture and to assess whether the activation is dependent on the estrogen receptors (ERs). In addition, the effect of estrogen and contraction...... on the mRNA levels of ERalpha and ERbeta was studied to determine the functional consequence of the transactivation. Myoblasts were isolated from rat skeletal muscle and transfected with a vector consisting of sequences of EREs coupled to the gene for luciferase. The transfected myoblasts were...

  7. Sedative and muscle relaxant activities of diterpenoids from Phlomidoschema parviflorum

    Directory of Open Access Journals (Sweden)

    Abdur Rauf

    Full Text Available Abstract Phlomidoschema parviflorum (Benth. Vved. (Basionym: Stachys parviflora Benth. Lamiaceae, have significance medicinal importance as it is used in number of health disorders including diarrhea, fever, sore mouth and throat, internal bleeding, weaknesses of the liver and heart genital tumors, sclerosis of the spleen, inflammatory tumors and cancerous ulcers. The present contribution deals with the sedative and muscle relaxant like effects of diterpenoids trivially named stachysrosane and stachysrosane, isolated from the ethyl acetate soluble fraction of P. parviflorum. Both compounds (at 5, 10 and 15 mg/kg, i.p were assessed for their in vivo sedative and muscle relaxant activity in open field and inclined plane test, respectively. The geometries of both compounds were optimized with density functional theory. The molecular docking of both compounds were performed with receptor gamma aminobutyric acid. Both compounds showed marked activity in a dose dependent manner. The docking studies showed that both compounds interact strongly with important residues in receptor gamma aminobutyric acid. The reported data demonstrate that both compounds exhibited significant sedative and muscle relaxant-like effects in animal models, which opens a door for novel therapeutic applications.

  8. Trapezius muscle activity increases during near work activity regardless of accommodation/vergence demand level.

    Science.gov (United States)

    Richter, H O; Zetterberg, C; Forsman, M

    2015-07-01

    To investigate if trapezius muscle activity increases over time during visually demanding near work. The vision task consisted of sustained focusing on a contrast-varying black and white Gabor grating. Sixty-six participants with a median age of 38 (range 19-47) fixated the grating from a distance of 65 cm (1.5 D) during four counterbalanced 7-min periods: binocularly through -3.5 D lenses, and monocularly through -3.5 D, 0 D and +3.5 D. Accommodation, heart rate variability and trapezius muscle activity were recorded in parallel. General estimating equation analyses showed that trapezius muscle activity increased significantly over time in all four lens conditions. A concurrent effect of accommodation response on trapezius muscle activity was observed with the minus lenses irrespective of whether incongruence between accommodation and convergence was present or not. Trapezius muscle activity increased significantly over time during the near work task. The increase in muscle activity over time may be caused by an increased need of mental effort and visual attention to maintain performance during the visual tasks to counteract mental fatigue.

  9. Suboptimal Muscle Synergy Activation Patterns Generalize their Motor Function across Postures.

    Science.gov (United States)

    Sohn, M Hongchul; Ting, Lena H

    2016-01-01

    We used a musculoskeletal model to investigate the possible biomechanical and neural bases of using consistent muscle synergy patterns to produce functional motor outputs across different biomechanical conditions, which we define as generalizability. Experimental studies in cats demonstrate that the same muscle synergies are used during reactive postural responses at widely varying configurations, producing similarly-oriented endpoint force vectors with respect to the limb axis. However, whether generalizability across postures arises due to similar biomechanical properties or to neural selection of a particular muscle activation pattern has not been explicitly tested. Here, we used a detailed cat hindlimb model to explore the set of feasible muscle activation patterns that produce experimental synergy force vectors at a target posture, and tested their generalizability by applying them to different test postures. We used three methods to select candidate muscle activation patterns: (1) randomly-selected feasible muscle activation patterns, (2) optimal muscle activation patterns minimizing muscle effort at a given posture, and (3) generalizable muscle activation patterns that explicitly minimized deviations from experimentally-identified synergy force vectors across all postures. Generalizability was measured by the deviation between the simulated force direction of the candidate muscle activation pattern and the experimental synergy force vectors at the test postures. Force angle deviations were the greatest for the randomly selected feasible muscle activation patterns (e.g., >100°), intermediate for effort-wise optimal muscle activation patterns (e.g., ~20°), and smallest for generalizable muscle activation patterns (e.g., synergy force vector was reduced by ~45% when generalizability requirements were imposed. Muscles recruited in the generalizable muscle activation patterns had less sensitive torque-producing characteristics to changes in postures. We

  10. Modulation of the Muscle Activity During Sleep in Cervical Dystonia.

    Science.gov (United States)

    Antelmi, Elena; Ferri, Raffaele; Provini, Federica; Scaglione, Cesa M L; Mignani, Francesco; Rundo, Francesco; Vandi, Stefano; Fabbri, Margherita; Pizza, Fabio; Plazzi, Giuseppe; Martinelli, Paolo; Liguori, Rocco

    2017-07-01

    Impaired sleep has been reported as an important nonmotor feature in dystonia, but so far, self-reported complaints have never been compared with nocturnal video-polysomnographic (PSG) recording, which is the gold standard to assess sleep-related disorders. Twenty patients with idiopathic isolated cervical dystonia and 22 healthy controls (HC) underwent extensive clinical investigations, neurological examination, and questionnaire screening for excessive daytime sleepiness and sleep-related disorders. A full-night video PSG was performed in both patients and HC. An ad hoc montage, adding electromyographic leads over the muscle affected with dystonia, was used. When compared to controls, patients showed significantly increased pathological values on the scale assessing self-reported complaints of impaired nocturnal sleep. Higher scores of impaired nocturnal sleep did not correlate with any clinical descriptors but for a weak correlation with higher scores on the scale for depression. On video-PSG, patients had significantly affected sleep architecture (with decreased sleep efficiency and increased sleep latency). Activity over cervical muscles disappears during all the sleep stages, reaching significantly decreased values when compared to controls both in nonrapid eye movements and rapid eye movements sleep. Patients with cervical dystonia reported poor sleep quality and showed impaired sleep architecture. These features however cannot be related to the persistence of muscle activity over the cervical muscles, which disappears in all the sleep stages, reaching significantly decreased values when compared to HC. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  11. Model identification of stomatognathic muscle system activity during mastication

    Science.gov (United States)

    Kijak, Edward; Margielewicz, Jerzy; Lietz-Kijak, Danuta; Wilemska-Kucharzewska, Katarzyna; Kucharzewski, Marek; Śliwiński, Zbigniew

    2017-01-01

    The present study aimed to determine the numeric projection of the function of the mandible and muscle system during mastication. An experimental study was conducted on a healthy 47 year-old subject. On clinical examination no functional disorders were observed. To evaluate the activity of mastication during muscle functioning, bread cubes and hazelnuts were selected (2 cm2 and 1.2/1.3 cm in diameter, respectively) for condyloid processing. An assessment of the activity of mastication during muscle functioning was determined on the basis of numeric calculations conducted with a novel software programme, Kinematics 3D, designed specifically for this study. The efficacy of the model was verified by ensuring the experimentally recorded trajectories were concordant with those calculated numerically. Experimental measurements of the characteristic points of the mandible trajectory were recorded six times. Using the configuration coordinates that were calculated, the dominant componential harmonics of the amplitude-frequency spectrum were identified. The average value of the dominant frequency during mastication of the bread cubes was ~1.16±0.06 Hz, whereas in the case of the hazelnut, this value was nearly two-fold higher at 1.84±0.07 Hz. The most asymmetrical action during mastication was demonstrated to be carried out by the lateral pterygoid muscles, provided that their functioning was not influenced by food consistency. The consistency of the food products had a decisive impact on the frequency of mastication and the number of cycles necessary to grind the food. Model tests on the function of the masticatory organ serve as effective tools since they provide qualitative and quantitative novel information on the functioning of the human masticatory organ. PMID:28123482

  12. On the origin of muscle synergies: invariant balance in the co-activation of agonist and antagonist muscle pairs

    Directory of Open Access Journals (Sweden)

    Hiroaki eHirai

    2015-11-01

    Full Text Available Investigation of neural representation of movement planning has attracted the attention of neuroscientists, as it may reveal the sensorimotor transformation essential to motor control. The analysis of muscle synergies based on the activity of agonist-antagonist (AA muscle pairs may provide insight into such transformations, especially for a reference frame in the muscle space. In this study, we examined the AA concept using the following explanatory variables: the AA ratio, which is related to the equilibrium-joint angle, and the AA sum, which is associated with joint stiffness. We formulated muscle synergies as a function of AA sums, positing that muscle synergies are composite units of mechanical impedance. The AA concept can be regarded as another form of the equilibrium-point (EP hypothesis, and it can be extended to the concept of EP-based synergies. We introduce here a novel tool for analyzing the neurological and motor functions underlying human movements and review some initial insights from our results about the relationships between muscle synergies, endpoint stiffness, and virtual trajectories (time series of EP. Our results suggest that (1 muscle synergies reflect an invariant balance in the co-activation of AA muscle pairs; (2 each synergy represents the basis for the radial, tangential, and null movements of the virtual trajectory in the polar coordinates centered on the specific joint at the base of the body; and (3 the alteration of muscle synergies (for example, due to spasticity or rigidity following neurological injury results in significant distortion of endpoint stiffness and concomitant virtual trajectories. These results indicate that muscle synergies (i.e., the balance of muscle mechanical impedance are essential for motor control.

  13. On the Origin of Muscle Synergies: Invariant Balance in the Co-activation of Agonist and Antagonist Muscle Pairs.

    Science.gov (United States)

    Hirai, Hiroaki; Miyazaki, Fumio; Naritomi, Hiroaki; Koba, Keitaro; Oku, Takanori; Uno, Kanna; Uemura, Mitsunori; Nishi, Tomoki; Kageyama, Masayuki; Krebs, Hermano Igo

    2015-01-01

    Investigation of neural representation of movement planning has attracted the attention of neuroscientists, as it may reveal the sensorimotor transformation essential to motor control. The analysis of muscle synergies based on the activity of agonist-antagonist (AA) muscle pairs may provide insight into such transformations, especially for a reference frame in the muscle space. In this study, we examined the AA concept using the following explanatory variables: the AA ratio, which is related to the equilibrium-joint angle, and the AA sum, which is associated with joint stiffness. We formulated muscle synergies as a function of AA sums, positing that muscle synergies are composite units of mechanical impedance. The AA concept can be regarded as another form of the equilibrium-point (EP) hypothesis, and it can be extended to the concept of EP-based synergies. We introduce, here, a novel tool for analyzing the neurological and motor functions underlying human movements and review some initial insights from our results about the relationships between muscle synergies, endpoint stiffness, and virtual trajectories (time series of EP). Our results suggest that (1) muscle synergies reflect an invariant balance in the co-activation of AA muscle pairs; (2) each synergy represents the basis for the radial, tangential, and null movements of the virtual trajectory in the polar coordinates centered on the specific joint at the base of the body; and (3) the alteration of muscle synergies (for example, due to spasticity or rigidity following neurological injury) results in significant distortion of endpoint stiffness and concomitant virtual trajectories. These results indicate that muscle synergies (i.e., the balance of muscle mechanical impedance) are essential for motor control.

  14. Whole body and muscle energy metabolism in preruminant calves: effects of nutrient synchrony and physical activity

    NARCIS (Netherlands)

    Borne, van den J.J.G.C.; Hocquette, J.F.; Verstegen, M.W.A.; Gerrits, W.J.J.

    2007-01-01

    The effects of asynchronous availability of amino acids and glucose on muscle composition and enzyme activities in skeletal muscle were studied in preruminant calves. It was hypothesized that decreased oxidative enzyme activities in muscle would explain a decreased whole body heat production with

  15. The effect of fear of movement on muscle activation in posttraumatic neck pain disability

    NARCIS (Netherlands)

    Nederhand, Marcus Johannes; Hermens, Hermanus J.; IJzerman, Maarten Joost; Groothuis-Oudshoorn, Catharina Gerarda Maria; Turk, Dennis C.

    Studies using surface electromyography have demonstrated a reorganization of muscle activation patterns of the neck and shoulder muscles in patients with posttraumatic neck pain disability. The neurophysiologically oriented "pain adaptation" model explains this reorganization as a useful adaptation

  16. Female PFP patients present alterations in eccentric muscle activity but not the temporal order of activation of the vastus lateralis muscle during the single leg triple hop test.

    Science.gov (United States)

    Kalytczak, Marcelo Martins; Lucareli, Paulo Roberto Garcia; Dos Reis, Amir Curcio; Bley, André Serra; Biasotto-Gonzalez, Daniela Aparecida; Correa, João Carlos Ferrari; Politti, Fabiano

    2018-04-07

    This study aimed to compare the concentric and eccentric activity and the temporal order of peak activity of the hip and knee muscles between women with patellofemoral pain (PFP) and healthy women during the single leg triple hop test (SLTHT). Electromyographic (EMG) and Kinematic data were collected from 14 healthy women (CG) and 14 women diagnosed with PFP (PFG) during a single session of the single leg triple hop test. Integral surface electromyography (iEMG) data of the hip and knee muscles in eccentric and concentric phases and the length of time that each muscle needed to reach the maximal peak of muscle activity were calculated. The iEMG in the eccentric phase was significantly higher (p < 0.05) than the concentric phase, for the gluteus maximus and gluteus medius muscles (CG and PFG) and for the vastus lateralis muscle (PFG). The vastus lateralis muscle was the first muscle to reach the highest peak of activity in the PFG, and the third to reach this peak in the CG. In the present study, the activity of the vastus lateralis muscle during the eccentric phase of the jump was greater than concentric phase, as a temporal anticipation of its peak in activity among women with PFP. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Age-associated changes in muscle activity during isometric contraction.

    Science.gov (United States)

    Arjunan, Sridhar P; Kumar, Dinesh K

    2013-04-01

    We investigated the effect of age on the complexity of muscle activity and the variance in the force of isometric contraction. Surface electromyography (sEMG) from biceps brachii muscle and force of contraction were recorded from 96 subjects (20-70 years of age) during isometric contractions. There was a reduction in the complexity of sEMG associated with aging. The relationship of age and complexity was approximated using a bilinear fit, with the average knee point at 45 years. There was an age-associated increase in the coefficient of variation (CoV) of the force of muscle contraction, and this increase was correlated with the decrease in complexity of sEMG (r(2) = 0.76). There was an age-associated increase in CoV and also a reduction in the complexity of sEMG. The correlation between these 2 factors can be explained based on the age-associated increase in motor unit density. Copyright © 2012 Wiley Periodicals, Inc.

  18. Direct optical activation of skeletal muscle fibres efficiently controls muscle contraction and attenuates denervation atrophy.

    Science.gov (United States)

    Magown, Philippe; Shettar, Basavaraj; Zhang, Ying; Rafuse, Victor F

    2015-10-13

    Neural prostheses can restore meaningful function to paralysed muscles by electrically stimulating innervating motor axons, but fail when muscles are completely denervated, as seen in amyotrophic lateral sclerosis, or after a peripheral nerve or spinal cord injury. Here we show that channelrhodopsin-2 is expressed within the sarcolemma and T-tubules of skeletal muscle fibres in transgenic mice. This expression pattern allows for optical control of muscle contraction with comparable forces to nerve stimulation. Force can be controlled by varying light pulse intensity, duration or frequency. Light-stimulated muscle fibres depolarize proportionally to light intensity and duration. Denervated triceps surae muscles transcutaneously stimulated optically on a daily basis for 10 days show a significant attenuation in atrophy resulting in significantly greater contractile forces compared with chronically denervated muscles. Together, this study shows that channelrhodopsin-2/H134R can be used to restore function to permanently denervated muscles and reduce pathophysiological changes associated with denervation pathologies.

  19. Trunk muscle activation during moderate- and high-intensity running.

    Science.gov (United States)

    Behm, David G; Cappa, Dario; Power, Geoffrey A

    2009-12-01

    Time constraints are cited as a barrier to regular exercise. If particular exercises can achieve multiple training functions, the number of exercises and the time needed to achieve a training goal may be decreased. It was the objective of this study to compare the extent of trunk muscle electromyographic (EMG) activity during running and callisthenic activities. EMG activity of the external obliques, lower abdominals (LA), upper lumbar erector spinae (ULES), and lumbosacral erector spinae (LSES) was monitored while triathletes and active nonrunners ran on a treadmill for 30 min at 60% and 80% of their maximum heart rate (HR) reserve, as well as during 30 repetitions of a partial curl-up and 3 min of a modified Biering-Sørensen back extension exercise. The mean root mean square (RMS) amplitude of the EMG signal was monitored over 10-s periods with measures normalized to a maximum voluntary contraction rotating curl-up (external obliques), hollowing exercise (LA), or back extension (ULES and LSES). A main effect for group was that triathletes had greater overall activation of the external obliques (p runs, respectively, than with the curl-ups (p = 0.001). The back extension exercise provided less ULES (p = 0.009) and LSES (p = 0.0001) EMG activity than the 60% and 80% runs, respectively. In conclusion, triathletes had greater trunk activation than nonrunners did while running, which could have contributed to their better performance. Back-stabilizing muscles can be activated more effectively with running than with a prolonged back extension activity. Running can be considered as an efficient, multifunctional exercise combining cardiovascular and trunk endurance benefits.

  20. Study of the striated nature of a glow discharge

    International Nuclear Information System (INIS)

    Hernandez A, M.

    1995-01-01

    In an investigation in progress here, plasma diagnostics and detection of standing and moving striations is being made in a discharge in Argon at pressures of 2 x 10 -1 to 9 x 10 -1 mb and currents of 2 to 9 m-amp inside an discharge tube. Measurement of the temperature of the electrons, the concentration of electrons and the plasma potential are obtained in different places of the discharge by the double probe method, together with the computation system reported in [1]. In similar way an experimental work of the striated column in a discharge plasma to find the regimen of appearance of the standing and moving striations show some properties of moving striations (frequency and velocity) and standing striations. Two different oscilations are observed in motion in contrary directions along the discharge tube with a photomultiplier. (Author)

  1. Assessment of bioelectrical activity of synergistic muscles during pelvic floor muscles activation in postmenopausal women with and without stress urinary incontinence: a preliminary observational study.

    Science.gov (United States)

    Ptaszkowski, Kuba; Paprocka-Borowicz, Małgorzata; Słupska, Lucyna; Bartnicki, Janusz; Dymarek, Robert; Rosińczuk, Joanna; Heimrath, Jerzy; Dembowski, Janusz; Zdrojowy, Romuald

    2015-01-01

    Muscles such as adductor magnus (AM), gluteus maximus (GM), rectus abdominis (RA), and abdominal external and internal oblique muscles are considered to play an important role in the treatment of stress urinary incontinence (SUI), and the relationship between contraction of these muscles and pelvic floor muscles (PFM) has been established in previous studies. Synergistic muscle activation intensifies a woman's ability to contract the PFM. In some cases, even for continent women, it is not possible to fully contract their PFM without involving the synergistic muscles. The primary aim of this study was to assess the surface electromyographic activity of synergistic muscles to PFM (SPFM) during resting and functional PFM activation in postmenopausal women with and without SUI. This study was a preliminary, prospective, cross-sectional observational study and included volunteers and patients who visited the Department and Clinic of Urology, University Hospital in Wroclaw, Poland. Forty-two patients participated in the study and were screened for eligibility criteria. Thirty participants satisfied the criteria and were categorized into two groups: women with SUI (n=16) and continent women (n=14). The bioelectrical activity of PFM and SPFM (AM, RA, GM) was recorded with a surface electromyographic instrument in a standing position during resting and functional PFM activity. Bioelectrical activity of RA was significantly higher in the incontinent group than in the continent group. These results concern the RA activity during resting and functional PFM activity. The results for other muscles showed no significant difference in bioelectrical activity between groups. In women with SUI, during the isolated activation of PFM, an increased synergistic activity of RA muscle was observed; however, this activity was not observed in asymptomatic women. This may indicate the important accessory contribution of these muscles in the mechanism of continence.

  2. Impact of exercise selection on hamstring muscle activation.

    Science.gov (United States)

    Bourne, Matthew N; Williams, Morgan D; Opar, David A; Al Najjar, Aiman; Kerr, Graham K; Shield, Anthony J

    2017-07-01

    To determine which strength training exercises selectively activate the biceps femoris long head (BF LongHead ) muscle. We recruited 24 recreationally active men for this two-part observational study . Part 1: We explored the amplitudes and the ratios of lateral (BF) to medial hamstring (MH) normalised electromyography (nEMG) during the concentric and eccentric phases of 10 common strength training exercises. Part 2: We used functional MRI (fMRI) to determine the spatial patterns of hamstring activation during two exercises which (1) most selectively and (2) least selectively activated the BF in part 1. Eccentrically, the largest BF/MH nEMG ratio occurred in the 45° hip-extension exercise; the lowest was in the Nordic hamstring (Nordic) and bent-knee bridge exercises. Concentrically, the highest BF/MH nEMG ratio occurred during the lunge and 45° hip extension; the lowest was during the leg curl and bent-knee bridge. fMRI revealed a greater BF (LongHead) to semitendinosus activation ratio in the 45° hip extension than the Nordic (phamstring muscles (p≤0.002). We highlight the heterogeneity of hamstring activation patterns in different tasks. Hip-extension exercise selectively activates the long hamstrings, and the Nordic exercise preferentially recruits the semitendinosus. These findings have implications for strategies to prevent hamstring injury as well as potentially for clinicians targeting specific hamstring components for treatment (mechanotherapy). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  3. In Graves' disease, increased muscle tension and reduced elasticity of affected muscles is primarily caused by active muscle contraction

    NARCIS (Netherlands)

    H.J. Simonsz (Huib); G. Kommerell (Guntram)

    1989-01-01

    textabstractIn three patients with Graves' disease of recent onset, length-tension diagrams were made during surgery for squint under eyedrop anesthesia, while the other eye looked ahead, into the field of action, or out of the field of action of the muscle that was measured. The affected muscles

  4. [Core muscle chains activation during core exercises determined by EMG-a systematic review].

    Science.gov (United States)

    Rogan, Slavko; Riesen, Jan; Taeymans, Jan

    2014-10-15

    Good core muscles strength is essential for daily life and sports activities. However, the mechanism how core muscles may be effectively triggered by exercises is not yet precisely described in the literature. The aim of this systematic review was to evaluate the rate of activation as measured by electromyography of the ventral, lateral and dorsal core muscle chains during core (trunk) muscle exercises. A total of 16 studies were included. Exercises with a vertical starting position, such as the deadlift or squat activated significantly more core muscles than exercises in the horizontal initial position.

  5. Associations between personality traits, physical activity level, and muscle strength

    Science.gov (United States)

    Tolea, Magdalena I.; Terracciano, Antonio; Simonsick, Eleanor M.; Metter, E. Jeffrey; Costa, Paul T.; Ferrucci, Luigi

    2013-01-01

    Associations among personality as measured by the Five Factor Model, physical activity, and muscle strength were assessed using data from the Baltimore Longitudinal Study of Aging (N = 1220, age: mean = 58, SD = 16). General linear modeling with adjustment for age, sex, race, and body mass index, and bootstrapping for mediation were used. We found neuroticism and most of its facets to negatively correlate with strength. The extraversion domain and its facets of warmth, activity, and positive-emotions were positively correlated with strength, independent of covariates. Mediation analysis results suggest that these associations are partly explained by physical activity level. Findings extend the evidence of an association between personality and physical function to its strength component and indicate health behavior as an important pathway. PMID:23966753

  6. Gait and muscle activation changes in men with knee osteoarthritis.

    Science.gov (United States)

    Liikavainio, Tuomas; Bragge, Timo; Hakkarainen, Marko; Karjalainen, Pasi A; Arokoski, Jari P

    2010-01-01

    The aim was to examine the biomechanics of level- and stair-walking in men with knee osteoarthritis (OA) at different pre-determined gait speeds and to compare the results with those obtained from healthy control subjects. Special emphasis was placed on the estimation of joint loading. Fifty-four men with knee OA (50-69 years) and 53 healthy age- and sex-matched controls were enrolled in the study. The participants walked barefoot in the laboratory (1.2 m/s+/-5%), corridor (1.2; 1.5 and 1.7 m/s+/-5%), and climbing and coming down stairs (0.5 and 0.8 m/s+/-5%) separately. Joint loading was assessed with skin mounted accelerometers (SMAs) attached just above and below the more affected knee joint. The 3-D ground reaction forces (GRFs) and muscle activation with surface-electromyography (EMG) from vastus medialis (VM) and biceps femoris (BF) were also measured simultaneously. There were no differences in SMA variables between groups during level-walking, but maximal loading rate (LR(max)) was higher bilaterally in the controls (Pstair descent at faster speed. The distinctions in muscle activation both at level- and stair ambulation in VM and BF muscles revealed that the patients used different strategies to execute the same walking tasks. It is concluded that the differences in measured SMA and GRF parameters between the knee OA patients and the controls were only minor at constant gait speeds. It is speculated that the faster speeds in the stair descent subjected the compensatory mechanisms to the maximum highlighting the differences between groups.

  7. Methods for demonstration of enzyme activity in muscle fibres at the muscle/bone interface in demineralized tissue

    DEFF Research Database (Denmark)

    Kirkeby, S; Vilmann, H

    1981-01-01

    A method for demonstration of activity for ATPase and various oxidative enzymes (succinic dehydrogenase, alpha-glycerophosphate dehydrogenase, and lactic dehydrogenase) in muscle/bone sections of fixed and demineralized tissue has been developed. It was found that it is possible to preserve...... considerable amounts of the above mentioned enzymes in the muscle fibres at the muscle/bone interfaces. The best results were obtained after 20 min fixation, and 2-3 weeks of storage in MgNa2EDTA containing media. As the same technique previously has been used to describe patterns of resorption and deposition...

  8. The Effects of Active Straight Leg Raising on Tonicity and Activity of Pelvic Stabilizer Muscles

    Directory of Open Access Journals (Sweden)

    Azadeh Shadmehr

    2011-01-01

    Full Text Available Objective: Active straight leg raising (SLR test is advocated as a valid diagnostic method in diagnosis of sacroiliac joint (SIJ dysfunction that can assess the quality of load transfer between trunk and lower limb. The aim of this study is Comparison of changes in tonicity and activity of pelvic stabilizer muscles during active SLR, between healthy individuals and patients with sacroiliac joint pain. Materials & Methods: A case – control study was designed in 26 women (19-50 years old. With use of simple sampling, surface electromyography from rectus abdominis, external oblique, internal oblique, adductor longus, erector spine, gluteus maximus and biceps femoris was recorded in 26 subjects (15 healthy females and 11 females with sacroiliac pain in resting position and during active SLR test. Resting muscle tonicity and rms during ramp time and hold time in active SLR test were assessed by non parametric-two independent sample test. Results: Biceps femoris activity in resting position was significantly larger in patients group (P<0.05. During the active SLR, the women with sacroiliac joint pain used much less activity in some pelvic stabilizer muscles compared to the healthy subjects (P<0.05. Conclusion: The increased resting tonicity of biceps femoris and decreased activity of pelvic stabilizer muscles in subjects with sacroiliac joint pain, suggests an alteration in the strategy for lumbopelvic stabilization that may disrupt load transference through the pelvis.

  9. Glycogen synthesis from lactate in a chronically active muscle

    International Nuclear Information System (INIS)

    Talmadge, R.J.; Scheide, J.I.; Silverman, H.

    1989-01-01

    In response to neural overactivity (pseudomyotonia), gastrocnemius muscle fibers from C57Bl/6Jdy2J/dy2J mice have different metabolic profiles compared with normal mice. A population of fibers in the fast-twitch superficial region of the dy2J gastrocnemius stores unusually high amounts of glycogen, leading to an increased glycogen storage in the whole muscle. The dy2J muscle also contains twice as much lactate as normal muscle. A [ 14 C]lactate intraperitoneal injection leads to preferential 14 C incorporation into glycogen in the dy2J muscle compared with normal muscle. To determine whether skeletal muscles were incorporating lactate into glycogen without body organ (liver, kidney) input, gastrocnemius muscles were bathed in 10 mM [ 14 C]lactate with intact neural and arterial supply but with impeded venous return. The contralateral gastrocnemius serves as a control for body organ input. By using this in situ procedure, we demonstrate that under conditions of high lactate both normal and dy2J muscle can directly synthesize glycogen from lactate. In this case, normal whole muscle incorporates [14C] lactate into glycogen at a higher rate than dy2J whole muscle. Autoradiography, however, suggests that the high-glycogen-containing muscle fibers in the dy2J muscle incorporate lactate into glycogen at nearly four times the rate of normal or surrounding muscle fibers

  10. Influence of botulinum toxin on rabbit jaw muscle activity and anatomy.

    Science.gov (United States)

    Korfage, J A M; Wang, Jeffrey; Lie, S H J T J; Langenbach, Geerling E J

    2012-05-01

    Muscles can adapt their fiber properties to accommodate to new conditions. We investigated the extent to which a decrease in muscle activation can cause an adaptation of fiber properties in synergistic and antagonistic jaw muscles. Three months after the injection of botulinum toxin type A in one masseter (anterior or posterior) muscle changes in fiber type composition and fiber cross-sectional areas in jaw muscles were studied at the microscopic level. The injected masseter showed a steep increase in myosin type IIX fibers, whereas fast fibers decreased by about 50% in size. Depending on the injection site, both synergistic and antagonistic muscles showed a significant increase in the size of their fast IIA fibers, sometimes combined with an increased number of IIX fibers. Silencing the activity in the masseter not only causes changes in the fibers of the injected muscle but also leads to changes in other jaw muscles. Copyright © 2012 Wiley Periodicals, Inc.

  11. Influence of botulinum toxin on rabbit jaw muscle activity and anatomy

    NARCIS (Netherlands)

    Korfage, J.A.M.; Wang, J.; Lie, S.H.J.T.J.; Langenbach, G.E.J.

    2012-01-01

    Introduction: Muscles can adapt their fiber properties to accommodate to new conditions. We investigated the extent to which a decrease in muscle activation can cause an adaptation of fiber properties in synergistic and antagonistic jaw muscles. Methods: Three months after the injection of botulinum

  12. Muscle networks: Connectivity analysis of EMG activity during postural control

    Science.gov (United States)

    Boonstra, Tjeerd W.; Danna-Dos-Santos, Alessander; Xie, Hong-Bo; Roerdink, Melvyn; Stins, John F.; Breakspear, Michael

    2015-12-01

    Understanding the mechanisms that reduce the many degrees of freedom in the musculoskeletal system remains an outstanding challenge. Muscle synergies reduce the dimensionality and hence simplify the control problem. How this is achieved is not yet known. Here we use network theory to assess the coordination between multiple muscles and to elucidate the neural implementation of muscle synergies. We performed connectivity analysis of surface EMG from ten leg muscles to extract the muscle networks while human participants were standing upright in four different conditions. We observed widespread connectivity between muscles at multiple distinct frequency bands. The network topology differed significantly between frequencies and between conditions. These findings demonstrate how muscle networks can be used to investigate the neural circuitry of motor coordination. The presence of disparate muscle networks across frequencies suggests that the neuromuscular system is organized into a multiplex network allowing for parallel and hierarchical control structures.

  13. Simulating the activation, contraction and movement of skeletal muscles using the bidomain model.

    Science.gov (United States)

    Lopez Rincon, A; Cantu, C; Soto, R; Shimoda, S

    2016-08-01

    A simulation of the muscle activation, contraction and movement is here presented. This system was developed based on the Bidomain mathematical model of the electrical propagation in muscles. This study shows an electrical stimuli input to a muscle and how this behave. The comparison between healthy subject and patient with muscle activation impairment is depicted, depending on whether the signal reaches a threshold. A 3D model of a bicep muscle and a forearm bone connected was constructed using OpenGL. This platform could be used for development of controllers for biomechatronic systems in future works. This kind of bioinspired model could be used for a better understanding of the neuromotor system.

  14. Adaptive responses of mouse skeletal muscle to contractile activity: The effect of age.

    Science.gov (United States)

    Vasilaki, A; McArdle, F; Iwanejko, L M; McArdle, A

    2006-11-01

    This study has characterised the time course of two major transcriptional adaptive responses to exercise (changes in antioxidant defence enzyme activity and heat shock protein (HSP) content) in muscles of adult and old male mice following isometric contractions and has examined the mechanisms involved in the age-related reduction in transcription factor activation. Muscles of B6XSJL mice were subjected to isometric contractions and analysed for antioxidant defence enzyme activities, heat shock protein content and transcription factor DNA binding activity. Data demonstrated a significant increase in superoxide dismutase (SOD) and catalase activity and HSP content of muscles of adult mice following contractile activity which was associated with increased activation of the transcription factors, nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1) and heat shock factor (HSF) following contractions. Significant increases in SOD and catalase activity and heat shock cognate (HSC70) content were seen in quiescent muscles of old mice. The increase in antioxidant defence enzyme activity following contractile activity seen in muscles of adult mice was not seen in muscles of old mice and this was associated with a failure to fully activate NF-kappaB and AP-1 following contractions. In contrast, although the production of HSPs was also reduced in muscles of old mice following contractile activity compared with muscles of adult mice following contractions, this was not due to a gross reduction in the DNA binding activity of HSF.

  15. Assessment of bioelectrical activity of synergistic muscles during pelvic floor muscles activation in postmenopausal women with and without stress urinary incontinence: a preliminary observational study

    Directory of Open Access Journals (Sweden)

    Ptaszkowski K

    2015-09-01

    Full Text Available Kuba Ptaszkowski,1 Małgorzata Paprocka-Borowicz,2 Lucyna Słupska,2 Janusz Bartnicki,1,3 Robert Dymarek,4 Joanna Rosińczuk,4 Jerzy Heimrath,5 Janusz Dembowski,6 Romuald Zdrojowy6 1Department of Obstetrics, 2Department of Clinical Biomechanics and Physiotherapy in Motor System Disorders, Wroclaw Medical University, Wroclaw, Poland; 3Department of Obstetrics and Gynecology, Health Center Bitterfeld/Wolfen gGmbH, Bitterfeld-Wolfen, Germany; 4Department of Nervous System Diseases, 5Department of Gynaecology and Obstetrics, Faculty of Health Science, 6Department and Clinic of Urology, Faculty of Postgraduate Medical Training, Wroclaw Medical University, Wroclaw, Poland Objective: Muscles such as adductor magnus (AM, gluteus maximus (GM, rectus abdominis (RA, and abdominal external and internal oblique muscles are considered to play an important role in the treatment of stress urinary incontinence (SUI, and the relationship between contraction of these muscles and pelvic floor muscles (PFM has been established in previous studies. Synergistic muscle activation intensifies a woman’s ability to contract the PFM. In some cases, even for continent women, it is not possible to fully contract their PFM without involving the synergistic muscles. The primary aim of this study was to assess the surface electromyographic activity of synergistic muscles to PFM (SPFM during resting and functional PFM activation in postmenopausal women with and without SUI.Materials and methods: This study was a preliminary, prospective, cross-sectional observational study and included volunteers and patients who visited the Department and Clinic of Urology, University Hospital in Wroclaw, Poland. Forty-two patients participated in the study and were screened for eligibility criteria. Thirty participants satisfied the criteria and were categorized into two groups: women with SUI (n=16 and continent women (n=14. The bioelectrical activity of PFM and SPFM (AM, RA, GM was

  16. Bioelectrical activity of the pelvic floor muscles after 6-week biofeedback training in nulliparous continent women.

    Science.gov (United States)

    Chmielewska, Daria; Stania, Magdalena; Smykla, Agnieszka; Kwaśna, Krystyna; Błaszczak, Edward; Sobota, Grzegorz; Skrzypulec-Plinta, Violetta

    2016-01-01

    The aim of the study was to evaluate the effects of a 6-week sEMG-biofeedback-assisted pelvic floor muscle training program on pelvic floor muscle activity in young continent women. Pelvic floor muscle activity was recorded using a vaginal probe during five experimental trials. Biofeedback training was continued for 6 weeks, 3 times a week. Muscle strenghtening and endurance exercises were performed alternately. SEMG (surface electromyography) measurements were recorded on four different occasions: before training started, after the third week of training, after the sixth week of training, and one month after training ended. A 6-week sEMG-biofeedback-assisted pelvic floor muscle training program significantly decreased the resting activity of the pelvic floor muscles in supine lying and standing. The ability to relax the pelvic floor muscles after a sustained 60-second contraction improved significantly after the 6-week training in both positions. SEMG-biofeedback training program did not seem to affect the activity of the pelvic floor muscles or muscle fatigue during voluntary pelvic floor muscle contractions. SEMG-biofeedback-assisted pelvic floor muscle training might be recommended for physiotherapists to improve the effectiveness of their relaxation techniques.

  17. Muscles provide protection during microbial infection by activating innate immune response pathways in Drosophila and zebrafish

    Directory of Open Access Journals (Sweden)

    Arunita Chatterjee

    2016-06-01

    Full Text Available Muscle contraction brings about movement and locomotion in animals. However, muscles have also been implicated in several atypical physiological processes including immune response. The role of muscles in immunity and the mechanism involved has not yet been deciphered. In this paper, using Drosophila indirect flight muscles (IFMs as a model, we show that muscles are immune-responsive tissues. Flies with defective IFMs are incapable of mounting a potent humoral immune response. Upon immune challenge, the IFMs produce anti-microbial peptides (AMPs through the activation of canonical signaling pathways, and these IFM-synthesized AMPs are essential for survival upon infection. The trunk muscles of zebrafish, a vertebrate model system, also possess the capacity to mount an immune response against bacterial infections, thus establishing that immune responsiveness of muscles is evolutionarily conserved. Our results suggest that physiologically fit muscles might boost the innate immune response of an individual.

  18. The association between premature plantarflexor muscle activity, muscle strength, and equinus gait in patients with various pathologies.

    Science.gov (United States)

    Schweizer, Katrin; Romkes, Jacqueline; Brunner, Reinald

    2013-09-01

    This study provides an overview on the association between premature plantarflexor muscle activity (PPF), muscle strength, and equinus gait in patients with various pathologies. The purpose was to evaluate whether muscular weakness and biomechanical alterations are aetiological factors for PPF during walking, independent of the underlying pathology. In a retrospective design, 716 patients from our clinical database with 46 different pathologies (orthopaedic and neurologic) were evaluated. Gait analysis data of the patients included kinematics, kinetics, electromyographic activity (EMG) data, and manual muscle strength testing. All patients were clustered three times. First, patients were grouped according to their primary pathology. Second, all patients were again clustered, this time according to their impaired joints. Third, groups of patients with normal EMG or PPF, and equinus or normal foot contact were formed to evaluate the association between PPF and equinus gait. The patient groups derived by the first two cluster methods were further subdivided into patients with normal or reduced muscle strength. Additionally, the phi correlation coefficient was calculated between PPF and equinus gait. Independent of the clustering, PPF was present in all patient groups. Weak patients revealed PPF more frequently. The correlations of PPF and equinus gait were lower than expected, due to patients with normal EMG during loading response and equinus. These patients, however, showed higher gastrocnemius activity prior to foot strike together with lower peak tibialis anterior muscle activity in loading response. Patients with PPF and a normal foot contact possibly apply the plantarflexion-knee extension couple during loading response. While increased gastrocnemius activity around foot strike seems essential for equinus gait, premature gastrocnemius activity does not necessarily produce an equinus gait. We conclude that premature gastrocnemius activity is strongly associated

  19. Effect of knee joint angle on neuromuscular activation of the vastus intermedius muscle during isometric contraction.

    Science.gov (United States)

    Watanabe, K; Akima, H

    2011-12-01

    The purpose of this study was to compare the relationship between surface electromyography (EMG) and knee joint angle of the vastus intermedius muscle (VI) with the synergistic muscles in the quadriceps femoris (QF) muscle group. Fourteen healthy men performed maximal voluntary contractions during isometric knee extension at four knee joint angles from 90°, 115°, 140°, and 165° (180° being full extension). During the contractions, surface EMG was recorded at four muscle components of the QF muscle group: the VI, vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) muscles. The root mean square of the surface EMG at each knee joint angle was calculated and normalized by that at a knee joint angle of 90° for individual muscles. The normalized RMS of the VI muscle was significantly lower than those of the VL and RF muscles at the knee joint angles of 115° and 165° and those of the VL, VM, and RF muscles at the knee joint angle of 140° (Pneuromuscular activation of the VI muscle is regulated in a manner different from the alteration of the knee joint angle compared with other muscle components of the QF muscle group. © 2011 John Wiley & Sons A/S.

  20. A functional magnetic resonance imaging investigation of visual hallucinations in the human striate cortex.

    Science.gov (United States)

    Abid, Hina; Ahmad, Fayyaz; Lee, Soo Y; Park, Hyun W; Im, Dongmi; Ahmad, Iftikhar; Chaudhary, Safee U

    2016-11-29

    Human beings frequently experience fear, phobia, migraine and hallucinations, however, the cerebral mechanisms underpinning these conditions remain poorly understood. Towards this goal, in this work, we aim to correlate the human ocular perceptions with visual hallucinations, and map them to their cerebral origins. An fMRI study was performed to examine the visual cortical areas including the striate, parastriate and peristriate cortex in the occipital lobe of the human brain. 24 healthy subjects were enrolled and four visual patterns including hallucination circle (HCC), hallucination fan (HCF), retinotopy circle (RTC) and retinotopy cross (RTX) were used towards registering their impact in the aforementioned visual related areas. One-way analysis of variance was used to evaluate the significance of difference between induced activations. Multinomial regression and and K-means were used to cluster activation patterns in visual areas of the brain. Significant activations were observed in the visual cortex as a result of stimulus presentation. The responses induced by visual stimuli were resolved to Brodmann areas 17, 18 and 19. Activation data clustered into independent and mutually exclusive clusters with HCC registering higher activations as compared to HCF, RTC and RTX. We conclude that small circular objects, in rotation, tend to leave greater hallucinating impressions in the visual region. The similarity between observed activation patterns and those reported in conditions such as epilepsy and visual hallucinations can help elucidate the cortical mechanisms underlying these conditions. Trial Registration 1121_GWJUNG.

  1. Differential activation of an identified motor neuron and neuromodulation provide Aplysia's retractor muscle an additional function.

    Science.gov (United States)

    McManus, Jeffrey M; Lu, Hui; Cullins, Miranda J; Chiel, Hillel J

    2014-08-15

    To survive, animals must use the same peripheral structures to perform a variety of tasks. How does a nervous system employ one muscle to perform multiple functions? We addressed this question through work on the I3 jaw muscle of the marine mollusk Aplysia californica's feeding system. This muscle mediates retraction of Aplysia's food grasper in multiple feeding responses and is innervated by a pool of identified neurons that activate different muscle regions. One I3 motor neuron, B38, is active in the protraction phase, rather than the retraction phase, suggesting the muscle has an additional function. We used intracellular, extracellular, and muscle force recordings in several in vitro preparations as well as recordings of nerve and muscle activity from intact, behaving animals to characterize B38's activation of the muscle and its activity in different behavior types. We show that B38 specifically activates the anterior region of I3 and is specifically recruited during one behavior, swallowing. The function of this protraction-phase jaw muscle contraction is to hold food; thus the I3 muscle has an additional function beyond mediating retraction. We additionally show that B38's typical activity during in vivo swallowing is insufficient to generate force in an unmodulated muscle and that intrinsic and extrinsic modulation shift the force-frequency relationship to allow contraction. Using methods that traverse levels from individual neuron to muscle to intact animal, we show how regional muscle activation, differential motor neuron recruitment, and neuromodulation are key components in Aplysia's generation of multifunctionality. Copyright © 2014 the American Physiological Society.

  2. The Changes of Muscle Strength and Functional Activities During Aging in Male and Female Populations

    Directory of Open Access Journals (Sweden)

    Shih-Jung Cheng

    2014-12-01

    Conclusion: We noted that the muscle strength and functional activities were decreased earlier in female than male individuals. The decrease of functional activities during the aging process seems to be earlier than the decrease of muscle strength. It is important to implement functional activities training in addition to strengthening exercise to maintain functional levels of the geriatric population.

  3. Na+-K+-ATPase in rat skeletal muscle: muscle fiber-specific differences in exercise-induced changes in ion affinity and maximal activity

    DEFF Research Database (Denmark)

    Juel, Carsten

    2008-01-01

    It is unclear whether muscle activity reduces or increases Na(+)-K(+)-ATPase maximal in vitro activity in rat skeletal muscle, and it is not known whether muscle activity changes the Na(+)-K(+)-ATPase ion affinity. The present study uses quantification of ATP hydrolysis to characterize muscle fiber...... membranes of glycolytic muscle, which abolished the fiber-type difference in Na(+) affinity. K(m) for K(+) (in the presence of Na(+)) was not influenced by running. Running only increased the maximal in vitro activity (V(max)) in total membranes from soleus, whereas V(max) remained constant in the three...... other muscles tested. In conclusion, muscle activity induces fiber type-specific changes both in Na(+) affinity and maximal in vitro activity of the Na(+)-K(+)-ATPase. The underlying mechanisms may involve translocation of subunits and increased association between PLM units and the alphabeta complex...

  4. Decorin binds myostatin and modulates its activity to muscle cells

    International Nuclear Information System (INIS)

    Miura, Takayuki; Kishioka, Yasuhiro; Wakamatsu, Jun-ichi; Hattori, Akihito; Hennebry, Alex; Berry, Carole J.; Sharma, Mridula; Kambadur, Ravi; Nishimura, Takanori

    2006-01-01

    Myostatin, a member of TGF-β superfamily of growth factors, acts as a negative regulator of skeletal muscle mass. The mechanism whereby myostatin controls the proliferation and differentiation of myogenic cells is mostly clarified. However, the regulation of myostatin activity to myogenic cells after its secretion in the extracellular matrix (ECM) is still unknown. Decorin, a small leucine-rich proteoglycan, binds TGF-β and regulates its activity in the ECM. Thus, we hypothesized that decorin could also bind to myostatin and participate in modulation of its activity to myogenic cells. In order to test the hypothesis, we investigated the interaction between myostatin and decorin by surface plasmon assay. Decorin interacted with mature myostatin in the presence of concentrations of Zn 2+ greater than 10 μM, but not in the absence of Zn 2+ . Kinetic analysis with a 1:1 binding model resulted in dissociation constants (K D ) of 2.02 x 10 -8 M and 9.36 x 10 -9 M for decorin and the core protein of decorin, respectively. Removal of the glycosaminoglycan chain by chondroitinase ABC digestion did not affect binding, suggesting that decorin could bind to myostatin with its core protein. Furthermore, we demonstrated that immobilized decorin could rescue the inhibitory effect of myostatin on myoblast proliferation in vitro. These results suggest that decorin could trap myostatin and modulate its activity to myogenic cells in the ECM

  5. α-smooth muscle actin is not a marker of fibrogenic cell activity in skeletal muscle fibrosis.

    Directory of Open Access Journals (Sweden)

    Wanming Zhao

    Full Text Available α-Smooth muscle actin (α-SMA is used as a marker for a subset of activated fibrogenic cells, myofibroblasts, which are regarded as important effector cells of tissue fibrogenesis. We address whether α-SMA-expressing myofibroblasts are detectable in fibrotic muscles of mdx5cv mice, a mouse model for Duchenne muscular dystrophy (DMD, and whether the α-SMA expression correlates with the fibrogenic function of intramuscular fibrogenic cells. α-SMA immunostaining signal was not detected in collagen I (GFP-expressing cells in fibrotic muscles of ColI-GFP/mdx5cv mice, but it was readily detected in smooth muscle cells lining intramuscular blood vessel walls. α-SMA expression was detected by quantitative RT-PCR and Western blot in fibrogenic cells sorted from diaphragm and quadriceps muscles of the ColI-GFP/mdx5cv mice. Consistent with the more severe fibrosis in the ColI-GFP/mdx5cv diaphragm, the fibrogenic cells in the diaphragm exerted a stronger fibrogenic function than the fibrogenic cells in the quadriceps as gauged by their extracellular matrix gene expression. However, both gene and protein expression of α-SMA was lower in the diaphragm fibrogenic cells than in the quadriceps fibrogenic cells in the ColI-GFP/mdx5cv mice. We conclude that myofibroblasts are present in fibrotic skeletal muscles, but their expression of α-SMA is not detectable by immunostaining. The level of α-SMA expression by intramuscular fibrogenic cells does not correlate positively with the level of collagen gene expression or the severity of skeletal muscle fibrosis in the mdx5cv mice. α-SMA is not a functional marker of fibrogenic cells in skeletal muscle fibrosis associated with muscular dystrophy.

  6. Changes in muscle activity and stature recovery after active rehabilitation for chronic low back pain.

    Science.gov (United States)

    Lewis, Sandra; Holmes, Paul; Woby, Steve; Hindle, Jackie; Fowler, Neil

    2014-06-01

    Patients with low back pain often demonstrate elevated paraspinal muscle activity compared to asymptomatic controls. This hyperactivity has been associated with a delayed rate of stature recovery following spinal loading tasks. The aim of this study was to investigate the changes in muscle activity and stature recovery in patients with chronic low back pain following an active rehabilitation programme. The body height recovery over a 40-min unloading period was assessed via stadiometry and surface electromyograms were recorded from the paraspinal muscles during standing. The measurements were repeated after patients had attended the rehabilitation programme and again at a six-month follow-up. Analysis was based on 17 patients who completed the post-treatment analysis and 12 of these who also participated in the follow-up. By the end of the six months, patients recovered significantly more height during the unloading session than at their initial visit (ES = 1.18; P < 0.01). Greater stature recovery immediately following the programme was associated with decreased pain (r = -0.55; P = 0.01). The increased height gain after six months suggests that delayed rates of recovery are not primarily caused by disc degeneration. Muscle activity did not decrease after treatment, perhaps reflecting a period of adaptation or altered patterns of motor control. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Estimating Co-Contraction Activation of Trunk Muscles Using a Novel Musculoskeletal Model for Pregnant Women

    Directory of Open Access Journals (Sweden)

    Saori Morino

    2017-10-01

    Full Text Available Weight gain and stretched abdominal muscles from an enlarged gravid uterus are remarkable features during pregnancy. These changes elicit postural instability and place strain on body segments, contributing to lower back pain. In general, the agonist and antagonist muscles act simultaneously to increase joint stabilization; however, this can cause additional muscle stress during movement. Furthermore, this activation can be observed in pregnant women because of their unstable body joints. Hence, physical modalities based on assessments of muscle activation are useful for managing low back pain during pregnancy. Musculoskeletal models are common when investigating muscle load. However, it is difficult to apply such models to pregnant women and estimate the co-contraction of muscles using musculoskeletal models. Therefore, the purpose of this study is to construct a musculoskeletal model for pregnant women that estimates the co-contraction of trunk muscles. First, motion analysis was conducted on a pregnant woman and the muscle activations of the rectus abdominis and erector spinae were measured. Then, the musculoskeletal model was specifically modified for pregnant women. Finally, the co-contraction was estimated from the results of the musculoskeletal model and electromyography data using a genetic algorithm. With the proposed methods, weakened abdominal muscle torque and the co-contraction activation of trunk muscles were estimated successfully.

  8. STAT3 Activation in Skeletal Muscle Links Muscle Wasting and the Acute Phase Response in Cancer Cachexia

    Science.gov (United States)

    Kunzevitzky, Noelia; Guttridge, Denis C.; Khuri, Sawsan; Koniaris, Leonidas G.; Zimmers, Teresa A.

    2011-01-01

    Background Cachexia, or weight loss despite adequate nutrition, significantly impairs quality of life and response to therapy in cancer patients. In cancer patients, skeletal muscle wasting, weight loss and mortality are all positively associated with increased serum cytokines, particularly Interleukin-6 (IL-6), and the presence of the acute phase response. Acute phase proteins, including fibrinogen and serum amyloid A (SAA) are synthesized by hepatocytes in response to IL-6 as part of the innate immune response. To gain insight into the relationships among these observations, we studied mice with moderate and severe Colon-26 (C26)-carcinoma cachexia. Methodology/Principal Findings Moderate and severe C26 cachexia was associated with high serum IL-6 and IL-6 family cytokines and highly similar patterns of skeletal muscle gene expression. The top canonical pathways up-regulated in both were the complement/coagulation cascade, proteasome, MAPK signaling, and the IL-6 and STAT3 pathways. Cachexia was associated with increased muscle pY705-STAT3 and increased STAT3 localization in myonuclei. STAT3 target genes, including SOCS3 mRNA and acute phase response proteins, were highly induced in cachectic muscle. IL-6 treatment and STAT3 activation both also induced fibrinogen in cultured C2C12 myotubes. Quantitation of muscle versus liver fibrinogen and SAA protein levels indicates that muscle contributes a large fraction of serum acute phase proteins in cancer. Conclusions/Significance These results suggest that the STAT3 transcriptome is a major mechanism for wasting in cancer. Through IL-6/STAT3 activation, skeletal muscle is induced to synthesize acute phase proteins, thus establishing a molecular link between the observations of high IL-6, increased acute phase response proteins and muscle wasting in cancer. These results suggest a mechanism by which STAT3 might causally influence muscle wasting by altering the profile of genes expressed and translated in muscle such

  9. ATPase activity and contraction in porcine and human cardiac muscle

    Czech Academy of Sciences Publication Activity Database

    Griffiths, P. J.; Isackson, H.; Redwood, C.; Marston, S.; Pelc, Radek; Funari, S.; Watkins, H.; Ashley, C. C.

    2008-01-01

    Roč. 29, 6-8 (2008), s. 277-277 ISSN 0142-4319. [European Muscle Conference of the European Society for Muscle Research /37./. 13.09.2008-16.09.2008, Oxford] R&D Projects: GA MŠk(CZ) LC06063 Grant - others:EC(XE) RII3-CT-2004-506008 Institutional research plan: CEZ:AV0Z50110509 Keywords : cpo1 * ATP-asa * cardiac muscle * molecular motor Subject RIV: ED - Physiology

  10. Epidemiological investigation of muscle-strengthening activities and cognitive function among older adults.

    Science.gov (United States)

    Loprinzi, Paul D

    2016-06-01

    Limited research has examined the association of muscle-strengthening activities and executive cognitive function among older adults, which was this study's purpose. Data from the 1999-2002 NHANES were employed (N = 2157; 60-85 years). Muscle-strengthening activities were assessed via self-report, with cognitive function assessed using the digit symbol substitution test. After adjusting for age, age-squared, gender, race-ethnicity, poverty level, body mass index, C-reactive protein, smoking, comorbid illness and physical activity, muscle-strengthening activities were significantly associated with cognitive function (βadjusted = 3.4; 95% CI: 1.7-5.1; P cognitive function score. In conclusion, muscle-strengthening activities are associated with executive cognitive function among older U.S. adults, underscoring the importance of promoting both aerobic exercise and muscle-strengthening activities to older adults. © The Author(s) 2016.

  11. Acute effects of massage or active exercise in relieving muscle soreness

    DEFF Research Database (Denmark)

    Andersen, Lars L; Jay, Kenneth; Andersen, Christoffer H

    2013-01-01

    Massage is commonly believed to be the best modality for relieving muscle soreness. However, actively warming up the muscles with exercise may be an effective alternative. The purpose of this study was to compare the acute effect of massage with active exercise for relieving muscle soreness. Twenty...... healthy female volunteers (mean age 32 years) participated in this examiner-blind randomized controlled trial (ClinicalTrials.gov NCT01478451). The participants performed eccentric contractions for the upper trapezius muscle on a Biodex dynamometer. Delayed onset muscle soreness (DOMS) presented 48 hours...... later, at which the participants (a) received 10 minutes of massage of the trapezius muscle or (b) performed 10 minutes of active exercise (shoulder shrugs 10 × 10 reps) with increasing elastic resistance (Thera-Band). First, 1 treatment was randomly applied to 1 shoulder while the contralateral...

  12. Muscle size, neuromuscular activation, and rapid force characteristics in elderly men and women

    DEFF Research Database (Denmark)

    Suetta, C; Aagaard, P; Magnusson, S P

    2007-01-01

    quadriceps muscle cross-sectional area (LCSA), contractile rate of force development (RFD, Delta force/Delta time), impulse (integral force dt), muscle activation deficit (interpolated twitch technique), maximal neuromuscular activity [electromyogram (EMG)], and antagonist muscle coactivation in elderly men......%), contractile RFD (W: 17-26%; M: 15-24%), impulse (W: 10-19%, M: 19-20%), maximal EMG amplitude (W: 22-25%, M: 22-28%), and an increased muscle activation deficit (-18%) compared with UN. Furthermore, women were less strong (AF: 40%; UN: 39%), had less muscle mass (AF: 33%; UN: 34%), and had a lower RFD (AF: 38......-50%; UN: 41-48%) compared with men. Similarly, maximum EMG amplitude was smaller for both agonists (AF: 51-63%; UN: 35-61%) and antagonist (AF: 49-64%; UN: 36-56%) muscles in women compared with men. However, when MVC and RFD were normalized to LCSA, there were no differences between genders. The present...

  13. A Trap Motion in Validating Muscle Activity Prediction from Musculoskeletal Model using EMG

    NARCIS (Netherlands)

    Wibawa, A. D.; Verdonschot, N.; Halbertsma, J.P.K.; Burgerhof, J.G.M.; Diercks, R.L.; Verkerke, G. J.

    2016-01-01

    Musculoskeletal modeling nowadays is becoming the most common tool for studying and analyzing human motion. Besides its potential in predicting muscle activity and muscle force during active motion, musculoskeletal modeling can also calculate many important kinetic data that are difficult to measure

  14. The activity pattern of shoulder muscles in subjects with and without subacromial impingement

    DEFF Research Database (Denmark)

    Diederichsen, Louise Pyndt; Nørregaard, Jesper; Dyhre-Poulsen, Poul

    2009-01-01

    Altered shoulder muscle activity is frequently believed to be a pathogenetic factor of subacromial impingement (SI) and therapeutic interventions have been directed towards restoring normal motor patterns. Still, there is a lack of scientific evidence regarding the changes in muscle activity in p...... that the different motor patterns might be a pathogenetic factor of SI, perhaps due to inappropriate neuromuscular strategies affecting both shoulders....

  15. Lower physical activity is associated with fat infiltration within skeletal muscle in young girls

    Science.gov (United States)

    Fat infiltration within skeletal muscle is strongly associated with obesity, type 2 diabetes mellitus, and metabolic syndrome. Lower physical activity may be a risk factor for greater fat infiltration within skeletal muscle, although whether lower physical activity is associated with fat infiltrati...

  16. Effects of training and weight support on muscle activation in Parkinson's disease.

    Science.gov (United States)

    Rose, Martin H; Løkkegaard, Annemette; Sonne-Holm, Stig; Jensen, Bente R

    2013-12-01

    The aim of this study was to investigate the effect of high-intensity locomotor training on knee extensor and flexor muscle activation and adaptability to increased body-weight (BW) support during walking in patients with Parkinson's disease (PD). Thirteen male patients with idiopathic PD and eight healthy participants were included. The PD patients completed an 8-week training program on a lower-body, positive-pressure treadmill. Knee extensor and flexor muscles activation during steady treadmill walking (3 km/h) were measured before, at the mid-point, and after training. Increasing BW support decreased knee extensor muscle activation (normalization) and increased knee flexor muscle activation (abnormal) in PD patients when compared to healthy participants. Training improved flexor peak muscle activation adaptability to increased (BW) support during walking in PD patients. During walking without BW support shorter knee extensor muscle off-activation time and increased relative peak muscle activation was observed in PD patients and did not improve with 8 weeks of training. In conclusion, patients with PD walked with excessive activation of the knee extensor and flexor muscles when compared to healthy participants. Specialized locomotor training may facilitate adaptive processes related to motor control of walking in PD patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Biofeedback effectiveness to reduce upper limb muscle activity during computer work is muscle specific and time pressure dependent

    DEFF Research Database (Denmark)

    Vedsted, Pernille; Søgaard, Karen; Blangsted, Anne Katrine

    2011-01-01

    trapezius (TRA) can reduce bilateral TRA activity but not extensor digitorum communis (EDC) activity; (2) biofeedback from EDC can reduce activity in EDC but not in TRA; (3) biofeedback is more effective in no time constraint than in the time constraint working condition. Eleven healthy women performed......Continuous electromyographic (EMG) activity level is considered a risk factor in developing muscle disorders. EMG biofeedback is known to be useful in reducing EMG activity in working muscles during computer work. The purpose was to test the following hypotheses: (1) unilateral biofeedback from...... computer work during two different working conditions (time constraint/no time constraint) while receiving biofeedback. Biofeedback was given from right TRA or EDC through two modes (visual/auditory) by the use of EMG or mechanomyography as biofeedback source. During control sessions (no biofeedback), EMG...

  18. An Active Learning Mammalian Skeletal Muscle Lab Demonstrating Contractile and Kinetic Properties of Fast- and Slow-Twitch Muscle

    Science.gov (United States)

    Head, S. I.; Arber, M. B.

    2013-01-01

    The fact that humans possess fast and slow-twitch muscle in the ratio of approximately 50% has profound implications for designing exercise training strategies for power and endurance activities. With the growth of exercise and sport science courses, we have seen the need to develop an undergraduate student laboratory that demonstrates the basic…

  19. Acute sex hormone suppression reduces skeletal muscle sympathetic nerve activity.

    Science.gov (United States)

    Day, Danielle S; Gozansky, Wendolyn S; Bell, Christopher; Kohrt, Wendy M

    2011-10-01

    Comparisons of sympathetic nervous system activity (SNA) between young and older women have produced equivocal results, in part due to inadequate control for potential differences in sex hormone concentrations, age, and body composition. The aim of the present study was to determine the effect of a short-term reduction in sex hormones on tonic skeletal muscle sympathetic nerve activity (MSNA), an indirect measure of whole body SNA, using an experimental model of sex hormone deficiency in young women. We also assessed the independent effects of estradiol and progesterone add-back therapy on MSNA. MSNA was measured in 9 women (30±2 years; mean±SE) on three separate occasions: during the mid-luteal menstrual cycle phase, on the fifth day of gonadotropin-releasing hormone antagonist (GnRHant) administration, and after 5 days add-back of either estradiol (n=4) or progesterone (n=3) during continued GnRHant administration. In response to GnRHant, there were significant reductions in serum estradiol and progesterone (both psuppression attenuates MSNA and that this may be related to the suppression of progesterone rather than estradiol.

  20. Increased Stiffness in Aged Skeletal Muscle Impairs Muscle Progenitor Cell Proliferative Activity.

    Directory of Open Access Journals (Sweden)

    Grégory Lacraz

    Full Text Available Skeletal muscle aging is associated with a decreased regenerative potential due to the loss of function of endogenous stem cells or myogenic progenitor cells (MPCs. Aged skeletal muscle is characterized by the deposition of extracellular matrix (ECM, which in turn influences the biomechanical properties of myofibers by increasing their stiffness. Since the stiffness of the MPC microenvironment directly impacts MPC function, we hypothesized that the increase in muscle stiffness that occurs with aging impairs the behavior of MPCs, ultimately leading to a decrease in regenerative potential.We showed that freshly isolated individual myofibers from aged mouse muscles contain fewer MPCs overall than myofibers from adult muscles, with fewer quiescent MPCs and more proliferative and differentiating MPCs. We observed alterations in cultured MPC behavior in aged animals, where the proliferation and differentiation of MPCs were lower and higher, respectively. These alterations were not linked to the intrinsic properties of aged myofibers, as shown by the similar values for the cumulative population-doubling values and fusion indexes. However, atomic force microscopy (AFM indentation experiments revealed a nearly 4-fold increase in the stiffness of the MPC microenvironment. We further showed that the increase in stiffness is associated with alterations to muscle ECM, including the accumulation of collagen, which was correlated with higher hydroxyproline and advanced glycation end-product content. Lastly, we recapitulated the impaired MPC behavior observed in aging using a hydrogel substrate that mimics the stiffness of myofibers.These findings provide novel evidence that the low regenerative potential of aged skeletal muscle is independent of intrinsic MPC properties but is related to the increase in the stiffness of the MPC microenvironment.

  1. Thoracic posture, shoulder muscle activation patterns and isokinetic ...

    African Journals Online (AJOL)

    Poor posture, scapular dyskinesia, altered scapular muscle recruitment patterns and ... postural deviation and incorrect shoulder kinematics.[5]. Knowledge of the .... the contra-lateral hand was placed as far down the spinal column as possible, and the ... produced by muscle contraction for rotation around a joint.[12] During.

  2. Daily durations of spontaneous activity in cat's ankle muscles

    NARCIS (Netherlands)

    Hensbergen, E; Kernell, D

    For an understanding of how various degrees of altered use (training, disuse) affect the properties of skeletal muscles, it is important to know how much they are used normally. The main aim of the present project was to produce such background knowledge for hindlimb muscles of the cat. In four

  3. The effects of surface condition on abdominal muscle activity during single-legged hold exercise.

    Science.gov (United States)

    Ha, Sung-min; Oh, Jae-seop; Jeon, In-cheol; Kwon, Oh-yun

    2015-02-01

    To treat low-back pain, various spinal stability exercises are commonly used to improve trunk muscle function and strength. Because human movement for normal daily activity occurs in multi-dimensions, the importance of exercise in multi-dimensions or on unstable surfaces has been emphasized. Recently, a motorized rotating platform (MRP) for facilitating multi-dimensions dynamic movement was introduced for clinical use. However, the abdominal muscle activity with this device has not been reported. The purpose of this study was to compare the abdominal muscle activity (rectus abdominis, external and internal oblique muscles) during an active single-leg-hold (SLH) exercise on a floor (stable surface), foam roll, and motorized rotating platform (MRP). Thirteen healthy male subjects participated in this study. Using electromyography, the abdominal muscle activity was measured while the subjects performed SLH exercises on floor (stable surface), foam roll, and MRP. There were significant differences in the abdominal muscle activities among conditions (P.05) (Fig. 2). After the Bonferroni correction, however, no significant differences among conditions remained, except for differences in both side IO muscle activity between the floor and foam roll conditions (padjexercises on a foam roll and MRP is more effective increased activities of both side of RA and IO, and Rt. EO compared to floor condition. However, there were no significant differences in abdominal muscles activity in the multiple comparison between conditions (mean difference were smaller than the standard deviation in the abdominal muscle activities) (padj>0.017), except for differences in both side IO muscle activity between the floor (stable surface) and foam roll (padj<0.017) (effect size: 0.79/0.62 (non-supporting/supporting leg) for foam-roll versus floor). Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Effects of training and weight support on muscle activation in Parkinson's disease

    DEFF Research Database (Denmark)

    Rose, Martin Høyer; Løkkegaard, Annemette; Sonne-Holm, Stig

    2013-01-01

    The aim of this study was to investigate the effect of high-intensity locomotor training on knee extensor and flexor muscle activation and adaptability to increased body-weight (BW) support during walking in patients with Parkinson's disease (PD). Thirteen male patients with idiopathic PD and eight...... healthy participants were included. The PD patients completed an 8-week training program on a lower-body, positive-pressure treadmill. Knee extensor and flexor muscles activation during steady treadmill walking (3km/h) were measured before, at the mid-point, and after training. Increasing BW support...... decreased knee extensor muscle activation (normalization) and increased knee flexor muscle activation (abnormal) in PD patients when compared to healthy participants. Training improved flexor peak muscle activation adaptability to increased (BW) support during walking in PD patients. During walking without...

  5. Quantification of muscle activity during sleep for patients with neurodegenerative diseases

    DEFF Research Database (Denmark)

    Hanif, Umaer; Trap, Lotte; Jennum, Poul

    2015-01-01

    Idiopathic REM sleep behavior disorder (iRBD) is a very strong predictor for later development of Parkinson's disease (PD), and is characterized by REM sleep without atonia (RSWA), resulting in increased muscle activity during REM sleep. Abundant studies have shown the loss of atonia during REM...... sleep, but our aim was to investigate whether iRBD and PD patients have increased muscle activity in both REM and NREM sleep compared to healthy controls. This was achieved by developing a semi-automatic algorithm for quantification of mean muscle activity per second during all sleep stages...... to the different sleep stages and muscle activity beyond the threshold was counted. The results were evaluated statistically using the two-sided Mann-Whitney U-test. The results suggested that iRBD patients also exhibit distinctive muscle activity characteristics in NREM sleep, however not as evident as in REM...

  6. Oxidative stress (glutathionylation and Na,K-ATPase activity in rat skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Carsten Juel

    Full Text Available Changes in ion distribution across skeletal muscle membranes during muscle activity affect excitability and may impair force development. These changes are counteracted by the Na,K-ATPase. Regulation of the Na,K-ATPase is therefore important for skeletal muscle function. The present study investigated the presence of oxidative stress (glutathionylation on the Na,K-ATPase in rat skeletal muscle membranes.Immunoprecipitation with an anti-glutathione antibody and subsequent immunodetection of Na,K-ATPase protein subunits demonstrated 9.0±1.3% and 4.1±1.0% glutathionylation of the α isoforms in oxidative and glycolytic skeletal muscle, respectively. In oxidative muscle, 20.0±6.1% of the β1 units were glutathionylated, whereas 14.8±2.8% of the β2-subunits appear to be glutathionylated in glycolytic muscle. Treatment with the reducing agent dithiothreitol (DTT, 1 mM increased the in vitro maximal Na,K-ATPase activity by 19% (P<0.05 in membranes from glycolytic muscle. Oxidized glutathione (GSSG, 0-10 mM increased the in vitro glutathionylation level detected with antibodies, and decreased the in vitro maximal Na,K-ATPase activity in a dose-dependent manner, and with a larger effect in oxidative compared to glycolytic skeletal muscle.This study demonstrates the existence of basal glutathionylation of both the α and the β units of rat skeletal muscle Na,K-ATPase. In addition, the study suggests a negative correlation between glutathionylation levels and maximal Na,K-ATPase activity.Glutathionylation likely contributes to the complex regulation of Na,K-ATPase function in skeletal muscle. Especially, glutathionylation induced by oxidative stress may have a role in Na,K-ATPase regulation during prolonged muscle activity.

  7. Resistance exercise-induced fluid shifts: change in active muscle size and plasma volume

    Science.gov (United States)

    Ploutz-Snyder, L. L.; Convertino, V. A.; Dudley, G. A.

    1995-01-01

    The purpose of this study was to test the hypothesis that the reduction in plasma volume (PV) induced by resistance exercise reflects fluid loss to the extravascular space and subsequently selective increase in cross-sectional area (CSA) of active but not inactive skeletal muscle. We compared changes in active and inactive muscle CSA and PV after barbell squat exercise. Magnetic resonance imaging (MRI) was used to quantify muscle involvement in exercise and to determine CSA of muscle groups or individual muscles [vasti (VS), adductor (Add), hamstring (Ham), and rectus femoris (RF)]. Muscle involvement in exercise was determined using exercise-induced contrast shift in spin-spin relaxation time (T2)-weighted MR images immediately postexercise. Alterations in muscle size were based on the mean CSA of individual slices. Hematocrit, hemoglobin, and Evans blue dye were used to estimate changes in PV. Muscle CSA and PV data were obtained preexercise and immediately postexercise and 15 and 45 min thereafter. A hierarchy of muscle involvement in exercise was found such that VS > Add > Ham > RF, with the Ham and RF showing essentially no involvement. CSA of the VS and Add muscle groups were increased 10 and 5%, respectively, immediately after exercise in each thigh with no changes in Ham and RF CSA. PV was decreased 22% immediately following exercise. The absolute loss of PV was correlated (r2 = 0.75) with absolute increase in muscle CSA immediately postexercise, supporting the notion that increased muscle size after resistance exercise reflects primarily fluid movement from the vascular space into active but not inactive muscle.

  8. Active pauses induce more variable electromyographic pattern of the trapezius muscle activity during computer work

    DEFF Research Database (Denmark)

    Samani, Afshin; Holtermann, Andreas; Søgaard, Karen

    2009-01-01

    , with passive (relax) and active (30% maximum voluntary contraction of shoulder elevation) pauses given every 2 min at two different work paces (low/high). Bipolar SEMG from four parts of the trapezius muscle was recorded. The relative rest time was higher for the lower parts compared with the upper......The aim of this laboratory study was to evaluate effects of active and passive pauses and investigate the distribution of the trapezius surface electromyographic (SEMG) activity during computer mouse work. Twelve healthy male subjects performed four sessions of computer work for 10 min in one day...... of the trapezius (pwork with active pause compared with passive one (p

  9. Regulation of myogenesis and skeletal muscle regeneration: effects of oxygen levels on satellite cell activity.

    Science.gov (United States)

    Chaillou, Thomas; Lanner, Johanna T

    2016-12-01

    Reduced oxygen (O 2 ) levels (hypoxia) are present during embryogenesis and exposure to altitude and in pathologic conditions. During embryogenesis, myogenic progenitor cells reside in a hypoxic microenvironment, which may regulate their activity. Satellite cells are myogenic progenitor cells localized in a local environment, suggesting that the O 2 level could affect their activity during muscle regeneration. In this review, we present the idea that O 2 levels regulate myogenesis and muscle regeneration, we elucidate the molecular mechanisms underlying myogenesis and muscle regeneration in hypoxia and depict therapeutic strategies using changes in O 2 levels to promote muscle regeneration. Severe hypoxia (≤1% O 2 ) appears detrimental for myogenic differentiation in vitro, whereas a 3-6% O 2 level could promote myogenesis. Hypoxia impairs the regenerative capacity of injured muscles. Although it remains to be explored, hypoxia may contribute to the muscle damage observed in patients with pathologies associated with hypoxia (chronic obstructive pulmonary disease, and peripheral arterial disease). Hypoxia affects satellite cell activity and myogenesis through mechanisms dependent and independent of hypoxia-inducible factor-1α. Finally, hyperbaric oxygen therapy and transplantation of hypoxia-conditioned myoblasts are beneficial procedures to enhance muscle regeneration in animals. These therapies may be clinically relevant to treatment of patients with severe muscle damage.-Chaillou, T. Lanner, J. T. Regulation of myogenesis and skeletal muscle regeneration: effects of oxygen levels on satellite cell activity. © FASEB.

  10. Scapular muscle activity from selected strengthening exercises performed at low and high intensity

    DEFF Research Database (Denmark)

    Andersen, Christoffer H; Zebis, Mette K; Saervoll, Charlotte

    2012-01-01

    A balanced level of muscle strength between the different parts of the scapular muscles is important to optimize performance and prevent injuries in athletes. Emerging evidence suggests that many athletes lack balanced strength in the scapular muscles. Evidence based recommendations are important...... for proper exercise prescription. This study determines scapular muscle activity during strengthening exercises for scapular muscles performed at low and high intensities (Borg-CR10 level 3 and 8). Surface electromyography (EMG) from selected scapular muscles was recorded during seven strengthening exercises...... and expressed as a percentage of the maximal EMG. Seventeen women (aged 24-55 years) without serious disorders participated. Several of the investigated exercises - press-up, prone flexion, one-arm row and prone abduction at Borg 3 and press-up, push-up plus and one-arm row at Borg 8 - predominantly activated...

  11. Dexamethasone up-regulates skeletal muscle maximal Na+,K+ pump activity by muscle group specific mechanisms in humans

    DEFF Research Database (Denmark)

    Nordsborg, Nikolai; Goodmann, Craig; McKenna, Michael J.

    2005-01-01

    Dexamethasone, a widely clinically used glucocorticoid, increases human skeletal muscle Na+,K+ pump content, but the effects on maximal Na+,K+ pump activity and subunit specific mRNA are unknown. Ten healthy male subjects ingested dexamethasone for 5 days and the effects on Na+,K+ pump content......, maximal activity and subunit specific mRNA level (a1, a2, ß1, ß2, ß3) in deltoid and vastus lateralis muscle were investigated. Before treatment, maximal Na+,K+ pump activity, as well as a1, a2, ß1 and ß2 mRNA levels were higher (P ... increased Na+,K+ pump maximal activity in vastus lateralis and deltoid by 14 ± 7% (P Na+,K+ pump content by 18 ± 9% (P

  12. Muscle Shear Moduli Changes and Frequency of Alternate Muscle Activity of Plantar Flexor Synergists Induced by Prolonged Low-Level Contraction

    Directory of Open Access Journals (Sweden)

    Ryota Akagi

    2017-09-01

    Full Text Available During prolonged low-level contractions, synergist muscles are activated in an alternating pattern of activity and silence called as alternate muscle activity. Resting muscle stiffness is considered to increase due to muscle fatigue. Thus, we investigated whether the difference in the extent of fatigue of each plantar flexor synergist corresponded to the difference in the frequency of alternate muscle activity between the synergists using muscle shear modulus as an index of muscle stiffness. Nineteen young men voluntarily participated in this study. The shear moduli of the resting medial and lateral gastrocnemius muscles (MG and LG and soleus muscle (SOL were measured using shear wave ultrasound elastography before and after a 1-h sustained contraction at 10% peak torque during maximal voluntary contraction of isometric plantar flexion. One subject did not accomplish the task and the alternate muscle activity for MG was not found in 2 subjects; therefore, data for 16 subjects were used for further analyses. The magnitude of muscle activation during the fatiguing task was similar in MG and SOL. The percent change in shear modulus before and after the fatiguing task (MG: 16.7 ± 12.0%, SOL: −4.1 ± 13.9%; mean ± standard deviation and the alternate muscle activity during the fatiguing task (MG: 33 [20–51] times, SOL: 30 [17–36] times; median [25th–75th percentile] were significantly higher in MG than in SOL. The contraction-induced change in shear modulus (7.4 ± 20.3% and the alternate muscle activity (37 [20–45] times of LG with the lowest magnitude of muscle activation during the fatiguing task among the plantar flexors were not significantly different from those of the other muscles. These results suggest that the degree of increase in muscle shear modulus induced by prolonged contraction corresponds to the frequency of alternate muscle activity between MG and SOL during prolonged contraction. Thus, it is likely that, compared with

  13. Impact of Functional Appliances on Muscle Activity: A Surface Electromyography Study in Children

    Science.gov (United States)

    Woźniak, Krzysztof; Piątkowska, Dagmara; Szyszka-Sommerfeld, Liliana; Buczkowska-Radlińska, Jadwiga

    2015-01-01

    Background Electromyography (EMG) is the most objective tool for assessing changes in the electrical activity of the masticatory muscles. The purpose of the study was to evaluate the tone of the masseter and anterior temporalis muscles in growing children before and after 6 months of treatment with functional removable orthodontic appliances. Material/Methods The sample conisted of 51 patients with a mean age 10.7 years with Class II malocclusion. EMG recordings were performed by using a DAB-Bluetooth instrument (Zebris Medical GmbH, Germany). Recordings were performed in mandibular rest position, during maximum voluntary contraction (MVC), and during maximum effort. Results The results of the study indicated that the electrical activity of the muscles in each of the clinical situations was the same in the group of girls and boys. The factor that determined the activity of the muscles was their type. In mandibular rest position and in MVC, the activity of the temporalis muscles was significantly higher that that of the masseter muscels. The maximum effort test indicated a higher fatigue in masseter than in temporalis muscles. Conclusions Surface electromyography is a useful tool for monitoring muscle activity. A 6-month period of functional therapy resulted in changes in the activity of the masticatory muscles. PMID:25600247

  14. Evaluation of muscle activity for loaded and unloaded dynamic squats during vertical whole-body vibration.

    Science.gov (United States)

    Hazell, Tom J; Kenno, Kenji A; Jakobi, Jennifer M

    2010-07-01

    The purpose of this investigation was to examine if the addition of a light external load would enhance whole-body vibration (WBV)-induced increases in muscle activity during dynamic squatting in 4 leg muscles. Thirteen recreationally active male university students performed a series of dynamic squats (unloaded with no WBV, unloaded with WBV, loaded with no WBV, and loaded with WBV). The load was set to 30% of body mass and WBV included 25-, 35-, and 45-Hz frequencies with 4-mm amplitude. Muscle activity was recorded with surface electromyography (EMG) on the vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GC) and is reported as EMGrms (root mean square) normalized to %maximal voluntary exertion. During unloaded dynamic squats, exposure to WBV (45 Hz) significantly (p squat exercise in all muscles but decreased the TA. This loaded level of muscle activity was further increased with WBV (45 Hz) in all muscles. The WBV-induced increases in muscle activity in the loaded condition (approximately 3.5%) were of a similar magnitude to the WBV-induced increases during the unloaded condition (approximately 2.5%) demonstrating the addition of WBV to unloaded or loaded dynamic squatting results in an increase in muscle activity. These results demonstrate the potential effectiveness of using external loads with exposure to WBV.

  15. Analysis of scapular muscle EMG activity in patients with idiopathic neck pain: a systematic review.

    Science.gov (United States)

    Castelein, Birgit; Cools, Ann; Bostyn, Emma; Delemarre, Jolien; Lemahieu, Trees; Cagnie, Barbara

    2015-04-01

    It is proposed that altered scapular muscle function can contribute to abnormal loading of the cervical spine. However, it is not clear if patients with idiopathic neck pain show altered activity of the scapular muscles. The aim of this paper was to systematically review the literature regarding the differences or similarities in scapular muscle activity, measured by electromyography ( = EMG), between patients with chronic idiopathic neck pain compared to pain-free controls. Case-control (neck pain/healthy) studies investigating scapular muscle EMG activity (amplitude, timing and fatigue parameters) were searched in Pubmed and Web of Science. 25 articles were included in the systematic review. During rest and activities below shoulder height, no clear differences in mean Upper Trapezius ( = UT) EMG activity exist between patients with idiopathic neck pain and a healthy control group. During overhead activities, no conclusion for scapular EMG amplitude can be drawn as a large variation of results were reported. Adaptation strategies during overhead tasks are not the same between studies. Only one study investigated timing of the scapular muscles and found a delayed onset and shorter duration of the SA during elevation in patients with idiopathic neck pain. For scapular muscle fatigue, no definite conclusions can be made as a wide variation and conflicting results are reported. Further high quality EMG research on scapular muscles (broader than the UT) is necessary to understand/draw conclusions on how scapular muscles react in the presence of idiopathic neck pain. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. An Analysis of Muscle Activities of Healthy Women during Pilates Exercises in a Prone Position.

    Science.gov (United States)

    Kim, Bo-In; Jung, Ju-Hyeon; Shim, Jemyung; Kwon, Hae-Yeon; Kim, Haroo

    2014-01-01

    [Purpose] This study analyzed the activities of the back and hip muscles during Pilates exercises conducted in a prone position. [Subjects] The subjects were 18 healthy women volunteers who had practiced at a Pilates center for more than three months. [Methods] The subjects performed three Pilates exercises. To examine muscle activity during the exercises, 8-channel surface electromyography (Noraxon USA, Inc., Scottsdale, AZ) was used. The surface electrodes were attached to the bilateral latissimus dorsi muscle, multifidus muscle, gluteus maximus, and semitendinous muscle. Three Pilates back exercises were compared: (1) double leg kick (DLK), (2) swimming (SW), and (3) leg beat (LB). Electrical muscle activation was normalized to maximal voluntary isometric contraction. Repeated measures analysis of variance was performed to assess the differences in activation levels among the exercises. [Results] The activity of the multifidus muscle was significantly high for the SW (52.3±11.0, 50.9±9.8) and LB exercises(51.8±12.8, 48.3±13.9) and the activity of the semitendinosus muscle was higher for the LB exercise (49.2±8.7, 52.9±9.3) than for the DLK and SW exercises. [Conclusion] These results may provide basic material for when Pilates exercises are performed in a prone position and may be useful information on clinical Pilates for rehabilitation programs.

  17. Transcriptional co-activator PGC-1 alpha drives the formation of slow-twitch muscle fibres.

    Science.gov (United States)

    Lin, Jiandie; Wu, Hai; Tarr, Paul T; Zhang, Chen-Yu; Wu, Zhidan; Boss, Olivier; Michael, Laura F; Puigserver, Pere; Isotani, Eiji; Olson, Eric N; Lowell, Bradford B; Bassel-Duby, Rhonda; Spiegelman, Bruce M

    2002-08-15

    The biochemical basis for the regulation of fibre-type determination in skeletal muscle is not well understood. In addition to the expression of particular myofibrillar proteins, type I (slow-twitch) fibres are much higher in mitochondrial content and are more dependent on oxidative metabolism than type II (fast-twitch) fibres. We have previously identified a transcriptional co-activator, peroxisome-proliferator-activated receptor-gamma co-activator-1 (PGC-1 alpha), which is expressed in several tissues including brown fat and skeletal muscle, and that activates mitochondrial biogenesis and oxidative metabolism. We show here that PGC-1 alpha is expressed preferentially in muscle enriched in type I fibres. When PGC-1 alpha is expressed at physiological levels in transgenic mice driven by a muscle creatine kinase (MCK) promoter, a fibre type conversion is observed: muscles normally rich in type II fibres are redder and activate genes of mitochondrial oxidative metabolism. Notably, putative type II muscles from PGC-1 alpha transgenic mice also express proteins characteristic of type I fibres, such as troponin I (slow) and myoglobin, and show a much greater resistance to electrically stimulated fatigue. Using fibre-type-specific promoters, we show in cultured muscle cells that PGC-1 alpha activates transcription in cooperation with Mef2 proteins and serves as a target for calcineurin signalling, which has been implicated in slow fibre gene expression. These data indicate that PGC-1 alpha is a principal factor regulating muscle fibre type determination.

  18. Muscle Activity in Single- vs. Double-Leg Squats.

    Science.gov (United States)

    DeFOREST, Bradley A; Cantrell, Gregory S; Schilling, Brian K

    Muscular activity, vertical displacement and ground reaction forces of back squats (BS), rear-leg elevated split squats (RLESS) and split squats (SS) were examined. Nine resistance-trained men reported for two sessions. The first session consisted of the consent process, practice, and BS 1-repetition maximum testing. In the second session, participants performed the three exercises while EMG, displacment and ground reaction force data (one leg on plate) were collected. EMG data were collected from the gluteus maximus (GMX), biceps femoris (BF), semitendinosus (ST), rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), tibialis anterior (TA), and medial gastrocnemius (MGas) of the left leg (non-dominant, front leg for unilateral squats). Load for BS was 85% one repetition maximum, and RLESS and SS were performed at 50% of BS load. Repeated measures ANOVA was used to compare all variables for the three exercises, with Bonferroni adjustments for post hoc multiple comparisons, in addition to calculation of standardized mean differences (ES). Muscle activity was similar between exercises except for biceps femoris, which was significantly higher during RLESS than SS during both concentric and eccentric phases (ES = 2.11; p=0.012 and ES= 2.19; p=0.008), and significantly higher during BS than the SS during the concentric phase (ES = 1.78; p=0.029). Vertical displacement was similar between all exercises. Peak vertical force was similar between BS and RLESS and significantly greater during RLESS than SS (ES = 3.03; p=0.001). These findings may be helpful in designing resistance training programs by using RLESS if greater biceps femoris activity is desired.

  19. Impaired voluntary neuromuscular activation limits muscle power in mobility-limited older adults

    Science.gov (United States)

    Background. Age-related alterations of neuromuscular activation may contribute to deficits in muscle power and mobility function. This study assesses whether impaired activation of the agonist quadriceps and antagonist hamstrings, including amplitude- and velocity-dependent characteristics of activa...

  20. Electromyographic activity of masticatory muscles in elderly women – a pilot study

    Directory of Open Access Journals (Sweden)

    Gaszynska E

    2017-01-01

    Full Text Available Ewelina Gaszynska,1 Karolina Kopacz,2 Magdalena Fronczek-Wojciechowska,2 Gianluca Padula,2 Franciszek Szatko1 1Department of Hygiene and Health Promotion, 2Academic Laboratory of Movement and Human Physical Performance “DynamoLab”, Medical University of Lodz, Lodz, PolandObjectives: To evaluate the effect of age and chosen factors related to aging such as dentition, muscle strength, and nutrition on masticatory muscles electromyographic activity during chewing in healthy elderly women.Background: With longer lifespan there is a need for maintaining optimal quality of life and health in older age. Skeletal muscle strength deteriorates in older age. This deterioration is also observed within masticatory muscles.Methods: A total of 30 women, aged 68–92 years, were included in the study: 10 indivi­duals had natural functional dentition, 10 were missing posterior teeth in the upper and lower jaw reconstructed with removable partial dentures, and 10 were edontoulous, using complete removable dentures. Surface electromyography was performed to evaluate masticatory muscles activity. Afterwards, measurement of masseter thickness with ultrasound imaging was performed, body mass index and body cell mass index were calculated, and isometric handgrip strength was measured.Results: Isometric maximal voluntary contraction decreased in active masseters with increasing age and in active and passive temporalis muscles with increasing age and increasing body mass index. In active masseter, mean electromyographic activity during the sequence (time from the start of chewing till the end when the test food became ready to swallow decreased with increasing age and during the cycle (single bite time decreased with increasing age and increasing body mass index. In active and passive temporalis muscles, mean electromyographic activity during the sequence and the cycle decreased with increasing age, increasing body mass index, and loss of natural dentition

  1. Comparative Statistical Mechanics of Muscle and Non-Muscle Contractile Systems: Stationary States of Near-Equilibrium Systems in A Linear Regime

    Directory of Open Access Journals (Sweden)

    Yves Lecarpentier

    2017-10-01

    Full Text Available A. Huxley’s equations were used to determine the mechanical properties of muscle myosin II (MII at the molecular level, as well as the probability of the occurrence of the different stages in the actin–myosin cycle. It was then possible to use the formalism of statistical mechanics with the grand canonical ensemble to calculate numerous thermodynamic parameters such as entropy, internal energy, affinity, thermodynamic flow, thermodynamic force, and entropy production rate. This allows us to compare the thermodynamic parameters of a non-muscle contractile system, such as the normal human placenta, with those of different striated skeletal muscles (soleus and extensor digitalis longus as well as the heart muscle and smooth muscles (trachea and uterus in the rat. In the human placental tissues, it was observed that the kinetics of the actin–myosin crossbridges were considerably slow compared with those of smooth and striated muscular systems. The entropy production rate was also particularly low in the human placental tissues, as compared with that observed in smooth and striated muscular systems. This is partly due to the low thermodynamic flow found in the human placental tissues. However, the unitary force of non-muscle myosin (NMII generated by each crossbridge cycle in the myofibroblasts of the human placental tissues was similar in magnitude to that of MII in the myocytes of both smooth and striated muscle cells. Statistical mechanics represents a powerful tool for studying the thermodynamics of all contractile muscle and non-muscle systems.

  2. Physical activity and respiratory muscle strength in elderly: a systematic review

    Directory of Open Access Journals (Sweden)

    Fabio Dutra Pereira

    Full Text Available Introduction The aging will inevitably bring some kind of functional decline in elderly, sarcopenia in this sense stands out because it damages the muscle function and extend also to the respiratory muscles. Objective Systematically review studies that have sought to compare the strength of respiratory muscles between sedentary and physically active elderly in training programs nonspecific respiratory musculature. Materials and methods From the descriptors motor activity, respiratory muscles and elderly, the databases LILACS, MedLine, Cochrane, PEDro, Scirus and Redalyc were consulted. Results Of 1.263 experiments available in said databases, 12 were recovered and 6 were selected due they meet all the inclusion criteria and selection requirements. Conclusion Physical activity programs offered by the selected studies led physically active elderly to have respiratory muscle strength statistically higher than the sedentary. However, this condition did not expressed itself as security to these elderly to present strength levels above of the minimum predictive of normality.

  3. Nitric oxide and Na,K-ATPase activity in rat skeletal muscle

    DEFF Research Database (Denmark)

    Juel, Carsten

    2016-01-01

    Aim: It has been suggested that nitric oxide (NO) stimulates the Na,K-ATPase in cardiac myocytes. Therefore, the aims of this study were to investigate whether NO increases Na,K-ATPase activity in skeletal muscle and, if that is the case, to identify the underlying mechanism. Method: The study used...... isolated rat muscle, muscle homogenates and purified membranes as model systems. Na,K-ATPase activity was quantified from phosphate release due to ATP hydrolysis. Results: Exposure to the NO donor spermine NONOate (10 μm) increased the maximal Na,K-ATPase activity by 27% in isolated glycolytic muscles...... activity was depressed by oxidized glutathione. Conclusion: NO and cGMP stimulate the Na,K-ATPase in glycolytic skeletal muscle. Direct S-nitrosylation and interference with S-glutathionylation seem to be excluded. In addition, phosphorylation of phospholemman at serine 68 is not involved. Most likely...

  4. A comparison of hamstring muscle activity during different screening tests for non-contact ACL injury

    DEFF Research Database (Denmark)

    Husted, Rasmus S; Bencke, Jesper; Andersen, Lars Louis

    2016-01-01

    phenomenon and thereby observable independently of the type of clinical screening tests used is not known. This cross sectional study investigated the rank correlation of knee joint neuromuscular activity between three different ACL injury risk screening tests. METHODS: Sixty-two adolescent female elite......BACKGROUND: Reduced ability to activate the medial hamstring muscles during a sports-specific sidecutting movement has been found to be a potential risk factor for non-contact ACL injury. However, whether a reduced ability to activate the medial hamstring muscle is a general neuromuscular...... football and handball players (16.7±1.3years) participated in the study. Using surface electromyography (EMG) assessment, the neuromuscular activity of medial hamstring muscle (semitendinosus, ST), lateral hamstring muscle (biceps femoris, BF) and quadriceps muscle (vastus lateralis, VL) were monitored...

  5. Comparing trapezius muscle activity in the different planes of shoulder elevation.

    Science.gov (United States)

    Ishigaki, Tomonobu; Ishida, Tomoya; Samukawa, Mina; Saito, Hiroshi; Hirokawa, Motoki; Ezawa, Yuya; Sugawara, Makoto; Tohyama, Harukazu; Yamanaka, Masanori

    2015-05-01

    [Purpose] The purpose of this study was to compare the upper, middle, and lower trapezius muscles' activity in the different planes of shoulder elevation. [Subjects] Twenty male subjects volunteered for this study. [Methods] Surface electromyographic (EMG) activity for each of the three regions of the trapezius muscles in the three different planes of elevation were collected while the participants maintained 30, 60, and 90 degrees of elevation in each plane. The EMG data were normalized with maximum voluntary isometric contraction (%MVIC), and compared among the planes at each angle of elevation. [Results] There were significantly different muscle activities among the elevation planes at each angle. [Conclusion] This study found that the three regions of the trapezius muscles changed their activity depending on the planes of shoulder elevation. These changes in the trapezius muscles could induce appropriate scapular motion to face the glenoid cavity in the correct directions in different planes of shoulder elevation.

  6. Application of Pilates principles increases paraspinal muscle activation.

    Science.gov (United States)

    Andrade, Letícia Souza; Mochizuki, Luís; Pires, Flávio Oliveira; da Silva, Renato André Sousa; Mota, Yomara Lima

    2015-01-01

    To analyze the effect of Pilates principles on the EMG activity of abdominal and paraspinal muscles on stable and unstable surfaces. Surface EMG data about the rectus abdominis (RA), iliocostalis (IL) and lumbar multifidus (MU) of 19 participants were collected while performing three repetitions of a crunch exercise in the following conditions: 1) with no Pilates technique and stable surface (nP + S); 2) with no Pilates technique and unstable surface (nP + U); 3) with Pilates technique and stable surface (P + S); 4) with Pilates and unstable surface (P + U). The EMG Fanalysis was conducted using a custom-made Matlab(®) 10. There was no condition effect in the RA iEMG with stable and unstable surfaces (F(1,290) = 0 p = 0.98) and with and without principles (F(1,290) = 1.2 p = 0.27). IL iEMG was higher for the stable surface condition (F(1,290) = 32.3 p Pilates principles (F(1,290) = 21.9 p Pilates principles (F(1,290) = 84.9 p < 0.001). Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Might as well jump: sound affects muscle activation in skateboarding.

    Directory of Open Access Journals (Sweden)

    Paola Cesari

    Full Text Available The aim of the study is to reveal the role of sound in action anticipation and performance, and to test whether the level of precision in action planning and execution is related to the level of sensorimotor skills and experience that listeners possess about a specific action. Individuals ranging from 18 to 75 years of age--some of them without any skills in skateboarding and others experts in this sport--were compared in their ability to anticipate and simulate a skateboarding jump by listening to the sound it produces. Only skaters were able to modulate the forces underfoot and to apply muscle synergies that closely resembled the ones that a skater would use if actually jumping on a skateboard. More importantly we showed that only skaters were able to plan the action by activating anticipatory postural adjustments about 200 ms after the jump event. We conclude that expert patterns are guided by auditory events that trigger proper anticipations of the corresponding patterns of movements.

  8. Might as well jump: sound affects muscle activation in skateboarding.

    Science.gov (United States)

    Cesari, Paola; Camponogara, Ivan; Papetti, Stefano; Rocchesso, Davide; Fontana, Federico

    2014-01-01

    The aim of the study is to reveal the role of sound in action anticipation and performance, and to test whether the level of precision in action planning and execution is related to the level of sensorimotor skills and experience that listeners possess about a specific action. Individuals ranging from 18 to 75 years of age--some of them without any skills in skateboarding and others experts in this sport--were compared in their ability to anticipate and simulate a skateboarding jump by listening to the sound it produces. Only skaters were able to modulate the forces underfoot and to apply muscle synergies that closely resembled the ones that a skater would use if actually jumping on a skateboard. More importantly we showed that only skaters were able to plan the action by activating anticipatory postural adjustments about 200 ms after the jump event. We conclude that expert patterns are guided by auditory events that trigger proper anticipations of the corresponding patterns of movements.

  9. Glucocorticoids activate the ATP-ubiquitin-dependent proteolytic system in skeletal muscle during fasting

    Science.gov (United States)

    Wing, S. S.; Goldberg, A. L.; Goldberger, A. L. (Principal Investigator)

    1993-01-01

    Glucocorticoids are essential for the increase in protein breakdown in skeletal muscle normally seen during fasting. To determine which proteolytic pathway(s) are activated upon fasting, leg muscles from fed and fasted normal rats were incubated under conditions that block or activate different proteolytic systems. After food deprivation (1 day), the nonlysosomal ATP-dependent process increased by 250%, as shown in experiments involving depletion of muscle ATP. Also, the maximal capacity of the lysosomal process increased 60-100%, but no changes occurred in the Ca(2+)-dependent or the residual energy-independent proteolytic processes. In muscles from fasted normal and adrenalectomized (ADX) rats, the protein breakdown sensitive to inhibitors of the lysosomal or Ca(2+)-dependent pathways did not differ. However, the ATP-dependent process was 30% slower in muscles from fasted ADX rats. Administering dexamethasone to these animals or incubating their muscles with dexamethasone reversed this defect. During fasting, when the ATP-dependent process rises, muscles show a two- to threefold increase in levels of ubiquitin (Ub) mRNA. However, muscles of ADX animals failed to show this response. Injecting dexamethasone into the fasted ADX animals increased muscle Ub mRNA within 6 h. Thus glucocorticoids activate the ATP-Ub-dependent proteolytic pathway in fasting apparently by enhancing the expression of components of this system such as Ub.

  10. Trunk muscle activation in a person with clinically complete thoracic spinal cord injury.

    Science.gov (United States)

    Bjerkefors, Anna; Carpenter, Mark G; Cresswell, Andrew G; Thorstensson, Alf

    2009-04-01

    The aim of this study was to assess if, and how, upper body muscles are activated in a person with high thoracic spinal cord injury, clinically classified as complete, during maximal voluntary contractions and in response to balance perturbations. Data from one person with spinal cord injury (T3 level) and one able-bodied person were recorded with electromyography from 4 abdominal muscles using indwelling fine-wire electrodes and from erector spinae and 3 upper trunk muscles with surface electrodes. Balance perturbations were carried out as forward or backward support surface translations. The person with spinal cord injury was able to activate all trunk muscles, even those below the injury level, both in voluntary efforts and in reaction to balance perturbations. Trunk movements were qualitatively similar in both participants, but the pattern and timing of muscle responses differed: upper trunk muscle involvement and occurrence of co-activation of ventral and dorsal muscles were more frequent in the person with spinal cord injury. These findings prompt further investigation into trunk muscle function in paraplegics, and highlight the importance of including motor tests for trunk muscles in persons with thoracic spinal cord injury, in relation to injury classification, prognosis and rehabilitation.

  11. [Cellular mechanism of the generation of spontaneous activity in gastric muscle].

    Science.gov (United States)

    Nakamura, Eri; Kito, Yoshihiko; Fukuta, Hiroyasu; Yanai, Yoshimasa; Hashitani, Hikaru; Yamamoto, Yoshimichi; Suzuki, Hikaru

    2004-03-01

    In gastric smooth muscles, interstitial cells of Cajal (ICC) might be the pacemaker cells of spontaneous activities since ICC are rich in mitochondria and are connected with smooth muscle cells via gap junctions. Several types of ICC are distributed widely in the stomach wall. A group of ICC distributed in the myenteric layer (ICC-MY) were the pacemaker cells of gastrointestinal smooth muscles. Pacemaker potentials were generated in ICC-MY, and the potentials were conducted to circular smooth muscles to trigger slow waves and also conducted to longitudinal muscles to form follower potentials. In circular muscle preparations, interstitial cells distributed within muscle bundles (ICC-IM) produced unitary potentials, which were conducted to circular muscles to form slow potentials by summation. In mutant mice lacking inositol trisphosphate (IP(3)) receptor, slow waves were absent in gastric smooth muscles. The generation of spontaneous activity was impaired by the inhibition of Ca(2+)-release from internal stores through IP(3) receptors, inhibition of mitochondrial Ca(2+)-handling with proton pump inhibitors, and inhibition of ATP-sensitive K(+)-channels at the mitochondrial inner membrane. These results suggested that mitochondrial Ca(2+)-handling causes the generation of spontaneous activity in pacemaker cells. Possible involvement of protein kinase C (PKC) in the Ca(2+) signaling system was also suggested.

  12. Transient receptor potential A1 channel contributes to activation of the muscle reflex.

    Science.gov (United States)

    Koba, Satoshi; Hayes, Shawn G; Sinoway, Lawrence I

    2011-01-01

    This study was undertaken to elucidate the role played by transient receptor potential A1 channels (TRPA1) in activating the muscle reflex, a sympathoexcitatory drive originating in contracting muscle. First, we tested the hypothesis that stimulation of the TRPA1 located on muscle afferents reflexly increases sympathetic nerve activity. In decerebrate rats, allyl isothiocyanate, a TRPA1 agonist, was injected intra-arterially into the hindlimb muscle circulation. This led to a 33% increase in renal sympathetic nerve activity (RSNA). The effect of allyl isothiocyanate was a reflex because the response was prevented by sectioning the sciatic nerve. Second, we tested the hypothesis that blockade of TRPA1 reduces RSNA response to contraction. Thirty-second continuous static contraction of the hindlimb muscles, induced by electrical stimulation of the peripheral cut ends of L(4) and L(5) ventral roots, increased RSNA and blood pressure. The integrated RSNA during contraction was reduced by HC-030031, a TRPA1 antagonist, injected intra-arterially (163 ± 24 vs. 95 ± 21 arbitrary units, before vs. after HC-030031, P reflex. Increases in RSNA in response to injection into the muscle circulation of arachidonic acid, bradykinin, and diprotonated phosphate, which are metabolic by-products of contraction and stimulants of muscle afferents during contraction, were reduced by HC-030031. These observations suggest that the TRPA1 located on muscle afferents is part of the muscle reflex and further support the notion that arachidonic acid metabolites, bradykinin, and diprotonated phosphate are candidates for endogenous agonists of TRPA1.

  13. PPARβ/δ regulates glucocorticoid- and sepsis-induced FOXO1 activation and muscle wasting.

    Directory of Open Access Journals (Sweden)

    Estibaliz Castillero

    Full Text Available FOXO1 is involved in glucocorticoid- and sepsis-induced muscle wasting, in part reflecting regulation of atrogin-1 and MuRF1. Mechanisms influencing FOXO1 expression in muscle wasting are poorly understood. We hypothesized that the transcription factor peroxisome proliferator-activated receptor β/δ (PPARβ/δ upregulates muscle FOXO1 expression and activity with a downstream upregulation of atrogin-1 and MuRF1 expression during sepsis and glucocorticoid treatment and that inhibition of PPARβ/δ activity can prevent muscle wasting. We found that activation of PPARβ/δ in cultured myotubes increased FOXO1 activity, atrogin-1 and MuRF1 expression, protein degradation and myotube atrophy. Treatment of myotubes with dexamethasone increased PPARβ/δ expression and activity. Dexamethasone-induced FOXO1 activation and atrogin-1 and MuRF1 expression, protein degradation, and myotube atrophy were inhibited by PPARβ/δ blocker or siRNA. Importantly, muscle wasting induced in rats by dexamethasone or sepsis was prevented by treatment with a PPARβ/δ inhibitor. The present results suggest that PPARβ/δ regulates FOXO1 activation in glucocorticoid- and sepsis-induced muscle wasting and that treatment with a PPARβ/δ inhibitor may ameliorate loss of muscle mass in these conditions.

  14. Dense-body aggregates as plastic structures supporting tension in smooth muscle cells.

    Science.gov (United States)

    Zhang, Jie; Herrera, Ana M; Paré, Peter D; Seow, Chun Y

    2010-11-01

    The wall of hollow organs of vertebrates is a unique structure able to generate active tension and maintain a nearly constant passive stiffness over a large volume range. These properties are predominantly attributable to the smooth muscle cells that line the organ wall. Although smooth muscle is known to possess plasticity (i.e., the ability to adapt to large changes in cell length through structural remodeling of contractile apparatus and cytoskeleton), the detailed structural basis for the plasticity is largely unknown. Dense bodies, one of the most prominent structures in smooth muscle cells, have been regarded as the anchoring sites for actin filaments, similar to the Z-disks in striated muscle. Here, we show that the dense bodies and intermediate filaments formed cable-like structures inside airway smooth muscle cells and were able to adjust the cable length according to cell length and tension. Stretching the muscle cell bundle in the relaxed state caused the cables to straighten, indicating that these intracellular structures were connected to the extracellular matrix and could support passive tension. These plastic structures may be responsible for the ability of smooth muscle to maintain a nearly constant tensile stiffness over a large length range. The finding suggests that the structural plasticity of hollow organs may originate from the dense-body cables within the smooth muscle cells.

  15. Intra-subject variability in muscle activity and co-contraction during jumps and landings in children and adults

    DEFF Research Database (Denmark)

    Raffalt, P C; Alkjaer, T; Simonsen, E B

    2017-01-01

    -subject variability in the muscle activity. Co-contraction was quantified for two thigh muscle pairs and one plantar flexor/dorsiflexor muscle pair and group differences were assessed (two-way ANOVA). No significant differences were observed in the less eccentric demanding CMJ while significantly higher muscle...

  16. Oral glucose ingestion attenuates exercise-induced activation of 5'-AMP-activated protein kinase in human skeletal muscle

    DEFF Research Database (Denmark)

    Åkerström, Thorbjörn; Birk, Jesper Bratz; Klein, Ditte Kjærsgaard

    2006-01-01

    5'-AMP-activated protein kinase (AMPK) has been suggested to be a 'metabolic master switch' regulating various aspects of muscle glucose and fat metabolism. In isolated rat skeletal muscle, glucose suppresses the activity of AMPK and in human muscle glycogen loading decreases exercise-induced AMPK...... activation. We hypothesized that oral glucose ingestion during exercise would attenuate muscle AMPK activation. Nine male subjects performed two bouts of one-legged knee-extensor exercise at 60% of maximal workload. The subjects were randomly assigned to either consume a glucose containing drink or a placebo...... drink during the two trials. Muscle biopsies were taken from the vastus lateralis before and after 2 h of exercise. Plasma glucose was higher (6.0 +/- 0.2 vs. 4.9 +/- 0.1 mmol L-1, P

  17. miR-378 attenuates muscle regeneration by delaying satellite cell activation and differentiation in mice.

    Science.gov (United States)

    Zeng, Ping; Han, Wanhong; Li, Changyin; Li, Hu; Zhu, Dahai; Zhang, Yong; Liu, Xiaohong

    2016-09-01

    Skeletal muscle mass and homeostasis during postnatal muscle development and regeneration largely depend on adult muscle stem cells (satellite cells). We recently showed that global overexpression of miR-378 significantly reduced skeletal muscle mass in mice. In the current study, we used miR-378 transgenic (Tg) mice to assess the in vivo functional effects of miR-378 on skeletal muscle growth and regeneration. Cross-sectional analysis of skeletal muscle tissues showed that the number and size of myofibers were significantly lower in miR-378 Tg mice than in wild-type mice. Attenuated cardiotoxin-induced muscle regeneration in miR-378 Tg mice was found to be associated with delayed satellite cell activation and differentiation. Mechanistically, miR-378 was found to directly target Igf1r in muscle cells both in vitro and in vivo These miR-378 Tg mice may provide a model for investigating the physiological and pathological roles of skeletal muscle in muscle-associated diseases in humans, particularly in sarcopenia. © The Author 2016. Published by Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. The effects of therapeutic hip exercise with abdominal core activation on recruitment of the hip muscles.

    Science.gov (United States)

    Chan, Mandy Ky; Chow, Ka Wai; Lai, Alfred Ys; Mak, Noble Kc; Sze, Jason Ch; Tsang, Sharon Mh

    2017-07-21

    Core stabilization has been utilized for rehabilitation and prevention of lower limb musculoskeletal injuries. Previous studies showed that activation of the abdominal core muscles enhanced the hip muscle activity in hip extension and abduction exercises. However, the lack of the direct measurement and quantification of the activation level of the abdominal core muscles during the execution of the hip exercises affect the level of evidence to substantiate the proposed application of core exercises to promote training and rehabilitation outcome of the hip region. The aim of the present study was to examine the effects of abdominal core activation, which is monitored directly by surface electromyography (EMG), on hip muscle activation while performing different hip exercises, and to explore whether participant characteristics such as gender, physical activity level and contractile properties of muscles, which is assessed by tensiomyography (TMG), have confounding effect to the activation of hip muscles in enhanced core condition. Surface EMG of bilateral internal obliques (IO), upper gluteus maximus (UGMax), lower gluteus maximus (LGMax), gluteus medius (GMed) and biceps femoris (BF) of dominant leg was recorded in 20 young healthy subjects while performing 3 hip exercises: Clam, side-lying hip abduction (HABD), and prone hip extension (PHE) in 2 conditions: natural core activation (NC) and enhanced core activation (CO). EMG signals normalized to percentage of maximal voluntary isometric contraction (%MVIC) were compared between two core conditions with the threshold of the enhanced abdominal core condition defined as >20%MVIC of IO. Enhanced abdominal core activation has significantly promoted the activation level of GMed in all phases of clam exercise (P recruitment in Clam, HABD and PHE exercises, and this enhancement is correlated with higher physical activity and stiffer hip muscle. Our results suggest the potential application of abdominal core activation for

  19. Isolation and individual electrical stimulation of single smooth-muscle cells from the urinary bladder of the pig

    NARCIS (Netherlands)

    J.J. Glerum (Jacobus); R. van Mastrigt (Ron); J.C. Romijn (Johannes); D.J. Griffiths (Derek)

    1987-01-01

    textabstractIn contrast to striated muscle, measurements on strips of smooth muscle cannot be uniquely interpreted in terms of an array of contractile units. Therefore scaling down to the single-cell level is necessary to gain detailed understanding of the contractile process in this type of muscle.

  20. Wrist muscle activity of khatrah approach in Mameluke technique using traditional bow archery

    Science.gov (United States)

    Ariffin, Muhammad Shahimi; Rambely, Azmin Sham; Ariff, Noratiqah Mohd

    2018-04-01

    An investigation of khatrah technique in archery was carried out. An electromyography (EMG) experiment was conducted towards six wrist muscles which are flexor carpi radialis, extensor carpi ulnaris and extensor digitorum communis for both arms. The maximum voluntary contraction (MVC) and activity data were recorded. The bow arm produced a higher muscle force compared to draw arm muscles during release phase. However, the muscle forces produced by bow arm had a consistency in term of pattern throughout the phases. In conclusion, the forces generated by the professional archer produced a force benchmark at the wrist joint to alleviate the risk of injury.

  1. Effect of generalized joint hypermobility on knee function and muscle activation in children and adults

    DEFF Research Database (Denmark)

    Jensen, Bente Rona; Olesen, Annesofie T.; Pedersen, Mogens Theisen

    2013-01-01

    Introduction: We investigated muscle activation strategy and performance of knee extensor and flexor muscles in children and adults with generalized joint hypermobility (GJH) and compared them with controls. Methods: Muscle activation, torque steadiness, electromechanical delay, and muscle strength...... were evaluated in 39 children and 36 adults during isometric knee extension and flexion. Subjects performed isometric maximum contractions, submaximal contractions at 25% maximum voluntary contraction (MVC), and explosive contractions. Results: Agonist activation was reduced, and coactivation ratio...... was greater in GJH during knee flexion compared with controls. Torque steadiness was impaired in adults with GJH during knee flexion. No effect of GJH was found on muscle strength or electromechanical delay. Correlation analysis revealed an association between GJH severity and function in adults. Conclusions...

  2. Muscles Activity in the elderly with Balance Impairments in walking under Dual tasks

    Directory of Open Access Journals (Sweden)

    Elaheh Azadian

    2016-09-01

    Full Text Available Objectives: Each step during gait requires different attention demands that will affect muscles activity. The study of changes in the timing and intensity of the muscles activity in walking with dual task has received less attention from researchers. The purpose of this study was to evaluate changes in electromyography patterns of gait with cognitive dual tasks in balance impaired elderly. Methods: Thirty older adults were recruited for this study. People were selected through berg balance test. Subjects walked 12-meters in two conditions, normal walking and walking with a cognitive dual task. Spatial-temporal kinematic parameters were recorded through the motion analysis and muscles activities were recorded through electromyography system. The data obtained was analyzed using repeated measures ANOVA at a significant level of p< 0.05.  Results: The results showed that walking under dual tasks would decrease gait speed and increase stride time and stance time. Also muscle activity in Tibialis anterior and Vastus lateralis in stance-phase would decrease significantly in dual tasks as compared with single task (p< 0.05, but timing of muscle activity would not change in dual task conditions.  Conclusions: Based on the results, it can be argued that walking under a dual task can change spatial-temporal parameters and muscle activity in gait pattern in the elderly with balance impairment. One explanation could be that the decreased control of the central nervous system on muscle activity in stance phase due to the performing of a dual task.

  3. Muscle activation timing and balance response in chronic lower back pain patients with associated radiculopathy.

    Science.gov (United States)

    Frost, Lydia R; Brown, Stephen H M

    2016-02-01

    Patients with chronic low back pain and associated radiculopathy present with neuromuscular symptoms both in their lower back and down their leg; however, investigations of muscle activation have so far been isolated to the lower back. During balance perturbations, it is necessary that lower limb muscles activate with proper timing and sequencing along with the lower back musculature to efficiently regain balance control. Patients with chronic low back pain and radiculopathy and matched controls completed a series of balance perturbations (rapid bilateral arm raise, unanticipated and anticipated sudden loading, and rapid rise to toe). Muscle activation timing and sequencing as well as kinetic response to the perturbations were analyzed. Patients had significantly delayed lower limb muscle activation in rapid arm raise trials as compared to controls. In sudden loading trials, muscle activation timing was not delayed in patients; however, some differences in posterior chain muscle activation sequencing were present. Patients demonstrated less anterior-posterior movement in unanticipated sudden loading trials, and greater medial-lateral movement in rise to toe trials. Patients with low back pain and radiculopathy demonstrated some significant differences from control participants in terms of muscle activation timing, sequencing, and overall balance control. The presence of differences between patients and controls, specifically in the lower limb, indicates that radiculopathy may play a role in altering balance control in these patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Changes in shoulder muscle activity pattern on surface electromyography after breast cancer surgery.

    Science.gov (United States)

    Yang, Eun Joo; Kwon, YoungOk

    2018-02-01

    Alterations in muscle activation and restricted shoulder mobility, which are common in breast cancer patients, have been found to affect upper limb function. The purpose of this study was to determine muscle activity patterns, and to compare the prevalence of abnormal patterns among the type of breast surgery. In total, 274 breast cancer patients were recruited after surgery. Type of breast surgery was divided into mastectomy without reconstruction (Mastectomy), reconstruction with tissue expander/implant (TEI), latissimus dorsi (LD) flap, or transverse rectus abdominis flap (TRAM). Activities of shoulder muscles were measured using surface electromyography. Experimental analysis was conducted using a Gaussian filter smoothing method with regression. Patients demonstrated different patterns of muscle activation, such as normal, lower muscle electrical activity, and tightness. After adjusting for BMI and breast surgery, the odds of lower muscle electrical activity and tightness in the TRAM are 40.2% and 38.4% less than in the Mastectomy only group. The prevalence of abnormal patterns was significantly greater in the ALND than SLNB in all except TRAM. Alterations in muscle activity patterns differed by breast surgery and reconstruction type. For breast cancer patients with ALND, TRAM may be the best choice for maintaining upper limb function. © 2017 Wiley Periodicals, Inc.

  5. Fueling the engine: induction of AMP-activated protein kinase in trout skeletal muscle by swimming

    NARCIS (Netherlands)

    Magnoni, L.J.; Palstra, A.P.; Planas, J.V.

    2014-01-01

    AMP-activated protein kinase (AMPK) is well known to be induced by exercise and to mediate important metabolic changes in the skeletal muscle of mammals. Despite the physiological importance of exercise as a modulator of energy use by locomotory muscle, the regulation of this enzyme by swimming has

  6. Single dose of fluoxetine increases muscle activation in chronic stroke patients.

    NARCIS (Netherlands)

    van Genderen, Hanneke Irene; Nijlant, Juliette M.M.; van Putten, Michel Johannes Antonius Maria; Movig, Kris L.L.; IJzerman, Maarten Joost

    2009-01-01

    Objectives: This pilot study explores the influence of a single dose of fluoxetine (20 mg) on the muscle activation patterns and functional ability of the muscles in the lower part of the arm in chronic stroke patients. Methods: A crossover, placebo-controlled clinical trial was conducted in 10

  7. Type and intensity of activity and risk of mobility limitation: the mediating role of muscle parameters

    NARCIS (Netherlands)

    Visser, M.; Simonsick, E.M.; Colbert, L.H.; Brach, J.S.; Rubin, S.M.; Kritchevsky, S.B.; Newman, A.B.; Harris, T.B.

    2005-01-01

    2,719 kcal/wk of total physical activity). The study outcome, incident mobility limitation, was defined as two consecutive, semiannual self-reports of any difficulty walking one quarter of a mile or climbing 10 steps. Thigh muscle area, thigh muscle attenuation (a marker of fat infiltration in

  8. Circadian and individual variations in duration of spontaneous activity among ankle muscles of the cat

    NARCIS (Netherlands)

    Hensbergen, E; Kernell, D

    This article concerns the spontaneous motor behavior of cat hindlimb muscles and muscle regions using 24-h electromyographic (EMG) recordings. Previously, we found marked differences in average daily "duty time" (i.e., the percentage of total sampling time filled with EMG activity) between different

  9. Muscle-strengthening and conditioning activities and risk of type 2 diabetes

    DEFF Research Database (Denmark)

    Grøntved, Anders; Pan, An; Mekary, Rania A

    2014-01-01

    BACKGROUND: It is well established that aerobic physical activity can lower the risk of type 2 diabetes (T2D), but whether muscle-strengthening activities are beneficial for the prevention of T2D is unclear. This study examined the association of muscle-strengthening activities with the risk of T2D...... at baseline. Participants reported weekly time spent on resistance exercise, lower intensity muscular conditioning exercises (yoga, stretching, toning), and aerobic moderate and vigorous physical activity (MVPA) at baseline and in 2004/2005. Cox regression with adjustment for major determinants for T2D...... include that muscle-strengthening and conditioning activity and other types of physical activity were assessed by a self-administered questionnaire and that the study population consisted of registered nurses with mostly European ancestry. CONCLUSIONS: Our study suggests that engagement in muscle...

  10. Modulation of jaw muscle spindle afferent activity following intramuscular injections with hypertonic saline.

    Science.gov (United States)

    Ro, J Y; Capra, N F

    2001-05-01

    Transient noxious chemical stimulation of small diameter muscle afferents modulates jaw movement-related responses of caudal brainstem neurons. While it is likely that the effect is mediated from the spindle afferents in the mesencephalic nucleus (Vmes) via the caudally projecting Probst's tract, the mechanisms of pain induced modulations of jaw muscle spindle afferents is not known. In the present study, we tested the hypothesis that jaw muscle nociceptors gain access to muscle spindle afferents in the same muscle via central mechanisms and alter their sensitivity. Thirty-five neurons recorded from the Vmes were characterized as muscle spindle afferents based on their responses to passive jaw movements, muscle palpation, and electrical stimulation of the masseter nerve. Each cell was tested by injecting a small volume (250 microl) of either 5% hypertonic and/or isotonic saline into the receptor-bearing muscle. Twenty-nine units were tested with 5% hypertonic saline, of which 79% (23/29) showed significant modulation of mean firing rates (MFRs) during one or more phases of ramp-and-hold movements. Among the muscle spindle primary-like units (n = 12), MFRs of 4 units were facilitated, five reduced, two showed mixed responses and one unchanged. In secondary-like units (n = 17), MFRs of 9 were facilitated, three reduced and five unchanged. Thirteen units were tested with isotonic saline, of which 77% showed no significant changes of MFRs. Further analysis revealed that the hypertonic saline not only affected the overall output of muscle spindle afferents, but also increased the variability of firing and altered the relationship between afferent signal and muscle length. These results demonstrated that activation of muscle nociceptors significantly affects proprioceptive properties of jaw muscle spindles via central neural mechanisms. The changes can have deleterious effects on oral motor function as well as kinesthetic sensibility.

  11. The Influence of Ambulatory Aid on Lower-Extremity Muscle Activation During Gait.

    Science.gov (United States)

    Sanders, Michael; Bowden, Anton E; Baker, Spencer; Jensen, Ryan; Nichols, McKenzie; Seeley, Matthew K

    2018-05-10

    Foot and ankle injuries are common and often require a nonweight-bearing period of immobilization for the involved leg. This nonweight-bearing period usually results in muscle atrophy for the involved leg. There is a dearth of objective data describing muscle activation for different ambulatory aids that are used during the aforementioned nonweight-bearing period. To compare activation amplitudes for 4 leg muscles during (1) able-bodied gait and (2) ambulation involving 3 different ambulatory aids that can be used during the acute phase of foot and ankle injury care. Within-subject, repeated measures. University biomechanics laboratory. Sixteen able-bodied individuals (7 females and 9 males). Each participant performed able-bodied gait and ambulation using 3 different ambulatory aids (traditional axillary crutches, knee scooter, and a novel lower-leg prosthesis). Muscle activation amplitude quantified via mean surface electromyography amplitude throughout the stance phase of ambulation. Numerous statistical differences (P < .05) existed for muscle activation amplitude between the 4 observed muscles, 3 ambulatory aids, and able-bodied gait. For the involved leg, comparing the 3 ambulatory aids: (1) knee scooter ambulation resulted in the greatest vastus lateralis activation, (2) ambulation using the novel prosthesis and traditional crutches resulted in greater biceps femoris activation than knee scooter ambulation, and (3) ambulation using the novel prosthesis resulted in the greatest gastrocnemius activation (P < .05). Generally speaking, muscle activation amplitudes were most similar to able-bodied gait when subjects were ambulating using the knee scooter or novel prosthesis. Type of ambulatory aid influences muscle activation amplitude. Traditional axillary crutches appear to be less likely to mitigate muscle atrophy during the nonweighting, immobilization period that often follows foot or ankle injuries. Researchers and clinicians should consider

  12. Determination of the Timing and Level of Activities of Lumbopelvic Muscles in Response to Postural Perturbations

    Directory of Open Access Journals (Sweden)

    S Ebrahimi Takamjani

    2005-05-01

    Full Text Available Background: One of the most important concerns in orthopedic medicine is the low back. Considering the importance of muscle function in preventing LBT by controlling too much load and stress applied on the spinal joints and ligaments. Materials and Methods: The aim of this research was to determine the timing and level of activities of lumbopelvic muscles in response to postural perturbations caused by unexpected loading of the upper limbs in standing on three different supporting surfaces (neutral, positive slope, negative slope in 20 healthy females 18 to 30 years old ( = 23.20 SD = 2.55 . The electromyographic signals were recorded from the deltoid, gluteus maximus, internal oblique abdominis and lumbar paraspinal muscles of the dominant side of the body to evaluate the onset time, end time, level of muscle activity (RMS and duration of different muscles in one task and one muscle in different tasks. Results: The results showed that the agonists (posterior muscles activated at first to compensate the flexor torque caused by loading and then the antagonists (anterior muscles switched-on to compensate the reaction forces caused by agonist activities. With regards to continuous activity of internal oblique and its attachments via thoracalumbar fascia to the transverse processes of the lumbar vertebrae, it can be considered as one of the major stabilizer muscles of the trunk . Conclusion: Finally the results indicated that supporting surface type didn’t have any effect on timing and scaling of muscle activities in different tasks suggesting that probably spinal and trunk priprioceptors are just responsible for triggering postural responses and they don’t have any role in determining timing and scaling.

  13. Mechanisms Explaining Muscle Fatigue and Muscle Pain in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): a Review of Recent Findings.

    Science.gov (United States)

    Gerwyn, Morris; Maes, Michael

    2017-01-01

    Here, we review potential causes of muscle dysfunction seen in many patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) such as the effects of oxidative and nitrosative stress (O&NS) and mitochondrial impairments together with reduced heat shock protein production and a range of metabolic abnormalities. Several studies published in the last few years have highlighted the existence of chronic O&NS, inflammation, impaired mitochondrial function and reduced heat shock protein production in many patients with ME/CFS. These studies have also highlighted the detrimental effects of chronically elevated O&NS on muscle functions such as reducing the time to muscle fatigue during exercise and impairing muscle contractility. Mechanisms have also been revealed by which chronic O&NS and or impaired heat shock production may impair muscle repair following exercise and indeed the adaptive responses in the striated muscle to acute and chronic increases in physical activity. The presence of chronic O&NS, low-grade inflammation and impaired heat shock protein production may well explain the objective findings of increased muscle fatigue, impaired contractility and multiple dimensions of exercise intolerance in many patients with ME/CFS.

  14. Bioelectrical activity of limb muscles during cold shivering of stimulation of the vestibular apparatus

    Science.gov (United States)

    Kuzmina, G. I.

    1980-01-01

    The effects of caloric and electric stimulation of the vestibular receptors on the EMG activity of limb muslces in anesthetized cats during cold induced shivering involved flexor muscles alone. Both types of stimulation suppressed bioelectrical activity more effectively in the ipsilateral muscles. The suppression of shivering activity seems to be due to the increased inhibitory effect of descending labyrinth pathways on the function of flexor motoneurons.

  15. Behavioral and Locomotor Measurements Using an Open Field Activity Monitoring System for Skeletal Muscle Diseases

    OpenAIRE

    Tatem, Kathleen S.; Quinn, James L.; Phadke, Aditi; Yu, Qing; Gordish-Dressman, Heather; Nagaraju, Kanneboyina

    2014-01-01

    The open field activity monitoring system comprehensively assesses locomotor and behavioral activity levels of mice. It is a useful tool for assessing locomotive impairment in animal models of neuromuscular disease and efficacy of therapeutic drugs that may improve locomotion and/or muscle function. The open field activity measurement provides a different measure than muscle strength, which is commonly assessed by grip strength measurements. It can also show how drugs may affect other body sy...

  16. Determination of Magnesium in Needle Biopsy Samples of Muscle Tissue by Means of Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Brune, D; Sjoeberg, H E

    1964-07-15

    Magnesium has been determined by means of neutron-activation analysis in needle biopsy samples of the order of magnitude 1 mg dry weight. The procedure applied was to extract the Mg-27 activity from irradiated muscle tissue with concentrated hydrochloric acid followed by a fast hydroxide precipitation and gamma-spectrometric measurements. The Mg activity was recovered in the muscle tissue samples to (97 {+-} 2) per cent. The sensitivity for the magnesium determination is estimated as 0.3 {mu}g.

  17. Muscle activity during functional coordination training: implications for strength gain and rehabilitation

    DEFF Research Database (Denmark)

    Jørgensen, Marie Birk; Andersen, Lars Louis; Kirk, Niels

    2010-01-01

    The purpose of this study was to evaluate if different types, body positions, and levels of progression of functional coordination exercises can provide sufficiently high levels of muscle activity to improve strength of the neck, shoulder, and trunk muscles. Nine untrained women were familiarized...... to the maximal EMG activity during maximal voluntary contractions, and a p value 60% of maximal EMG activity). Type of exercise played a significant role...

  18. Muscle activation described with a differential equation model for large ensembles of locally coupled molecular motors.

    Science.gov (United States)

    Walcott, Sam

    2014-10-01

    Molecular motors, by turning chemical energy into mechanical work, are responsible for active cellular processes. Often groups of these motors work together to perform their biological role. Motors in an ensemble are coupled and exhibit complex emergent behavior. Although large motor ensembles can be modeled with partial differential equations (PDEs) by assuming that molecules function independently of their neighbors, this assumption is violated when motors are coupled locally. It is therefore unclear how to describe the ensemble behavior of the locally coupled motors responsible for biological processes such as calcium-dependent skeletal muscle activation. Here we develop a theory to describe locally coupled motor ensembles and apply the theory to skeletal muscle activation. The central idea is that a muscle filament can be divided into two phases: an active and an inactive phase. Dynamic changes in the relative size of these phases are described by a set of linear ordinary differential equations (ODEs). As the dynamics of the active phase are described by PDEs, muscle activation is governed by a set of coupled ODEs and PDEs, building on previous PDE models. With comparison to Monte Carlo simulations, we demonstrate that the theory captures the behavior of locally coupled ensembles. The theory also plausibly describes and predicts muscle experiments from molecular to whole muscle scales, suggesting that a micro- to macroscale muscle model is within reach.

  19. Are muscle activation patterns altered during shod and barefoot running with a forefoot footfall pattern?

    Science.gov (United States)

    Ervilha, Ulysses Fernandes; Mochizuki, Luis; Figueira, Aylton; Hamill, Joseph

    2017-09-01

    This study aimed to investigate the activation of lower limb muscles during barefoot and shod running with forefoot or rearfoot footfall patterns. Nine habitually shod runners were asked to run straight for 20 m at self-selected speed. Ground reaction forces and thigh and shank muscle surface electromyographic (EMG) were recorded. EMG outcomes (EMG intensity [iEMG], latency between muscle activation and ground reaction force, latency between muscle pairs and co-activation index between muscle pairs) were compared across condition (shod and barefoot), running cycle epochs (pre-strike, strike, propulsion) and footfall (rearfoot and forefoot) by ANOVA. Condition affected iEMG at pre-strike epoch. Forefoot and rearfoot strike patterns induced different EMG activation time patterns affecting co-activation index for pairs of thigh and shank muscles. All these timing changes suggest that wearing shoes or not is less important for muscle activation than the way runners strike the foot on the ground. In conclusion, the guidance for changing external forces applied on lower limbs should be pointed to the question of rearfoot or forefoot footfall patterns.

  20. Activation of selected shoulder muscles during unilateral wall and bench press tasks under submaximal isometric effort.

    Science.gov (United States)

    Tucci, Helga T; Ciol, Marcia A; de Araújo, Rodrigo C; de Andrade, Rodrigo; Martins, Jaqueline; McQuade, Kevin J; Oliveira, Anamaria S

    2011-07-01

    Controlled laboratory study. To assess the activation of 7 shoulder muscles under 2 closed kinetic chain (CKC) tasks for the upper extremity using submaximal isometric effort, thus providing relative quantification of muscular isometric effort for these muscles across the CKC exercises, which may be applied to rehabilitation protocols for individuals with shoulder weakness. CKC exercises favor joint congruence, reduce shear load, and promote joint dynamic stability. Additionally, knowledge about glenohumeral and periscapular muscle activity elicited during CKC exercises may help clinicians to design protocols for shoulder rehabilitation. Using surface electromyography, activation level was measured across 7 shoulder muscles in 20 healthy males, during the performance of a submaximal isometric wall press and bench press. Signals were normalized to the maximal voluntary isometric contraction, and, using paired t tests, data were analyzed between the exercises for each muscle. Compared to the wall press, the bench press elicited higher activity for most muscles, except for the upper trapezius. Levels of activity were usually low but were above 20% maximal voluntary isometric contraction for the serratus anterior on both tasks, and for the long head triceps brachii on the bench press. Both the bench press and wall press, as performed in this study, led to relatively low EMG activation levels for the muscles measured and may be considered for use in the early phases of rehabilitation.

  1. CORE MUSCLE ACTIVITY DURING THE CLEAN AND JERK LIFT WITH BARBELL VERSUS SANDBAGS AND WATER BAGS.

    Science.gov (United States)

    Calatayud, Joaquin; Colado, Juan C; Martin, Fernando; Casaña, José; Jakobsen, Markus D; Andersen, Lars L

    2015-11-01

    While the traditional clean and jerk maneuver implies simultaneous participation of a large number of muscle groups, the use of this exercise with some variations to enhance core muscle activity remains uninvestigated. The purpose of this study was to compare the muscle activity during clean and jerk lift when performed with a barbell, sandbag and a water bag at same absolute load. Descriptive, repeated-measures study. Twenty-one young fit male university students (age: 25 ± 2.66 years; height: 180.71 ± 5.42 cm; body mass: 80.32 ± 9.8 kg; body fat percentage: 12.41 ± 3.56 %) participated. Surface electromyographic (EMG) signals were recorded from the anterior deltoid (AD), external oblique (OBLIQ), lumbar erector spinae (LUMB), and gluteus medius (GM) and were expressed as a percentage of the maximum voluntary isometric contraction (MVIC). There were no significantly significant differences for AD muscle activity between conditions, whereas muscle activation values for OBLIQ (60%MVIC), GM (29%MVIC) and LUMB (85%MVIC) were significantly higher during the water bag power clean and jerk maneuver when compared with the other conditions. The clean and jerk is an exercise that may be used to enhance core muscle activity. Performing the maneuver with water bags resulted in higher core muscle activity compared with sandbag and standard barbell versions. 3.

  2. Trunk muscle activity during different variations of the supine plank exercise

    DEFF Research Database (Denmark)

    Calatayud, Joaquin; Casaña, Jose; Martín, Fernando

    2017-01-01

    Background Exercises providing neuromuscular challenges of the spinal muscles are desired for core stability, which is important for workers with heavy manual labour as well as people recovering from back pain. Purpose This study evaluated whether using a suspended modality increases trunk muscle...... voluntary isometric contraction (MVIC). Results No differences between exercises were found for UP ABS, LOW ABS and OBLIQ muscle activity. The unilateral suspended supine plank provided the highest LUMB activity (20% of MVIC) whiles the bilateral stable supine plank provided the lowest activity (11% of MVIC...

  3. Effects of the belt electrode skeletal muscle electrical stimulation system on lower extremity skeletal muscle activity: Evaluation using positron emission tomography.

    Science.gov (United States)

    Numata, Hitoaki; Nakase, Junsuke; Inaki, Anri; Mochizuki, Takafumi; Oshima, Takeshi; Takata, Yasushi; Kinuya, Seigo; Tsuchiya, Hiroyuki

    2016-01-01

    Lower-extremity muscle weakness in athletes after lower limb trauma or surgery can hinder their return to sports, and the associated muscle atrophy may lead to deterioration in performance after returning to sports. Recently, belt electrode skeletal muscle electrical stimulation (B-SES) which can contract all the lower limb skeletal muscles simultaneously was developed. However, no study has evaluated skeletal muscle activity with B-SES. Since only superficial muscles as well as a limited number of muscles can be investigated using electromyography, we investigated whether positron emission tomography (PET) can evaluate the activity of all the skeletal muscles in the body simultaneously. The purpose of this study was to evaluate the effectiveness of the B-SES system using PET. Twelve healthy males (mean age, 24.3 years) were divided into two groups. The subjects in the control group remained in a sitting position for 10 min, and [(18)F] fluorodeoxyglucose (FDG) was intravenously injected. In the exercise group, subjects exercised using the B-SES system for 20 min daily for three consecutive days as a pre-test exercise. On the measurement day, they exercised for 10 min, received an injection of FDG, and exercised for another 10 min. PET-computed tomography images were obtained in each group 60 min after the FDG injection. Regions of interest were drawn in each lower-extremity muscle. We compared each skeletal muscle metabolism using the standardized uptake value. In the exercise group, FDG accumulation in the gluteus maximus, gluteus medius, gluteus minimus, quadriceps femoris, sartorius, and hamstrings was significantly higher than the muscles in the control (P skeletal muscle activity of the gluteal muscles as well as the most lower-extremity muscles simultaneously. Copyright © 2015 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.

  4. Upper limb muscle activation during sports video gaming of persons with spinal cord injury.

    Science.gov (United States)

    Jaramillo, Jeffrey P; Johanson, M Elise; Kiratli, B Jenny

    2018-04-04

    Video gaming as a therapeutic tool has largely been studied within the stroke population with some benefits reported in upper limb motor performance, balance, coordination, and cardiovascular status. To date, muscle activation of upper limb muscles in persons with spinal cord injuries (SCI) has not been studied during video game play. In this paper, we provide descriptive and comparative data for muscle activation and strength during gaming for players with tetraplegia and paraplegia, as well as, compare these results with data from traditional arm exercises (ie, biceps curl and shoulder press) with light weights which are commonly prescribed for a home program. Fourteen individuals with chronic SCI (9 tetraplegia, 5 paraplegia). We measured upper limb muscle activation with surface electromyography (EMG) during Wii Sports video game play. Muscle activation was recorded from the playing arm during 4 selected games and normalized to a maximum voluntary contraction (MVC). Heart rate and upper limb motion were recorded simultaneously with EMG. Wilcoxon signed rank tests were used to analyze differences in muscle activation between participants with paraplegia versus tetraplegia and compare gaming with traditional arm exercises with light weights. A Friedman 2-way analysis of variance identified key muscle groups active during game play. Overall muscle activation across the games was not different between those with paraplegia and tetraplegia. Heart rate during video game play for tennis and boxing were on average 10 to 20 beats/minute above resting heart rate. The magnitude of EMG was relatively greater for traditional arm exercises with light weights compared with game play. The selected Wii games were able to elicit upper extremity muscle activation and elevated heart rates for individuals with SCI that may be used to target therapeutic outcomes.

  5. Time course in calpain activity and autolysis in slow and fast skeletal muscle during clenbuterol treatment.

    Science.gov (United States)

    Douillard, Aymeric; Galbes, Olivier; Rossano, Bernadette; Vernus, Barbara; Bonnieu, Anne; Candau, Robin; Py, Guillaume

    2011-02-01

    Calpains are Ca2+ cysteine proteases that have been proposed to be involved in the cytoskeletal remodeling and wasting of skeletal muscle. Cumulative evidence also suggests that β2-agonists can lead to skeletal muscle hypertrophy through a mechanism probably related to calcium-dependent proteolytic enzyme. The aim of our study was to monitor calpain activity as a function of clenbuterol treatment in both slow and fast phenotype rat muscles. For this purpose, for 21 days we followed the time course of the calpain activity and of the ubiquitous calpain 1 and 2 autolysis, as well as muscle remodeling in the extensor digitorum longus (EDL) and soleus muscles of male Wistar rats treated daily with clenbuterol (4 mg·kg-1). A slow to fast fiber shift was observed in both the EDL and soleus muscles after 9 days of treatment, while hypertrophy was observed only in EDL after 9 days of treatment. Soleus muscle but not EDL muscle underwent an early apoptonecrosis phase characterized by hematoxylin and eosin staining. Total calpain activity was increased in both the EDL and soleus muscles of rats treated with clenbuterol. Moreover, calpain 1 autolysis increased significantly after 14 days in the EDL, but not in the soleus. Calpain 2 autolysis increased significantly in both muscles 6 hours after the first clenbuterol injection, indicating that clenbuterol-induced calpain 2 autolysis occurred earlier than calpain 1 autolysis. Together, these data suggest a preferential involvement of calpain 2 autolysis compared with calpain 1 autolysis in the mechanisms underlying the clenbuterol-induced skeletal muscle remodeling.

  6. Muscle activation patterns during walking from transtibial amputees recorded within the residual limb-prosthetic interface

    Directory of Open Access Journals (Sweden)

    Huang Stephanie

    2012-08-01

    Full Text Available Abstract Background Powered lower limb prostheses could be more functional if they had access to feedforward control signals from the user’s nervous system. Myoelectric signals are one potential control source. The purpose of this study was to determine if muscle activation signals could be recorded from residual lower limb muscles within the prosthetic socket-limb interface during walking. Methods We recorded surface electromyography from three lower leg muscles (tibilias anterior, gastrocnemius medial head, gastrocnemius lateral head and four upper leg muscles (vastus lateralis, rectus femoris, biceps femoris, and gluteus medius of 12 unilateral transtibial amputee subjects and 12 non-amputee subjects during treadmill walking at 0.7, 1.0, 1.3, and 1.6 m/s. Muscle signals were recorded from the amputated leg of amputee subjects and the right leg of control subjects. For amputee subjects, lower leg muscle signals were recorded from within the limb-socket interface and from muscles above the knee. We quantified differences in the muscle activation profile between amputee and control groups during treadmill walking using cross-correlation analyses. We also assessed the step-to-step inter-subject variability of these profiles by calculating variance-to-signal ratios. Results We found that amputee subjects demonstrated reliable muscle recruitment signals from residual lower leg muscles recorded within the prosthetic socket during walking, which were locked to particular phases of the gait cycle. However, muscle activation profile variability was higher for amputee subjects than for control subjects. Conclusion Robotic lower limb prostheses could use myoelectric signals recorded from surface electrodes within the socket-limb interface to derive feedforward commands from the amputee’s nervous system.

  7. Neck movement and muscle activity characteristics in female office workers with neck pain.

    Science.gov (United States)

    Johnston, V; Jull, G; Souvlis, T; Jimmieson, N L

    2008-03-01

    Cross-sectional study. To explore aspects of cervical musculoskeletal function in female office workers with neck pain. Evidence of physical characteristics that differentiate computer workers with and without neck pain is sparse. Patients with chronic neck pain demonstrate reduced motion and altered patterns of muscle control in the cervical flexor and upper trapezius (UT) muscles during specific tasks. Understanding cervical musculoskeletal function in office workers will better direct intervention and prevention strategies. Measures included neck range of motion; superficial neck flexor muscle activity during a clinical test, the craniocervical flexion test; and a motor task, a unilateral muscle coordination task, to assess the activity of both the anterior and posterior neck muscles. Office workers with and without neck pain were formed into 3 groups based on their scores on the Neck Disability Index. Nonworking women without neck pain formed the control group. Surface electromyographic activity was recorded bilaterally from the sternocleidomastoid, anterior scalene (AS), cervical extensor (CE) and UT muscles. Workers with neck pain had reduced rotation range and increased activity of the superficial cervical flexors during the craniocervical flexion test. During the coordination task, workers with pain demonstrated greater activity in the CE muscles bilaterally. On completion of the task, the UT and dominant CE and AS muscles demonstrated an inability to relax in workers with pain. In general, there was a linear relationship between the workers' self-reported levels of pain and disability and the movement and muscle changes. These results are consistent with those found in other cervical musculoskeletal disorders and may represent an altered muscle recruitment strategy to stabilize the head and neck. An exercise program including motor reeducation may assist in the management of neck pain in office workers.

  8. Synaptic and functional linkages between spinal premotor interneurons and hand-muscle activity during precision grip

    Directory of Open Access Journals (Sweden)

    Tomohiko eTakei

    2013-04-01

    Full Text Available Grasping is a highly complex movement that requires the coordination of a number of hand joints and muscles. Previous studies showed that spinal premotor interneurons (PreM-INs in the primate cervical spinal cord have divergent synaptic effects on hand motoneurons and that they might contribute to hand-muscle synergies. However, the extent to which these PreM-IN synaptic connections functionally contribute to modulating hand-muscle activity is not clear. In this paper, we explored the contribution of spinal PreM-INs to hand-muscle activation by quantifying the synaptic linkage (SL and functional linkage (FL of the PreM-INs with hand-muscle activities. The activity of 23 PreM-INs was recorded from the cervical spinal cord (C6–T1, with EMG signals measured simultaneously from hand and arm muscles in two macaque monkeys performing a precision grip task. Spike-triggered averages (STAs of rectified EMGs were compiled for 456 neuron–muscle pairs; 63 pairs showed significant post-spike effects (i.e., SL. Conversely, 231 of 456 pairs showed significant cross-correlations between the IN firing rate and rectified EMG (i.e., FL. Importantly, a greater proportion of the neuron–muscle pairs with SL showed FL (43/63 pairs, 68% compared with the pairs without SL (203/393, 52%, and the presence of SL was significantly associated with that of FL. However, a significant number of pairs had SL without FL (SL∩!FL, n = 20 or FL without SL (!SL∩FL, n = 203, and the proportions of these incongruities exceeded the number expected by chance. These results suggested that spinal PreM-INs function to significantly modulate hand-muscle activity during precision grip, but the contribution of other neural structures is also needed to recruit an adequate combination of hand-muscle motoneurons.

  9. The Regulation of Skeletal Muscle Active Hyperemia: The Differential Role of Adenosine in Muscles of Varied Fiber Types

    Science.gov (United States)

    1986-04-21

    cyclase mediates the coronary relaxation induced by adenosine. Adenosine-induced relaxation is accompanied by cyclic AMP accumulation in bovine ...and the reaction was started by adding 0.01 ml L-glutamic dehydrogenase ( bovine liver; 1200 U•ml-1 in SO% glycerol and vhosphate buffer; p~ 7.4...Physiol: London 68: 213-237, 1929. Dudley, G.A. and R.L. Terjung. Influence of acidosis on AMP deaTIIinase activity in contracting fast-twitch muscle

  10. Physical activity is associated with retained muscle metabolism in human myotubes challenged with palmitate

    DEFF Research Database (Denmark)

    Green, C J; Bunprajun, T; Pedersen, B K

    2013-01-01

    in satellite cells challenged with palmitate. Although the benefits of physical activity on whole body physiology have been well investigated, this paper presents novel findings that both diet and exercise impact satellite cells directly. Given the fact that satellite cells are important for muscle maintenance......  The aim of this study was to investigate whether physical activity is associated with preserved muscle metabolism in human myotubes challenged with saturated fatty acids. Human muscle satellite cells were isolated from sedentary or active individuals and differentiated into myocytes in culture...... and correlated positively to JNK phosphorylation. In conclusion, muscle satellite cells retain metabolic differences associated with physical activity. Physical activity partially protects myocytes from fatty acid-induced insulin resistance and inactivity is associated with dysregulation of metabolism...

  11. Gene expression profiling of porcine skeletal muscle in the early recovery phase following acute physical activity

    DEFF Research Database (Denmark)

    Hansen, Jeanette; Conley, Lene; Hedegaard, Jakob

    2012-01-01

    Acute physical activity elicits changes in gene expression in skeletal muscles to promote metabolic changes and to repair exercise-induced muscle injuries. In the present time-course study, pigs were submitted to an acute bout of treadmill running until near exhaustion to determine the impact...... associated with proteolytic events, such as the muscle-specific E3 ubiquitin ligase atrogin-1, were significantly upregulated, suggesting that protein breakdown, prevention of protein aggregation and stabilization of unfolded proteins are important processes for restoration of cellular homeostasis. We also...... detected an upregulation of genes that are associated with muscle cell proliferation and differentiation, including MUSTN1, ASB5 and CSRP3, possibly reflecting activation, differentiation and fusion of satellite cells to facilitate repair of muscle damage. In addition, exercise increased expression...

  12. The Masticatory Contractile Load Induced Expression and Activation of Akt1/PKBα in Muscle Fibers at the Myotendinous Junction within Muscle-Tendon-Bone Unit

    Directory of Open Access Journals (Sweden)

    Yüksel Korkmaz

    2010-01-01

    Full Text Available The cell specific detection of enzyme activation in response to the physiological contractile load within muscle-tendon-bone unit is essential for understanding of the mechanical forces transmission from muscle cells via tendon to the bone. The hypothesis that the physiological mechanical loading regulates activation of Akt1/PKBα at Thr308 and at Ser473 in muscle fibers within muscle-tendon-bone unit was tested using quantitative immunohistochemistry, confocal double fluorescence analysis, and immunoblot analysis. In comparison to the staining intensities in peripheral regions of the muscle fibers, Akt1/PKBα was detected with a higher staining intensity in muscle fibers at the myotendinous junction (MTJ areas. In muscle fibers at the MTJ areas, Akt1/PKBα is dually phosphorylated at Thr308 and Ser473. The immunohistochemical results were confirmed by immunoblot analysis. We conclude that contractile load generated by masticatory muscles induces local domain-dependent expression of Akt1/PKBα as well as activation by dually phosphorylation at Thr308 and Ser473 in muscle fibers at the MTJ areas within muscle-tendon-bone unit.

  13. Exploring Muscle Activation during Nordic Walking: A Comparison between Conventional and Uphill Walking.

    Directory of Open Access Journals (Sweden)

    Barbara Pellegrini

    Full Text Available Nordic Walking (NW owes much of its popularity to the benefits of greater energy expenditure and upper body engagement than found in conventional walking (W. Muscle activation during NW is still understudied, however. The aim of the present study was to assess differences in muscle activation and physiological responses between NW and W in level and uphill walking conditions. Nine expert Nordic Walkers (mean age 36.8±11.9 years; BMI 24.2±1.8 kg/m2 performed 5-minute treadmill trials of W and NW at 4 km/h on inclines of 0% and 15%. The electromyographic activity of seven upper body and five leg muscles and oxygen consumption (VO2 were recorded and pole force during NW was measured. VO2 during NW was 22.3% higher at 0% and only 6.9% higher at 15% than during W, while upper body muscle activation was 2- to 15-fold higher under both conditions. Lower body muscle activation was similarly increased during NW and W in the uphill condition, whereas the increase in erector spinae muscle activity was lower during NW than W. The lack of a significant increase in pole force during uphill walking may explain the lower extra energy expenditure of NW, indicating less upper body muscle activation to lift the body against gravity. NW seemed to reduce lower back muscle contraction in the uphill condition, suggesting that walking with poles may reduce effort to control trunk oscillations and could contribute to work production during NW. Although the difference in extra energy expenditure between NW and W was smaller in the uphill walking condition, the increased upper body muscle involvement during exercising with NW may confer additional benefit compared to conventional walking also on uphill terrains. Furthermore, people with low back pain may gain benefit from pole use when walking uphill.

  14. Exploring Muscle Activation during Nordic Walking: A Comparison between Conventional and Uphill Walking.

    Science.gov (United States)

    Pellegrini, Barbara; Peyré-Tartaruga, Leonardo Alexandre; Zoppirolli, Chiara; Bortolan, Lorenzo; Bacchi, Elisabetta; Figard-Fabre, Hélène; Schena, Federico

    2015-01-01

    Nordic Walking (NW) owes much of its popularity to the benefits of greater energy expenditure and upper body engagement than found in conventional walking (W). Muscle activation during NW is still understudied, however. The aim of the present study was to assess differences in muscle activation and physiological responses between NW and W in level and uphill walking conditions. Nine expert Nordic Walkers (mean age 36.8±11.9 years; BMI 24.2±1.8 kg/m2) performed 5-minute treadmill trials of W and NW at 4 km/h on inclines of 0% and 15%. The electromyographic activity of seven upper body and five leg muscles and oxygen consumption (VO2) were recorded and pole force during NW was measured. VO2 during NW was 22.3% higher at 0% and only 6.9% higher at 15% than during W, while upper body muscle activation was 2- to 15-fold higher under both conditions. Lower body muscle activation was similarly increased during NW and W in the uphill condition, whereas the increase in erector spinae muscle activity was lower during NW than W. The lack of a significant increase in pole force during uphill walking may explain the lower extra energy expenditure of NW, indicating less upper body muscle activation to lift the body against gravity. NW seemed to reduce lower back muscle contraction in the uphill condition, suggesting that walking with poles may reduce effort to control trunk oscillations and could contribute to work production during NW. Although the difference in extra energy expenditure between NW and W was smaller in the uphill walking condition, the increased upper body muscle involvement during exercising with NW may confer additional benefit compared to conventional walking also on uphill terrains. Furthermore, people with low back pain may gain benefit from pole use when walking uphill.

  15. Comparison of the electrical activity of trunk core muscles and knee muscles in subjects with and without patellofemoral pain syndrome during gait

    Directory of Open Access Journals (Sweden)

    Raheleh Dorosti

    2017-10-01

    Conclusion: It seems that electromyographic activities of some of core muscles in patients with patellofemoral pain syndrome in comparison with healthy subjects are different. However, there was no differences in electromyographic activities in some of the muscles around the knee between patients and healthy subjects.

  16. The effects of workplace stressors on muscle activity in the neck-shoulder and forearm muscles during computer work: a systematic review and meta-analysis

    NARCIS (Netherlands)

    Eijckelhof, B.H.W.; Huijsmans, M.A.; Bruno-Garza, J.L.; Blatter, B.M.; van Dieen, J.H.; Dennerlein, J.T.; van der Beek, A.J.

    2013-01-01

    Workplace stressors have been indicated to play a role in the development of neck and upper extremity pain possibly through an increase of sustained (low-level) muscle activity. The aim of this review was to study the effects of workplace stressors on muscle activity in the neck-shoulder and forearm

  17. Relationships between lower limb muscle architecture and activities and participation of children with cerebral palsy.

    Science.gov (United States)

    Ko, In-Hee; Kim, Jung-Hee; Lee, Byoung-Hee

    2013-01-01

    The purpose of this study was to determine the effects of the structure of skeletal muscle of lower extremities on function, activity, and participation of children with cerebral palsy. The subjects were 38 hospitalized patients and 13 infants with normal development. The following clinical measures were used for assessment of activity daily living and functional level of gross motor: Gross Motor Function Classification System (GMFCS), Gross Motor Function Measure (GMFM), Wee Functional Independence Measure (WeeFIM), International Classification of Functioning Child and Youth (ICF CY). Muscle thickness and strength of knee extensor and ankle extensor were collected using ultrasonography and manual muscle tester. Following the results of ICF CY evaluation for body function, activity, learning and application of knowledge, communication and environmental factors showed a decline (Psocial acknowledgement (Pfunction, daily activity and participation; the score of ICF-CY was shown to decline due to the high score for differences in thickness of muscle, muscle strength, WeeFIM, and GMFM. The thickness and muscle strength of lower extremities affect main functions of the body and improvement of muscle strength of lower extremities may have positive effects on social standards such as activity and participation of cerebral palsy.

  18. Nitric oxide and Na,K-ATPase activity in rat skeletal muscle.

    Science.gov (United States)

    Juel, C

    2016-04-01

    It has been suggested that nitric oxide (NO) stimulates the Na,K-ATPase in cardiac myocytes. Therefore, the aims of this study were to investigate whether NO increases Na,K-ATPase activity in skeletal muscle and, if that is the case, to identify the underlying mechanism. The study used isolated rat muscle, muscle homogenates and purified membranes as model systems. Na,K-ATPase activity was quantified from phosphate release due to ATP hydrolysis. Exposure to the NO donor spermine NONOate (10 μm) increased the maximal Na,K-ATPase activity by 27% in isolated glycolytic muscles, but had no effect in oxidative muscles. Spermine NONOate increased the maximal Na,K-ATPase activity by 58% (P Na,K-ATPase α-isoform. Incubation with cGMP (1 mm) increased the maximal Na,K-ATPase activity in homogenates from glycolytic muscle by 16% (P Na,K-ATPase in glycolytic skeletal muscle. Direct S-nitrosylation and interference with S-glutathionylation seem to be excluded. In addition, phosphorylation of phospholemman at serine 68 is not involved. Most likely, the NO/cGMP/protein kinase G signalling pathway is involved. © 2015 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  19. Motor unit activity after eccentric exercise and muscle damage in humans.

    Science.gov (United States)

    Semmler, J G

    2014-04-01

    It is well known that unaccustomed eccentric exercise leads to muscle damage and soreness, which can produce long-lasting effects on muscle function. How this muscle damage influences muscle activation is poorly understood. The purpose of this brief review is to highlight the effect of eccentric exercise on the activation of muscle by the nervous system, by examining the change in motor unit activity obtained from surface electromyography (EMG) and intramuscular recordings. Previous research shows that eccentric exercise produces unusual changes in the EMG–force relation that influences motor performance during isometric, shortening and lengthening muscle contractions and during fatiguing tasks. When examining the effect of eccentric exercise at the single motor unit level, there are substantial changes in recruitment thresholds, discharge rates, motor unit conduction velocities and synchronization, which can last for up to 1 week after eccentric exercise. Examining the time course of these changes suggests that the increased submaximal EMG after eccentric exercise most likely occurs through a decrease in motor unit conduction velocity and an increase in motor unit activity related to antagonist muscle coactivation and low-frequency fatigue. Furthermore, there is a commonly held view that eccentric exercise produces preferential damage to high-threshold motor units, but the evidence for this in humans is limited. Further research is needed to establish whether there is preferential damage to high-threshold motor units after eccentric exercise in humans, preferably by linking changes in motor unit activity with estimates of motor unit size using selective intramuscular recording techniques.

  20. Does metabosensitive afferent fibers activity differ from slow- and fast-twitch muscles?

    Science.gov (United States)

    Caron, Guillaume; Decherchi, Patrick; Marqueste, Tanguy

    2015-09-01

    This study was designed to investigate the metabosensitive afferent response evoked by electrically induced fatigue (EIF), lactic acid (LA) and potassium chloride (KCl) in three muscle types. We recorded the activity of groups III-IV afferents originating from soleus, gastrocnemius and tibialis anterior muscles. Our data showed a same pattern of response in the three muscles after chemical injections, i.e., a bell curve with maximal discharge rate at 1 mM for LA injections and a linear relationship between KCl concentrations and the afferent discharge rate. Furthermore, a stronger response was recorded after EIF in the gastrocnemius muscle compared to the two other muscles. The change in afferent discharge after 1 mM LA injection was higher for the gastrocnemius muscle compared to the response obtained with the corresponding concentration applied in the two other muscles, whereas changes to KCl injections did not dramatically differ between the three muscles. We conclude that anatomical (mass, phenotype, vascularization, receptor and afferent density…) and functional (flexor vs. extensor) differences between muscles could explain the amplitude of these responses.

  1. Changes in contractile activation characteristics of rat fast and slow skeletal muscle fibres during regeneration.

    Science.gov (United States)

    Gregorevic, Paul; Plant, David R; Stupka, Nicole; Lynch, Gordon S

    2004-07-15

    Damaged skeletal muscle fibres are replaced with new contractile units via muscle regeneration. Regenerating muscle fibres synthesize functionally distinct isoforms of contractile and regulatory proteins but little is known of their functional properties during the regeneration process. An advantage of utilizing single muscle fibre preparations is that assessment of their function is based on the overall characteristics of the contractile apparatus and regulatory system and as such, these preparations are sensitive in revealing not only coarse, but also subtle functional differences between muscle fibres. We examined the Ca(2+)- and Sr(2+)-activated contractile characteristics of permeabilized fibres from rat fast-twitch (extensor digitorum longus) and slow-twitch (soleus) muscles at 7, 14 and 21 days following myotoxic injury, to test the hypothesis that fibres from regenerating fast and slow muscles have different functional characteristics to fibres from uninjured muscles. Regenerating muscle fibres had approximately 10% of the maximal force producing capacity (P(o)) of control (uninjured) fibres, and an altered sensitivity to Ca(2+) and Sr(2+) at 7 days post-injury. Increased force production and a shift in Ca(2+) sensitivity consistent with fibre maturation were observed during regeneration such that P(o) was restored to 36-45% of that in control fibres by 21 days, and sensitivity to Ca(2+) and Sr(2+) was similar to that of control (uninjured) fibres. The findings support the hypothesis that regenerating muscle fibres have different contractile activation characteristics compared with mature fibres, and that they adopt properties of mature fast- or slow-twitch muscle fibres in a progressive manner as the regeneration process is completed.

  2. The effects of Pilates breathing trainings on trunk muscle activation in healthy female subjects: a prospective study.

    Science.gov (United States)

    Kim, Sung-Tae; Lee, Joon-Hee

    2017-02-01

    [Purpose] To investigate the effects of Pilates breathing on trunk muscle activation. [Subjects and Methods] Twenty-eight healthy female adults were selected for this study. Participants' trunk muscle activations were measured while they performed curl-ups, chest-head lifts, and lifting tasks. Pilates breathing trainings were performed for 60 minutes per each session, 3 times per week for 2 weeks. Post-training muscle activations were measured by the same methods used for the pre-training muscle activations. [Results] All trunk muscles measured in this study had increased activities after Pilates breathing trainings. All activities of the transversus abdominis/internal abdominal oblique, and multifidus significantly increased. [Conclusion] Pilates breathing increased activities of the trunk stabilizer muscles. Activation of the trunk muscle indicates that practicing Pilates breathing while performing lifting tasks will reduce the risk of trunk injuries.

  3. Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy

    Science.gov (United States)

    Fry, Christopher S.; Lee, Jonah D.; Jackson, Janna R.; Kirby, Tyler J.; Stasko, Shawn A.; Liu, Honglu; Dupont-Versteegden, Esther E.; McCarthy, John J.; Peterson, Charlotte A.

    2014-01-01

    Our aim in the current study was to determine the necessity of satellite cells for long-term muscle growth and maintenance. We utilized a transgenic Pax7-DTA mouse model, allowing for the conditional depletion of > 90% of satellite cells with tamoxifen treatment. Synergist ablation surgery, where removal of synergist muscles places functional overload on the plantaris, was used to stimulate robust hypertrophy. Following 8 wk of overload, satellite cell-depleted muscle demonstrated an accumulation of extracellular matrix (ECM) and fibroblast expansion that resulted in reduced specific force of the plantaris. Although the early growth response was normal, an attenuation of hypertrophy measured by both muscle wet weight and fiber cross-sectional area occurred in satellite cell-depleted muscle. Isolated primary myogenic progenitor cells (MPCs) negatively regulated fibroblast ECM mRNA expression in vitro, suggesting a novel role for activated satellite cells/MPCs in muscle adaptation. These results provide evidence that satellite cells regulate the muscle environment during growth.—Fry, C. S., Lee, J. D., Jackson, J. R., Kirby, T. J., Stasko, S. A., Liu, H., Dupont-Versteegden, E. E., McCarthy, J. J., Peterson, C. A. Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy. PMID:24376025

  4. Mitochondrial oxidative enzyme activity in individual fibre types in hypo- and hyperthyroid rat skeletal muscles.

    Science.gov (United States)

    Johnson, M A; Turnbull, D M

    1984-04-01

    Quantitative cytochemical and biochemical techniques have been used in combination to study the response of mitochondrial oxidative enzymes in individual muscle fibre types to hypo- and hyperthyroidism. Hypothyroidism resulted in decreased activity of succinate dehydrogenase (SDH), L-glycerol-3-phosphate dehydrogenase (L-GPDH), and D-3-hydroxybutyrate dehydrogenase (D-HBDH) in all fibre types of both slow-twitch soleus and fast-twitch extensor digitorum longus (e.d.l.) muscles. In hyperthyroidism, only L-GPDH activity increased in e.d.l. but more marked increases were seen in soleus muscles, which also showed increased SDH activity. In addition to these alterations in the enzyme activity in individual fibre types the metabolic profile of the muscle is further modified by the hormone-induced interconversion of slow- to fast-twitch fibres and vice versa.

  5. COMPARISON OF HAMSTRING MUSCLE ACTIVATION DURING HIGH-SPEED RUNNING AND VARIOUS HAMSTRING STRENGTHENING EXERCISES

    Science.gov (United States)

    Solheim, Jens Asmund Brevik; Bencke, Jesper

    2017-01-01

    Purpose/Background Several studies have examined the effect of hamstring strength exercises upon hamstring strains in team sports that involve many sprints. However, there has been no cross comparison among muscle activation of these hamstring training exercises with actual sprinting. Therefore, the aim of this study was to examine different hamstring exercises and compare the muscle activity in the hamstring muscle group during various exercises with the muscular activity produced during maximal sprints. Methods Twelve male sports students (age 25 ± 6.2 years, 1.80 ± 7.1 m, body mass 81.1 ± 15.6 kg) participated in this study. Surface EMG electrodes were placed on semimembranosus, semitendinosus and biceps femoris to measure muscle activity during seven hamstrings exercises and sprinting together with 3D motion capture to establish at what hip and knee angles maximal muscle activation (EMG) occurs. Maximal EMG activity during sprints for each muscle was used in order to express each exercise as a percentage of max activation during sprinting. Results The main findings were that maximal EMG activity of the different hamstring exercises were on average between 40-65% (Semitendinosus), 18-40% (biceps femoris) and 40-75% (Semimembranosus) compared with the max EMG activity in sprints, which were considered as 100%. The laying kick together with the Nordic hamstring exercises and its variations had the highest muscle activations, while the cranes showed the lowest muscle activation (in all muscles) together with the standing kick for the semimembranosus. In addition, angles at which the peak EMG activity of the hamstring muscle occurs were similar for the Nordic hamstring exercises and different for the two crane exercises (hip angle), standing kick (hip angle) and the laying kick (knee angle) compared with the sprint. Conclusions Nordic hamstring exercises with its variation together with the laying kick activates the hamstrings at high levels and

  6. Stretch activates myosin light chain kinase in arterial smooth muscle

    International Nuclear Information System (INIS)

    Barany, K.; Rokolya, A.; Barany, M.

    1990-01-01

    Stretching of porcine carotid arterial muscle increased the phosphorylation of the 20 kDa myosin light chain from 0.23 to 0.68 mol [32P]phosphate/mol light chain, whereas stretching of phorbol dibutyrate treated muscle increased the phosphorylation from 0.30 to 0.91 mol/mol. Two-dimensional gel electrophoresis followed by two-dimensional tryptic phosphopeptide mapping was used to identify the enzyme involved in the stretch-induced phosphorylation. Quantitation of the [32P]phosphate content of the peptides revealed considerable light chain phosphorylation by protein kinase C only in the phorbol dibutyrate treated arterial muscle, whereas most of the light chain phosphorylation was attributable to myosin light chain kinase. Upon stretch of either the untreated or treated muscle, the total increment in [32P]phosphate incorporation into the light chain could be accounted for by peptides characteristic for myosin light chain kinase catalyzed phosphorylation, demonstrating that the stretch-induced phosphorylation is caused by this enzyme exclusively

  7. Activation of respiratory muscles during weaning from mechanical ventilation.

    Science.gov (United States)

    Walterspacher, Stephan; Gückler, Julia; Pietsch, Fabian; Walker, David Johannes; Kabitz, Hans-Joachim; Dreher, Michael

    2017-04-01

    Respiratory muscle dysfunction is a key component of weaning failure. Balancing respiratory muscle loading and unloading by applying different ventilation modes along with spontaneous breathing episodes are established weaning strategies. However, the effects of body positioning on the respiratory muscles during weaning remains unclear. This study aimed at assessing respiratory drive by surface electromyography (EMG) of the diaphragm (EMG dia ) and parasternal muscles (EMG para ) in tracheotomized patients during prolonged weaning in 3 randomized body positions-supine, 30° semirecumbent, and 80° sitting-during mechanical ventilation and spontaneous breathing. Nine patients were included for analysis. Cardiorespiratory parameters (heart rate, blood pressure, arterial oxygen saturation, dyspnea) did not change under each condition (all P>.05). EMG para and EMG dia did not change under mechanical ventilation (both P>.05). EMG dia changed under spontaneous breathing from supine to sitting (0.45±0.26 vs 0.32±0.19; P=.012) and between semirecumbent to sitting (0.41±0.23 vs 0.32±0.19; P=.039), whereas EMG para did not change. This is the first study to show that body positioning influences respiratory drive to the diaphragm in tracheotomized patients with prolonged weaning from mechanical ventilation during unassisted breathing. Sitting position reduces respiratory drive compared with semirecumbent and supine positioning and might therefore be favored during spontaneous breathing trials. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Muscle Activation during Push-Ups with Different Suspension Training Systems.

    Science.gov (United States)

    Calatayud, Joaquin; Borreani, Sebastien; Colado, Juan C; Martín, Fernando F; Rogers, Michael E; Behm, David G; Andersen, Lars L

    2014-09-01

    The purpose of this study was to analyze upper extremity and core muscle activation when performing push-ups with different suspension devices. Young fit male university students (n = 29) performed 3 push-ups each with 4 different suspension systems. Push-up speed was controlled using a metronome and testing order was randomized. Average amplitude of the electromyographic root mean square of Triceps Brachii, Upper Trapezius, Anterior Deltoid, Clavicular Pectoralis, Rectus Abdominis, Rectus Femoris, and Lumbar Erector Spinae was recorded. Electromyographic signals were normalized to the maximum voluntary isometric contraction (MVIC). Electromyographic data were analyzed with repeated-measures analysis of variance with a Bonferroni post hoc. Based upon global arithmetic mean of all muscles analyzed, the suspended push-up with a pulley system provided the greatest activity (37.76% of MVIC; p push-up with a pulley system also provided the greatest triceps brachii, upper trapezius, rectus femoris and erector lumbar spinae muscle activation. In contrast, more stable conditions seem more appropriate for pectoralis major and anterior deltoid muscles. Independent of the type of design, all suspension systems were especially effective training tools for reaching high levels of rectus abdominis activation. Key PointsCompared with standard push-ups on the floor, suspended push-ups increase core muscle activation.A one-anchor system with a pulley is the best option to increase TRICEP, TRAPS, LUMB and FEM muscle activity.More stable conditions such as the standard push-up or a parallel band system provide greater increases in DELT and PEC muscle activation.A suspended push-up is an effective method to achieve high muscle activity levels in the ABS.

  9. POST-EXERCISE MUSCLE GLYCOGEN REPLETION IN THE EXTREME: EFFECT OF FOOD ABSENCE AND ACTIVE RECOVERY

    Directory of Open Access Journals (Sweden)

    Paul A. Fournier

    2004-09-01

    Full Text Available Glycogen plays a major role in supporting the energy demands of skeletal muscles during high intensity exercise. Despite its importance, the amount of glycogen stored in skeletal muscles is so small that a large fraction of it can be depleted in response to a single bout of high intensity exercise. For this reason, it is generally recommended to ingest food after exercise to replenish rapidly muscle glycogen stores, otherwise one's ability to engage in high intensity activity might be compromised. But what if food is not available? It is now well established that, even in the absence of food intake, skeletal muscles have the capacity to replenish some of their glycogen at the expense of endogenous carbon sources such as lactate. This is facilitated, in part, by the transient dephosphorylation-mediated activation of glycogen synthase and inhibition of glycogen phosphorylase. There is also evidence that muscle glycogen synthesis occurs even under conditions conducive to an increased oxidation of lactate post-exercise, such as during active recovery from high intensity exercise. Indeed, although during active recovery glycogen resynthesis is impaired in skeletal muscle as a whole because of increased lactate oxidation, muscle glycogen stores are replenished in Type IIa and IIb fibers while being broken down in Type I fibers of active muscles. This unique ability of Type II fibers to replenish their glycogen stores during exercise should not come as a surprise given the advantages in maintaining adequate muscle glycogen stores in those fibers that play a major role in fight or flight responses

  10. A difference in [14C]deoxyglucose autoradiographic patterns in striate cortex between Macaca and Saimiri monkeys following monocular stimulation

    International Nuclear Information System (INIS)

    Hendrickson, A.E.; Wilson, J.R.

    1979-01-01

    Since the apparent absence of ocular dominance columns (ODC) in some New World primates could be caused by deficiencies of the transsynaptic autoradiographic technique, such as spillage of label in the poorly laminated dorsal lateral geniculate nucleus, the authors have examined this question using a functional autoradiographic tracing technique based on the uptake of [ 14 C]2-deoxyglucose ([ 14 C]dG) by active neurons. When only one eye is stimulated, this innovative method graphically demonstrates a repetitive pattern in Macaca monkey striate cortex which has been interpreted to be the ODC driven by the open eye. They now report on the results of a comparative study of Old World Macaca and New World Saimiri monkeys using [ 14 C]dG autoradiography in which evidence is found for repetitive patterns of [ 14 C]dG in Saimiri for layers above, but not in, layer IV. (Auth.)

  11. MicroRNAs promote skeletal muscle differentiation of mesodermal iPSC-derived progenitors

    NARCIS (Netherlands)

    Giacomazzi, G. (Giorgia); Holvoet, B. (Bryan); Trenson, S. (Sander); Caluwé, E. (Ellen); Kravic, B. (Bojana); Grosemans, H. (Hanne); Cortés-Calabuig, Á. (Álvaro); Deroose, C.M. (Christophe M.); D. Huylebroeck (Danny); Hashemolhosseini, S. (Said); S. Janssens (Stefan); McNally, E. (Elizabeth); Quattrocelli, M. (Mattia); Sampaolesi, M. (Maurilio)

    2017-01-01

    textabstractMuscular dystrophies (MDs) are often characterized by impairment of both skeletal and cardiac muscle. Regenerative strategies for both compartments therefore constitute a therapeutic avenue. Mesodermal iPSC-derived progenitors (MiPs) can regenerate both striated muscle types

  12. Upper Limb Muscle and Brain Activity in Light Assembly Task on Different Load Levels

    Science.gov (United States)

    Zadry, Hilma Raimona; Dawal, Siti Zawiah Md.; Taha, Zahari

    2010-10-01

    A study was conducted to investigate the effect of load on upper limb muscles and brain activities in light assembly task. The task was conducted at two levels of load (Low and high). Surface electromyography (EMG) was used to measure upper limb muscle activities of twenty subjects. Electroencephalography (EEG) was simultaneously recorded with EMG to record brain activities from Fz, Pz, O1 and O2 channels. The EMG Mean Power Frequency (MPF) of the right brachioradialis and the left upper trapezius activities were higher on the high-load task compared to low-load task. The EMG MPF values also decrease as time increases, that reflects muscle fatigue. Mean power of the EEG alpha bands for the Fz-Pz channels were found to be higher on the high-load task compared to low-load task, while for the O1-O2 channels, they were higher on the low-load task than on the high-load task. These results indicated that the load levels effect the upper limb muscle and brain activities. The high-load task will increase muscle activities on the right brachioradialis and the left upper tapezius muscles, and will increase the awareness and motivation of the subjects. Whilst the low-load task can generate drowsiness earlier. It signified that the longer the time and the more heavy of the task, the subjects will be more fatigue physically and mentally.

  13. A novel spatiotemporal muscle activity imaging approach based on the Extended Kalman Filter.

    Science.gov (United States)

    Wang, Jing; Zhang, Yingchun; Zhu, Xiangjun; Zhou, Ping; Liu, Chenguang; Rymer, William Z

    2012-01-01

    A novel spatiotemporal muscle activity imaging (sMAI) approach has been developed using the Extended Kalman Filter (EKF) to reconstruct internal muscle activities from non-invasive multi-channel surface electromyogram (sEMG) recordings. A distributed bioelectric dipole source model is employed to describe the internal muscle activity space, and a linear relationship between the muscle activity space and the sEMG measurement space is then established. The EKF is employed to recursively solve the ill-posed inverse problem in the sMAI approach, in which the weighted minimum norm (WMN) method is utilized to calculate the initial state and a new nonlinear method is developed based on the propagating features of muscle activities to predict the recursive state. A series of computer simulations was conducted to test the performance of the proposed sMAI approach. Results show that the localization error rapidly decreases over 35% and the overlap ratio rapidly increases over 45% compared to the results achieved using the WMN method only. The present promising results demonstrate the feasibility of utilizing the proposed EKF-based sMAI approach to accurately reconstruct internal muscle activities from non-invasive sEMG recordings.

  14. Activated protein C attenuates acute ischaemia reperfusion injury in skeletal muscle.

    LENUS (Irish Health Repository)

    Dillon, J P

    2012-02-03

    Activated protein C (APC) is an endogenous anti-coagulant with anti-inflammatory properties. The purpose of the present study was to evaluate the effects of activated protein C in the setting of skeletal muscle ischaemia reperfusion injury (IRI). IRI was induced in rats by applying rubber bands above the levels of the greater trochanters bilaterally for a period of 2h followed by 12h reperfusion. Treatment groups received either equal volumes of normal saline or activated protein C prior to tourniquet release. Following 12h reperfusion, muscle function was assessed electrophysiologically by electrical field stimulation. The animals were then sacrificed and skeletal muscle harvested for evaluation. Activated protein C significantly attenuated skeletal muscle reperfusion injury as shown by reduced myeloperoxidase content, wet to dry ratio and electrical properties of skeletal muscle. Further in vitro work was carried out on neutrophils isolated from healthy volunteers to determine the direct effect of APC on neutrophil function. The effects of APC on TNF-alpha stimulated neutrophils were examined by measuring CD18 expression as well as reactive oxygen species generation. The in vitro work demonstrated a reduction in CD18 expression and reactive oxygen species generation. We conclude that activated protein C may have a protective role in the setting of skeletal muscle ischaemia reperfusion injury and that this is in part mediated by a direct inhibitory effect on neutrophil activation.

  15. Muscle assembly: a titanic achievement?

    Science.gov (United States)

    Gregorio, C C; Granzier, H; Sorimachi, H; Labeit, S

    1999-02-01

    The formation of perfectly aligned myofibrils in striated muscle represents a dramatic example of supramolecular assembly in eukaryotic cells. Recently, considerable progress has been made in deciphering the roles that titin, the third most abundant protein in muscle, has in this process. An increasing number of sarcomeric proteins (ligands) are being identified that bind to specific titin domains. Titin may serve as a molecular blueprint for sarcomere assembly and turnover by specifying the precise position of its ligands within each half-sarcomere in addition to functioning as a molecular spring that maintains the structural integrity of the contracting myofibrils.

  16. Ground reaction forces, kinematics, and muscle activations during the windmill softball pitch.

    Science.gov (United States)

    Oliver, Gretchen D; Plummer, Hillary

    2011-07-01

    The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic-hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.

  17. Muscle activity during knee-extension strengthening exercise performed with elastic tubing and isotonic resistance

    DEFF Research Database (Denmark)

    Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H

    2012-01-01

    muscle during 10-RM knee-extensions performed with elastic tubing and an isotonic strength training machine. METHODS: 7 women and 9 men aged 28-67 years (mean age 44 and 41 years, respectively) participated. Electromyographic (EMG) activity was recorded in 10 muscles during the concentric and eccentric......BACKGROUND/PURPOSE: While elastic resistance training, targeting the upper body is effective for strength training, the effect of elastic resistance training on lower body muscle activity remains questionable. The purpose of this study was to evaluate the EMG-angle relationship of the quadriceps...... tubing induces similar high (>70% nEMG) quadriceps muscle activity during the concentric contraction phase, but slightly lower during the eccentric contraction phase, as knee extensions performed using an isotonic training machine. During the concentric contraction phase the two different conditions...

  18. Asymmetric activation of temporalis, masseter, and sternocleidomastoid muscles in temporomandibular disorder patients.

    Science.gov (United States)

    Ries, Lilian Gerdi Kittel; Alves, Marcelo Correa; Bérzin, Fausto

    2008-01-01

    The aim of this study was to analyze the symmetry of the electromyographic (EMG) activity of the temporalis, masseter, and sternocleidomastoid (SCM) muscles in volunteers divided into a control group and a temporomandibular disorder (TMD) group. The surface EMG recordings were made during mandibular rest position, maximal intercuspal position, and during the chewing cycle. Normalized EMG waves of paired muscles were compared by computing a percentage overlapping coefficient (POC). The difference between the groups and between the static and dynamic clenching tests was analyzed through repeated measures, ANOVA. Symmetry of the temporalis, masseter, and SCM muscles activity was smaller in the TMD group compared to the control group. The mandibular postures were also significantly different among themselves. The asymmetric activation of jaw and neck muscles was interpreted as a compensatory strategy to achieve stability for the mandibular and cervical systems during masticatory function.

  19. Muscle activity during knee-extension strengthening exercise performed with elastic tubing and isotonic resistance

    DEFF Research Database (Denmark)

    Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H

    2012-01-01

    tubing induces similar high (>70% nEMG) quadriceps muscle activity during the concentric contraction phase, but slightly lower during the eccentric contraction phase, as knee extensions performed using an isotonic training machine. During the concentric contraction phase the two different conditions......BACKGROUND/PURPOSE: While elastic resistance training, targeting the upper body is effective for strength training, the effect of elastic resistance training on lower body muscle activity remains questionable. The purpose of this study was to evaluate the EMG-angle relationship of the quadriceps...... muscle during 10-RM knee-extensions performed with elastic tubing and an isotonic strength training machine. METHODS: 7 women and 9 men aged 28-67 years (mean age 44 and 41 years, respectively) participated. Electromyographic (EMG) activity was recorded in 10 muscles during the concentric and eccentric...

  20. Exercise induces transient transcriptional activation of the PGC-1a gene in human skeletal muscle

    DEFF Research Database (Denmark)

    Pilegaard, Henriette; Saltin, Bengt; Neufer, P. Darrell

    2003-01-01

    Endurance exercise training induces mitochondrial biogenesis in skeletal muscle. The peroxisome proliferator activated receptor co-activator 1a (PGC-1a) has recently been identified as a nuclear factor critical for coordinating the activation of genes required for mitochondrial biogenesis in cell...... culture and rodent skeletal muscle. To determine whether PGC-1a transcription is regulated by acute exercise and exercise training in human skeletal muscle, seven male subjects performed 4 weeks of one-legged knee extensor exercise training. At the end of training, subjects completed 3 h of two......-legged knee extensor exercise. Biopsies were obtained from the vastus lateralis muscle of both the untrained and trained legs before exercise and after 0, 2, 6 and 24 h of recovery. Time to exhaustion (2 min maximum resistance), as well as hexokinase II (HKII), citrate synthase and 3-hydroxyacyl...

  1. Work related perceived stress and muscle activity during standardized computer work among female computer users

    DEFF Research Database (Denmark)

    Larsman, P; Thorn, S; Søgaard, K

    2009-01-01

    The current study investigated the associations between work-related perceived stress and surface electromyographic (sEMG) parameters (muscle activity and muscle rest) during standardized simulated computer work (typing, editing, precision, and Stroop tasks). It was part of the European case......-control study, NEW (Neuromuscular assessment in the Elderly Worker). The present cross-sectional study was based on a questionnaire survey and sEMG measurements among Danish and Swedish female computer users aged 45 or older (n=49). The results show associations between work-related perceived stress...... and trapezius muscle activity and rest during standardized simulated computer work, and provide partial empirical support for the hypothesized pathway of stress induced muscle activity in the association between an adverse psychosocial work environment and musculoskeletal symptoms in the neck and shoulder....

  2. Relationships among nocturnal jaw muscle activities, decreased esophageal pH, and sleep positions.

    Science.gov (United States)

    Miyawaki, Shouichi; Tanimoto, Yuko; Araki, Yoshiko; Katayama, Akira; Imai, Mikako; Takano-Yamamoto, Teruko

    2004-11-01

    The purpose of this study was to examine the relationships among nocturnal jaw muscle activities, decreased esophageal pH, and sleep positions. Twelve adult volunteers, including 4 bruxism patients, participated in this study. Portable pH monitoring, electromyography of the temporal muscle, and audio-video recordings were conducted during the night in the subjects' homes. Rhythmic masticatory muscle activity (RMMA) episodes were observed most frequently, with single short-burst episodes the second most frequent. The frequencies of RMMA, single short-burst, and clenching episodes were significantly higher during decreased esophageal pH episodes than those during other times. Both the electromyography and the decreased esophageal pH episodes were most frequently observed in the supine position. These results suggest that most jaw muscle activities, ie, RMMA, single short-burst, and clenching episodes, occur in relation to gastroesophageal reflux mainly in the supine position.

  3. Alterations of cAMP-dependent signaling in dystrophic skeletal muscle

    Directory of Open Access Journals (Sweden)

    Rüdiger eRudolf

    2013-10-01

    Full Text Available Autonomic regulation processes in striated muscles are largely mediated by cAMP/PKA-signaling. In order to achieve specificity of signaling its spatial-temporal compartmentation plays a critical role. We discuss here how specificity of cAMP/PKA-signaling can be achieved in skeletal muscle by spatio-temporal compartmentation. While a microdomain containing PKA type I in the region of the neuromuscular junction is important for post-synaptic, activity-dependent stabilization of the nicotinic acetylcholine receptor, PKA type I and II microdomains in the sarcomeric part of skeletal muscle are likely to play different roles, including the regulation of muscle homeostasis. These microdomains are due to specific A-kinase anchoring proteins, like rapsyn and myospryn. Importantly, recent evidence indicates that compartmentation of the cAMP/PKA-dependent signaling pathway and pharmacological activation of cAMP production are aberrant in different skeletal muscles disorders. Thus, we discuss here their potential as targets for palliative treatment of certain forms of dystrophy and myasthenia. Under physiological conditions, the neuropeptide, α-calcitonin-related peptide, as well as beta-adrenergic agonists are the most-mentioned natural triggers for activating cAMP/PKA signaling in skeletal muscle. While the precise domains and functions of these first messengers are still under investigation, agonists of β2-adrenoceptors clearly exhibit anabolic activity under normal conditions and reduce protein degradation during atrophic periods. Past and recent studies suggest direct sympathetic innervation of skeletal muscle fibers. In summary, the organization and roles of cAMP-dependent signaling in skeletal muscle are increasingly understood, revealing crucial functions in processes like nerve-muscle interaction and muscle trophicity.

  4. Selumetinib Attenuates Skeletal Muscle Wasting in Murine Cachexia Model through ERK Inhibition and AKT Activation.

    Science.gov (United States)

    Quan-Jun, Yang; Yan, Huo; Yong-Long, Han; Li-Li, Wan; Jie, Li; Jin-Lu, Huang; Jin, Lu; Peng-Guo, Chen; Run, Gan; Cheng, Guo

    2017-02-01

    Cancer cachexia is a multifactorial syndrome affecting the skeletal muscle. Previous clinical trials showed that treatment with MEK inhibitor selumetinib resulted in skeletal muscle anabolism. However, it is conflicting that MAPK/ERK pathway controls the mass of the skeletal muscle. The current study investigated the therapeutic effect and mechanisms of selumetinib in amelioration of cancer cachexia. The classical cancer cachexia model was established via transplantation of CT26 colon adenocarcinoma cells into BALB/c mice. The effect of selumetinib on body weight, tumor growth, skeletal muscle, food intake, serum proinflammatory cytokines, E3 ligases, and MEK/ERK-related pathways was analyzed. Two independent experiments showed that 30 mg/kg/d selumetinib prevented the loss of body weight in murine cachexia mice. Muscle wasting was attenuated and the expression of E3 ligases, MuRF1 and Fbx32, was inhibited following selumetinib treatment of the gastrocnemius muscle. Furthermore, selumetinib efficiently reduced tumor burden without influencing the cancer cell proliferation, cumulative food intake, and serum cytokines. These results indicated that the role of selumetinib in attenuating muscle wasting was independent of cancer burden. Detailed analysis of the mechanism revealed AKT and mTOR were activated, while ERK, FoxO3a, and GSK3β were inhibited in the selumetinib -treated cachexia group. These indicated that selumetinib effectively prevented skeletal muscle wasting in cancer cachexia model through ERK inhibition and AKT activation in gastrocnemius muscle via cross-inhibition. The study not only elucidated the mechanism of MEK/ERK inhibition in skeletal muscle anabolism, but also validated selumetinib therapy as an effective intervention against cancer cachexia. Mol Cancer Ther; 16(2); 334-43. ©2016 AACR. ©2016 American Association for Cancer Research.

  5. Muscle activation patterns in the Nordic hamstring exercise: Impact of prior strain injury.

    Science.gov (United States)

    Bourne, M N; Opar, D A; Williams, M D; Al Najjar, A; Shield, A J

    2016-06-01

    This study aimed to determine: (a) the spatial patterns of hamstring activation during the Nordic hamstring exercise (NHE); (b) whether previously injured hamstrings display activation deficits during the NHE; and (c) whether previously injured hamstrings exhibit altered cross-sectional area (CSA). Ten healthy, recreationally active men with a history of unilateral hamstring strain injury underwent functional magnetic resonance imaging of their thighs before and after six sets of 10 repetitions of the NHE. Transverse (T2) relaxation times of all hamstring muscles [biceps femoris long head (BFlh); biceps femoris short head (BFsh); semitendinosus (ST); semimembranosus (SM)] were measured at rest and immediately after the NHE and CSA was measured at rest. For the uninjured limb, the ST's percentage increase in T2 with exercise was 16.8%, 15.8%, and 20.2% greater than the increases exhibited by the BFlh, BFsh, and SM, respectively (P hamstring muscles (n = 10) displayed significantly smaller increases in T2 post-exercise than the homonymous muscles in the uninjured contralateral limb (mean difference -7.2%, P = 0.001). No muscles displayed significant between-limb differences in CSA. During the NHE, the ST is preferentially activated and previously injured hamstring muscles display chronic activation deficits compared with uninjured contralateral muscles. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Influence of experimental occlusal discrepancy on masticatory muscle activity during clenching.

    Science.gov (United States)

    Baba, K; Ai, M; Mizutani, H; Enosawa, S

    1996-01-01

    The influence of the experimental occlusal discrepancy on masticatory muscle activity was investigated on 12 subjects. Specially designed occlusal interferences were fabricated and various occlusal states were simulated with their aid. Subjects were asked to carry out eccentric clenching efforts and electromyographic activity of the masseter plus the anterior and posterior temporal muscles was measured. When compared with clenching on the unaltered natural dentition, clenching on the experimental interferences resulted in distinct patterns in the jaw elevator muscles, and the most characteristic change was observed when clenching effort was exerted on the experimental non-working side interference. Electromyographic activity in the anterior and posterior temporal muscles was decreased on the working side and increased on the non-working side and originally unilateral activity pattern with clear dominance on the working side was altered to a bilateral pattern, while that of the masseter muscles remained uninfluenced. Resultant bilateral activity in the anterior and posterior temporal muscles is thought to cause a superior movement of the working side condyle and an inferior movement of the non-working side condyle.

  7. Control of upper airway muscle activity in younger versus older men during sleep onset

    Science.gov (United States)

    Fogel, Robert B; White, David P; Pierce, Robert J; Malhotra, Atul; Edwards, Jill K; Dunai, Judy; Kleverlaan, Darci; Trinder, John

    2003-01-01

    Pharyngeal dilator muscles are clearly important in the pathophysiology of obstructive sleep apnoea syndrome (OSA). We have previously shown that the activity of both the genioglossus (GGEMG) and tensor palatini (TPEMG) are decreased at sleep onset, and that this decrement in muscle activity is greater in the apnoea patient than in healthy controls. We have also previously shown this decrement to be greater in older men when compared with younger ones. In order to explore the mechanisms responsible for this decrement in muscle activity nasal continuous positive airway pressure (CPAP) was applied to reduce negative pressure mediated muscle activation. We then investigated the effect of sleep onset (transition from predominantly α to predominantly θ EEG activity) on ventilation, upper airway muscle activation and upper airway resistance (UAR) in middle-aged and younger healthy men. We found that both GGEMG and TPEMG were reduced by the application of nasal CPAP during wakefulness, but that CPAP did not alter the decrement in activity in either muscle seen in the first two breaths following an α to θ transition. However, CPAP prevented both the rise in UAR at sleep onset that occurred on the control night, and the recruitment in GGEMG seen in the third to fifth breaths following the α to θ transition. Further, GGEMG was higher in the middle-aged men than in the younger men during wakefulness and was decreased more in the middle-aged men with the application of nasal CPAP. No differences were seen in TPEMG between the two age groups. These data suggest that the initial sleep onset reduction in upper airway muscle activity is due to loss of a ‘wakefulness’ stimulus, rather than to loss of responsiveness to negative pressure. In addition, it suggests that in older men, higher wakeful muscle activity is due to an anatomically more collapsible upper airway with more negative pressure driven muscle activation. Sleep onset per se does not appear to have a greater

  8. Oblique abdominal muscle activity in response to external perturbations when pushing a cart.

    Science.gov (United States)

    Lee, Yun-Ju; Hoozemans, Marco J M; van Dieën, Jaap H

    2010-05-07

    Cyclic activation of the external and internal oblique muscles contributes to twisting moments during normal gait. During pushing while walking, it is not well understood how these muscles respond to presence of predictable (cyclic push-off forces) and unpredictable (external) perturbations that occur in pushing tasks. We hypothesized that the predictable perturbations due to the cyclic push-off forces would be associated with cyclic muscle activity, while external perturbations would be counteracted by cocontraction of the oblique abdominal muscles. Eight healthy male subjects pushed at two target forces and two handle heights in a static condition and while walking without and with external perturbations. For all pushing tasks, the median, the static (10th percentile) and the peak levels (90th percentile) of the electromyographic amplitudes were determined. Linear models with oblique abdominal EMGs and trunk angles as input were fit to the twisting moments, to estimate trunk stiffness. There was no significant difference between the static EMG levels in pushing while walking compared to the peak levels in pushing while standing. When pushing while walking, the additional dynamic activity was associated with the twisting moments, which were actively modulated by the pairs of oblique muscles as in normal gait. The median and static levels of trunk muscle activity and estimated trunk stiffness were significantly higher when perturbations occurred than without perturbations. The increase baseline of muscle activity indicated cocontraction of the antagonistic muscle pairs. Furthermore, this cocontraction resulted in an increased trunk stiffness around the longitudinal axis. Copyright 2010 Elsevier Ltd. All rights reserved.

  9. Differences in muscle activity between natural forefoot and rearfoot strikers during running.

    Science.gov (United States)

    Yong, Jennifer R; Silder, Amy; Delp, Scott L

    2014-11-28

    Running research has focused on reducing injuries by changing running technique. One proposed method is to change from rearfoot striking (RFS) to forefoot striking (FFS) because FFS is thought to be a more natural running pattern that may reduce loading and injury risk. Muscle activity affects loading and influences running patterns; however, the differences in muscle activity between natural FFS runners and natural RFS runners are unknown. The purpose of this study was to measure muscle activity in natural FFS runners and natural RFS runners. We tested the hypotheses that tibialis anterior activity would be significantly lower while activity of the plantarflexors would be significantly greater in FFS runners, compared to RFS runners, during late swing phase and early stance phase. Gait kinematics, ground reaction forces and electromyographic patterns of ten muscles were collected from twelve natural RFS runners and ten natural FFS runners. The root mean square (RMS) of each muscle׳s activity was calculated during terminal swing phase and early stance phase. We found significantly lower RMS activity in the tibialis anterior in FFS runners during terminal swing phase, compared to RFS runners. In contrast, the medial and lateral gastrocnemius showed significantly greater RMS activity in terminal swing phase in FFS runners. No significant differences were found during early stance phase for the tibialis anterior or the plantarflexors. Recognizing the differences in muscle activity between FFS and RFS runners is an important step toward understanding how foot strike patterns may contribute to different types of injury. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Muscle activation patterns of the upper and lower extremity during the windmill softball pitch.

    Science.gov (United States)

    Oliver, Gretchen D; Plummer, Hillary A; Keeley, David W

    2011-06-01

    Fast-pitch softball has become an increasingly popular sport for female athletes. There has been little research examining the windmill softball pitch in the literature. The purpose of this study was to describe the muscle activation patterns of 3 upper extremity muscles (biceps, triceps, and rhomboids [scapular stabilizers]) and 2 lower extremity muscles (gluteus maximus and medius) during the 5 phases of the windmill softball pitch. Data describing muscle activation were collected on 7 postpubescent softball pitchers (age 17.7 ± 2.6 years; height 169 ± 5.4 cm; mass 69.1 ± 5.4 kg). Surface electromyographic data were collected using a Myopac Jr 10-channel amplifier (RUN Technologies Scientific Systems, Laguna Hills, CA, USA) synchronized with The MotionMonitor™ motion capture system (Innovative Sports Training Inc, Chicago IL, USA) and presented as a percent of maximum voluntary isometric contraction. Gluteus maximus activity reached (196.3% maximum voluntary isometric contraction [MVIC]), whereas gluteus medius activity was consistent during the single leg support of phase 3 (101.2% MVIC). Biceps brachii activity was greatest during phase 4 of the pitching motion. Triceps brachii activation was consistently >150% MVIC throughout the entire pitching motion, whereas the scapular stabilizers were most active during phase 2 (170.1% MVIC). The results of this study indicate the extent to which muscles are activated during the windmill softball pitch, and this knowledge can lead to the development of proper preventative and rehabilitative muscle strengthening programs. In addition, clinicians will be able to incorporate strengthening exercises that mimic the timing of maximal muscle activation most used during the windmill pitching phases.

  11. Muscle activation patterns and motor anatomy of Anna's hummingbirds Calypte anna and zebra finches Taeniopygia guttata.

    Science.gov (United States)

    Donovan, Edward R; Keeney, Brooke K; Kung, Eric; Makan, Sirish; Wild, J Martin; Altshuler, Douglas L

    2013-01-01

    Flying animals exhibit profound transformations in anatomy, physiology, and neural architecture. Although much is known about adaptations in the avian skeleton and musculature, less is known about neuroanatomy and motor unit integration for bird flight. Hummingbirds are among the most maneuverable and specialized of vertebrate fliers, and two unusual neuromuscular features have been previously reported: (1) the pectoralis major has a unique distribution pattern of motor end plates (MEPs) compared with all other birds and (2) electromyograms (EMGs) from the hummingbird's pectoral muscles, the pectoralis major and the supracoracoideus, show activation bursts composed of one or a few spikes that appear to have a very consistent pattern. Here, we place these findings in a broader context by comparing the MEPs, EMGs, and organization of the spinal motor neuron pools of flight muscles of Anna's hummingbird Calypte anna, zebra finches Taeniopygia guttata, and, for MEPs, several other species. The previously shown MEP pattern of the hummingbird pectoralis major is not shared with its closest taxonomic relative, the swift, and appears to be unique to hummingbirds. MEP arrangements in previously undocumented wing muscles show patterns that differ somewhat from other avian muscles. In the parallel-fibered strap muscles of the shoulder, MEP patterns appear to relate to muscle length, with the smallest muscles having fibers that span the entire muscle. MEP patterns in pennate distal wing muscles were the same regardless of size, with tightly clustered bands in the middle portion of the muscle, not evenly distributed bands over the muscle's entire length. Muscle activations were examined during slow forward flight in both species, during hovering in hummingbirds, and during slow ascents in zebra finches. The EMG bursts of a wing muscle, the pronator superficialis, were highly variable in peak number, size, and distribution across wingbeats for both species. In the pectoralis

  12. Increased sternocleidomastoid, but not trapezius, muscle activity in response to increased chewing load.

    Science.gov (United States)

    Häggman-Henrikson, Birgitta; Nordh, Erik; Eriksson, Per-Olof

    2013-10-01

    Previous findings, during chewing, that boluses of larger size and harder texture result in larger amplitudes of both mandibular and head-neck movements suggest a relationship between increased chewing load and incremental recruitment of jaw and neck muscles. The present report evaluated jaw (masseter and digastric) and neck [sternocleidomastoid (SCM) and trapezius] muscle activity during the chewing of test foods of different sizes and textures by 10 healthy subjects. Muscle activity was recorded by surface electromyography and simultaneous mandibular and head movements were recorded using an optoelectronic technique. Each subject performed continuous jaw-opening/jaw-closing movements whilst chewing small and large boluses of chewing gum and rubber silicone (Optosil). For jaw opening/jaw closing without a bolus, SCM activity was recorded for jaw opening concomitantly with digastric activity. During chewing, SCM activity was recorded for jaw closing concomitantly with masseter activity. Trapezius activity was present in some, but not all, cycles. For the masseter and SCM muscles, higher activity was seen with larger test foods, suggesting increased demand and recruitment of these muscles in response to an increased chewing load. This result reinforces the previous notion of a close functional connection between the jaw and the neck motor systems in jaw actions and has scientific and clinical significance for studying jaw function and dysfunction. © 2013 Eur J Oral Sci.

  13. Inhibition of FoxO transcriptional activity prevents muscle fiber atrophy during cachexia and induces hypertrophy

    Science.gov (United States)

    Reed, Sarah A.; Sandesara, Pooja B.; Senf, Sarah M.; Judge, Andrew R.

    2012-01-01

    Cachexia is characterized by inexorable muscle wasting that significantly affects patient prognosis and increases mortality. Therefore, understanding the molecular basis of this muscle wasting is of significant importance. Recent work showed that components of the forkhead box O (FoxO) pathway are increased in skeletal muscle during cachexia. In the current study, we tested the physiological significance of FoxO activation in the progression of muscle atrophy associated with cachexia. FoxO-DNA binding dependent transcription was blocked in the muscles of mice through injection of a dominant negative (DN) FoxO expression plasmid prior to inoculation with Lewis lung carcinoma cells or the induction of sepsis. Expression of DN FoxO inhibited the increased mRNA levels of atrogin-1, MuRF1, cathepsin L, and/or Bnip3 and inhibited muscle fiber atrophy during cancer cachexia and sepsis. Interestingly, during control conditions, expression of DN FoxO decreased myostatin expression, increased MyoD expression and satellite cell proliferation, and induced fiber hypertrophy, which required de novo protein synthesis. Collectively, these data show that FoxO-DNA binding-dependent transcription is necessary for normal muscle fiber atrophy during cancer cachexia and sepsis, and further suggest that basal levels of FoxO play an important role during normal conditions to depress satellite cell activation and limit muscle growth.—Reed, S. A., Sandesara, P. B., Senf, S. F., Judge, A. R. Inhibition of FoxO transcriptional activity prevents muscle fiber atrophy during cachexia and induces hypertrophy. PMID:22102632

  14. Metabolic stabilization of acetylcholine receptors in vertebrate neuromuscular junction by muscle activity

    International Nuclear Information System (INIS)

    Rotzler, S.; Brenner, H.R.

    1990-01-01

    The effects of muscle activity on the growth of synaptic acetylcholine receptor (AChR) accumulations and on the metabolic AChR stability were investigated in rat skeletal muscle. Ectopic end plates induced surgically in adult soleus muscle were denervated early during development when junctional AChR number and stability were still low and, subsequently, muscles were either left inactive or they were kept active by chronic exogenous stimulation. AChR numbers per ectopic AChR cluster and AChR stabilities were estimated from the radioactivity and its decay with time, respectively, of end plate sites whose AChRs had been labeled with 125 I-alpha-bungarotoxin (alpha-butx). The results show that the metabolic stability of the AChRs in ectopic clusters is reversibly increased by muscle activity even when innervation is eliminated very early in development. 1 d of stimulation is sufficient to stabilize the AChRs in ectopic AChR clusters. Muscle stimulation also produced an increase in the number of AChRs at early denervated end plates. Activity-induced cluster growth occurs mainly by an increase in area rather than in AChR density, and for at least 10 d after denervation is comparable to that in normally developing ectopic end plates. The possible involvement of AChR stabilization in end plate growth is discussed

  15. Experimentally induced masseter-pain changes masseter but not sternocleidomastoid muscle-related activity during mastication.

    Science.gov (United States)

    Pasinato, Fernanda; Santos-Couto-Paz, Clarissa C; Zeredo, Jorge Luis Lopes; Macedo, Sergio Bruzadelli; Corrêa, Eliane C R

    2016-12-01

    The aim of this study was to verify the effects of induced masseter-muscle pain on the amplitude of muscle activation, symmetry and coactivation of jaw- and neck-muscles during mastication. Twenty-eight male volunteers, mean age±SD 20.6±2.0years, participated in this study. Surface electromyography of the masseter and sternocleidomastoid (SCM) muscles was performed bilaterally during mastication of a gummy candy before and after injections of monosodium glutamate solution and isotonic saline solution. As a result, we observed a decrease in the amplitude of activation of the masseter muscle on the working side (p=0.009; d=0.34) and a reduction in the asymmetry between the working and the balancing side during mastication (p=0.007; d=0.38). No changes were observed either on the craniocervical electromyographic variables. In conclusion, experimentally induced pain reduced the masseter muscle activation on the working side, thereby reducing the physiological masseters' recruitment asymmetry between the two sides during mastication. No effects on SCM activity were detected. These results may partly explain the initial maladaptative changes underlying TMD conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. A fully resolved fluid-structure-muscle-activation model for esophageal transport

    Science.gov (United States)

    Kou, Wenjun; Bhalla, Amneet P. S.; Griffith, Boyce E.; Johnson, Mark; Patankar, Neelesh A.

    2013-11-01

    Esophageal transport is a mechanical and physiological process that transfers the ingested food bolus from the pharynx to the stomach through a multi-layered esophageal tube. The process involves interactions between the bolus, esophageal wall composed of mucosal, circular muscle (CM) and longitudinal muscle (LM) layers, and neurally coordinated muscle activation including CM contraction and LM shortening. In this work, we present a 3D fully-resolved model of esophageal transport based on the immersed boundary method. The model describes the bolus as a Newtonian fluid, the esophageal wall as a multi-layered elastic tube represented by springs and beams, and the muscle activation as a traveling wave of sequential actuation/relaxation of muscle fibers, represented by springs with dynamic rest lengths. Results on intraluminal pressure profile and bolus shape will be shown, which are qualitatively consistent with experimental observations. Effects of activating CM contraction only, LM shortening only or both, for the bolus transport, are studied. A comparison among them can help to identify the role of each type of muscle activation. The support of grant R01 DK56033 and R01 DK079902 from NIH is gratefully acknowledged.

  17. Lower Extremity Muscle Activation and Kinematics of Catchers When Throwing Using Various Squatting and Throwing Postures

    Directory of Open Access Journals (Sweden)

    Yi-Chien Peng, Kuo-Cheng Lo, Lin-Hwa Wang

    2015-09-01

    Full Text Available This study investigated the differences in joint motions and muscle activities of the lower extremities involved in various squatting postures. The motion capture system with thirty-one reflective markers attached on participants was used for motion data collection. The electromyography system was applied over the quadriceps, biceps femoris, tibialis anterior, and gastrocnemius muscles of the pivot and stride leg. The joint extension and flexion in wide squatting are greater than in general squatting (p = 0.005. Knee joint extension and flexion in general squatting are significantly greater than in wide squatting (p = 0.001. The adduction and abduction of the hip joint in stride passing are significantly greater than in step squatting (p = 0.000. Furthermore, the adduction and abduction of the knee joint in stride passing are also significantly greater than in step squatting (p = 0.000. When stride passing is performed, the muscle activation of the hamstring of the pivot foot in general squatting is significantly greater than in wide squatting (p < 0.05, and this difference continues to the stride period. Most catchers use a general or wide squatting width, exclusive of a narrow one. Therefore, the training design for strengthening the lower extremity muscles should consider the appropriateness of the common squat width to enhance squat-up performance. For lower limb muscle activation, wide squatting requires more active gastrocnemius and tibialis anterior muscles. Baseball players should extend the knee angle of the pivot foot before catching the ball.

  18. Human brain activity associated with painful mechanical stimulation to muscle and bone.

    Science.gov (United States)

    Maeda, Lynn; Ono, Mayu; Koyama, Tetsuo; Oshiro, Yoshitetsu; Sumitani, Masahiko; Mashimo, Takashi; Shibata, Masahiko

    2011-08-01

    The purpose of this study was to elucidate the central processing of painful mechanical stimulation to muscle and bone by measuring blood oxygen level-dependent signal changes using functional magnetic resonance imaging (fMRI). Twelve healthy volunteers were enrolled. Mechanical pressure on muscle and bone were applied at the right lower leg by an algometer. Intensities were adjusted to cause weak and strong pain sensation at either target site in preliminary testing. Brain activation in response to mechanical nociceptive stimulation targeting muscle and bone were measured by fMRI and analyzed. Painful mechanical stimulation targeting muscle and bone activated the common areas including bilateral insula, anterior cingulate cortex, posterior cingulate cortex, secondary somatosensory cortex (S2), inferior parietal lobe, and basal ganglia. The contralateral S2 was more activated by strong stimulation than by weak stimulation. Some areas in the basal ganglia (bilateral putamen and caudate nucleus) were more activated by muscle stimulation than by bone stimulation. The putamen and caudate nucleus may have a more significant role in brain processing of muscle pain compared with bone pain.

  19. Noradrenaline spillover during exercise in active versus resting skeletal muscle in man

    DEFF Research Database (Denmark)

    Savard, G; Strange, S; Kiens, Bente

    1987-01-01

    Increases in plasma noradrenaline (NA) concentration occur during moderate to heavy exercise in man. This study was undertaken to examine the spillover of NA from both resting and contracting skeletal muscle during exercise. Six male subjects performed one-legged knee-extension so that all...... in the exercising leg than in the resting leg both during 50% and 100% leg exercise. These results suggest that contracting skeletal muscle may contribute to a larger extent than resting skeletal muscle to increasing the level of plasma NA during exercise. Contractile activity may influence the NA spillover from...

  20. A striated muscle on the hard palate of rodents and rabbits

    Czech Academy of Sciences Publication Activity Database

    Pavlíková, H.; Witter, Kirsti; Míšek, Ivan

    2004-01-01

    Roč. 33, - (2004), s. 96-99 ISSN 0340-2096 R&D Projects: GA ČR GP304/01/P021; GA ČR GA304/02/0448; GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z5045916 Keywords : hard palate * rabbits * rodents Subject RIV: EA - Cell Biology Impact factor: 0.625, year: 2004

  1. 2-Deoxyglucose autoradiography of single motor units: labelling of individual acutely active muscle fibers

    International Nuclear Information System (INIS)

    Toop, J.; Burke, R.E.; Dum, R.P.; O'Donovan, M.J.; Smith, C.B.

    1982-01-01

    2-Deoxy-D-[1- 14 C]glucose (2DG) was given intravenously during repetitive stimulation of single motor units in adult cats and autoradiographs were made of frozen sections of the target muscles in order to evaluate methods designed to improve the spatial resolution of [ 14 C]2DG autoradiography. With the modifications used, acutely active muscle fibers, independently identified by depletion of intrafiber glycogen, were associated with highly localized accumulations of silver grains over the depleted fibers. The results indicate that [ 14 C]2DG autoradiography can successfully identify individual active muscle fibers and might in principle be used to obtain quantitative data about rates of glucose metabolism in single muscle fibers of defined histochemical type. The modifications may be applicable also to other tissues to give improved spatial resolution with [ 14 C]-labeled metabolic markers. (Auth.)

  2. RAPID KNEE-EXTENSIONS TO INCREASE QUADRICEPS MUSCLE ACTIVITY IN PATIENTS WITH TOTAL KNEE ARTHROPLASTY

    DEFF Research Database (Denmark)

    Husted, Rasmus Skov; Wilquin, Lousia; Jakobsen, Thomas Linding

    2017-01-01

    rapid knee-extensions were associated with greater voluntary quadriceps muscle activity during an experimental strength training session, compared to that elicited using slow knee-extensions. STUDY DESIGN: A randomized cross-over study. METHODS: Twenty-four patients (age 66.5) 4-8 weeks post total knee...... agonist muscle activity, especially if the exercise is conducted using rapid muscle contractions. PURPOSE: The purpose of this study was to examine if patients with total knee arthroplasty could perform rapid knee-extensions using a 10 RM load four to eight weeks after surgery, and the degree to which...... arthroplasty randomly performed one set of five rapid, and one set of five slow knee-extensions with the operated leg, using a load of their 10 repetition maximum, while surface electromyography recordings were obtained from the vastus medialis and lateralis of the quadriceps muscle. RESULTS: Data from 23...

  3. Rapid knee-extensions to increase quadriceps muscle activity in patients with total knee arthroplasty

    DEFF Research Database (Denmark)

    Husted, Rasmus Skov; Wilquin, Lousia; Jakobsen, Thomas Linding

    2017-01-01

    rapid knee-extensions were associated with greater voluntary quadriceps muscle activity during an experimental strength training session, compared to that elicited using slow knee-extensions. STUDY DESIGN: A randomized cross-over study. METHODS: Twenty-four patients (age 66.5) 4-8 weeks post total knee...... agonist muscle activity, especially if the exercise is conducted using rapid muscle contractions. PURPOSE: The purpose of this study was to examine if patients with total knee arthroplasty could perform rapid knee-extensions using a 10 RM load four to eight weeks after surgery, and the degree to which...... arthroplasty randomly performed one set of five rapid, and one set of five slow knee-extensions with the operated leg, using a load of their 10 repetition maximum, while surface electromyography recordings were obtained from the vastus medialis and lateralis of the quadriceps muscle. RESULTS: Data from 23...

  4. Effect of sprint cycle training on activities of antioxidant enzymes in human skeletal muscle

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Apple, F. S.; Sjödin, B.

    1996-01-01

    (P anaerobic capacity in the trained muscle. The present study demonstrates that intermittent sprint cycle training that induces an enhanced capacity for anaerobic energy generation also improves......The effect of intermittent sprint cycle training on the level of muscle antioxidant enzyme protection was investigated. Resting muscle biopsies, obtained before and after 6 wk of training and 3, 24, and 72 h after the final session of an additional 1 wk of more frequent training, were analyzed...... for activities of the antioxidant enzymes glutathione peroxidase (GPX), glutathione reductase (GR), and superoxide dismutase (SOD). Activities of several muscle metabolic enzymes were determined to assess the effectiveness of the training. After the first 6-wk training period, no change in GPX, GR, or SOD...

  5. Effect of instruction, surface stability, and load intensity on trunk muscle activity.

    Science.gov (United States)

    Bressel, Eadric; Willardson, Jeffrey M; Thompson, Brennan; Fontana, Fabio E

    2009-12-01

    The aim of this study was to assess the effect of verbal instruction, surface stability, and load intensity on trunk muscle activity levels during the free weight squat exercise. Twelve trained males performed a free weight squat under four conditions: (1) standing on stable ground lifting 50% of their 1-repetition maximum (RM), (2) standing on a BOSU balance trainer lifting 50% of their 1-RM, (3) standing on stable ground lifting 75% of their 1-RM, and (4) receiving verbal instructions to activate the trunk muscles followed by lifting 50% of their 1-RM. Surface EMG activity from muscles rectus abdominis (RA), external oblique (EO), transversus abdominis/internal oblique (TA/IO), and erector spinae (ES) were recorded for each condition and normalized for comparisons. Muscles RA, EO, and TA/IO displayed greater peak activity (39-167%) during squats with instructions compared to the other squat conditions (P=0.04-0.007). Peak EMG activity of muscle ES was greater for the 75% 1-RM condition than squats with instructions or lifting 50% of 1-RM (P=0.04-0.02). The results indicate that if the goal is to enhance EMG activity of the abdominal muscles during a multi-joint squat exercise then verbal instructions may be more effective than increasing load intensity or lifting on an unstable surface. However, in light of other research, conscious co-activation of the trunk muscles during the squat exercise may lead to spinal instability and hazardous compression forces in the lumbar spine.

  6. Differences in feedforward trunk muscle activity in subgroups of patients with mechanical low back pain.

    Science.gov (United States)

    Silfies, Sheri P; Mehta, Rupal; Smith, Sue S; Karduna, Andrew R

    2009-07-01

    To investigate alterations in trunk muscle timing patterns in subgroups of patients with mechanical low back pain (MLBP). Our hypothesis was that subjects with MLBP would demonstrate delayed muscle onset and have fewer muscles functioning in a feedforward manner than the control group. We further hypothesized that we would find differences between subgroups of our patients with MLBP, grouped according to diagnosis (segmental instability and noninstability). Case-control. Laboratory. Forty-three patients with chronic MLBP (25 instability, 18 noninstability) and 39 asymptomatic controls. Not applicable. Surface electromyography was used to measure onset time of 10 trunk muscles during a self-perturbation task. Trunk muscle onset latency relative to the anterior deltoid was calculated and the number of muscles functioning in feedforward determined. Activation timing patterns (Pfeedforward (P=.02; eta=.30; 1-beta=.83) were statistically different between patients with MLBP and controls. The control group activated the external oblique, lumbar multifidus, and erector spinae muscles in a feedforward manner. The heterogeneous MLBP group did not activate the trunk musculature in feedforward, but responded with significantly delayed activations. MLBP subgroups demonstrated significantly different timing patterns. The noninstability MLBP subgroup activated trunk extensors in a feedforward manner, similar to the control group, but significantly earlier than the instability subgroup. Lack of feedforward activation of selected trunk musculature in patients with MLBP may result in a period of inefficient muscular stabilization. Activation timing was more impaired in the instability than the noninstability MLBP subgroup. Training specifically for recruitment timing may be an important component of the rehabilitation program.

  7. Melanocortin 4 Receptor Activation Attenuates Mitochondrial Dysfunction in Skeletal Muscle of Diabetic Rats.

    Science.gov (United States)

    Zhang, Hao-Hao; Liu, Jiao; Qin, Gui-Jun; Li, Xia-Lian; Du, Pei-Jie; Hao, Xiao; Zhao, Di; Tian, Tian; Wu, Jing; Yun, Meng; Bai, Yan-Hui

    2017-11-01

    A previous study has confirmed that the central melanocortin system was able to mediate skeletal muscle AMP-activated protein kinase (AMPK) activation in mice fed a high-fat diet, while activation of the AMPK signaling pathway significantly induced mitochondrial biogenesis. Our hypothesis was that melanocortin 4 receptor (MC4R) was involved in the development of skeletal muscle injury in diabetic rats. In this study, we treated diabetic rats intracerebroventricularly with MC4R agonist R027-3225 or antagonist SHU9119, respectively. Then, we measured the production of reactive oxygen species (ROS), the levels of malondialdehyde (MDA) and glutathione (GSH), the mitochondrial DNA (mtDNA) content and mitochondrial biogenesis, and the protein levels of p-AMPK, AMPK, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α), sirtuin 1 (SIRT1), and manganese superoxide dismutase (MnSOD) in the skeletal muscle of diabetic rats. The results showed that there was significant skeletal muscle injury in the diabetic rats along with serious oxidative stress and decreased mitochondrial biogenesis. Treatment with R027-3225 reduced oxidative stress and induced mitochondrial biogenesis in skeletal muscle, and also activated the AMPK-SIRT1-PGC-1α signaling pathway. However, diabetic rats injected with MC4R antagonist SHU9119 showed an aggravated oxidative stress and mitochondrial dysfunction in skeletal muscle. In conclusion, our results revealed that MC4R activation was able to attenuate oxidative stress and mitochondrial dysfunction in skeletal muscle induced by diabetes partially through activating the AMPK-SIRT1-PGC-1α signaling pathway. J. Cell. Biochem. 118: 4072-4079, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Evaluation of human muscle in vivo by potassium radiometric measuring

    International Nuclear Information System (INIS)

    Sousa, Wanderson de P.

    2000-01-01

    Potassium is an essential element to the human metabolism and is present in all living cells, mainly in the striated muscular fibers. K-40 is one of the natural potassium isotopes with mass percentage of 0,0118% . This isotope emits beta particle and gamma rays with 1460 keV. The energy of K-40 photon and its uniform distribution within the human body allows its in vivo measurement. The objective of this study is to optimize this technique and evaluate the possibility of its medical application in order to quantify muscle increase during recovering procedures. Subjects of both sexes measured until this moment were divided into two groups. Subjects of Group 1 do not exercise routinely and subjects of Group 2 does. In Group 1 the average potassium mass, muscle mass and potassium concentration were (101±16)g of K, (20±3)kg of muscle and (1,3±0,3)g of K/kg of body mass, respectively, while in Group 2 average values were (125±38)g of K, (25±8)kg of muscle and (1,7±0,2)g of K/kg of body mass. The comparison between average values shows a clear difference, which allows to correlate a higher K mass with routine body activity. The technique has shown enough sensitivity for this application. (author)

  9. Do Changes in Muscle Architecture Affect Post-Activation Potentiation?

    Directory of Open Access Journals (Sweden)

    Danielle Reardon, Jay R. Hoffman, Gerald T. Mangine, Adam J. Wells, Adam M. Gonzalez, Adam R. Jajtner, Jeremy R. Townsend, William P. McCormack, Jeffrey R. Stout, Maren S. Fragala, David H. Fukuda

    2014-09-01

    Full Text Available The purpose of this randomized, cross-over design study was to examine the effect of three different muscle potentiation protocols on acute changes in muscle architecture and vertical jump performance. Eleven experienced, resistance trained men (25.2±3.6y completed three potentiation squat protocols using moderate intensity (MI; 75%, 3 sets x 10 repetitions, high intensity (HI; 90%, 3 sets x 3 repetitions and 100% (1RM; 1 set x 1repetition of their 1RM. In addition, all participants completed a control session (CTL in which no protocol was performed. During each testing session, muscle architecture and vertical jump testing were assessed at baseline (BL, 8min post (8P and 20min post (20P workout. Ultrasound measures included cross sectional area (CSA and pennation angle (PANG of both the rectus femoris (RF and vastus lateralis (VL. Following each ultrasound measure, peak vertical jump power (PVJP and mean (MVJP power was assessed using an accelerometer. Magnitude based inferences were used to make comparisons between trials. The MI trial resulted in a likely greater increase from BL to 8P and 20P in RF-CSA and VL-CSA, while the HI trial resulted in a likely greater change from BL to 20P in both RF-CSA and VL-CSA. Meanwhile, changes in PVJP and MVJP for the MI trial was likely decreased at BL-8P and BL–20P, while the HI trial was shown to result in a likely or possible decrease compared to CTL at BL-8P and BL–20P, respectively. A likely negative relationship was observed between changes in VL-PANG and MVJP (r = -0.35; p , 0.018 at BL-8P, and between changes in PVJP and RF-CSA (r = -0.37; p , 0.014 at BL–20P. Results of this study were unable to demonstrate any potentiation response from the trials employed, however these protocols did result in acute muscle architectural changes.

  10. Novel Mechanism of Plasma Prekallikrein (PK) Activation by Vascular Smooth Muscle Cells: Evidence of the presence of PK Activator

    OpenAIRE

    Keum, Joo-Seob; Jaffa, Miran A; Luttrell, Louis M; Jaffa, Ayad A.

    2014-01-01

    The contribution of plasma prekallikrein (PK) to vascular remodeling is becoming increasingly recognized. Plasma PK is activated when the zymogen PK is digested to an active enzyme by activated factor XII (FXII). Here, we present our findings that vascular smooth muscle cells (VSMC) activate plasma PK in the absence of FXII. Extracted plasma membrane and cytosolic fractions of VSMCs activate PK, but the rate of PK activation was greater by the membrane fraction. FXII neutralizing antibody did...

  11. Distal muscle activity alterations during the stance phase of gait in restless leg syndrome (RLS) patients.

    Science.gov (United States)

    Dafkin, Chloe; Green, Andrew; Olivier, Benita; McKinon, Warrick; Kerr, Samantha

    2018-05-01

    To assess if there is a circadian variation in electromyographical (EMG) muscle activity during gait in restless legs syndrome (RLS) patients and healthy control participants. Gait assessment was done in 14 RLS patients and 13 healthy control participants in the evening (PM) and the morning (AM). Muscle activity was recorded bilaterally from the tibialis anterior (TA), lateral gastrocnemius (GL), rectus femoris (RF) and biceps femoris (BF) muscles. A circadian variation during the stance phase in only TA (PM > AM, p  Controls, p < 0.05) during early stance and decreased GL activity (RLS < Controls, p < 0.01) during terminal stance in comparison to control participants in the evening. No other significant differences were noted between RLS patients and control participants. Activation of GL during the swing phase was noted in 79% of RLS patients and in 23% of control participants in the morning compared to 71% and 38% in the evening, respectively. EMG muscle activity shows no circadian variation in RLS patients. Evening differences in gait muscle activation patterns between RLS patients and control participants are evident. These results extend our knowledge about alterations in spinal processing during gait in RLS. A possible explanation for these findings is central pattern generator sensitization caused by increased sensitivity in cutaneous afferents in RLS patients. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Evaluation of methods for extraction of the volitional EMG in dynamic hybrid muscle activation

    Directory of Open Access Journals (Sweden)

    Mizrahi Joseph

    2006-11-01

    Full Text Available Abstract Background Hybrid muscle activation is a modality used for muscle force enhancement, in which muscle contraction is generated from two different excitation sources: volitional and external, by means of electrical stimulation (ES. Under hybrid activation, the overall EMG signal is the combination of the volitional and ES-induced components. In this study, we developed a computational scheme to extract the volitional EMG envelope from the overall dynamic EMG signal, to serve as an input signal for control purposes, and for evaluation of muscle forces. Methods A "synthetic" database was created from in-vivo experiments on the Tibialis Anterior of the right foot to emulate hybrid EMG signals, including the volitional and induced components. The database was used to evaluate the results obtained from six signal processing schemes, including seven different modules for filtration, rectification and ES component removal. The schemes differed from each other by their module combinations, as follows: blocking window only, comb filter only, blocking window and comb filter, blocking window and peak envelope, comb filter and peak envelope and, finally, blocking window, comb filter and peak envelope. Results and conclusion The results showed that the scheme including all the modules led to an excellent approximation of the volitional EMG envelope, as extracted from the hybrid signal, and underlined the importance of the artifact blocking window module in the process. The results of this work have direct implications on the development of hybrid muscle activation rehabilitation systems for the enhancement of weakened muscles.

  13. Insulin receptor binding and protein kinase activity in muscles of trained rats

    International Nuclear Information System (INIS)

    Dohm, G.L.; Sinha, M.K.; Caro, J.F.

    1987-01-01

    Exercise has been shown to increase insulin sensitivity, and muscle is quantitatively the most important tissue of insulin action. Since the first step in insulin action is the binding to a membrane receptor, the authors postulated that exercise training would change insulin receptors in muscle and in this study they have investigated this hypothesis. Female rats initially weighing ∼ 100 g were trained by treadmill running for 2 h/day, 6 days/wk for 4 wk at 25 m/min (0 grade). Insulin receptors from vastus intermedius muscles were solubilized by homogenizing in a buffer containing 1% Triton X-100 and then partially purified by passing the soluble extract over a wheat germ agglutinin column. The 4 wk training regimen resulted in a 65% increase in citrate synthase activity in red vastus lateralis muscle, indicating an adaptation to exercise [ 125 I]. Insulin binding by the partially purified receptor preparations was approximately doubled in muscle of trained rats at all insulin concentrations, suggesting an increase in the number of receptors. Training did not alter insulin receptor structure as evidenced by electrophoretic mobility under reducing and nonreducing conditions. Basal insulin receptor protein kinase activity was higher in trained than untrained animals and this was likely due to the greater number of receptors. However, insulin stimulation of the protein kinase activity was depressed by training. These results demonstrate that endurance training does alter receptor number and function in muscle and these changes may be important in increasing insulin sensitivity after exercise training

  14. Trunk Muscle Activation at the Initiation and Braking of Bilateral Shoulder Flexion Movements of Different Amplitudes.

    Directory of Open Access Journals (Sweden)

    M Eriksson Crommert

    Full Text Available The aim of this study was to investigate if trunk muscle activation patterns during rapid bilateral shoulder flexions are affected by movement amplitude. Eleven healthy males performed shoulder flexion movements starting from a position with arms along sides (0° to either 45°, 90° or 180°. EMG was measured bilaterally from transversus abdominis (TrA, obliquus internus (OI with intra-muscular electrodes, and from rectus abdominis (RA, erector spinae (ES and deltoideus with surface electrodes. 3D kinematics was recorded and inverse dynamics was used to calculate the reactive linear forces and torque about the shoulders and the linear and angular impulses. The sequencing of trunk muscle onsets at the initiation of arm movements was the same across movement amplitudes with ES as the first muscle activated, followed by TrA, RA and OI. All arm movements induced a flexion angular impulse about the shoulders during acceleration that was reversed during deceleration. Increased movement amplitude led to shortened onset latencies of the abdominal muscles and increased level of activation in TrA and ES. The activation magnitude of TrA was similar in acceleration and deceleration where the other muscles were specific to acceleration or deceleration. The findings show that arm movements need to be standardized when used as a method to evaluate trunk muscle activation patterns and that inclusion of the deceleration of the arms in the analysis allow the study of the relationship between trunk muscle activation and direction of perturbing torque during one and the same arm movement.

  15. Coordination of intrinsic and extrinsic hand muscle activity as a function of wrist joint angle during two-digit grasping.

    Science.gov (United States)

    Johnston, Jamie A; Bobich, Lisa R; Santello, Marco

    2010-04-26

    Fingertip forces result from the activation of muscles that cross the wrist and muscles whose origins and insertions reside within the hand (extrinsic and intrinsic hand muscles, respectively). Thus, tasks that involve changes in wrist angle affect the moment arm and length, hence the force-producing capabilities, of extrinsic muscles only. If a grasping task requires the exertion of constant fingertip forces, the Central Nervous System (CNS) may respond to changes in wrist angle by modulating the neural drive to extrinsic or intrinsic muscles only or by co-activating both sets of muscles. To distinguish between these scenarios, we recorded electromyographic (EMG) activity of intrinsic and extrinsic muscles of the thumb and index finger as a function of wrist angle during a two-digit object hold task. We hypothesized that changes in wrist angle would elicit EMG amplitude modulation of the extrinsic and intrinsic hand muscles. In one experimental condition we asked subjects to exert the same digit forces at each wrist angle, whereas in a second condition subjects could choose digit forces for holding the object. EMG activity was significantly modulated in both extrinsic and intrinsic muscles as a function of wrist angle (both pextrinsic and intrinsic muscles as a muscle synergy. These findings are discussed within the theoretical frameworks of synergies and common neural input across motor nuclei of hand muscles. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  16. Assessment of muscle function using hybrid PET/MRI: comparison of 18F-FDG PET and T2-weighted MRI for quantifying muscle activation in human subjects

    International Nuclear Information System (INIS)

    Haddock, Bryan; Holm, Soeren; Poulsen, Jakup M.; Enevoldsen, Lotte H.; Larsson, Henrik B.W.; Kjaer, Andreas; Suetta, Charlotte

    2017-01-01

    The aim of this study was to determine the relationship between relative glucose uptake and MRI T 2 changes in skeletal muscles following resistance exercise using simultaneous PET/MRI scans. Ten young healthy recreationally active men (age 21 - 28 years) were injected with 18 F-FDG while activating the quadriceps of one leg with repeated knee extension exercises followed by hand-grip exercises for one arm. Immediately following the exercises, the subjects were scanned simultaneously with 18 F-FDG PET/MRI and muscle groups were evaluated for increases in 18 F-FDG uptake and MRI T 2 values. A significant linear correlation between 18 F-FDG uptake and changes in muscle T 2 (R 2 = 0.71) was found. for both small and large muscles and in voxel to voxel comparisons. Despite large intersubject differences in muscle recruitment, the linear correlation between 18 F-FDG uptake and changes in muscle T 2 did not vary among subjects. This is the first assessment of skeletal muscle activation using hybrid PET/MRI and the first study to demonstrate a high correlation between 18 F-FDG uptake and changes in muscle T 2 with physical exercise. Accordingly, it seems that changes in muscle T 2 may be used as a surrogate marker for glucose uptake and lead to an improved insight into the metabolic changes that occur with muscle activation. Such knowledge may lead to improved treatment strategies in patients with neuromuscular pathologies such as stroke, spinal cord injuries and muscular dystrophies. (orig.)

  17. Muscle activity and masticatory efficiency with bilateral extension base removable partial dentures with different cusp angles.

    Science.gov (United States)

    Al-Omiri, Mahmoud K

    2018-03-01

    Whether masticatory efficiency and electromyographic activity are influenced by type of artificial teeth and food is unclear. The purpose of this clinical study was to evaluate the influence of extension base removable partial dentures (RPDs) with different cusp angles: anatomic (33 degrees), semianatomic (20 degrees), and nonanatomic (0 degrees) teeth on masticatory efficiency and muscle activity during the mastication of test foods with different textures. Twelve participants with RPDs were selected to perform masticatory efficiency and electromyographic tests. Surface electromyograms (EMGs) were used to record the activities of the masseter and temporalis muscles during the mastication of different types of test foods. The maximal voltage and duration were measured on the integrated EMG signal in each muscle during food mastication, and the mean reading of both sides was then recorded. Analysis of variance and the Tukey post hoc test were used to perform statistical analyses (α=.05). The masticatory efficiency of RPDs with nonanatomic teeth was significantly inferior to that of RPDs with anatomic and semianatomic teeth (P.05). Also, muscle activity (according to EMG) with RPDs with NA teeth was significantly higher than that with anatomic and semianatomic teeth (P<.05). RPDs with NA teeth were associated with higher EMG muscle activity and reduced masticatory efficiency than anatomic or semianatomic teeth. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  18. Are cervical multifidus muscles active during whiplash and startle? An initial experimental study

    Directory of Open Access Journals (Sweden)

    Carpenter Mark G

    2008-06-01

    Full Text Available Abstract Background The cervical multifidus muscles insert onto the lower cervical facet capsular ligaments and the cervical facet joints are the source of pain in some chronic whiplash patients. Reflex activation of the multifidus muscle during a whiplash exposure could potentially contribute to injuring the facet capsular ligament. Our goal was to determine the onset latency and activation amplitude of the cervical multifidus muscles to a simulated rear-end collision and a loud acoustic stimuli. Methods Wire electromyographic (EMG electrodes were inserted unilaterally into the cervical multifidus muscles of 9 subjects (6M, 3F at the C4 and C6 levels. Seated subjects were then exposed to a forward acceleration (peak acceleration 1.55 g, speed change 1.8 km/h and a loud acoustic tone (124 dB, 40 ms, 1 kHz. Results Aside from one female, all subjects exhibited multifidus activity after both stimuli (8 subjects at C4, 6 subjects at C6. Neither onset latencies nor EMG amplitude varied with stimulus type or spine level (p > 0.13. Onset latencies and amplitudes varied widely, with EMG activity appearing within 160 ms of stimulus onset (for at least one of the two stimuli in 7 subjects. Conclusion These data indicate that the multifidus muscles of some individuals are active early enough to potentially increase the collision-induced loading of the facet capsular ligaments.

  19. Impaired exercise performance and muscle Na(+),K(+)-pump activity in renal transplantation and haemodialysis patients.

    Science.gov (United States)

    Petersen, Aaron C; Leikis, Murray J; McMahon, Lawrence P; Kent, Annette B; Murphy, Kate T; Gong, Xiaofei; McKenna, Michael J

    2012-05-01

    We examined whether abnormal skeletal muscle Na(+),K(+)-pumps underlie impaired exercise performance in haemodialysis patients (HDP) and whether these are improved in renal transplant recipients (RTx). Peak oxygen consumption ( O(2peak)) and plasma [K(+)] were measured during incremental exercise in 9RTx, 10 HDP and 10 healthy controls (CON). Quadriceps peak torque (PT), fatigability (decline in strength during thirty contractions), thigh muscle cross-sectional area (TMCSA) and vastus lateralis Na(+),K(+)-pump maximal activity, content and isoform (α(1)-α(3), β(1)-β(3)) abundance were measured. O(2peak) was 32 and 35% lower in RTx and HDP than CON, respectively (P Na(+),K(+)-pump activity was 28 and 31% lower in RTx and HDP, respectively than CON (P Na(+),K(+)-pump activity (r = 0.45, P = 0.02). O(2peak) and muscle Na(+),K(+)-pump activity were depressed and muscle fatigability increased in HDP, with no difference observed in RTx. These findings are consistent with the possibility that impaired exercise performance in HDP and RTx may be partially due to depressed muscle Na(+),K(+)-pump activity and relative TMCSA.

  20. Effects of Resistance Training on Matrix Metalloproteinase Activity in Skeletal Muscles and Blood Circulation During Aging

    Directory of Open Access Journals (Sweden)

    Ivo V. de Sousa Neto

    2018-03-01

    Full Text Available Aging is a complex, multifactorial process characterized by the accumulation of deleterious effects, including biochemical adaptations of the extracellular matrix (ECM. The purpose of this study was to investigate the effects of 12 weeks of resistance training (RT on metalloproteinase 2 (MMP-2 activity in skeletal muscles and, MMP-2 and MMP-9 activity in the blood circulation of young and old rats. Twenty-eight Wistar rats were randomly divided into four groups (n = 7 per group: young sedentary (YS; young trained (YT, old sedentary (OS, and old trained (OT. The stair climbing RT consisted of one training session every 2 other day, with 8–12 dynamic movements per climb. The animals were euthanized 48 h after the end of the experimental period. MMP-2 and MMP-9 activity was measured by zymography. There was higher active MMP-2 activity in the lateral gastrocnemius and flexor digitorum profundus muscles in the OT group when compared to the OS, YS, and YT groups (p ≤ 0.001. Moreover, there was higher active MMP-2 activity in the medial gastrocnemius muscle in the OT group when compared to the YS and YT groups (p ≤ 0.001. The YS group presented lower active MMP-2 activity in the soleus muscle than the YT, OS, OT groups (p ≤ 0.001. With respect to active MMP-2/9 activity in the bloodstream, the OT group displayed significantly reduced activity (p ≤ 0.001 when compared to YS and YT groups. In conclusion, RT up-regulates MMP-2 activity in aging muscles, while down-regulating MMP-2 and MMP-9 in the blood circulation, suggesting that it may be a useful tool for the maintenance of ECM remodeling.

  1. A comparison of muscle activity in concentric and counter movement maximum bench press.

    Science.gov (United States)

    van den Tillaar, Roland; Ettema, Gertjan

    2013-01-01

    The purpose of this study was to compare the kinematics and muscle activation patterns of regular free-weight bench press (counter movement) with pure concentric lifts in the ascending phase of a successful one repetition maximum (1-RM) attempt in the bench press. Our aim was to evaluate if diminishing potentiation could be the cause of the sticking region. Since diminishing potentiation cannot occur in pure concentric lifts, the occurrence of a sticking region in this type of muscle actions would support the hypothesis that the sticking region is due to a poor mechanical position. Eleven male participants (age 21.9 ± 1.7 yrs, body mass 80.7 ± 10.9 kg, body height 1.79 ± 0.07 m) conducted 1-RM lifts in counter movement and in pure concentric bench presses in which kinematics and EMG activity were measured. In both conditions, a sticking region occurred. However, the start of the sticking region was different between the two bench presses. In addition, in four of six muscles, the muscle activity was higher in the counter movement bench press compared to the concentric one. Considering the findings of the muscle activity of six muscles during the maximal lifts it was concluded that the diminishing effect of force potentiation, which occurs in the counter movement bench press, in combination with a delayed muscle activation unlikely explains the existence of the sticking region in a 1-RM bench press. Most likely, the sticking region is the result of a poor mechanical force position.

  2. A comparison of hamstring muscle activity during different screening tests for non-contact ACL injury.

    Science.gov (United States)

    Husted, Rasmus S; Bencke, Jesper; Andersen, Lars L; Myklebust, Grethe; Kallemose, Thomas; Lauridsen, Hanne B; Hölmich, Per; Aagaard, Per; Zebis, Mette K

    2016-06-01

    Reduced ability to activate the medial hamstring muscles during a sports-specific sidecutting movement has been found to be a potential risk factor for non-contact ACL injury. However, whether a reduced ability to activate the medial hamstring muscle is a general neuromuscular phenomenon and thereby observable independently of the type of clinical screening tests used is not known. This cross sectional study investigated the rank correlation of knee joint neuromuscular activity between three different ACL injury risk screening tests. Sixty-two adolescent female elite football and handball players (16.7±1.3years) participated in the study. Using surface electromyography (EMG) assessment, the neuromuscular activity of medial hamstring muscle (semitendinosus, ST), lateral hamstring muscle (biceps femoris, BF) and quadriceps muscle (vastus lateralis, VL) were monitored during three standardized screening tests - i.e. one-legged horizontal hop (OLH), drop vertical jump (DJ) and sidecutting (SC). Neuromuscular pre-activity was measured in the time interval 10ms prior to initial contact on a force plate. For neuromuscular hamstring muscle pre-activity, correlation analysis (Spearman correlation coefficient) showed low-to-moderate correlations between SC and 1) DJ (rs=0.34-0.36, Phamstring pre-activity share some common variance during the examined tests. However, a lack of strong correlation suggests that we cannot generalize one risk factor during one test to another test. The present data demonstrate that one-legged horizontal hop and drop vertical jump testing that are commonly used in the clinical setting does not resemble the specific neuromuscular activity patterns known to exist during sidecutting, a well known high risk movement for non-contact ACL injury. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Cytoskeleton, L-type Ca2+ and stretch activated channels in injured skeletal muscle

    Directory of Open Access Journals (Sweden)

    Fabio Francini

    2013-07-01

    Full Text Available The extra-sarcomeric cytoskeleton (actin microfilaments and anchoring proteins is involved in maintaining the sarco-membrane stiffness and integrity and in turn the mechanical stability and function of the intra- and sub-sarcoplasmic proteins. Accordingly, it regulates Ca2+ entry through the L-type Ca2+ channels and the mechano-sensitivity of the stretch activated channels (SACs. Moreover, being intra-sarcomeric cytoskeleton bound to costameric proteins and other proteins of the sarcoplasma by intermediate filaments, as desmin, it integrates the properties of the sarcolemma with the skeletal muscle fibres contraction. The aim of this research was to compare the cytoskeleton, SACs and the ECC alterations in two different types of injured skeletal muscle fibres: by muscle denervation and mechanical overload (eccentric contraction. Experiments on denervation were made in isolated Soleus muscle of male Wistar rats; forced eccentric-contraction (EC injury was achieved in Extensor Digitorum Longus muscles of Swiss mice. The method employed conventional intracellular recording with microelectrodes inserted in a single fibre of an isolated skeletal muscle bundle. The state of cytoskeleton was evaluated by recording SAC currents and by evaluating the resting membrane potential (RMP value determined in current-clamp mode. The results demonstrated that in both injured skeletal muscle conditions the functionality of L-type Ca2+ current, ICa, was affected. In parallel, muscle fibres showed an increase of the resting membrane permeability and of the SAC current. These issues, together with a more depolarized RMP are an index of altered cytoskeleton. In conclusion, we found a symilar alteration of ICa, SAC and cytoskeleton in both injured skeletal muscle conditions.

  4. AMP kinase expression and activity in human skeletal muscle: effects of immobilization, retraining, and creatine supplementation

    DEFF Research Database (Denmark)

    Eijnde, Bert O.; Derave, Wim; Wojtaszewski, Jørgen

    2005-01-01

    The effects of leg immobilization and retraining in combination with oral creatine intake on muscle AMP-activated protein kinase (AMPK) protein expression and phosphorylation status were investigated. A double-blind trial was performed in young healthy volunteers (n = 22). A cast immobilized...... the right leg for 2 wk, whereafter the knee-extensor muscles of that leg were retrained for 6 wk. Half of the subjects received creatine monohydrate throughout the study (Cr; from 15 g down to 2.5 g daily), and the others ingested placebo (P; maltodextrin). Before and after immobilization and retraining...... that immobilization-induced muscle inactivity for 2 wk does not alter AMPK a1-, a2-, and ß2-subunit expression or a-AMPK phosphorylation status. Furthermore, the present observations indicate that AMPK probably is not implicated in the previously reported beneficial effects of oral creatine supplementation on muscle...

  5. Physical activity as intervention for age-related loss of muscle mass and function

    DEFF Research Database (Denmark)

    Eriksen, Christian Skou; Garde, Ellen; Reislev, Nina Linde

    2016-01-01

    insights into training-induced promotion of functional ability and independency after retirement and will help to formulate national recommendations regarding physical activity schemes for the growing population of older individuals in western societies. Results will be published in scientific peer......INTRODUCTION: Physical and cognitive function decline with age, accelerating during the 6th decade. Loss of muscle power (force×velocity product) is a dominant physical determinant for loss of functional ability, especially if the lower extremities are affected. Muscle strength training is known...... to maintain or even improve muscle power as well as physical function in older adults, but the optimal type of training for beneficial long-term training effects over several years is unknown. Moreover, the impact of muscle strength training on cognitive function and brain structure remains speculative...

  6. Decreased torque and electromyographic activity in the extensor thigh muscles in chondromalacia patellae.

    Science.gov (United States)

    Väätäinen, U; Airaksinen, O; Jaroma, H; Kiviranta, I

    1995-01-01

    The alterations in thigh muscle properties of chondromalacia patellae patients during isometric and dynamic endurance tests were studied using a variokinetic knee testing system linked to surface EMG. A total of 41 patients (chondromalacia group) with arthroscopically certified chondromalacia of the patella were studied. The control group consisted of 31 healthy adult volunteers with no history of knee pain or trauma. Peak torque values were 21% (p chondromalacia group than in the control group. The decrease in the ratio between integrated EMG (IEMG) and measured force were found in all parts of the quadriceps femoris muscle in patients with chondromalacia of the patella in isometric extension. No change in the normalized IEMG levels of the thigh muscles were found between chondromalacia patients and controls in dynamic endurance test. The severity of the chondromalacia of the patella did not affect the level of electromyographic activation in thigh muscles. The ratio of normalized EMG levels of vastus medialis and vastus lateralis did not differ between the groups. The present study showed that chondromalacia patellae patients have reduced force and electromyographic activation levels of quadriceps femoris muscle. Especially, the explosive strength of the quadriceps femoris muscle is reduced.

  7. Trunk muscle activation. The effects of torso flexion, moment direction, and moment magnitude.

    Science.gov (United States)

    Lavender, S; Trafimow, J; Andersson, G B; Mayer, R S; Chen, I H

    1994-04-01

    This study was performed to quantify the electromyographic trunk muscle activities in response to variations in moment magnitude and direction while in forward-flexed postures. Recordings were made over eight trunk muscles in 19 subjects who maintained forward-flexed postures of 30 degrees and 60 degrees. In each of the two flexed postures, external moments of 20 Nm and 40 Nm were applied via a chest harness. The moment directions were varied in seven 30 degrees increments to a subject's right side, such that the direction of the applied load ranged from the upper body's anterior midsagittal plane (0 degree) to the posterior midsagittal plane (180 degrees). Statistical analyses yielded significant moment magnitude by moment-direction interaction effects for the EMG output from six of the eight muscles. Trunk flexion by moment-direction interactions were observed in the responses from three muscles. In general, the primary muscle supporting the torso and the applied load was the contralateral (left) erector spinae. The level of electromyographic activity in the anterior muscles was quite low, even with the posterior moment directions.

  8. [Relationship between muscle activity and kinematics of the lower extremity in slow motions of squats in humans].

    Science.gov (United States)

    Khorievin, V I; Horkovenko, A V; Vereshchaka, I V

    2013-01-01

    Squatting can be performed on ankle strategy when ankle joint is flexed more than a hip joint and on hip strategy when large changes occur at the hip joint. The relationships between changes ofjoint angles and electromyogram (EMG) of the leg muscles were studied in five healthy men during squatting that was performed at the ankle and hip strategies with a slow changes in the knee angle of 40 and 60 degrees. It is established that at ankle strategy the ankle muscles were activated ahead of joint angle changes and shifting the center of pressure (CT) on stabilographic platform, whereas activation of the thigh muscles began simultaneously with the change of the joint angles, showing the clear adaptation in successive trials and a linear relationships between the static EMG component and the angle changes of the ankle joint. In the case of hip strategy of squatting the thigh muscles were activated simultaneously with the change in the joint angles and the displacement of CT, whereas the ankle muscles were activated later than the thigh muscles, especially the muscle tibialis anterior, showing some adaptations in consecutive attempts. At the ankle strategy the EMG amplitude was greatest in thigh muscles, reproducing contour of changes in joint angles, whereas the ankle muscles were activated only slightly during changes of joint angles. In the case of hip strategy dominated the EMG amplitude of the muscle tibialis anterior, which was activated when driving down the trunk and fixation of the joint angles that was accompanied by a slight coactivation of the calf muscles with the step-like increase in the amplitude of the EMG of the thigh muscles. Choice of leg muscles to start the squatting on both strategies occurred without a definite pattern, which may indicate the existence of a wide range of options for muscle activity in a single strategy.

  9. Differences in the EMG pattern of lea muscle activation during locomotion in Parkinson's disease

    NARCIS (Netherlands)

    Albani, G; Sandrini, G; Kunig, G; Martin-Soelch, C; Mauro, A; Pignatti, R; Pacchetti, C; Dietz, [No Value; Leenders, KL

    2003-01-01

    In this pilot study, EMG patterns of leg muscle activation were studied in five parkinsonian patients with (B1) and five without (B2) freezing. Gastrocnemius medialis (GM) and tibialis anterior (TA) activity was analysed, by means of surface electromyography (EMG), during treadmill walking at two

  10. Effects of alpha-AMPK knockout on exercise-induced gene activation in mouse skeletal muscle

    DEFF Research Database (Denmark)

    Jørgensen, Sebastian Beck; Wojtaszewski, Jørgen; Viollet, Benoit

    2005-01-01

    We tested the hypothesis that 5'AMP-activated protein kinase (AMPK) plays an important role in regulating the acute, exercise-induced activation of metabolic genes in skeletal muscle, which were dissected from whole-body a2- and a1-AMPK knockout (KO) and wild-type (WT) mice at rest, after treadmi...

  11. Cervico-mandibular muscle activity in females with chronic cervical pain

    OpenAIRE

    T. Lang; R. Parker; T. Burgess

    2013-01-01

    Pathophysiological mechanisms behind pain in chroniccervical musculoskeletal conditions (MSC) in office workers remainunclear. Chronic cervical pain has established links with temporomandibular(TM) disorders. Yet there is no current published evidence to reportwhether individuals with cervical dysfunction exhibit altered masseterand cervical extensor (CE) muscle activity. Objective: To explore CE andmasseter surface electromyographic (sEMG) activity and teeth clenchinghabits in females with c...

  12. Evolution of asynchronous motor activity in paired muscles: effects of ecology, morphology, and phylogeny.

    Science.gov (United States)

    Gerry, Shannon P; Ramsay, Jason B; Dean, Mason N; Wilga, Cheryl D

    2008-08-01

    Many studies of feeding behavior have implanted electrodes unilaterally (in muscles on only one side of the head) to determine the basic motor patterns of muscles controlling the jaws. However, bilateral implantation has the potential to achieve a more comprehensive understanding of modification of the motor activity that may be occurring between the left and right sides of the head. In particular, complex processing of prey is often characterized by bilaterally asynchronous and even unilateral activation of the jaw musculature. In this study, we bilaterally implant feeding muscles in species from four orders of elasmobranchs (Squaliformes, Orectolobiformes, Carcharhiniformes, Rajoidea) in order to characterize the effects of type of prey, feeding behavior, and phylogeny on the degree of asynchronous muscle activation. Electrodes were implanted in three of the jaw adductors, two divisions of the quadratomandibularis and the preorbitalis, as well as in a cranial elevator in sharks, the epaxialis. The asynchrony of feeding events (measured as the degree to which activity of members of a muscle pair is out of phase) was compared across species for capture versus processing and simple versus complex prey, then interpreted in the contexts of phylogeny, morphology, and ecology to clarify determinants of asynchronous activity. Whereas capture and processing of prey were characterized by statistically similar degrees of asynchrony for data pooled across species, events involving complex prey were more asynchronous than were those involving simple prey. The two trophic generalists, Squalus acanthias and Leucoraja erinacea, modulated the degree of asynchrony according to type of prey, whereas the two behavioral specialists, Chiloscyllium plagiosum and Mustelus canis, activated the cranial muscles synchronously regardless of type of prey. These differences in jaw muscle activity would not have been detected with unilateral implantation. Therefore, we advocate bilateral

  13. Denervation-Induced Activation of the Ubiquitin-Proteasome System Reduces Skeletal Muscle Quantity Not Quality.

    Science.gov (United States)

    Baumann, Cory W; Liu, Haiming M; Thompson, LaDora V

    2016-01-01

    It is well known that the ubiquitin-proteasome system is activated in response to skeletal muscle wasting and functions to degrade contractile proteins. The loss of these proteins inevitably reduces skeletal muscle size (i.e., quantity). However, it is currently unknown whether activation of this pathway also affects function by impairing the muscle's intrinsic ability to produce force (i.e., quality). Therefore, the purpose of this study was twofold, (1) document how the ubiquitin-proteasome system responds to denervation and (2) identify the physiological consequences of these changes. To induce soleus muscle atrophy, C57BL6 mice underwent tibial nerve transection of the left hindlimb for 7 or 14 days (n = 6-8 per group). At these time points, content of several proteins within the ubiquitin-proteasome system were determined via Western blot, while ex vivo whole muscle contractility was specifically analyzed at day 14. Denervation temporarily increased several key proteins within the ubiquitin-proteasome system, including the E3 ligase MuRF1 and the proteasome subunits 19S, α7 and β5. These changes were accompanied by reductions in absolute peak force and power, which were offset when expressed relative to physiological cross-sectional area. Contrary to peak force, absolute and relative forces at submaximal stimulation frequencies were significantly greater following 14 days of denervation. Taken together, these data represent two keys findings. First, activation of the ubiquitin-proteasome system is associated with reductions in skeletal muscle quantity rather than quality. Second, shortly after denervation, it appears the muscle remodels to compensate for the loss of neural activity via changes in Ca2+ handling.

  14. Muscle satellite cells are activated after exercise to exhaustion in Thoroughbred horses.

    Science.gov (United States)

    Kawai, M; Aida, H; Hiraga, A; Miyata, H

    2013-07-01

    Although satellite cells are well known as muscle stem cells capable of adding myonuclei during muscle repair and hypertrophy, the response of satellite cells in horse muscles to a run to exhaustion is still unknown. To investigate the time course of satellite cell activation in Thoroughbred horse muscle after running to exhaustion. We hypothesised that this type of intense exercise would induce satellite cell activation in skeletal muscle similar to a resistance exercise. Nine de-trained Thoroughbred horses (6 geldings and 3 mares) aged 3-6 years were studied. Biopsy samples were taken from the gluteus medius muscle of the horses before and 1 min, 3 h, 1 day, 3 days, 1 week and 2 weeks after a treadmill run to exhaustion. The numbers of satellite cells for each fibre type were determined by using immunofluorescence staining. Total RNA was extracted from these samples, and the expressions of interleukin (IL)-6, paired box transcriptional factor (Pax) 7, myogenic differentiation 1 (MyoD), myogenin, proliferating cell nuclear antigen (PCNA), insulin-like growth factor (IGF)-I and hepatocyte growth factor (HGF) mRNA were analysed using real-time reverse transcription-PCR. The numbers of satellite cells were significantly increased in type I and IIa fibres at 1 week and in type IIa/x fibre at 2 weeks post exercise. The expression of IL-6 mRNA increased significantly by 3 h post exercise. The expression of PCNA mRNA also increased by 1 day after running, indicating that running can initiate satellite cell proliferation. The expression of Pax7, MyoD, myogenin, IGF-I and HGF mRNA peaked at 1 week post exercise. Satellite cell activation and proliferation could be enhanced after a run to exhaustion without detectable injury as assessed by the histochemical analysis. Understanding the response of satellite cell activation to running exercise provides fundamental information about the skeletal muscle adaptation in Thoroughbred horses. © 2012 EVJ Ltd.

  15. Muscle force output and electromyographic activity in squats with various unstable surfaces.

    Science.gov (United States)

    Saeterbakken, Atle H; Fimland, Marius S

    2013-01-01

    The purpose of the study was to compare force output and muscle activity of leg and trunk muscles in isometric squats executed on stable surface (i.e., floor), power board, BOSU ball, and balance cone. Fifteen healthy men (23.3 ± 2.7 years, mass: 80.5 ± 8.5 kg, height: 1.81 ± 0.09 m) volunteered. The force output and electromyographic (EMG) activities of the rectus femoris, vastus medialis, vastus lateralis, biceps femoris, soleus, rectus abdominis, oblique external, and erector spinae were assessed. The order of the surfaces was randomized. One familiarization session was executed before the experimental test. Compared with stable surface (749 ± 222 N), the force output using power board was similar (-7%, p = 0.320) but lower for BOSU ball (-19%, p = 0.003) and balance cone (-24%, p ≤ 0.001). The force output using BOSU ball and balance cone was approximately 13% (p = 0.037) and approximately 18% (p = 0.001) less than the power board. There were similar EMG activities between the surfaces in all muscles except for rectus femoris, in which stable squat provided greater EMG activity than did the other exercises (p = 0.004-0.030). Lower EMG activity was observed in the rectus femoris using balance cone compared with the BOSU ball (p = 0.030). In conclusion, increasing the instability of the surface during maximum effort isometric squats usually maintains the muscle activity of lower-limb and superficial trunk muscles although the force output is reduced. This suggests that unstable surfaces in the squat may be beneficial in rehabilitation and as a part of periodized training programs, because similar muscle activity can be achieved with reduced loads.

  16. Activation of the skeletal alpha-actin promoter during muscle regeneration.

    Science.gov (United States)

    Marsh, D R; Carson, J A; Stewart, L N; Booth, F W

    1998-11-01

    Little is known concerning promoter regulation of genes in regenerating skeletal muscles. In young rats, recovery of muscle mass and protein content is complete within 21 days. During the initial 5-10 days of regeneration, mRNA abundance for IGF-I, myogenin and MyoD have been shown to be dramatically increased. The skeletal alpha-actin promoter contains E box and serum response element (SRE) regulatory regions which are directly or indirectly activated by myogenin (or MyoD) and IGF-I proteins, respectively. We hypothesized that the skeletal alpha-actin promoter activity would increase during muscle regeneration, and that this induction would occur before muscle protein content returned to normal. Total protein content and the percentage content of skeletal alpha-actin protein was diminished at 4 and 8 days and re-accumulation had largely occurred by 16 days post-bupivacaine injection. Skeletal alpha-actin mRNA per whole muscle was decreased at day 8, and thereafter returned to control values. During regeneration at day 8, luciferase activity (a reporter of promoter activity) directed by -424 skeletal alpha-actin and -99 skeletal alpha-actin promoter constructs was increased by 700% and 250% respectively; however, at day 16, skeletal alpha-actin promoter activities were similar to control values. Thus, initial activation of the skeletal alpha-actin promoter is associated with regeneration of skeletal muscle, despite not being sustained during the later stages of regrowth. The proximal SRE of the skeletal alpha-actin promoter was not sufficient to confer a regeneration-induced promoter activation, despite increased serum response factor protein binding to this regulatory element in electrophoretic mobility shift assays. Skeletal alpha-actin promoter induction during regeneration is due to a combination of regulatory elements, at least including the SRE and E box.

  17. Functional and morphological adaptations to aging in knee extensor muscles of physically active men.

    Science.gov (United States)

    Baroni, Bruno Manfredini; Geremia, Jeam Marcel; Rodrigues, Rodrigo; Borges, Marcelo Krás; Jinha, Azim; Herzog, Walter; Vaz, Marco Aurélio

    2013-10-01

    It is not known if a physically active lifestyle, without systematic training, is sufficient to combat age-related muscle and strength loss. Therefore, the purpose of this study was to evaluate if the maintenance of a physically active lifestyle prevents muscle impairments due to aging. To address this issue, we evaluated 33 healthy men with similar physical activity levels (IPAQ = 2) across a large range of ages. Functional (torque-angle and torque-velocity relations) and morphological (vastus lateralis muscle architecture) properties of the knee extensor muscles were assessed and compared between three age groups: young adults (30 ± 6 y), middle-aged subjects (50 ± 7 y) and elderly subjects (69 ± 5 y). Isometric peak torques were significantly lower (30% to 36%) in elderly group subjects compared with the young adults. Concentric peak torques were significantly lower in the middle aged (18% to 32%) and elderly group (40% to 53%) compared with the young adults. Vastus lateralis thickness and fascicles lengths were significantly smaller in the elderly group subjects (15.8 ± 3.9 mm; 99.1 ± 25.8 mm) compared with the young adults (19.8 ± 3.6 mm; 152.1 ± 42.0 mm). These findings suggest that a physically active lifestyle, without systematic training, is not sufficient to avoid loss of strength and muscle mass with aging.

  18. Effects of treadmill grade and speed on medial gastrocnemius muscle activity in chronic stroke patients

    Directory of Open Access Journals (Sweden)

    Roghayeh Mohammadi

    2017-01-01

    Full Text Available Introduction: Plantarflexor muscles produce propulsive force in the second half of stance phase; deficient motor output from these muscles would lead to inadequate propulsion at push off phase of gait following stroke. It is important to develop strategies to improve plantarflexor output. This study examined the effects of walking on a treadmill at varying gradients and speeds on medial gastrocnemius (MG muscle activation in stroke survivors. Materials and Methods: Nineteen stroke survivors (13M/6F: average age 55.37±7.54 years; body mass index 29.10±4.52kg/m2 participated in the study. Participants walked  on  a  standard  treadmill  at  three  different positive inclines (0°, 3°, and 6°  and speeds (self-selected, self-selected+20%, self-selected+40%. The electromyographic activity of MG recorded at push off phase of the gait. Results: A linear mixed model regression analysis was used to analysis. The paretic MG muscle activity increased at faster speeds irrespective of incline (p0.05. Conclusion: It would appear that stroke survivors employ distinct muscle activation strategies on the paretic and non-paretic sides in response to different walking speeds and inclines

  19. Muscle activation patterns in acceleration-based phases during reach-to-grasp movement.

    Science.gov (United States)

    Tokuda, Keisuke; Lee, Bumsuk; Shiihara, Yasufumi; Takahashi, Kazuhiro; Wada, Naoki; Shirakura, Kenji; Watanabe, Hideomi

    2016-11-01

    [Purpose] An earlier study divided reaching activity into characteristic phases based on hand velocity profiles. By synchronizing muscle activities and the acceleration profile, a phasing approach for reaching movement, based on hand acceleration profiles, was attempted in order to elucidate the roles of individual muscle activities in the different phases of the acceleration profile in reaching movements. [Subjects and Methods] Ten healthy volunteer subjects participated in this study. The aim was to electromyographically evaluate muscles around the shoulder, the upper trapezius, the anterior deltoid, the biceps brachii, and the triceps brachii, most of which have been used to evaluate arm motion, as well as the acceleration of the upper limb during simple reaching movement in the reach-to-grasp task. [Results] Analysis showed the kinematic trajectories of the acceleration during a simple biphasic profile of the reaching movement could be divided into four phases: increasing acceleration (IA), decreasing acceleration (DA), increasing deceleration (ID), and decreasing deceleration (DD). Muscles around the shoulder showed different activity patterns, which were closely associated with these acceleration phases. [Conclusion] These results suggest the important role of the four phases, derived from the acceleration trajectory, in the elucidation of the muscular mechanisms which regulate and coordinate the muscles around the shoulder in reaching movements.

  20. The Kinetics of Myosin Light Chain Kinase Activation of Smooth Muscle Myosin in an In Vitro Model System

    OpenAIRE

    Hong, Feng; Facemyer, Kevin C.; Carter, Michael S.; Jackson, Del R.; Haldeman, Brian D.; Ruana, Nick; Sutherland, Cindy; Walsh, Michael P.; Cremo, Christine R.; Baker, Josh E.

    2013-01-01

    During activation of smooth muscle contraction, one myosin light chain kinase (MLCK) molecule rapidly phosphorylates many smooth muscle myosin (SMM) molecules, suggesting that muscle activation rates are influenced by the kinetics of MLCK-SMM interactions. To determine the rate-limiting step underlying activation of SMM by MLCK, we measured the kinetics of calcium-calmodulin (Ca2+-CaM)-MLCK-mediated SMM phosphorylation and the corresponding initiation of SMM-based F-actin motility in an in vi...

  1. Effect of exhalation exercise on trunk muscle activity and oswestry disability index of patients with chronic low back pain

    OpenAIRE

    Kang, Jeong-Il; Jeong, Dae-Keun; Choi, Hyun

    2016-01-01

    [Purpose] This study investigated the effect of exhalation exercises on trunk muscle activity and Oswestry Disability Index by inducing trunk muscle activity through increasing intra-abdominal pressure and activating muscles, contributing to spinal stability. [Subjects and Methods] This intervention program included 20 male patients with chronic low back pain. A total of 10 subjects each were randomly assigned to an exhalation exercise group as the experimental group and a spinal stabilizatio...

  2. The cell nuclei of skeletal muscle cells are transcriptionally active in hibernating edible dormice

    Directory of Open Access Journals (Sweden)

    Muller Sylviane

    2009-03-01

    Full Text Available Abstract Background Skeletal muscle is able to react in a rapid, dynamic way to metabolic and mechanical stimuli. In particular, exposure to either prolonged starvation or disuse results in muscle atrophy. At variance, in hibernating animals muscle atrophy may be scarce or absent after bouts of hibernation i.e., periods of prolonged (months inactivity and food deprivation, and muscle function is fully preserved at arousal. In this study, myocytes from the quadriceps muscle of euthermic and hibernating edible dormice were investigated by a combination of morphological, morphometrical and immunocytochemical analyses at the light and electron microscopy level. The focus was on cell nuclei and mitochondria, which are highly sensitive markers of changing metabolic rate. Results Findings presented herein demonstrate that: 1 the general histology of the muscle, inclusive of muscle fibre shape and size, and the ratio of fast and slow fibre types are not affected by hibernation; 2 the fine structure of cytoplasmic and nuclear constituents is similar in euthermia and hibernation but for lipid droplets, which accumulate during lethargy; 3 during hibernation, mitochondria are larger in size with longer cristae, and 4 myonuclei maintain the same amount and distribution of transcripts and transcription factors as in euthermia. Conclusion In this study we demonstrate that skeletal muscle cells of the hibernating edible dormouse maintain their structural and functional integrity in full, even after months in the nest. A twofold explanation for that is envisaged: 1 the maintenance, during hibernation, of low-rate nuclear and mitochondrial activity counterbalancing myofibre wasting, 2 the intensive muscle stimulation (shivering during periodic arousals in the nest, which would mimic physical exercise. These two factors would prevent muscle atrophy usually occurring in mammals after prolonged starvation and/or inactivity as a consequence of prevailing catabolism

  3. Economy, Movement Dynamics, and Muscle Activity of Human Walking at Different Speeds

    DEFF Research Database (Denmark)

    Raffalt, Peter Christian; Guul, Martin Kjær; Nielsen, A. N.

    2017-01-01

    The complex behaviour of human walking with respect to movement variability, economy and muscle activity is speed dependent. It is well known that a U-shaped relationship between walking speed and economy exists. However, it is an open question if the movement dynamics of joint angles and centre...... of mass and muscle activation strategy also exhibit a U-shaped relationship with walking speed. We investigated the dynamics of joint angle trajectories and the centre of mass accelerations at five different speeds ranging from 20 to 180% of the predicted preferred speed (based on Froude speed) in twelve...... healthy males. The muscle activation strategy and walking economy were also assessed. The movement dynamics was investigated using a combination of the largest Lyapunov exponent and correlation dimension. We observed an intermediate stage of the movement dynamics of the knee joint angle and the anterior...

  4. Quality assessment of shoulder plyometric exercises: Examining the relationship to scapular muscle activity.

    Science.gov (United States)

    Calé-Benzoor, Maya; Maenhout, Annelies; Arnon, Michal; Tenenbaum, Gershon; Werrin, Mia; Cools, Ann

    2017-07-01

    The purpose of the study was to evaluate performance quality of shoulder plyometric exercises, and examine the relationship to scapular muscle activation during an intense exercise bout. Observational study. University laboratory. 32 healthy university students (male/female: 14/18) volunteers. Subjects performed 10 plyometric exercises. Surface EMG of upper (UT), middle (MT) and lower (LT) trapezius and serratus anterior (SA) was registered. A quality assessment questionnaire was administered at the beginning and end of the exercise bout. Muscle activation at the beginning and end was evaluated by t-test. Mixed repeated measures ANOVA was conducted to test the effects of criterion-quality, time, muscles, exercises, and their interactions. Increased EMG activation was noted in 34/40 cases, (21/40 significant (p plyometric exercises. Ability to keep a consistent arc of motion was the most sensitive marker of decline of performance quality. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Predominant alpha2/beta2/gamma3 AMPK activation during exercise in human skeletal muscle

    DEFF Research Database (Denmark)

    Birk, Jesper Bratz; Wojtaszewski, Jørgen

    2006-01-01

    -Thr-172 AMPK phosphorylation (r2 = 0.84, P important actor in exercise-regulated AMPK signalling in human skeletal muscle, probably mediating phosphorylation of ACCß.......5'AMP-activated protein kinase (AMPK) is a key regulator of cellular metabolism and is regulated in muscle during exercise. We have previously established that only three of 12 possible AMPK a/ß/¿-heterotrimers are present in human skeletal muscle. Previous studies describe discrepancies between...... total AMPK activity and regulation of its target acetyl-CoA-carboxylase (ACC)ß. Also, exercise training decreases expression of the regulatory ¿3 AMPK subunit and attenuates a2 AMPK activity during exercise. We hypothesize that these observations reflect a differential regulation of the AMPK...

  6. Differentially activated macrophages orchestrate myogenic precursor cell fate during human skeletal muscle regeneration

    DEFF Research Database (Denmark)

    Saclier, Marielle; Yacoub-Youssef, Houda; Mackey, Abigail

    2013-01-01

    , we explored both in vitro and in vivo, in human, the interactions of differentially activated MPs with myogenic precursor cells (MPCs) during adult myogenesis and skeletal muscle regeneration. We showed in vitro that through the differential secretion of cytokines and growth factors, proinflammatory...... anti-inflammatory markers. These data demonstrate for the first time in human that MPs sequentially orchestrate adult myogenesis during regeneration of damaged skeletal muscle. These results support the emerging concept that inflammation, through MP activation, controls stem cell fate and coordinates......Macrophages (MPs) exert either beneficial or deleterious effects on tissue repair, depending on their activation/polarization state. They are crucial for adult skeletal muscle repair, notably by acting on myogenic precursor cells. However, these interactions have not been fully characterized. Here...

  7. Oxygen dependence of respiration in rat spinotrapezius muscle in situ

    OpenAIRE

    Golub, Aleksander S.; Pittman, Roland N.

    2012-01-01

    The oxygen dependence of respiration in striated muscle in situ was studied by measuring the rate of decrease of interstitial Po2 [oxygen disappearance curve (ODC)] following rapid arrest of blood flow by pneumatic tissue compression, which ejected red blood cells from the muscle vessels and made the ODC independent from oxygen bound to hemoglobin. After the contribution of photo-consumption of oxygen by the method was evaluated and accounted for, the corrected ODCs were converted into the Po...

  8. Evaluation of high-density, multi-contact nerve cuffs for activation of grasp muscles in monkeys

    Science.gov (United States)

    Brill, N. A.; Naufel, S. N.; Polasek, K.; Ethier, C.; Cheesborough, J.; Agnew, S.; Miller, L. E.; Tyler, D. J.

    2018-06-01

    Objective. The objective of this work was to evaluate whether nerve cuffs can selectively activate hand muscles for functional electrical stimulation (FES). FES typically involves identifying and implanting electrodes in many individual muscles, but nerve cuffs only require implantation at a single site around the nerve. This method is surgically more attractive. Nerve cuffs may also more effectively stimulate intrinsic hand muscles, which are difficult to implant and stimulate without spillover to adjacent muscles. Approach. To evaluate its ability to selectively activate muscles, we implanted and tested the flat interface nerve electrode (FINE), which is designed to selectively stimulate peripheral nerves that innervate multiple muscles (Tyler and Durand 2002 IEEE Trans. Neural Syst. Rehabil. Eng. 10 294-303). We implanted FINEs on the nerves and bipolar intramuscular wires for recording compound muscle action potentials (CMAPs) from up to 20 muscles in each arm of six monkeys. We then collected recruitment curves while the animals were anesthetized. Main result. A single FINE implanted on an upper extremity nerve in the monkey can selectively activate muscles or small groups of muscles to produce multiple, independent hand functions. Significance. FINE cuffs can serve as a viable supplement to intramuscular electrodes in FES systems, where they can better activate intrinsic and extrinsic muscles with lower currents and less extensive surgery.

  9. PRE-ACTIVITY MODULATION OF LOWER EXTREMITY MUSCLES WITHIN DIFFERENT TYPES AND HEIGHTS OF DEEP JUMP

    Directory of Open Access Journals (Sweden)

    Vladimir Mrdakovic

    2008-06-01

    Full Text Available The purpose of this study was to determine modulation of pre- activity related to different types and heights of deep jump. Sixteen male soccer players without experience in deep jumps training (the national competition; 15.0 ± 0.5yrs; weight 61.9 ± 6.1kg; height 1.77 ± 0.07m, who participated in the study, performed three types of deep jump (bounce landing, counter landing, and bounce drop jump from three different heights (40cm, 60cm, and 80cm. Surface EMG device (1000Hz was used to estimate muscle activity (maximal amplitude of EMG - AmaxEMG; integral EMG signal - iEMG of five muscles (mm.gastrocnemii, m.soleus, m.tibialis anterior, m.vastus lateralis within 150ms before touchdown. All the muscles, except m. gastrocnemius medialis, showed systematic increase in pre-activity when platform height was raised. For most of the lower extremity muscles, the most significant differences were between values of pre-activity obtained for 40 cm and 80 cm platforms. While the amount of muscle pre-activity in deep jumps from the heights above and beneath the optimal one did not differ significantly from that generated in deep jumps from the optimal drop height of 60 cm, the patterns of muscle pre-activity obtained for the heights above the optimal one did differ from those obtained for the optimal drop height. That suggests that deep jumps from the heights above the optimal one do not seem to be an adequate exercise for adjusting muscle activity for the impact. Muscle pre-activity in bounce drop jumps differed significantly from that in counter landing and bounce landing respectively, which should indicate that a higher amount of pre-activity generated during bounce drop jumps was used for performing take-offs. As this study included the subjects who were not familiar with deep jumps training, the prospective studies should reveal the results of athletes with previous experience

  10. Muscle Activation During ACL Injury Risk Movements in Young Female Athletes: A Narrative Review

    Directory of Open Access Journals (Sweden)

    Jesper Bencke

    2018-05-01

    Full Text Available Young, adolescent female athletes are at particular high risk of sustaining a non-contact anterior cruciate ligament (ACL injury during sport. Through the last decades much attention has been directed toward various anatomical and biomechanical risk factors for non-contact ACL injury, and important information have been retrieved about the influence of external loading factors on ACL injury risk during given sports-specific movements. However, much less attention has been given to the aspect of neuromuscular control during such movements and only sparse knowledge exists on the specific muscle activation patterns involved during specific risk conditions. Therefore, the aim of this narrative review was (1 to describe anatomical aspects, strength aspects and biomechanical aspects relevant for the understanding of ACL non-contact injury mechanisms in young female athletes, and (2 to review the existing literature on lower limb muscle activation in relation to risk of non-contact ACL-injury and prevention of ACL injury in young female athletes. Studies investigating muscle activity patterns associated with sports-specific risk situations were identified, comprising cohort studies, intervention studies and prospective studies. Based on the retrieved studies, clear gender-specific differences in muscle activation and coordination were identified demonstrating elevated quadriceps activity and reduced hamstring activity in young female athletes compared to their male counterparts, and suggesting young female athletes to be at elevated risk of non-contact ACL injury. Only few studies (n = 6 examined the effect of preventive exercise-based intervention protocols on lower limb muscle activation during sports-specific movements. A general trend toward enhanced hamstring activation was observed during selected injury risk situations (e.g., sidecutting and drop landings. Only a single study examined the association between muscle activation deficits and ACL

  11. Muscle Activation During ACL Injury Risk Movements in Young Female Athletes: A Narrative Review.

    Science.gov (United States)

    Bencke, Jesper; Aagaard, Per; Zebis, Mette K

    2018-01-01

    Young, adolescent female athletes are at particular high risk of sustaining a non-contact anterior cruciate ligament (ACL) injury during sport. Through the last decades much attention has been directed toward various anatomical and biomechanical risk factors for non-contact ACL injury, and important information have been retrieved about the influence of external loading factors on ACL injury risk during given sports-specific movements. However, much less attention has been given to the aspect of neuromuscular control during such movements and only sparse knowledge exists on the specific muscle activation patterns involved during specific risk conditions. Therefore, the aim of this narrative review was (1) to describe anatomical aspects, strength aspects and biomechanical aspects relevant for the understanding of ACL non-contact injury mechanisms in young female athletes, and (2) to review the existing literature on lower limb muscle activation in relation to risk of non-contact ACL-injury and prevention of ACL injury in young female athletes. Studies investigating muscle activity patterns associated with sports-specific risk situations were identified, comprising cohort studies, intervention studies and prospective studies. Based on the retrieved studies, clear gender-specific differences in muscle activation and coordination were identified demonstrating elevated quadriceps activity and reduced hamstring activity in young female athletes compared to their male counterparts, and suggesting young female athletes to be at elevated risk of non-contact ACL injury. Only few studies ( n = 6) examined the effect of preventive exercise-based intervention protocols on lower limb muscle activation during sports-specific movements. A general trend toward enhanced hamstring activation was observed during selected injury risk situations (e.g., sidecutting and drop landings). Only a single study examined the association between muscle activation deficits and ACL injury risk

  12. Ankle muscle activity modulation during single-leg stance differs between children, young adults and seniors.

    Science.gov (United States)

    Kurz, Eduard; Faude, Oliver; Roth, Ralf; Zahner, Lukas; Donath, Lars

    2018-02-01

    Incomplete maturation and aging-induced declines of the neuromuscular system affect postural control both in children and older adults and lead to high fall rates. Age-specific comparisons of the modulation of ankle muscle activation and behavioral center of pressure (COP) indices during upright stance have been rarely conducted. The objective of the present study was to quantify aging effects on a neuromuscular level. Thus, surface electromyography (SEMG) modulation and co-activity of ankle muscles during single-leg standing was compared in healthy children, young adults and seniors. Postural steadiness (velocity and mean sway frequency of COP), relative muscle activation (SEMG modulation) and co-activation of two ankle muscles (tibialis anterior, TA; soleus, SO) were examined during single-leg stance in 19 children [age, 9.7 (SD 0.5) years], 30 adults [23.3 (1.5) years] and 29 seniors [62.7 (6.1) years]. Velocity of COP in medio-lateral and anterior-posterior directions, mean sway frequency in anterior-posterior direction, relative muscle activation (TA and SO) and co-activation revealed large age effects (P  0.14). Post-hoc comparisons indicated higher COP velocities, anterior-posterior frequencies, relative SO activation and co-activation in children and seniors when compared with adults. Relative TA activation was higher in children and adults compared with seniors (P seniors seems to be counteracted with higher TA/SO co-activity and SO modulation. However, TA modulation is higher in children and adults, whereas seniors' TA modulation capacity is diminished. An aging-induced decline of TA motor units might account for deteriorations of TA modulation in seniors.

  13. Muscle activation in the loaded free barbell squat: a brief review.

    Science.gov (United States)

    Clark, Dave R; Lambert, Mike I; Hunter, Angus M

    2012-04-01

    The purpose of this article was to review a series of studies (n = 18) where muscle activation in the free barbell back squat was measured and discussed. The loaded barbell squat is widely used and central to many strength training programs. It is a functional and safe exercise that is obviously transferable to many movements in sports and life. Hence, a large and growing body of research has been published on various aspects of the squat. Training studies have measured the impact of barbell squat loading schemes on selected training adaptations including maximal strength and power changes in the squat. Squat exercise training adaptations and their impact on a variety of performance parameters, in particular countermovement jump, acceleration, and running speed, have also been reported. Furthermore, studies have reported on the muscle activation of the lower limb resulting from variations of squat depth, foot placement, training status, and training intensity. There have also been studies on the impact of squatting with or without a weight belt on trunk muscle activation (TMA). More recently, studies have reported on the effect of instability on TMA and squat performance. Research has also shown that muscle activation of the prime movers in the squat exercise increases with an increase in the external load. Also common variations such as stance width, hip rotation, and front squat do not significantly affect muscle activation. However, despite many studies, this information has not been consolidated, resulting in a lack of consensus about how the information can be applied. Therefore, the purpose of this review was to examine studies that reported muscle activation measured by electromyography in the free barbell back squat with the goal of clarifying the understanding of how the exercise can be applied.

  14. Muscle activity during backward and forward running with body weight support.

    Science.gov (United States)

    Masumoto, Kenji; Soucy, Michael T; Bailey, Joshua P; Mercer, John A

    2017-10-01

    We investigated muscle activity during backward (BR) and forward (FR) running with body weight support (BWS). Ten participants completed BR and FR on a lower body positive pressure treadmill while selecting a preferred speed (PS) for different BWS conditions (0%, 20%, 40%, 60%, and 80%BWS). Muscle activity from the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and gastrocnemius (GA), rating of perceived exertion (RPE), preferred stride frequency (PSF), and PS were measured. Magnitude of muscle activity (BF, TA, and GA), RPE, PSF, and PS were not influenced by the interaction of direction and BWS (P>0.05). BF, TA, and GA were not different between directions (P>0.05) but were different between BWS conditions (P<0.01). RF was influenced by the interaction of direction and BWS (P<0.01). RF, BF, TA, and GA during BR were lower with increasing BWS. RF during BR was 59-86% higher than that of FR within BWS condition. RPE was lower with increasing BWS (P<0.001), regardless of direction of locomotion. PSF was lower and PS was higher during BR and FR with increasing BWS (both P<0.001). PSF during BR was 6-9% higher than that of FR. PS during BR was 24-31% lower than that of FR. These observations demonstrate that a change in BWS influences magnitude of muscle activity, PS, PSF, and RPE for both BR and FR. However, a change in direction of locomotion may not influence magnitude of muscle activity or RPE during running for a given BWS, even though muscle activity pattern, PS, and PSF were different between BR and FR. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Changes in muscle activation following balance and technique training and a season of Australian football.

    Science.gov (United States)

    Donnelly, C J; Elliott, B C; Doyle, T L A; Finch, C F; Dempsey, A R; Lloyd, D G

    2015-05-01

    Determine if balance and technique training implemented adjunct to 1001 male Australian football players' training influenced the activation/strength of the muscles crossing the knee during pre-planned and unplanned sidestepping. Randomized Control Trial. Each Australian football player participated in either 28 weeks of balance and technique training or 'sham' training. Twenty-eight Australian football players (balance and technique training, n=12; 'sham' training, n=16) completed biomechanical testing pre-to-post training. Peak knee moments and directed co-contraction ratios in three degrees of freedom, as well as total muscle activation were calculated during pre-planned and unplanned sidestepping. No significant differences in muscle activation/strength were observed between the 'sham' training and balance and technique training groups. Following a season of Australian football, knee extensor (p=0.023) and semimembranosus (p=0.006) muscle activation increased during both pre-planned sidestepping and unplanned sidestepping. Following a season of Australian football, total muscle activation was 30% lower and peak valgus knee moments 80% greater (p=0.022) during unplanned sidestepping when compared with pre-planned sidestepping. When implemented in a community level training environment, balance and technique training was not effective in changing the activation of the muscles crossing the knee during sidestepping. Following a season of Australian football, players are better able to support both frontal and sagittal plane knee moments. When compared to pre-planned sidestepping, Australian football players may be at increased risk of anterior cruciate ligament injury during unplanned sidestepping in the latter half of an Australian football season. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  16. The relationship between skeletal muscle mitochondrial citrate synthase activity and whole body oxygen uptake adaptations in response to exercise training

    DEFF Research Database (Denmark)

    Vigelsø Hansen, Andreas; Andersen, Nynne Bjerre; Dela, Flemming

    2014-01-01

    Citrate synthase (CS) activity is a validated biomarker for mitochondrial density in skeletal muscle. CS activity is also used as a biochemical marker of the skeletal muscle oxidative adaptation to a training intervention, and a relationship between changes in whole body aerobic capacity and chan......Citrate synthase (CS) activity is a validated biomarker for mitochondrial density in skeletal muscle. CS activity is also used as a biochemical marker of the skeletal muscle oxidative adaptation to a training intervention, and a relationship between changes in whole body aerobic capacity...

  17. Histological study of human sublingual gland with special emphasis on intercalated and striated ducts

    International Nuclear Information System (INIS)

    Rana, R.; Minhas, L.A.; Mubarik, A.

    2012-01-01

    Objective: To study the histomorphological characteristics of human sublingual gland, specially of intercalated and striated ducts. Study design: Descriptive study Place and duration of study: Army Medical College from Jan 2002 to Dec 2002 Materials and methods: Fifteen sublingual glands (right and left) from postmortem cases were obtained from District Headquarter Hospital Rawalpindi, within twelve hours of death. Five micrometer thick sections were made and stained with Haematoxylin and Eosin (H and E). Morphology of intercalated and striated ducts was studied and their number was counted. Results: The mean number of intercalated ducts in the right gland 'a'and 'b' parts, and in the left gland 'a' and 'b' parts was 1.45+-0.14, 1.39+-.009, 1.31+-0.11 and 1.18+-0.10 respectively. The mean diameter of intercalated ducts in the same parts was 19.76+-0.44 micro m, 20.6+-0.53 micro m, 20.34+-0.49 micro m and 19.84+-0.98 micro m respectively. The mean number of striated ducts in the right gland ''a'' and ''b'' parts, and in the left gland ''a'' and ''b'' parts was 0.55+-.008, 0.57+-.008, 0.80+-0.14 and 0.80+-0.14 while mean diameter of striated ducts in the right gland ''a'' and ''b'' parts, and in the left gland ''a'' and ''b'' parts was 49.90+-4.70 micro m, 53.23+-2.50 micro m, 61.68+-3.93 micro m and 57.73+-2.85 micro m respectively. Conclusion: The difference between the mean number and diameter of the ducts of right and left glands was statistically insignificant. (author)

  18. Shoulder girdle muscle activity and fatigue in traditional and improved design carpet weaving workstations.

    Science.gov (United States)

    Allahyari, Teimour; Mortazavi, Narges; Khalkhali, Hamid Reza; Sanjari, Mohammad Ali

    2016-01-01

    Work-related musculoskeletal disorders in the neck and shoulder regions are common among carpet weavers. Working for prolonged hours in a static and awkward posture could result in an increased muscle activity and may lead to musculoskeletal disorders. Ergonomic workstation improvements can reduce muscle fatigue and the risk of musculoskeletal disorders. The aim of this study is to assess and to compare upper trapezius and middle deltoid muscle activity in 2 traditional and improved design carpet weaving workstations. These 2 workstations were simulated in a laboratory and 12 women carpet weavers worked for 3 h. Electromyography (EMG) signals were recorded during work in bilateral upper trapezius and bilateral middle deltoid. The root mean square (RMS) and median frequency (MF) values were calculated and used to assess muscle load and fatigue. Repeated measure ANOVA was performed to assess the effect of independent variables on muscular activity and fatigue. The participants were asked to report shoulder region fatigue on the Borg's Category-Ratio scale (Borg CR-10). Root mean square values in workstation A are significantly higher than in workstation B. Furthermore, EMG amplitude was higher in bilateral trapezius than in bilateral deltoid. However, muscle fatigue was not observed in any of the workstations. The results of the study revealed that muscle load in a traditional workstation was high, but fatigue was not observed. Further studies investigating other muscles involved in carpet weaving tasks are recommended. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  19. Effect of fullerene C(60 on ATPase activity and superprecipitation of skeletal muscle actomyosin

    Directory of Open Access Journals (Sweden)

    K. S. Andreichenko

    2013-04-01

    Full Text Available Creation of new biocompatible nanomaterials, which can exhibit the specific biological effects, is an important complex problem that requires the use of last accomplishments of biotechnology. The effect of pristine water-soluble fullerene C60 on ATPase activity and superprecipitation reaction of rabbit skeletal muscle natural actomyosin has been revealed, namely an increase of actomyosin superprecipitation and Мg2+, Са2+– and K+-ATPase activity by fullerene was investigated. We conclude that this finding offers a real possibility for the regulation of contraction-relaxation of skeletal muscle with fullerene C60.

  20. Regulation of pH in human skeletal muscle: adaptations to physical activity

    DEFF Research Database (Denmark)

    Juel, C

    2008-01-01

    -transport) and describes the contribution of each transport system in pH regulation at rest and during muscle activity. It is reported that the mechanisms involved in pH regulation can undergo adaptational changes in association with physical activity and that these changes are of functional importance....... resonance technique to exercise experiments including blood sampling and muscle biopsies. The present review characterizes the cellular buffering system as well as the most important membrane transport systems involved (Na(+)/H(+) exchange, Na-bicarbonate co-transport and lactate/H(+) co...

  1. Active stretching for lower extremity muscle tightness in pediatric patients with lumbar spondylolysis.

    Science.gov (United States)

    Sato, Masahiro; Mase, Yasuyoshi; Sairyo, Koichi

    2017-01-01

    It was reported that hamstring muscle tightness may increase mechanical loading on the lumbar spine. Therefore, we attempt to decrease tightness in the leg muscles in pediatric patients. Forty-six pediatric patients with spondylolysis underwent rehabilitation. We applied active stretching to the hamstrings, quadriceps, and triceps surae. Tightness in each muscle was graded as good, fair, or poor. We educated each patient on how to perform active stretching at home. They were re-evaluated for muscle tightness 2 months later. Tightness at baseline and after 2 months was as follows: for the hamstrings, good in 3 patients, fair in 9, and poor in 34 and significant improved after 2 months (p<0.05), with improvement by least 1 grade seen in 86% of patients with fair or poor at baseline; for the quadriceps, 7, 3, and 30 patients had good, fair and poor, with significant improvements in 72% (p<0.05). For the triceps surae, 6, 3 and 10 patients had good, fair and poor, which improved significantly (p<0.05). Home-based active stretching was effective for relieving muscle tightness in the leg in a pediatric population. Adolescent athletes should perform such exercise to maintain flexibility and prevent lumbar disorders. J. Med. Invest. 64: 136-139, February, 2017.

  2. The effect of material characteristics of shoe soles on muscle activation and energy aspects during running.

    Science.gov (United States)

    Nigg, B M; Stefanyshyn, D; Cole, G; Stergiou, P; Miller, J

    2003-04-01

    The purposes of this study were (a) to determine group and individual differences in oxygen consumption during heel-toe running and (b) to quantify the differences in EMG activity for selected muscle groups of the lower extremities when running in shoes with different mechanical heel characteristics. Twenty male runners performed heel-toe running using two shoe conditions, one with a mainly elastic and a visco-elastic heel. Oxygen consumption was quantified during steady state runs of 6 min duration, running slightly above the aerobic threshold providing four pairs of oxygen consumption results for comparison. Muscle activity was quantified using bipolar surface EMG measurements from the tibialis anterior, medial gastrocnemius, vastus medialis and the hamstrings muscle groups. EMG data were sampled for 5 s every minute for the 6 min providing 30 trials. EMG data were compared for the different conditions using an ANOVA (alpha=0.05). The findings of this study showed that changes in the heel material characteristics of running shoes were associated with (a) subject specific changes in oxygen consumption and (b) subject and muscle specific changes in the intensities of muscle activation before heel strike in the lower extremities. It is suggested that further study of these phenomena will help understand many aspects of human locomotion, including work, performance, fatigue and possible injuries.

  3. Comparing electro- and mechano-myographic muscle activation patterns in self-paced pediatric gait.

    Science.gov (United States)

    Plewa, Katherine; Samadani, Ali; Chau, Tom

    2017-10-01

    Electromyography (EMG) is the standard modality for measuring muscle activity. However, the convenience and availability of low-cost accelerometer-based wearables makes mechanomyography (MMG) an increasingly attractive alternative modality for clinical applications. Literature to date has demonstrated a strong association between EMG and MMG temporal alignment in isometric and isokinetic contractions. However, the EMG-MMG relationship has not been studied in gait. In this study, the concurrence of EMG- and MMG-detected contractions in the tibialis anterior, lateral gastrocnemius, vastus lateralis, and biceps femoris muscles were investigated in children during self-paced gait. Furthermore, the distribution of signal power over the gait cycle was statistically compared between EMG-MMG modalities. With EMG as the reference, muscular contractions were detected based on MMG with balanced accuracies between 88 and 94% for all muscles except the gastrocnemius. MMG signal power differed from that of EMG during certain phases of the gait cycle in all muscles except the biceps femoris. These timing and power distribution differences between the two modalities may in part be related to muscle fascicle length changes that are unique to muscle motion during gait. Our findings suggest that the relationship between EMG and MMG appears to be more complex during gait than in isometric and isokinetic contractions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Stretching of Active Muscle Elicits Chronic Changes in Multiple Strain Risk Factors.

    Science.gov (United States)

    Kay, Anthony David; Richmond, Dominic; Talbot, Chris; Mina, Minas; Baross, Anthony William; Blazevich, Anthony John

    2016-07-01

    The muscle stretch intensity imposed during "flexibility" training influences the magnitude of joint range of motion (ROM) adaptation. Thus, stretching while the muscle is voluntarily activated was hypothesized to provide a greater stimulus than passive stretching. The effect of a 6-wk program of stretch imposed on an isometrically contracting muscle (i.e., qualitatively similar to isokinetic eccentric training) on muscle-tendon mechanics was therefore studied in 13 healthy human volunteers. Before and after the training program, dorsiflexion ROM, passive joint moment, and maximal isometric plantarflexor moment were recorded on an isokinetic dynamometer. Simultaneous real-time motion analysis and ultrasound imaging recorded gastrocnemius medialis muscle and Achilles tendon elongation. Training was performed twice weekly and consisted of five sets of 12 maximal isokinetic eccentric contractions at 10°·s. Significant increases (P tendon stiffness) was detected (-1.5%, P > 0.05), a significant increase in tendon stiffness (31.2%, P tendon stiffness simultaneous with significant increases in tendon stiffness and decreases in passive muscle stiffness indicates that tissue-specific effects were elicited.

  5. Adipogenic Differentiation of Muscle Derived Cells is Repressed by Inhibition of GSK-3 Activity

    Directory of Open Access Journals (Sweden)

    Zoe Redshaw

    2018-06-01

    Full Text Available Intramuscular fat is important in large animal livestock species in regard to meat quality and in humans is of clinical significance in particular in relation to insulin resistance. The canonical Wnt signalling pathway has been implicated at a whole body level in regulating relative levels of adiposity versus lean body mass. Previously we have shown that pig muscle cells can undergo adipogenic differentiation to a degree that is dependent upon the specific muscle source. In this work we examine the role of the canonical Wnt pathway which acts through inactivation of glycogen synthase kinase-3 (GSK-3 in the regulation of adipogenic differentiation in muscle cells derived from the pig semimembranosus muscle.The application of lithium chloride to muscle derived cells significantly increased the phosphorylation of GSK-3β and thus inhibited its activity thus mimicking Wnt signaling. This was associated with a significant decrease in the expression of the adipogenic transcription factor PPARγ and an almost complete inhibition of adipogenesis in the cells. The data also suggest that GSK-3α plays, at most, a small role in this process.Studies in vivo have suggested that the Wnt pathway is a major regulator of whole body adiposity. In this study we have shown that the ability of cells derived from porcine skeletal muscle to differentiate along an adipogenic lineage, in vitro, is severely impaired by mimicking the action of this pathway. This was done by inactivation of GSK-3β by the use of Lithium Chloride.

  6. Activation of the hip adductor muscles varies during a simulated weight-bearing task.

    Science.gov (United States)

    Hides, Julie A; Beall, Paula; Franettovich Smith, Melinda M; Stanton, Warren; Miokovic, Tanja; Richardson, Carolyn

    2016-01-01

    To investigate the pattern of muscle activation of the individual hip adductor muscles using a standardised simulated unilateral weight-bearing task. A repeated measures design. Laboratory. 20 healthy individuals (11 females, 9 males) participated in the study. Age ranged from 20 to 25 years. Surface electromyography recordings from adductor magnus and adductor longus muscles were taken at levels representing 10-50% of body weight during a simulated weight-bearing task. Electromyography (EMG) data were normalised to maximal voluntary isometric contraction. The adductor magnus was recruited at significantly higher levels than the adductor longus muscle during a simulated weight-bearing task performed across 10-50% of body weight (p bearing task. This information should be considered when selecting exercises for management and prevention of groin strains. Closed chain exercises with weight-bearing through the lower limb are more likely to recruit the adductor magnus muscle over the adductor longus muscle. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Myofibril ATPase activity of cardiac and skeletal muscle of exhaustively exercised rats.

    Science.gov (United States)

    Belcastro, A N; Turcotte, R; Rossiter, M; Secord, D; Maybank, P E

    1984-01-01

    The activation characteristics of Mg-ATP and Ca2+ on cardiac and skeletal muscle myofibril ATPase activity were studied in rats following a run to exhaustion. In addition, the effect of varying ionic strength was determined on skeletal muscle from exhausted animals. The exhausted group (E) ran at a speed of 25 m min-1 with an 8% incline. Myofibril ATPase activities for control (C) and E were determined with 1, 3 and 5 mM Mg-ATP and 1 and 10 microM Ca2+ at pH 7.0 and 30 degrees C. For control skeletal muscle, at 1 and 10 microM Ca2+, there was an increase in ATPase activity from 1 to 5 mM Mg-ATP (P less than 0.05). For E animals the myofibril ATPase activities at 10 microM Ca2+ and all Mg-ATP concentrations were similar to C (P greater than 0.05). At 1.0 microM Ca2+ and all Mg-ATP concentrations were similar to C (P greater than 0.05). At 1.0 microM Ca2+ the activities at 3 and 5 mM Mg-ATP were greater for the E animals (P less than 0.05). Increasing KCl concentrations resulted in greater inhibition for E animals. With cardiac muscle, the myofibril ATPase activities at 1.0 microM free Ca2+ were lower for E at all Mg-ATP levels (P less than 0.05). In contrast, at 10 microM Ca2+, the E group exhibited an elevated myofibril ATPase activity. The results indicate that Mg-ATP and Ca2+ activation of cardiac and skeletal muscle myofibril ATPase is altered with exhaustive exercise.

  8. Cycle Training Increased GLUT4 and Activation of mTOR in Fast Twitch Muscle Fibers

    Science.gov (United States)

    Stuart, Charles A.; Howell, Mary E.A.; Baker, Jonathan D.; Dykes, Rhesa J.; Duffourc, Michelle M.; Ramsey, Michael W.; Stone, Michael H.

    2009-01-01

    Purpose To determine if cycle training of sedentary subjects would increase the expression of the principle muscle glucose transporters, six volunteers completed six weeks of progressively increasing intensity stationary cycle cycling. Methods In vastus lateralis muscle biopsies, changes in expression of GLUT1, GLUT4, GLUT5, and GLUT12 were compared using quantitative immunoblots with specific protein standards. Regulatory pathway components were evaluated by immunoblots of muscle homogenates and immunohistochemistry of microscopic sections. Results GLUT1 was unchanged, GLUT4 increased 66%, GLUT12 increased 104%, and GLUT5 decreased 72%. A mitochondrial marker (cytochrome c) and regulators of mitochondrial biogenesis (PGC-1α and phospho-AMPK) were unchanged, but the muscle hypertrophy pathway component, phospho-mTOR increased 83% after the exercise program. In baseline biopsies, GLUT4 by immunohistochemical techniques was 37% greater in Type I (slow twitch, red) muscle fibers, but the exercise training increased GLUT4 expression in Type II (fast twitch, white) fibers by 50%, achieving parity with the Type I fibers. Baseline phospho-mTOR expression was 50% higher in Type II fibers and increased more in Type II fibers (62%) with training, but also increased in Type I fibers (34%). Conclusion Progressive intensity stationary cycle training of previously sedentary subjects increased muscle insulin-responsive glucose transporters (GLUT4 and GLUT12) and decreased the fructose transporter (GLUT5). The increase in GLUT4 occurred primarily in Type II muscle fibers and this coincided with activation of the mTOR muscle hypertrophy pathway. There was little impact on Type I fiber GLUT4 expression and no evidence of change in mitochondrial biogenesis. PMID:20010125

  9. [Fall risk assessment and knee extensor muscle activity in elderly people].

    Science.gov (United States)

    Oya, Yukiko; Nakamura, Masumi; Tabata, Emi; Morizono, Ryo; Mori, Sachiko; Kimuro, Yukari; Horikawa, Etsuo

    2008-05-01

    The purpose of this study was to analyze relationships between the history of falls, tripping, sway, and knee extensor muscle strengths as a tool for fall risk assessment in elderly people. We examined effective fall prevention measures. We investigated 102 elderly volunteers in the community. The subjects were classified according to history of falls, tripping, sway and 5 performance tests conducted to assess fall risk including Timed up-and-go test (TUG), Functional Reach test (FR), Hand grip and Reaction time (RT). In addition, the time serial data of the knee extensor muscle strength were acquired using a hand-held dynamometer. In comparison to the non-faller group, the faller group showed a significantly higher incident rate of tripping and sway. A frequency analysis using the Maximum Entropy Method revealed that the fallers group showed lower peak frequency (p=0.025). Also, the slope of the logarithmical spectrum was less steep in the fallers group (p=0.035). Also results from analysis of the peak force latency from the beginning of measurement to 50%, 80%, and 100% muscle strength, also showed that the faller group took more time for maximal voluntary contraction. The frequency analysis of the time series date of peak force latency of knee extensor muscle strength revealed that the muscle activity differs in faller compared to non-fallers. This study suggested that knee extensor muscle isometric performance could possibly be used as a new tool for fall risk assessment. We concluded that exercises to raise maximal muscle strength and muscle response speed are useful for the prevention of falls.

  10. Effect of voluntary vs. artificial activation on the relationship of muscle torque to speed

    Science.gov (United States)

    Dudley, Gary A.; Harris, Robert T.; Duvoisin, Marc R.; Hather, Bruce M.; Buchanan, Paul

    1990-01-01

    The suggestion by Phillips and Petrofsky (1980) and Wickiewicz et al. (1984) that artificial activation of the knee extensor muscles should result in greater relative changes in torque than those evident with maximal voluntary activation is examined by investigating the speed-torque relationship of the right knee extensor muscle group in eight human subjects in whom activation was achieved by 'maximal' voluntary effort or by electrical stimulation. Torque was measured at a specific knee angle during isokinetic concentric or eccentric actions at velocities between 0.17 and 3.66 rad/s and during isometric actions. It is shown that, with artificial activation, the relative changes in both eccentric and concentric torque were greater as the speed increased; the speed-torque relationship was independed of the extent of activation and was similar to that of an isolated muscle. On the other hand, activation by the central nervous system during maximal effort depended on the speed and the type of muscle action performed.

  11. Shoulder muscle activation during stable and suspended push-ups at different heights in healthy subjects.

    Science.gov (United States)

    Borreani, Sebastien; Calatayud, Joaquin; Colado, Juan C; Tella, Victor; Moya-Nájera, Diego; Martin, Fernando; Rogers, Michael E

    2015-08-01

    To analyze shoulder muscle activation when performing push-ups under different stability conditions and heights. Comparative study by repeated measures. Valencia University laboratory. 29 healthy males participated. Subjects performed 3 push-ups each with their hands at 2 different heights (10 vs. 65 cm) under stable conditions and using a suspension device. Push-up speed was controlled and the testing order was randomized. The average amplitudes of the electromyographic root mean square of the long head of the triceps brachii (TRICEP), upper trapezius (TRAPS), anterior deltoid (DELT) and clavicular pectoralis (PEC) were recorded. The electromyographic signals were normalized to the maximum voluntary isometric contraction (MVIC). Suspended push-ups at 10 cm resulted in greater activation in the TRICEP (17.14 ± 1.31 %MVIC vs. 37.03 ± 1.80 %MVIC) and TRAPS (5.83 ± 0.58 %MVIC vs. 14.69 ± 1.91 %MVIC) than those performed on the floor. For DELT and PEC similar or higher activation was found performing the push-ups on the floor, respectively. Height determines different muscle activation patterns. Stable push-ups elicit similar PEC and higher DELT muscle activation, being greater at 10 cm; whereas suspended push-ups elicit greater TRAPS and TRICEP muscle activation, being greater at 65 cm. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Investigation of the Effect of Neck Muscle Active Force on Whiplash Injury of the Cervical Spine

    Directory of Open Access Journals (Sweden)

    Yu Yan

    2018-01-01

    Full Text Available The objective of the present study is to investigate the influence of neck muscle activation on whiplash neck injury of the occupants of a passenger vehicle under different severities of frontal and rear-end impact collisions. The finite element (FE model has been used as a versatile tool to simulate and understand the whiplash injury mechanism for occupant injury prevention. However, whiplash injuries and injury mechanisms have rarely been investigated in connection with neck active muscle forces, which restricts the complete reappearance and understanding of the injury mechanism. In this manuscript, a mixed FE human model in a sitting posture with an active head-neck was developed. The response of the cervical spine under frontal and rear-end collision conditions was then studied using the FE model with and without neck muscle activation. The effect of the neck muscle activation on the whiplash injury was studied based on the results of the FE simulations. The results indicated that the neck active force influenced the head-neck dynamic response and whiplash injury during a collision, especially in a low-speed collision.

  13. Correction tool for Active Shape Model based lumbar muscle segmentation.

    Science.gov (United States)

    Valenzuela, Waldo; Ferguson, Stephen J; Ignasiak, Dominika; Diserens, Gaelle; Vermathen, Peter; Boesch, Chris; Reyes, Mauricio

    2015-08-01

    In the clinical environment, accuracy and speed of the image segmentation process plays a key role in the analysis of pathological regions. Despite advances in anatomic image segmentation, time-effective correction tools are commonly needed to improve segmentation results. Therefore, these tools must provide faster corrections with a low number of interactions, and a user-independent solution. In this work we present a new interactive correction method for correcting the image segmentation. Given an initial segmentation and the original image, our tool provides a 2D/3D environment, that enables 3D shape correction through simple 2D interactions. Our scheme is based on direct manipulation of free form deformation adapted to a 2D environment. This approach enables an intuitive and natural correction of 3D segmentation results. The developed method has been implemented into a software tool and has been evaluated for the task of lumbar muscle segmentation from Magnetic Resonance Images. Experimental results show that full segmentation correction could be performed within an average correction time of 6±4 minutes and an average of 68±37 number of interactions, while maintaining the quality of the final segmentation result within an average Dice coefficient of 0.92±0.03.

  14. SELECTIVE ACTIVATION OF THE RECTUS ABDOMINIS MUSCLE DURING LOW-INTENSITY AND FATIGUING TASKS

    Directory of Open Access Journals (Sweden)

    Paulo H. Marchetti

    2011-06-01

    Full Text Available In order to understand the potential selective activation of the rectus abdominis muscle, we conducted two experiments. In the first, subjects performed two controlled isometric exercises: the curl up (supine trunk raise and the leg raise (supine bent leg raise at low intensity (in which only a few motor units are recruited. In the second experiment, subjects performed the same exercises, but they were required to maintain a certain force level in order to induce fatigue. We recorded the electromyographic (EMG activities of the lower and upper portions of the rectus abdominis muscle during the exercises and used spatial-temporal and frequency analyses to describe muscle activation patterns. At low-intensity contractions, the ratio between the EMG intensities of the upper and lower portions during the curl up exercise was significantly larger than during the leg raise exercise (p = 0.02. A cross-correlation analysis indicated that the signals of the abdominal portions were related to each other and this relation did not differ between the tasks (p = 0.12. In the fatiguing condition, fatigue for the upper portion was higher than for the lower portion during the curl up exercise (p = 0.008. We conclude that different exercises evoked, to a certain degree, individualized activation of each part of the rectus abdominis muscle, but different portions of the rectus abdominis muscle contributed to the same task, acting like a functional unit. These results corroborate the relevance of varying exercise to modify activation patterns of the rectus abdominis muscle

  15. Baroreflex and neurovascular responses to skeletal muscle mechanoreflex activation in humans: an exercise in integrative physiology.

    Science.gov (United States)

    Drew, Rachel C

    2017-12-01

    Cardiovascular adjustments to exercise resulting in increased blood pressure (BP) and heart rate (HR) occur in response to activation of several neural mechanisms: the exercise pressor reflex, central command, and the arterial baroreflex. Neural inputs from these feedback and feedforward mechanisms integrate in the cardiovascular control centers in the brain stem and modulate sympathetic and parasympathetic neural outflow, resulting in the increased BP and HR observed during exercise. Another specific consequence of the central neural integration of these inputs during exercise is increased sympathetic neural outflow directed to the kidneys, causing renal vasoconstriction, a key reflex mechanism involved in blood flow redistribution during increased skeletal muscle work. Studies in humans have shown that muscle mechanoreflex activation inhibits cardiac vagal outflow, decreasing the sensitivity of baroreflex control of HR. Metabolite sensitization of muscle mechanoreceptors can lead to reduced sensitivity of baroreflex control of HR, with thromboxane being one of the metabolites involved, via greater inhibition of cardiac vagal outflow without affecting baroreflex control of BP or baroreflex resetting. Muscle mechanoreflex activation appears to play a predominant role in causing renal vasoconstriction, both in isolation and in the presence of local metabolites. Limited investigations in older adults and patients with cardiovascular-related disease have provided some insight into how the influence of muscle mechanoreflex activation on baroreflex function and renal vasoconstriction is altered in these populations. However, future research is warranted to better elucidate the specific effect of muscle mechanoreflex activation on baroreflex and neurovascular responses with aging and cardiovascular-related disease. Copyright © 2017 the American Physiological Society.

  16. Patterning Muscles Using Organizers: Larval Muscle Templates and Adult Myoblasts Actively Interact to Pattern the Dorsal Longitudinal Flight Muscles of Drosophila

    Science.gov (United States)

    Roy, Sudipto; VijayRaghavan, K.

    1998-01-01

    Pattern formation in muscle development is often mediated by special cells called muscle organizers. During metamorphosis in Drosophila, a set of larval muscles function as organizers and provide scaffolding for the development of the dorsal longitudinal flight muscles. These organizers undergo defined morphological changes and dramatically split into templates as adult fibers differentiate during pupation. We have investigated the cellular mechanisms involved in the use of larval fibers as templates. Using molecular markers that label myoblasts and the larval muscles themselves, we show that splitting of the larval muscles is concomitant with invasion by imaginal myoblasts and the onset of differentiation. We show that the Erect wing protein, an early marker of muscle differentiation, is not only expressed in myoblasts just before and after fusion, but also in remnant larval nuclei during muscle differentiation. We also show that interaction between imaginal myoblasts and larval muscles is necessary for transformation of the larval fibers. In the absence of imaginal myoblasts, the earliest steps in metamorphosis, such as the escape of larval muscles from histolysis and changes in their innervation, are normal. However, subsequent events, such as the splitting of these muscles, fail to progress. Finally, we show that in a mutant combination, null for Erect wing function in the mesoderm, the splitting of the larval muscles is aborted. These studies provide a genetic and molecular handle for the understanding of mechanisms underlying the use of muscle organizers in muscle patterning. Since the use of such organizers is a common theme in myogenesis in several organisms, it is likely that many of the processes that we describe are conserved. PMID:9606206

  17. Activity of masticatory muscles in subjects with different orofacial pain conditions.

    Science.gov (United States)

    Bodéré, Céline; Téa, Say Hack; Giroux-Metges, Marie Agnes; Woda, Alain

    2005-07-01

    The existence of a pathophysiological link between tonic muscle activity and chronic muscle pain is still being debated. The purpose of this retrospective, controlled study was to evaluate the electromyographic (EMG) activity of masticatory muscles in subjects with different orofacial pain conditions. The temporal and masseter EMG activity at rest and the masseteric reflex were recorded in two groups of patients with either myofascial pain (n=33) or neuropathic pain (n=20), one group of non-pain patients with disc derangement disorders (n=27) and one control group of healthy, asymptomatic subjects (n=32). The EMG activities of both muscles at rest were significantly higher in the pain patient groups compared to the asymptomatic control group. There was no significant difference between the disc derangement disorder group and the control group. The masseteric reflex amplitude was reduced in all patient groups when compared with the control group. In pain patient groups, the increased EMG activity at rest and the reduction of the masseteric reflex amplitude were equally distributed in the pain and non-pain sides. In addition, subjects presenting with bilateral pain showed higher EMG activity at rest than those with unilateral pain. These results suggested that the modulation of muscle activity was not the direct consequence of a peripheral nociceptive mechanism and seemed to indicate that a central mechanism was at work. The contrast between the increased EMG activity at rest and the reduction of the masseteric reflex amplitude may reflect modulations of motoneurones that differed in tonic versus phasic conditions in chronic pain patients.

  18. Commercial golf glove effects on golf performance and forearm muscle activity.

    Science.gov (United States)

    Sorbie, Graeme G; Darroch, Paul; Grace, Fergal M; Gu, Yaodong; Baker, Julien S; Ugbolue, Ukadike C

    2017-01-01

    The study aimed to determine whether or not commercial golf gloves influence performance variables and forearm muscle activity during golf play. Fifteen golfers participated in the laboratory based study, each performing 8 golf swings with a Driver and 7-iron whilst wearing a glove and 8 without wearing the glove. Club head speed, ball speed and absolute carry distance performance variables were calculated. Surface electromyography was recorded from the flexor digitorum superficialis and extensor carpi radialis brevis on both forearm muscles. Club head speed, ball speed and absolute carry distance was significantly higher when using the Driver with the glove in comparison to the Driver without the glove (p < 0.05). No significant differences were evident when using the 7-iron and no significant differences were displayed in muscle activity in either of the conditions. Findings from this study suggest that driving performance is improved when wearing a glove.

  19. Ankle torque steadiness is related to muscle activation variability and co-activation in children with cerebral palsy

    DEFF Research Database (Denmark)

    Bandholm, Thomas; Rose, Martin; Sløk, Rikke

    2009-01-01

    The aims of this study were to: (1) investigate the significance of muscle activation variability and coactivation for the ability to perform steady submaximal ankle torque (torque steadiness) in healthy children and those with cerebral palsy (CP), and (2) assess ankle function during isometric...... contractions in those children. Fourteen children with CP who walked with equinus foot deformity and 14 healthy (control) children performed maximal and steady submaximal ankle dorsi- and plantarflexions. Dorsiflexion torque steadiness was related to agonist and antagonist muscle activation variability as well...

  20. Developmental changes in the activation properties and ultrastructure of fast- and slow-twitch muscles from fetal sheep.

    Science.gov (United States)

    West, J M; Barclay, C J; Luff, A R; Walker, D W

    1999-04-01

    At early stages of muscle development, skeletal muscles contract and relax slowly, regardless of whether they are destined to become fast- or slow-twitch. In this study, we have characterised the activation profiles of developing fast- and slow-twitch muscles from a precocial species, the sheep, to determine if the activation profiles of the muscles are characteristically slow when both the fast- and slow-twitch muscles have slow isometric contraction profiles. Single skinned muscle fibres from the fast-twitch flexor digitorum longus (FDL) and slow-twitch soleus muscles from fetal (gestational ages 70, 90, 120 and 140 days; term 147 days) and neonatal (8 weeks old) sheep were used to determine the isometric force-pCa (pCa = -log10[Ca2+]) and force-pSr relations during development. Fast-twitch mammalian muscles generally have a greatly different sensitivity to Ca2+ and Sr2+ whereas slow-twitch muscles have a similar sensitivity to these divalent cations. At all ages studied, the force-pCa and force-pSr relations of the FDL muscle were widely separated. The mean separation of the mid-point of the curves (pCa50-pSr50) was approximately 1.1. This is typical of adult fast-twitch muscle. The force-pCa and force-pSr curves for soleus muscle were also widely separated at 70 and 90 days gestation (pCa50-pSr50 approximately 0.75); between 90 days and 140 days this separation decreased significantly to approximately 0.2. This leads to a paradoxical situation whereby at early stages of muscle development the fast muscles have contraction dynamics of slow muscles but the slow muscles have activation profiles more characteristic of fast muscles. The time course for development of the FDL and soleus is different, based on sarcomere structure with the soleus muscle developing clearly defined sarcomere structure earlier in gestation than the FDL. At 70 days gestation the FDL muscle had no clearly defined sarcomeres. Force (N cm-2) increased almost linearly between 70 and 140 days

  1. Role of PARP activity in lung cancer-induced cachexia: Effects on muscle oxidative stress, proteolysis, anabolic markers, and phenotype.

    Science.gov (United States)

    Chacon-Cabrera, Alba; Mateu-Jimenez, Mercè; Langohr, Klaus; Fermoselle, Clara; García-Arumí, Elena; Andreu, Antoni L; Yelamos, Jose; Barreiro, Esther

    2017-12-01

    Strategies to treat cachexia are still at its infancy. Enhanced muscle protein breakdown and ubiquitin-proteasome system are common features of cachexia associated with chronic conditions including lung cancer (LC). Poly(ADP-ribose) polymerases (PARP), which play a major role in chromatin structure regulation, also underlie maintenance of muscle metabolism and body composition. We hypothesized that protein catabolism, proteolytic markers, muscle fiber phenotype, and muscle anabolism may improve in respiratory and limb muscles of LC-cachectic Parp-1-deficient (Parp-1 -/- ) and Parp-2 -/- mice. In diaphragm and gastrocnemius of LC (LP07 adenocarcinoma) bearing mice (wild type, Parp-1 -/- , and Parp-2 -/- ), PARP activity (ADP-ribose polymers, pADPr), redox balance, muscle fiber phenotype, apoptotic nuclei, tyrosine release, protein ubiquitination, muscle-specific E3 ligases, NF-κB signaling pathway, markers of muscle anabolism (Akt, mTOR, p70S6K, and mitochondrial DNA) were evaluated along with body and muscle weights, and limb muscle force. Compared to wild type cachectic animals, in both respiratory and limb muscles of Parp-1 -/- and Parp-2 -/- cachectic mice: cancer induced-muscle wasting characterized by increased PARP activity, protein oxidation, tyrosine release, and ubiquitin-proteasome system (total protein ubiquitination, atrogin-1, and 20S proteasome C8 subunit) were blunted, the reduction in contractile myosin and atrophy of the fibers was attenuated, while no effects were seen in other structural features (inflammatory cells, internal or apoptotic nuclei), and markers of muscle anabolism partly improved. Activation of either PARP-1 or -2 is likely to play a role in muscle protein catabolism via oxidative stress, NF-κB signaling, and enhanced proteasomal degradation in cancer-induced cachexia. Therapeutic potential of PARP activity inhibition deserves attention. © 2017 Wiley Periodicals, Inc.

  2. Nandrolone reduces activation of Notch signaling in denervated muscle associated with increased Numb expression

    International Nuclear Information System (INIS)

    Liu, Xin-Hua; Yao, Shen; Qiao, Rui-Fang; Levine, Alice C.; Kirschenbaum, Alexander; Pan, Jiangping; Wu, Yong; Qin, Weiping; Bauman, William A.; Cardozo, Christopher P.

    2011-01-01

    Highlights: → Nerve transection increased Notch signaling in paralyzed muscle. → Nandrolone prevented denervation-induced Notch signaling. → Nandrolone induced the expression of an inhibitor of the Notch signaling, Numb. → Reduction of denervation-induced Notch signaling by nandrolone is likely through upregulation of Numb. -- Abstract: Nandrolone, an anabolic steroid, slows denervation-atrophy in rat muscle. The molecular mechanisms responsible for this effect are not well understood. Androgens and anabolic steroids activate Notch signaling in animal models of aging and thereby mitigate sarcopenia. To explore the molecular mechanisms by which nandrolone prevents denervation-atrophy, we investigated the effects of nandrolone on Notch signaling in denervated rat gastrocnemius muscle. Denervation significantly increased Notch activity reflected by elevated levels of nuclear Notch intracellular domain (NICD) and expression of Hey1 (a Notch target gene). Activation was greatest at 7 and 35 days after denervation but remained present at 56 days after denervation. Activation of Notch in denervated muscle was prevented by nandrolone associated with upregulated expression of Numb mRNA and protein. These data demonstrate that denervation activates Notch signaling, and that nandrolone abrogates this response associated with increased expression of Numb, suggesting a potential mechanism by which nandrolone reduces denervation-atrophy.

  3. Nandrolone reduces activation of Notch signaling in denervated muscle associated with increased Numb expression

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xin-Hua [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Yao, Shen; Qiao, Rui-Fang; Levine, Alice C. [Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Kirschenbaum, Alexander [Department of Urology, Mount Sinai School of Medicine, New York, NY 10029 (United States); Pan, Jiangping; Wu, Yong [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Qin, Weiping [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Bauman, William A. [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Rehabilitation Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Cardozo, Christopher P., E-mail: chris.cardozo@mssm.edu [Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peter VA Medical Center, Bronx, NY 10468 (United States); Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States); Rehabilitation Medicine, Mount Sinai School of Medicine, New York, NY 10029 (United States)

    2011-10-14

    Highlights: {yields} Nerve transection increased Notch signaling in paralyzed muscle. {yields} Nandrolone prevented denervation-induced Notch signaling. {yields} Nandrolone induced the expression of an inhibitor of the Notch signaling, Numb. {yields} Reduction of denervation-induced Notch signaling by nandrolone is likely through upregulation of Numb. -- Abstract: Nandrolone, an anabolic steroid, slows denervation-atrophy in rat muscle. The molecular mechanisms responsible for this effect are not well understood. Androgens and anabolic steroids activate Notch signaling in animal models of aging and thereby mitigate sarcopenia. To explore the molecular mechanisms by which nandrolone prevents denervation-atrophy, we investigated the effects of nandrolone on Notch signaling in denervated rat gastrocnemius muscle. Denervation significantly increased Notch activity reflected by elevated levels of nuclear Notch intracellular domain (NICD) and expression of Hey1 (a Notch target gene). Activation was greatest at 7 and 35 days after denervation but remained present at 56 days after denervation. Activation of Notch in denervated muscle was prevented by nandrolone associated with upregulated expression of Numb mRNA and protein. These data demonstrate that denervation activates Notch signaling, and that nandrolone abrogates this response associated with increased expression of Numb, suggesting a potential mechanism by which nandrolone reduces denervation-atrophy.

  4. A comparison of muscle activation between a Smith machine and free weight bench press.

    Science.gov (United States)

    Schick, Evan E; Coburn, Jared W; Brown, Lee E; Judelson, Daniel A; Khamoui, Andy V; Tran, Tai T; Uribe, Brandon P

    2010-03-01

    The bench press exercise exists in multiple forms including the machine and free weight bench press. It is not clear though how each mode differs in its effect on muscle activation. The purpose of this study was to compare muscle activation of the anterior deltoid, medial deltoid, and pectoralis major during a Smith machine and free weight bench press at lower (70% 1 repetition maximum [1RM]) and higher (90% 1RM) intensities. Normalized electromyography amplitude values were used during the concentric phase of the bench press to compare muscle activity between a free weight and Smith machine bench press. Participants were classified as either experienced or inexperienced bench pressers. Two testing sessions were used, each of which entailed either all free weight or all Smith machine testing. In each testing session, each participant's 1RM was established followed by 2 repetitions at 70% of 1RM and 2 repetitions at 90% of 1RM. Results indicated greater activation of the medial deltoid on the free weight bench press than on the Smith machine bench press. Also, there was greater muscle activation at the 90% 1RM load than at the 70% 1RM load. The results of this study suggest that strength coaches should consider choosing the free weight bench press over the Smith machine bench press because of its potential for greater upper-body muscular development.

  5. The effects of smart phone gaming duration on muscle activation and spinal posture: Pilot study.

    Science.gov (United States)

    Park, Joo-Hee; Kang, Sun-Young; Lee, Sa-Gyeom; Jeon, Hye-Seon

    2017-08-01

    This study investigates changes in the posture angles of the neck and trunk, together with changes in the muscle activation of users, at the start of and at 5, 10, and 15 minutes of smartphone use. Eighteen males participated in this study. Surface electromyography (EMG) and a digital camera were used to measure the muscle activation and angular changes of the neck and trunk of participants during smartphone use for a period of 16 minutes. Neck and trunk flexion significantly increased at 5, 10, and 15 minutes (p smartphone usage. The EMG activation and 10th%amplitude probability distribution function (APDF) values of the bilateral cervical erector spinae at 5-6, 10-11, and 15-16 minutes of usage (p Smartphone use induced more flexed posture on the neck and trunk than other visual display terminal (VDT) work. Smartphone use also changed posture and muscle activation within a relatively short amount of time, just 5 minutes. Pain after 16 minutes of smartphone use was also observed. Thus, clinicians should consider the influences of smartphone use in posture and muscle activity in evaluation, intervention, and prevention of neck and trunk conditions.

  6. Coordination of deep hip muscle activity is altered in symptomatic femoroacetabular impingement.

    Science.gov (United States)

    Diamond, Laura E; Van den Hoorn, Wolbert; Bennell, Kim L; Wrigley, Tim V; Hinman, Rana S; O'Donnell, John; Hodges, Paul W

    2017-07-01

    Diagnosis of femoroacetabular impingement (FAI) is increasing, yet the associated physical impairments remain poorly defined. This morphological hip condition can cause joint pain, stiffness, impaired function, and eventually hip osteoarthritis. This exploratory study compared coordination of deep hip muscles between people with and without symptomatic FAI using analysis of muscle synergies (i.e., patterns of activity of groups of muscles activated in synchrony) during gait. Fifteen individuals (11 males) with symptomatic FAI (clinical examination and imaging) and 14 age- and sex-comparable controls without morphological FAI underwent testing. Intramuscular fine-wire and surface electrodes recorded electromyographic activity of selected deep and superficial hip muscles. A non-negative matrix factorization algorithm extracted three synergies which were compared between groups. Information regarding which muscles were activated together in the FAI group (FAI group synergy vector) was used to reconstruct individual electromyography patterns and compare groups. Variance accounted for (VAF) by three synergies was less for the control (94.8 [1.4]%) than FAI (96.0 [1.0]%) group (p = 0.03). VAF of obturator internus was significantly higher in the FAI group (p = 0.02). VAF of the reconstructed individual electromyography patterns with the FAI or control group vector were significantly higher for the FAI group (p hip muscles in the synergy related to hip joint control during early swing differed between groups. This phase involves movement towards the impingement position, which has relevance for the interpretation of synergy differences and potential clinical importance. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1494-1504, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  7. Differentiation and fiber type-specific activity of a muscle creatine kinase intronic enhancer

    Directory of Open Access Journals (Sweden)

    Tai Phillip WL

    2011-07-01

    Full Text Available Abstract Background Hundreds of genes, including muscle creatine kinase (MCK, are differentially expressed in fast- and slow-twitch muscle fibers, but the fiber type-specific regulatory mechanisms are not well understood. Results Modulatory region 1 (MR1 is a 1-kb regulatory region within MCK intron 1 that is highly active in terminally differentiating skeletal myocytes in vitro. A MCK small intronic enhancer (MCK-SIE containing a paired E-box/myocyte enhancer factor 2 (MEF2 regulatory motif resides within MR1. The SIE's transcriptional activity equals that of the extensively characterized 206-bp MCK 5'-enhancer, but the MCK-SIE is flanked by regions that can repress its activity via the individual and combined effects of about 15 different but highly conserved 9- to 24-bp sequences. ChIP and ChIP-Seq analyses indicate that the SIE and the MCK 5'-enhancer are occupied by MyoD, myogenin and MEF2. Many other E-boxes located within or immediately adjacent to intron 1 are not occupied by MyoD or myogenin. Transgenic analysis of a 6.5-kb MCK genomic fragment containing the 5'-enhancer and proximal promoter plus the 3.2-kb intron 1, with and without MR1, indicates that MR1 is critical for MCK expression in slow- and intermediate-twitch muscle fibers (types I and IIa, respectively, but is not required for expression in fast-twitch muscle fibers (types IIb and IId. Conclusions In this study, we discovered that MR1 is critical for MCK expression in slow- and intermediate-twitch muscle fibers and that MR1's positive transcriptional activity depends on a paired E-box MEF2 site motif within a SIE. This is the first study to delineate the DNA controls for MCK expression in different skeletal muscle fiber types.

  8. Effect of Active-Assisted Stretching of 30 Seconds and 60 Seconds in Muscle Force

    Directory of Open Access Journals (Sweden)

    Mirian dos Santos Monteiro

    2018-01-01

    Full Text Available This study aims to analyze the interference of the active-assisted stretching technique in muscle strength. Participating in this study were 39 healthy and physically active individuals subdivided into three groups of active-assisted stretching G30 - 30 seconds, G60 - 60 seconds and CG - control. The muscular strength was evaluated using the isokinetic dynamometer, obtaining the analyzed conditions of torque peak, total work and agonist and antagonist relationship of the dorsiflexor and flexor muscles ankle. The values obtained were statistically analyzed by the SPSS from the “t-test for paired sample” (p ≤ 0.05. When analyzing the effect produced by the stretching, it was observed that the 30-second elongation showed a reduction of the average of the muscular torque in all conditions analyzed, with the exception of the relation between the agonist and the left antagonist and the total work of the right plantar flexors, the G60 - 60 seconds group had a reduction in average muscle torque in all conditions analyzed, except for the relation between agonist and left antagonist that obtained an increase in muscle torque and the CG - control group, there was a reduction in the average of the muscular torque in all the analyzed conditions, except for the torque and total work of the left plantar flexor muscles that presented increase. Thus, it can be concluded that there were differences between the groups of active-assisted stretching of 30 and 60 and that the effect produced by stretching did not present a significant reduction of muscle strength.

  9. Unloaded shortening velocity of voluntarily and electrically activated human dorsiflexor muscles in vivo.

    Directory of Open Access Journals (Sweden)

    Kazushige Sasaki

    Full Text Available We have previously shown that unloaded shortening velocity (V(0 of human plantar flexors can be determined in vivo, by applying the "slack test" to submaximal voluntary contractions (J Physiol 567:1047-1056, 2005. In the present study, to investigate the effect of motor unit recruitment pattern on V(0 of human muscle, we modified the slack test and applied this method to both voluntary and electrically elicited contractions of dorsiflexors. A series of quick releases (i.e., rapid ankle joint rotation driven by an electrical dynamometer was applied to voluntarily activated dorsiflexor muscles at three different contraction intensities (15, 50, and 85% of maximal voluntary contraction; MVC. The quick-release trials were also performed on electrically activated dorsiflexor muscles, in which three stimulus conditions were used: submaximal (equal to 15%MVC 50-Hz stimulation, supramaximal 50-Hz stimulation, and supramaximal 20-Hz stimulation. Modification of the slack test in vivo resulted in good reproducibility of V(0, with an intraclass correlation coefficient of 0.87 (95% confidence interval: 0.68-0.95. Regression analysis showed that V(0 of voluntarily activated dorsiflexor muscles significantly increased with increasing contraction intensity (R(2 = 0.52, P<0.001. By contrast, V(0 of electrically activated dorsiflexor muscles remained unchanged (R(2<0.001, P = 0.98 among three different stimulus conditions showing a large variation of tetanic torque. These results suggest that the recruitment pattern of motor units, which is quite different between voluntary and electrically elicited contractions, plays an important role in determining shortening velocity of human skeletal muscle in vivo.

  10. Learning new gait patterns: Exploratory muscle activity during motor learning is not predicted by motor modules

    Science.gov (United States)

    Ranganathan, Rajiv; Krishnan, Chandramouli; Dhaher, Yasin Y.; Rymer, William Z.

    2018-01-01

    The motor module hypothesis in motor control proposes that the nervous system can simplify the problem of controlling a large number of muscles in human movement by grouping muscles into a smaller number of modules. Here, we tested one prediction of the modular organization hypothesis by examining whether there is preferential exploration along these motor modules during the learning of a new gait pattern. Healthy college-aged participants learned a new gait pattern which required increased hip and knee flexion during the swing phase while walking in a lower-extremity robot (Lokomat). The new gait pattern was displayed as a foot trajectory in the sagittal plane and participants attempted to match their foot trajectory to this template. We recorded EMG from 8 lower-extremity muscles and we extracted motor modules during both baseline walking and target-tracking using non-negative matrix factorization (NMF). Results showed increased trajectory variability in the first block of learning, indicating that participants were engaged in exploratory behavior. Critically, when we examined the muscle activity during this exploratory phase, we found that the composition of motor modules changed significantly within the first few strides of attempting the new gait pattern. The lack of persistence of the motor modules under even short time scales suggests that motor modules extracted during locomotion may be more indicative of correlated muscle activity induced by the task constraints of walking, rather than reflecting a modular control strategy. PMID:26916510

  11. Evaluating the Relationship Between Muscle Activation and Spine Kinematics Through Wavelet Coherence.

    Science.gov (United States)

    Hay, Dean C; Wachowiak, Mark P; Graham, Ryan B

    2016-10-01

    Advances in time-frequency analysis can provide new insights into the important, yet complex relationship between muscle activation (ie, electromyography [EMG]) and motion during dynamic tasks. We use wavelet coherence to compare a fundamental cyclical movement (lumbar spine flexion and extension) to the surface EMG linear envelope of 2 trunk muscles (lumbar erector spinae and internal oblique). Both muscles cohere to the spine kinematics at the main cyclic frequency, but lumbar erector spinae exhibits significantly greater coherence than internal oblique to kinematics at 0.25, 0.5, and 1.0 Hz. Coherence phase plots of the 2 muscles exhibit different characteristics. The lumbar erector spinae precedes trunk extension at 0.25 Hz, whereas internal oblique is in phase with spine kinematics. These differences may be due to their proposed contrasting functions as a primary spine mover (lumbar erector spinae) versus a spine stabilizer (internal oblique). We believe that this method will be useful in evaluating how a variety of factors (eg, pain, dysfunction, pathology, fatigue) affect the relationship between muscles' motor inputs (ie, activation measured using EMG) and outputs (ie, the resulting joint motion patterns).

  12. Influence of short-term unweighing and reloading on running kinetics and muscle activity.

    Science.gov (United States)

    Sainton, Patrick; Nicol, Caroline; Cabri, Jan; Barthelemy-Montfort, Joëlle; Berton, Eric; Chavet, Pascale

    2015-05-01

    In running, body weight reduction is reported to result in decreased lower limb muscle activity with no change in the global activation pattern (Liebenberg et al. in J Sports Sci 29:207-214). Our study examined the acute effects on running mechanics and lower limb muscle activity of short-term unweighing and reloading conditions while running on a treadmill with a lower body positive pressure (LBPP) device. Eleven healthy males performed two randomized running series of 9 min at preferred speed. Each series included three successive running conditions of 3 min [at 100 % body weight (BW), 60 or 80 % BW, and 100 % BW]. Vertical ground reaction force and center of mass accelerations were analyzed together with surface EMG activity recorded from six major muscles of the left lower limb for the first and last 30 s of each running condition. Effort sensation and mean heart rate were also recorded. In both running series, the unloaded running pattern was characterized by a lower step frequency (due to increased flight time with no change in contact time), lower impact and active force peaks, and also by reduced loading rate and push-off impulse. Amplitude of muscle activity overall decreased, but pre-contact and braking phase extensor muscle activity did not change, whereas it was reduced during the subsequent push-off phase. The combined neuro-mechanical changes suggest that LBPP technology provides runners with an efficient support during the stride. The after-effects recorded after reloading highlight the fact that 3 min of unweighing may be sufficient for updating the running pattern.

  13. The effects of whole body vibration combined computerized postural control training on the lower extremity muscle activity and cerebral cortex activity in stroke patients.

    Science.gov (United States)

    Uhm, Yo-Han; Yang, Dae-Jung

    2018-02-01

    [Purpose] The purpose of this study was to examine the effect of computerized postural control training using whole body vibration on lower limb muscle activity and cerebral cortical activation in acute stroke patients. [Subjects and Methods] Thirty stroke patients participated and were divided into groups of 10, a group of the computerized postural control training using whole body vibration (Group I), the computerized postural control training combined with aero step (Group II) and computerized postural control training (Group III). MP100 was used to measure lower limb muscle activity, and QEEG-8 was used to measure cerebral cortical activation. [Results] Comparison of muscle activity and cerebral cortical activation before and after intervention between groups showed that Group I had significant differences in lower limb muscle activity and cerebral cortical activation compared to Groups II and III. [Conclusion] This study showed that whole body vibration combined computerized postural control training is effective for improving muscle activity and cerebral cortex activity in stroke patients.

  14. Respiratory muscle stretch gymnastics in patients with post coronary artery bypass grafting pain : Impact on respiratory muscle function, activity, mood and exercise capacity

    OpenAIRE

    會田, 信子; 渋谷, 優子; 吉野, 克樹; Komoda, Masaji; 井上, 智子

    2002-01-01

    A new rehabilitation (New-RH) program including respiratory muscle stretch gymnastics (RMSG) was developed to alleviate post-coronary artery bypass grafting pain (PCP). Effects on respiratory muscle function, pain, activities of daily living (ADL), mood and exercise capacity were investigated. Subjects were 16 consecutive patients undergoing median full sternotomy coronary artery bypass grafting (CABG), and were randomly divided into equal New-RH (S-group) and conventional therapy (C-group) g...

  15. The Generalized Hill Model: A Kinematic Approach Towards Active Muscle Contraction

    Science.gov (United States)

    Menzel, Andreas; Kuhl, Ellen

    2014-01-01

    Excitation-contraction coupling is the physiological process of converting an electrical stimulus into a mechanical response. In muscle, the electrical stimulus is an action potential and the mechanical response is active contraction. The classical Hill model characterizes muscle contraction though one contractile element, activated by electrical excitation, and two non-linear springs, one in series and one in parallel. This rheology translates into an additive decomposition of the total stress into a passive and an active part. Here we supplement this additive decomposition of the stress by a multiplicative decomposition of the deformation gradient into a passive and an active part. We generalize the one-dimensional Hill model to the three-dimensional setting and constitutively define the passive stress as a function of the total deformation gradient and the active stress as a function of both the total deformation gradient and its active part. We show that this novel approach combines the features of both the classical stress-based Hill model and the recent active-strain models. While the notion of active stress is rather phenomenological in nature, active strain is micro-structurally motivated, physically measurable, and straightforward to calibrate. We demonstrate that our model is capable of simulating excitation-contraction coupling in cardiac muscle with its characteristic features of wall thickening, apical lift, and ventricular torsion. PMID:25221354

  16. Effects of balance training by knee joint motions on muscle activity in adult men with functional ankle instability.

    Science.gov (United States)

    Nam, Seung-Min; Kim, Won-Bok; Yun, Chang-Kyo

    2016-05-01

    [Purpose] This study examined the effects of balance training by applying knee joint movements on muscle activity in male adults with functional ankle instability. [Subjects and Methods] 28 adults with functional ankle instability, divided randomly into an experimental group, which performed balance training by applying knee joint movements for 20 minutes and ankle joint exercises for 10 minutes, and a control group, which performed ankle joint exercise for 30 minutes. Exercises were completed three times a week for 8 weeks. Electromyographic values of the tibialis anterior, peroneus longus, peroneus brevis, and the lateral gastrocnemius muscles were obtained to compare and analyze muscle activity before and after the experiments in each group. [Results] The experimental group had significant increases in muscle activity in the tibialis anterior, peroneus longus, and lateral gastrocnemius muscles, while muscle activity in the peroneus brevis increased without significance. The control group had significant increases in muscle activity in the tibialis anterior and peroneus longus, while muscle activity in the peroneus brevis and lateral gastrocnemius muscles increased without significance. [Conclusion] In conclusion, balance training by applying knee joint movements can be recommended as a treatment method for patients with functional ankle instability.

  17. Examination of contraction-induced muscle pain as a behavioral correlate of physical activity in women with and without fibromyalgia.

    Science.gov (United States)

    Umeda, Masataka; Corbin, Lisa W; Maluf, Katrina S

    2015-01-01

    This study aimed to compare muscle pain intensity during a sustained isometric contraction in women with and without fibromyalgia (FM), and examine the association between muscle pain and self-reported levels of physical activity. Fourteen women with FM and 14 healthy women completed the study, where muscle pain ratings (MPRs) were obtained every 30 s during a 3 min isometric handgrip task at 25% maximal strength, and self-reported physical activity was quantified using the Baecke Physical Activity Questionnaire. Women with FM were less physically active than healthy controls. During the isometric contraction, MPR progressively increased in both groups at a comparable rate, but women with FM generally reported a greater intensity of muscle pain than healthy controls. Among all women, average MPR scores were inversely associated with self-reported physical activity levels. Women with FM exhibit augmented muscle pain during isometric contractions and reduced physical activity than healthy controls. Furthermore, contraction-induced muscle pain is inversely associated with physical activity levels. These observations suggest that augmented muscle pain may serve as a behavioral correlate of reduced physical activity in women with FM. Implications for Rehabilitation Women with fibromyalgia experience a greater intensity of localized muscle pain in a contracting muscle compared to healthy women. The intensity of pain during muscle contraction is inversely associated with the amount of physical activity in women with and without fibromyalgia. Future studies should determine whether exercise adherence can be improved by considering the relationship between contraction-induced muscle pain and participation in routine physical activity.

  18. Effect of Forefoot Strike on Lower Extremity Muscle Activity and Knee Joint Angle During Cutting in Female Team Handball Players.

    Science.gov (United States)

    Yoshida, Naruto; Kunugi, Shun; Mashimo, Sonoko; Okuma, Yoshihiro; Masunari, Akihiko; Miyazaki, Shogo; Hisajima, Tatsuya; Miyakawa, Shumpei

    2015-06-01

    The purpose of this study is to examine the effects of different strike forms, during cutting, on knee joint angle and lower limb muscle activity. Surface electromyography was used to measure muscle activity in individuals performing cutting manoeuvres involving either rearfoot strikes (RFS) or forefoot strikes (FFS). Three-dimensional motion analysis was used to calculate changes in knee angles, during cutting, and to determine the relationship between muscle activity and knee joint angle. Force plates were synchronized with electromyography measurements to compare muscle activity immediately before and after foot strike. The valgus angle tends to be smaller during FFS cutting than during RFS cutting. Just prior to ground contact, biceps femoris, semitendinosus, and lateral head of the gastrocnemius muscle activities were significantly greater during FFS cutting than during RFS cutting; tibialis anterior muscle activity was greater during RFS cutting. Immediately after ground contact, biceps femoris and lateral head of the gastrocnemius muscle activities were significantly greater during FFS cutting than during RFS cutting; tibialis anterior muscle activity was significantly lower during FFS cutting. The results of the present study suggest that the hamstrings demonstrate greater activity, immediately after foot strike, during FFS cutting than during RFS cutting. Thus, FFS cutting may involve a lower risk of anterior cruciate ligament injury than does RFS cutting.

  19. Chronic Effects of Different Rest Intervals Between Sets on Dynamic and Isometric Muscle Strength and Muscle Activity in Trained Older Women.

    Science.gov (United States)

    Jambassi Filho, José Claudio; Gurjão, André Luiz Demantova; Ceccato, Marilia; Prado, Alexandre Konig Garcia; Gallo, Luiza Herminia; Gobbi, Sebastião

    2017-09-01

    This study investigated the chronic effects of different rest intervals (RIs) between sets on dynamic and isometric muscle strength and muscle activity. We used a repeated-measures design (pretraining and posttraining) with independent groups (different RI). Twenty-one resistance-trained older women (66.4 ± 4.4 years) were randomly assigned to either a 1-minute RI group (G-1 min; n = 10) or 3-minute RI group (G-3 min; n = 11). Both groups completed 3 supervised sessions per week during 8 weeks. In each session, participants performed 3 sets of 15 repetitions of leg press exercise, with a load that elicited muscle failure in the third set. Fifteen maximum repetitions, maximal voluntary contraction, peak rate of force development, and integrated electromyography activity of the vastus lateralis and vastus medialis muscles were assessed pretraining and posttraining. There was a significant increase in load of 15 maximum repetitions posttraining for G-3 min only (3.6%; P 0.05). The findings suggest that different RIs between sets did not influence dynamic and isometric muscle strength and muscle activity in resistance-trained older women.

  20. Leg muscle activation during gait in Parkinson's disease : Adaptation and interlimb coordination

    NARCIS (Netherlands)

    Dietz, [No Value; Zijlstra, W; Prokop, T; Berger, W

    1995-01-01

    Adaptation in leg muscle activity and coordination between lower limbs were studied during walking on a treadmill with split belts in one group of parkinsonian patients and one of age-matched healthy subjects. Four different belt speeds (0.25/0.5/0.75/1.0 m/sec) were applied in selected combinations

  1. The effects of a 28-Hz vibration on arm muscle activity during isometric exercise

    NARCIS (Netherlands)

    Mischi, M.; Cardinale, M. (Marco)

    2009-01-01

    The aim of this study was to evaluate activation and coactivation of biceps and triceps muscles during isometric exercise performed with and without superimposing a vibration stimulation. Methods: Twelve healthy volunteers (age = 22.7 +/- 2.6 yr) participated in this study. The subjects performed

  2. Afferent-mediated modulation of the soleus muscle activity during the stance phase of human walking

    DEFF Research Database (Denmark)

    Nazarena, Mazzaro; Grey, Michael James; do Nascimento, Omar Feix

    2006-01-01

    The aim of this study was to investigate the contribution of proprioceptive feedback to the amplitude modulation of the soleus muscle activity during human walking. We have previously shown that slow-velocity, small-amplitude ankle dorsiflexion enhancements and reductions applied during the stance...

  3. Muscle activity during leg strengthening exercise using free weights and elastic resistance

    DEFF Research Database (Denmark)

    Jakobsen, Markus Due; Sundstrup, Emil; Andersen, Christoffer H

    2013-01-01

    ) activity was recorded in nine muscles during a standardized forward lunge movement performed with dumbbells and elastic bands during (1) ballistic vs. controlled exertion, and (2) at low, medium and high loads (33%, 66% and 100% of 10 RM, respectively). The recorded EMG signals were normalized to MVC EMG...

  4. Muscle Activation during Push-Ups with Different Suspension Training Systems

    Directory of Open Access Journals (Sweden)

    Joaquin Calatayud, Sebastien Borreani, Juan C. Colado, Fernando F Martín, Michael E. Rogers

    2014-09-01

    Full Text Available The purpose of this study was to analyze upper extremity and core muscle activation when performing push-ups with different suspension devices. Young fit male university students (n = 29 performed 3 push-ups each with 4 different suspension systems. Push-up speed was controlled using a metronome and testing order was randomized. Average amplitude of the electromyographic root mean square of Triceps Brachii, Upper Trapezius, Anterior Deltoid, Clavicular Pectoralis, Rectus Abdominis, Rectus Femoris, and Lumbar Erector Spinae was recorded. Electromyographic signals were normalized to the maximum voluntary isometric contraction (MVIC. Electromyographic data were analyzed with repeated-measures analysis of variance with a Bonferroni post hoc. Based upon global arithmetic mean of all muscles analyzed, the suspended push-up with a pulley system provided the greatest activity (37.76% of MVIC; p < 0.001. Individually, the suspended push-up with a pulley system also provided the greatest triceps brachii, upper trapezius, rectus femoris and erector lumbar spinae muscle activation. In contrast, more stable conditions seem more appropriate for pectoralis major and anterior deltoid muscles. Independent of the type of design, all suspension systems were especially effective training tools for reaching high levels of rectus abdominis activation.

  5. The change in spatial distribution of upper trapezius muscle activity is correlated to contraction duration.

    Science.gov (United States)

    Farina, Dario; Leclerc, Frédéric; Arendt-Nielsen, Lars; Buttelli, Olivier; Madeleine, Pascal

    2008-02-01

    The aim of the study was to confirm the hypothesis that the longer a contraction is sustained, the larger are the changes in the spatial distribution of muscle activity. For this purpose, surface electromyographic (EMG) signals were recorded with a 13 x 5 grid of electrodes from the upper trapezius muscle of 11 healthy male subjects during static contractions with shoulders 90 degrees abducted until endurance. The entropy (degree of uniformity) and center of gravity of the EMG root mean square map were computed to assess spatial inhomogeneity in muscle activation and changes over time in EMG amplitude spatial distribution. At the endurance time, entropy decreased (mean+/-SD, percent change 2.0+/-1.6%; Pgrid) root mean square was positively correlated with the shift in the center of gravity (R(2)=0.51, P<0.05). Moreover, the shift in the center of gravity was negatively correlated to both initial and final (at the endurance) entropy (R(2)=0.54 and R(2)=0.56, respectively; P<0.01 in both cases), indicating that subjects with less uniform root mean square maps had larger shift of the center of gravity over time. The spatial changes in root mean square EMG were likely due to spatially-dependent changes in motor unit activation during the sustained contraction. It was concluded that the changes in spatial muscle activity distribution play a role in the ability to maintain a static contraction.

  6. The effects of psychosocial factors on trapezius muscle activity levels during computer use

    NARCIS (Netherlands)

    Bruno Garza, Jennifer L.; Eijckelhof, Belinda H W; Huysmans, Maaike A.; Johnson, Peter W.; Van Dieen, Jaap H.; Van Der Beek, Allard J.; Dennerlein, Jack T.

    2012-01-01

    The goal of the present study, a part of the PROOF (Predicting Occupational biomechanics among OFfice workers) study, was to determine if there was a relationship between psychosocial stress, measured by reward and over-commitment, and trapezius muscle activity while workers performed their own

  7. Cardiopulmonary exercise capacity, muscle strength, and physical activity in children and adolescents with achondroplasia

    NARCIS (Netherlands)

    Takken, Tim; van Bergen, Monique W. M.; Sakkers, Ralph J. B.; Helders, Paul J. M.; Engelbert, Raoul H. H.

    2007-01-01

    To study in children with achondroplasia the response to exercise and muscle strength compared with healthy peers and to describe the relation between exercise capacity, anthropometric factors, and physical activity. Patients (7 boys and 10 girls; mean age, 11.8 +/- 3.3 years) with achondroplasia

  8. Voluntary resistance running wheel activity pattern and skeletal muscle growth in rats.

    Science.gov (United States)

    Legerlotz, Kirsten; Elliott, Bradley; Guillemin, Bernard; Smith, Heather K

    2008-06-01

    The aims of this study were to characterize the pattern of voluntary activity of young rats in response to resistance loading on running wheels and to determine the effects of the activity on the growth of six limb skeletal muscles. Male Sprague-Dawley rats (4 weeks old) were housed individually with a resistance running wheel (R-RUN, n = 7) or a conventional free-spinning running wheel (F-RUN, n = 6) or without a wheel, as non-running control animals (CON, n = 6). The torque required to move the wheel in the R-RUN group was progressively increased, and the activity (velocity, distance and duration of each bout) of the two running wheel groups was recorded continuously for 45 days. The R-RUN group performed many more, shorter and faster bouts of running than the F-RUN group, yet the mean daily distance was not different between the F-RUN (1.3 +/- 0.2 km) and R-RUN group (1.4 +/- 0.6 km). Only the R-RUN resulted in a significantly (P RUN and R-RUN led to a significantly greater wet mass relative to increase in body mass and muscle fibre cross-sectional area in the soleus muscle compared with CON. We conclude that the pattern of voluntary activity on a resistance running wheel differs from that on a free-spinning running wheel and provides a suitable model to induce physiological muscle hypertrophy in rats.

  9. Lipolytic activity in the flight muscles of Locusta migratoria measured with haemolymph lipoproteins as substrates

    NARCIS (Netherlands)

    Horst, D.J. van der; Wheeler, C.H.; Beenakkers, A.M.Th.

    1984-01-01

    A radiochemical assay is described in which neutral lipids presented as part of authentic haemolymph lipoproteins have been used as substrates to measure the lipolytic activity in the flight muscles of Locusta migratoria. The radiolabel in the substrate was located almost exclusively in the glycerol

  10. Ankle torque steadiness is related to muscle activation variability and coactivation in children with cerebral palsy

    DEFF Research Database (Denmark)

    Bandholm, Thomas; Rose, Martin Høyer; Sløk, Rikke

    2009-01-01

    The aims of this study were to: (1) investigate the significance of muscle activation variability and coactivation for the ability to perform steady submaximal ankle torque (torque steadiness) in healthy children and those with cerebral palsy (CP), and (2) assess ankle function during isometric...

  11. Type and intensity of activity and risk of mobility limitation : the mediating role of muscle parameters

    NARCIS (Netherlands)

    Visser, M.; Simonsick, E.M.; Rubin, S; Newman, A.B.; Kritchevsky, S.B.; Harris, T.B.

    2005-01-01

    OBJECTIVES: To investigate the association between different types of physical activity behavior and incident mobility limitation in older men and women and to examine whether muscle parameters mediate these associations. DESIGN: Cohort study with 4.5-year follow-up. SETTING: Metropolitan areas

  12. Human-robot interaction: kinematics and muscle activity inside a powered compliant knee exoskeleton.

    Science.gov (United States)

    Knaepen, Kristel; Beyl, Pieter; Duerinck, Saartje; Hagman, Friso; Lefeber, Dirk; Meeusen, Romain

    2014-11-01

    Until today it is not entirely clear how humans interact with automated gait rehabilitation devices and how we can, based on that interaction, maximize the effectiveness of these exoskeletons. The goal of this study was to gain knowledge on the human-robot interaction, in terms of kinematics and muscle activity, between a healthy human motor system and a powered knee exoskeleton (i.e., KNEXO). Therefore, temporal and spatial gait parameters, human joint kinematics, exoskeleton kinetics and muscle activity during four different walking trials in 10 healthy male subjects were studied. Healthy subjects can walk with KNEXO in patient-in-charge mode with some slight constraints in kinematics and muscle activity primarily due to inertia of the device. Yet, during robot-in-charge walking the muscular constraints are reversed by adding positive power to the leg swing, compensating in part this inertia. Next to that, KNEXO accurately records and replays the right knee kinematics meaning that subject-specific trajectories can be implemented as a target trajectory during assisted walking. No significant differences in the human response to the interaction with KNEXO in low and high compliant assistance could be pointed out. This is in contradiction with our hypothesis that muscle activity would decrease with increasing assistance. It seems that the differences between the parameter settings of low and high compliant control might not be sufficient to observe clear effects in healthy subjects. Moreover, we should take into account that KNEXO is a unilateral, 1 degree-of-freedom device.

  13. The influence of anaerobic muscle activity, maturation and season on the flesh quality of farmed turbot

    NARCIS (Netherlands)

    Roth, B.; Imsland, A.; Stien, L.H.; Schelvis-Smit, A.A.M.; Gunnarsson, S.; Foss, A.

    2010-01-01

    In order to test seasonal, rearing, maturing and anaerobic muscle activity effect on the flesh quality of turbot (Scophthalmus maximus) a total of 80 farmed turbot from three different strains from reared under natural or continuous light were killed by a percussive blow to the head in November

  14. Adaptations of upper trapezius muscle activity during sustained contractions in women with fibromyalgia

    DEFF Research Database (Denmark)

    Falla, Deborah Lorraine; Andersen, Helle; Danneskiold-Samsøe, Bente

    2010-01-01

    a topographical map of the distribution of muscle activity. The pain level rated by the patients at the beginning of the sustained contraction was 5.9+/-1.5. The peak pain intensity for the control group following the injection of hypertonic saline was 6.0+/-1.6. During the sustained contractions, the EMG...

  15. Force Per Active Area and Muscle Injury during Electrically Stimulated Contractions

    OpenAIRE

    BLACK, CHRISTOPHER D.; MCCULLY, KEVIN K.

    2008-01-01

    Multiple mechanical factors have been implicated in the initiation of exercise-induced muscle injury. Although high absolute force levels are associated with greater injury, the importance of high force per active area independent of absolute force remains to be determined, especially in humans.

  16. Biting Force and Muscle Activity in Implant-Supported Single Mandibular Overdentures Opposing Fixed Maxillary Dentition.

    Science.gov (United States)

    Al-Magaleh, Wafaʼa R; Abbas, Nadia A; Amer, Ashraf A; Abdelkader, Ann A; Bahgat, Basma

    2016-04-01

    This study aimed to investigate the relation between biting force and masticatory muscle activity in patients treated by 3 modalities of single mandibular dentures. Forty implants were placed in 10 patients with completely edentulous mandibles. The study was divided into 3 treatment stages. Initially, each patient received a conventional mandibular complete denture. At the second stage, 4 mandibular implants were placed and the denture was refitted to their abutments. Third stage comprised connecting the denture to the implants through ball attachments. During each treatment stage, maximum biting force and muscle activity were measured during maximum clenching and chewing of soft and hard food. Biting force demonstrated a statistically significant increase by time for the 3 treatment stages. The highest muscle activity was recorded for the conventional denture followed by the implant-supported overdenture without attachment, whereas the lowest values were recorded for the implant-supported overdenture with attachment. Biting force was related mainly to the quality of denture support. Muscle activity was higher in patients with conventional denture than with implant-supported prostheses (with or without attachments).

  17. Motor unit activation order during electrically evoked contractions of paralyzed or partially paralyzed muscles

    NARCIS (Netherlands)

    Thomas, CK; Nelson, G; Than, L; Zijdewind, Inge

    The activation order of motor units during electrically evoked contractions of paralyzed or partially paralyzed thenar muscles was determined in seven subjects with chronic cervical spinal cord injury. The median nerve was stimulated percutaneously with pulses of graded intensity to produce

  18. Evaluation of muscle activity during a standardized shoulder resistance training bout in novice individuals

    DEFF Research Database (Denmark)

    Jakobsen, Markus D; Sundstrup, Emil; Andersen, Christoffer H

    2012-01-01

    training bout. The purpose of this study was to evaluate muscle activity during a shoulder resistance training bout with 15 repetitions maximum (RM) loadings in novice individuals. Twelve healthy sedentary women (age = 27-58 years; weight = 54-85 kg; height = 160-178 cm) were recruited for this study...

  19. Muscle activation and perceived loading during rehabilitation exercises: comparison of dumbbells and elastic resistance

    DEFF Research Database (Denmark)

    Andersen, Lars L; Andersen, Christoffer H; Mortensen, Ole S

    2010-01-01

    High-intensity resistance training plays an essential role in the prevention and rehabilitation of musculoskeletal injuries and disorders. Although resistance exercises with heavy weights yield high levels of muscle activation, the efficacy of more user-friendly forms of exercise needs to be exam...

  20. Muscle inactivity and activity patterns after sedentary time--targeted randomized controlled trial.

    Science.gov (United States)

    Pesola, Arto J; Laukkanen, Arto; Haakana, Piia; Havu, Marko; Sääkslahti, Arja; Sipilä, Sarianna; Finni, Taija

    2014-11-01

    Interventions targeting sedentary time are needed. We used detailed EMG recordings to study the short-term effectiveness of simple sedentary time-targeted tailored counseling on the total physical activity spectrum. This cluster randomized controlled trial was conducted between 2011 and 2013 (InPact, ISRCTN28668090), and short-term effectiveness of counseling is reported in the present study. A total of 133 office workers volunteered to participate, from which muscle activity data were analyzed from 48 (intervention, n = 24; control, n = 24). After a lecture, face-to-face tailored counseling was used to set contractually binding goals regarding breaking up sitting periods and increasing family based physical activity. Primary outcome measures were assessed 11.8 ± 1.1 h before and a maximum of 2 wk after counseling including quadriceps and hamstring muscle inactivity time, sum of the five longest muscle inactivity periods, and light muscle activity time during work, commute, and leisure time. Compared with those in the controls, counseling decreased the intervention group's muscle inactivity time by 32.6 ± 71.8 min from 69.1% ± 8.5% to 64.6% ± 10.9% (whole day, P work, P activity time increased by 20.6 ± 52.6 min, from 22.2% ± 7.9% to 25.0% ± 9.7% (whole day, P work, P work time, average EMG amplitude (percentage of EMG during maximal voluntary isometric contraction (MVC) (%EMG MVC)) increased from 1.6% ± 0.9% to 1.8% ± 1.0% (P activity. During work time, average EMG amplitude increased by 13%, reaching an average of 1.8% of EMG MVC. If maintained, this observed short-term effect may have health-benefiting consequences.

  1. Membrane-stabilizing copolymers confer marked protection to dystrophic skeletal muscle in vivo

    Directory of Open Access Journals (Sweden)

    Evelyne M Houang

    Full Text Available Duchenne muscular dystrophy (DMD is a fatal disease of striated muscle deterioration. A unique therapeutic approach for DMD is the use of synthetic membrane stabilizers to protect the fragile dystrophic sarcolemma against contraction-induced mechanical stress. Block copolymer-based membrane stabilizer poloxamer 188 (P188 has been shown to protect the dystrophic myocardium. In comparison, the ability of synthetic membrane stabilizers to protect fragile DMD skeletal muscles has been less clear. Because cardiac and skeletal muscles have distinct structural and functional features, including differences in the mechanism of activation, variance in sarcolemma phospholipid composition, and differences in the magnitude and types of forces generated, we speculated that optimized membrane stabilization could be inherently different. Our objective here is to use principles of pharmacodynamics to evaluate membrane stabilization therapy for DMD skeletal muscles. Results show a dramatic differential effect of membrane stabilization by optimization of pharmacodynamic-guided route of poloxamer delivery. Data show that subcutaneous P188 delivery, but not intravascular or intraperitoneal routes, conferred significant protection to dystrophic limb skeletal muscles undergoing mechanical stress in vivo. In addition, structure-function examination of synthetic membrane stabilizers further underscores the importance of copolymer composition, molecular weight, and dosage in optimization of poloxamer pharmacodynamics in vivo.

  2. Subglottal pressure, tracheal airflow, and intrinsic laryngeal muscle activity during rat ultrasound vocalization

    Science.gov (United States)

    2011-01-01

    Vocal production requires complex planning and coordination of respiratory, laryngeal, and vocal tract movements, which are incompletely understood in most mammals. Rats produce a variety of whistles in the ultrasonic range that are of communicative relevance and of importance as a model system, but the sources of acoustic variability were mostly unknown. The goal was to identify sources of fundamental frequency variability. Subglottal pressure, tracheal airflow, and electromyographic (EMG) data from two intrinsic laryngeal muscles were measured during 22-kHz and 50-kHz call production in awake, spontaneously behaving adult male rats. During ultrasound vocalization, subglottal pressure ranged between 0.8 and 1.9 kPa. Pressure differences between call types were not significant. The relation between fundamental frequency and subglottal pressure within call types was inconsistent. Experimental manipulations of subglottal pressure had only small effects on fundamental frequency. Tracheal airflow patterns were also inconsistently associated with frequency. Pressure and flow seem to play a small role in regulation of fundamental frequency. Muscle activity, however, is precisely regulated and very sensitive to alterations, presumably because of effects on resonance properties in the vocal tract. EMG activity of cricothyroid and thyroarytenoid muscle was tonic in calls with slow or no fundamental frequency modulations, like 22-kHz and flat 50-kHz calls. Both muscles showed brief high-amplitude, alternating bursts at rates up to 150 Hz during production of frequency-modulated 50-kHz calls. A differentiated and fine regulation of intrinsic laryngeal muscles is critical for normal ultrasound vocalization. Many features of the laryngeal muscle activation pattern during ultrasound