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Neuromuscular fatigue

Axel Van Der Gucht, Mehdi Aoun Sebaiti, Eric Guedj, Jessie Aouizerate, Sabrina Yara, Romain Gherardi, Eva Evangelista, Julia Chalaye, Anne-Ségolène Cottereau, Antoine Verger, Anne-Catherine Bachoud-Levi, Emmanuel Itti, Francois Jerome Authier
PURPOSE: Macrophagic myofasciitis (MMF) is an emerging condition with specific muscle lesions characterized by an abnormal long-term persistence of aluminum hydroxide particles within macrophages at the site of previous immunization. Patients present with diffuse arthromyalgias, chronic fatigue, and cognitive dysfunction. The aim of this study was to characterize brain FDG-PET metabolic abnormalities in MMF patients, and the relation with cognitive dysfunction. METHODS: FDG-PET brain imaging and a comprehensive battery of neuropsychological tests were performed in 100 consecutive MMF patients (mean age, 45...
October 20, 2016: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Cory M Smith, Terry J Housh, Nathaniel D M Jenkins, Ethan C Hill, Kristen C Cochrane, Amelia A Miramonti, Richard J Schmidt, Glen O Johnson
The purposes of the present study were to apply a unique method for the identification of the time course of changes in neuromuscular responses and to infer the motor unit activation strategies used to maintain force during a fatiguing, intermittent isometric workbout. Eleven men performed 50, 6 s intermittent isometric muscle actions of the leg extensors, each separated by 2 s of rest at 60% maximal voluntary isometric contraction (MVIC). Electromyographic (EMG) and mechanomyographic (MMG) amplitude (root mean square; RMS) and frequency (mean power frequency; MPF) were obtained from the vastus lateralis (VL) every 5 of the 50 repetitions and normalized as a percent of the initial repetition...
October 18, 2016: Physiological Measurement
Marc Jubeau, Thomas Rupp, John Temesi, Stéphane Perrey, Bernard Wuyam, Guillaume Y Millet, Samuel Verges
PURPOSE: Prolonged cycling exercise performance in normoxia is limited due to both peripheral and central neuromuscular impairments. It has been reported that cerebral perturbations are greater during short-duration exercise in hypoxia compared to normoxia. The purpose of this study was to test the hypothesis that central deficits are accentuated in hypoxia compared to normoxia during prolonged (3 bouts of 80 min separated by 25 min) whole-body exercise at the same relative intensity...
October 6, 2016: Medicine and Science in Sports and Exercise
Yasuhide Yoshitake, Hiroaki Kanehisa, Minoru Shinohara
PURPOSE: The purpose of this study was to determine the modulation of common low-frequency oscillations in pools of motor units across antagonistic muscles due to the difference in the activation level of pools of spinal motor neurons and the presence of neuromuscular fatigue during intended co-contraction. METHODS: Ten healthy young men (21.8 ± 1.5 yr) performed intended steady co-contractions of elbow flexors and extensors at maximal and a submaximal (10% of maximal electromyogram, EMG) effort...
October 6, 2016: Medicine and Science in Sports and Exercise
David A Shearer, William Sparkes, Jonny Northeast, Daniel J Cunningham, Christian J Cook, Liam P Kilduff
OBJECTIVES: Biochemical (e.g. creatine kinase (CK)) and neuromuscular (e.g. peak power output (PPO)) markers of recovery are expensive and require specialist equipment. Perceptual measures are an effective alternative, yet most validated scales are too long for daily use. DESIGN: This study utilises a longitudinal multi-level design to test an adapted Brief Assessment of Mood (BAM+), with four extra items and a 100mm visual analogue scale to measure recovery. METHODS: Elite under-21 academy soccer players (N=11) were monitored across five games with data (BAM+, CK and PPO) collected for each game at 24h pre, 24h and 48h post-match...
October 5, 2016: Journal of Science and Medicine in Sport
Gregory Roe, Joshua Darrall-Jones, Kevin Till, Padraic Phibbs, Dale Read, Jonathon Weakley, Ben Jones
PURPOSE: The purpose of this study was to evaluate changes in performance of a 6-second cycle ergometer test (CET) and countermovement jump (CMJ) during a 6-week training block in professional rugby union players. METHODS: Twelve young professional rugby union players performed two CET and CMJ on the first and fourth morning of every week prior to the commencement of daily training during a 6-week training block. Standardised changes in the highest score of two CET and CMJ efforts were assessed using linear mixed modelling and magnitude-based inferences...
October 13, 2016: International Journal of Sports Physiology and Performance
Thashi Chang, Judith Cossins, David Beeson
BACKGROUND: Congenital myasthenic syndromes (CMSs) occur as a result of genetic mutations that cause aberrations in structure and/or function of proteins involved in neuromuscular transmission. Acetylcholine receptor epsilon (ε) subunit (CHRNE) gene mutations account for about 30-50 % of genetically diagnosed cases. We report a rare CHRNE gene mutation in a South Asian female with CMS. CASE PRESENTATION: A 17-year-old Maldivian female presented with bilateral partial ptosis, fatigable proximal muscle weakness and slurring of speech noted since the age of 2 years...
October 7, 2016: BMC Neurology
T K Khong, V S Selvanayagam, S K Sidhu, A Yusof
Carbohydrate (CHO) depletion is linked to neuromuscular fatigue during exercise. While its role at peripheral level is relatively well understood, less is known about its impact centrally. The aim of this systematic review was to critically analyze the effects of CHO on central fatigue (CF) assessed by various neurophysiological techniques. Four databases were searched using PRISMA guidelines through February 2016. The inclusion criteria were: CHO as intervention against a placebo control, fatigue induced by prolonged exercise and assessed using neurophysiological measures [voluntary activation (VA), superimposed twitch (SIT), M-wave, electromyography], alongside maximal voluntary contraction (MVC)...
October 7, 2016: Scandinavian Journal of Medicine & Science in Sports
Daniel B Drachman
The basic abnormality in myasthenia gravis (MG) is a reduction in acetylcholine receptors (AChRs) at neuromuscular junctions due to the effects of autoantibodies that are directed against the AChRs in most patients, or against neighboring proteins involved in the clustering of AChRs (MuSK, LRP-4, or agrin). Clinically, MG is characterized by muscle weakness and fatigue, often in typical patterns. The diagnosis may be missed early, and depends on the recognition of clinical manifestations, the measurement of autoantibodies, and/or electrophysiological features...
October 2016: Seminars in Neurology
Marcus Yung, Richard P Wells
Many contemporary occupations are characterised by long periods of low loads. These lower force levels, which are relevant to the development of work-related musculoskeletal disorders, are usually not the focus of fatigue studies. In studies that did measure fatigue in light manual or precision work, within and between measurement responses were inconsistent. The aim of this study was to identify fatigue measures that were responsive at lower force levels (<10% MVC) over the course of an 8-h period. A complementary set of fatigue measures, reflecting both neuromuscular and cognitive mechanisms, was measured during a light precision micro-pipetting task performed by 11 participants...
October 14, 2016: Ergonomics
João Gustavo Claudino, John Cronin, Bruno Mezêncio, Daniel Travis McMaster, Michael McGuigan, Valmor Tricoli, Alberto Carlos Amadio, Julio Cerca Serrão
OBJECTIVES: The primary objective of this meta-analysis was to compare countermovement jump (CMJ) performance in studies that reported the highest value as opposed to average value for the purposes of monitoring neuromuscular status (i.e., fatigue and supercompensation). The secondary aim was to determine the sensitivity of the dependent variables. DESIGN: Systematic review with meta-analysis. METHODS: The meta-analysis was conducted on the highest or average of a number of CMJ variables...
August 25, 2016: Journal of Science and Medicine in Sport
Clécio Gabriel de Souza, Daniel Tezoni Borges, Liane de Brito Macedo, Jamilson Simões Brasileiro
Low-level laser therapy (LLLT) has been suggested as a resource capable of increasing resistance to fatigue and enhancing muscle performance through its metabolic and photochemical effects. This study evaluated the immediate effects of the application of LLLT on neuromuscular performance of the plantar ankle flexors in healthy subjects through a fatigue-induced protocol. This is a randomized controlled clinical trial, attended by 60 young and physically active volunteers of both genders. The subjects were randomly assigned into three groups, control, placebo, and laser, and underwent a preliminary evaluation of the isokinetic performance of plantar flexors and electromyographic activity of the soleus muscle to ensure homogeneity between groups...
September 17, 2016: Lasers in Medical Science
Thomas Cattagni, Clément Billet, Christophe Cornu, Marc Jubeau
CONTEXT: The prolonged tendon vibration may induce muscle fatigue, as assessed by a decrease in maximal force production. It remains however unknown whether the decrease in muscle strength after prolonged Achilles tendon vibration is related to the vibration frequency. OBJECTIVE: This study aimed to assess the maximal capacity of plantar flexor neuromuscular function before and after prolonged Achilles tendon vibration at low and high frequencies generated using a portable device...
August 24, 2016: Journal of Sport Rehabilitation
Ram Haddas, Steven F Sawyer, Phillip S Sizer, Toby Brooks, Ming-Chien Chyu, C Roger James
INTRODUCTION: Recurrent LBP (rLBP) and neuromuscular fatigue are independently thought to increase the risk of lower extremity (LE) injury. Volitional preemptive abdominal contraction (VPAC) is thought to improve lumbar spine and pelvis control in individuals with rLBP. The effects of VPAC on fatigued landing performance in individuals with rLBP are unknown. OBJECTIVES: To determine the effects of VPAC and LE fatigue on landing performance in a rLBP population. DESIGN: Cross-sectional pretest-posttest cohort control design...
August 24, 2016: Journal of Sport Rehabilitation
Kathryn A Webster, Brian G Pietrosimone, Phillip A Gribble
CONTEXT:  Ankle instability is a common condition in physically active individuals. It often occurs during a jump landing or lateral motion, particularly when participants are fatigued. OBJECTIVE:  To compare muscle activation during a lateral hop prefatigue and postfatigue in individuals with or without chronic ankle instability (CAI). DESIGN:  Cross-sectional study. SETTING:  Sports medicine research laboratory...
September 14, 2016: Journal of Athletic Training
Fernando Pareja-Blanco, Luis Sánchez-Medina, Luis Suárez-Arrones, Juan José González-Badillo
AIM: To analyze the effects of two resistance training (RT) programs that used the same relative loading but different repetition volume, using the velocity loss during the set as the independent variable: 15% (VL15) vs. 30% (VL30). METHODS: Sixteen professional soccer players with RT experience (age 23.8 ± 3.5 years, body mass 75.5 ± 8.6 kg) were randomly assigned to two groups: VL15 (n = 8) or VL30 (n = 8) that followed a 6-week (18 sessions) velocity-based squat training program...
September 6, 2016: International Journal of Sports Physiology and Performance
Francesco Bombelli, Ludovico Lispi, Sandro Costanzi Porrini, Manlio Giacanelli, Chiara Terracciano, Roberto Massa, Antonio Petrucci
OBJECTIVES: Weakness and fatigue are frequent symptoms in myotonic dystrophy type 1 (DM1), mainly as a result of muscle impairment. However, neuromuscular junction (NMJ) abnormalities could play an additional role in determining these manifestations. We aimed to document the possible NMJ involvement in DM1. PATIENTS AND METHODS: In order to substantiate this hypothesis we performed low rate repetitive nerve stimulation (RNS) and single fiber electromyography (SFEMG), in 14 DM1 subjects...
November 2016: Clinical Neurology and Neurosurgery
Wei Chen, Qing-Fang Meng, Jun-Kang Sui, Yan-Jun Wang, Xiao-Li Li, Shen Liu, Heng Li, Cong-Cong Wang, Chun-Hong Li, Yan-Bin Li
Myasthenia gravis (MG) is an autoimmune neuromuscular disease characterized by fatigue and muscle weakness. Ginseng is used in the treatment of MG. Ginsenoside Rb1 (G-Rb1), the most abundant ginsenoside in ginseng root, has been proved to be immune regulatory in various diseases. In this study, we investigated the effects and mechanisms of G-Rb1 in treatment for MG in a rat model. Our data showed that G-Rb1 treatment markedly ameliorated the symptoms of experimental autoimmune myasthenia gravis (EAMG) rats, decreased the percentage of Th17 cells in mononuclear cells (MNCs), and increased the number of Treg and Th2 cells in MNCs...
September 2, 2016: International Immunopharmacology
Hidemi Misawa, Daijiro Inomata, Miseri Kikuchi, Sae Maruyama, Yasuhiro Moriwaki, Takashi Okuda, Nobuyuki Nukina, Tomoyuki Yamanaka
VAChT-Cre.Fast and VAChT-Cre.Slow mice selectively express Cre recombinase in approximately one half of post-natal somatic motor neurons. The mouse lines have been used in various studies with selective genetic modifications in adult motor neurons. In the present study, we crossed VAChT-Cre lines with a reporter line, CAG-Syp/tdTomato, in which synaptophysin-tdTomato fusion proteins are efficiently sorted to axon terminals, making it possible to label both cell bodies and axon terminals of motor neurons. In the mice, Syp/tdTomato fluorescence preferentially co-localized with osteopontin, a recently discovered motor neuron marker for slow-twitch fatigue-resistant (S) and fast-twitch fatigue-resistant (FR) types...
September 6, 2016: Genesis: the Journal of Genetics and Development
Stuart Goodall, Kevin Thomas, Robert Hunter, Paul Parker, Gareth Woolley, Liam Harper, Emma Stevenson, Daniel West, Mark Russell, Glyn Howatson
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
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