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https://www.readbyqxmd.com/read/29144602/neuroplasticity-following-short-term-strength-training-occurs-at-supraspinal-level-and-is-specific-for-the-trained-task
#1
Louis-Solal Giboin, Benjamin Weiss, Felix Thomas, Markus Gruber
AIMS: Different modalities of strength training cause performance enhancements, which are specific for the trained task. However, the involved mechanisms are still largely unknown. It has been demonstrated that strength training could induce neuroplasticity, which might underlie the performance improvements during the first training sessions. Thus, we hypothesized to find task-specific neuroplasticity after a short-term strength training of two distinct strength tasks. METHODS: Young healthy male subjects were exposed to 4 sessions of either maximal isometric explosive (EXPL group, N = 9) or slow sustained (SUS group, N = 10) knee extensions...
November 16, 2017: Acta Physiologica
https://www.readbyqxmd.com/read/29142099/assessing-tms-induced-d-and-i-waves-with-spinal-h-reflexes
#2
Niclas Niemann, Patrick Wiegel, Alexander Kurz, John C Rothwell, Christian Leukel
Transcranial magnetic stimulation (TMS) of motor cortex produces a series of descending volleys known as D- (direct) and I- (indirect) waves. In the present study, we questioned whether spinal H-reflexes can be used to dissect D-waves, early and late I-waves from TMS. We therefore probed H-reflex facilitation at arrival times of D- and I-waves at the spinal level and thereby changed TMS parameters that have previously been shown to have selective effects on evoked D- and different I-waves. We changed TMS intensity and current direction, and applied a double-pulse paradigm known as short-interval intracortical inhibition (SICI)...
November 15, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29140761/limb-segment-load-inhibits-the-recovery-of-soleus-h-reflex-after-segmental-vibration-in-humans
#3
Shih-Chiao Tseng, Richard K Shields
We investigated the effects of vertical vibration and compressive load on soleus H-reflex amplitude and postactivation depression. We hypothesized that, in the presence of a compressive load, limb vibration induces a longer suppression of soleus H-reflex. Eleven healthy adults received vibratory stimulation at a fixed frequency (30 Hz) over two loading conditions (0% and 50% of individual's body weight). H-reflex amplitude was depressed ∼88% in both conditions during vibration. Cyclic application of compression after cessation of the vibration caused a persistent reduction in H-reflex excitability and postactivation depression for > 2...
November 15, 2017: Journal of Motor Behavior
https://www.readbyqxmd.com/read/29126270/neural-plasticity-with-age-unilateral-maximal-strength-training-augments-efferent-neural-drive-to-the-contralateral-limb-in-older-adults
#4
Tiril Tøien, Runar Unhjem, Thomas Storehaug Øren, Ann Charlotte Gjertsen Kvellestad, Jan Hoff, Eivind Wang
Efferent neural drive during strong muscle contractions is attenuated with age, even after lifelong strength training. However, it is unknown if this deterioration may impede contralateral neural plasticity, and limit the clinical value of unilateral strength training. We assessed muscle force-generating capacity, evoked potentials recordings (V-wave and H-reflex normalized to M-wave; V/M-ratio and H/M-ratio) and voluntary activation (VA) in the plantar flexors of the contralateral limb following unilateral maximal strength training (MST) with the dominant limb for three weeks (9 sessions)...
November 4, 2017: Journals of Gerontology. Series A, Biological Sciences and Medical Sciences
https://www.readbyqxmd.com/read/29119209/relationship-between-spasticity-and-spinal-neural-circuits-in-patients-with-chronic-hemiparetic-stroke
#5
Kohei Okuyama, Michiyuki Kawakami, Miho Hiramoto, Kaori Muraoka, Toshiyuki Fujiwara, Meigen Liu
Spasticity is a common problem in patients with stroke that contributes to motor dysfunction. However, the pathophysiological mechanisms underlying spasticity are not fully understood. The purpose of the present study was to explain the relationship between features of spinal neural circuits assessed using electrophysiological techniques and the clinical manifestations of stroke. The participants were 71 patients with chronic hemiparetic stroke. To assess spinal neural circuits, Hmax/Mmax of the forearm flexor muscles and reciprocal inhibition (RI) between forearm extensor and flexor muscles with the H reflex conditioning-test paradigm were measured...
November 8, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/29118191/effects-of-muscle-action-type-on-corticospinal-excitability-and-triceps-surae-muscle-tendon-mechanics
#6
Pedro Valadao, Sadao Kurokawa, Taija Finni, Janne Avela
This study investigated if the specific motor control strategy reported for eccentric muscle actions is dependent of muscle mechanical behavior. Motor-evoked potentials (MEP), Hoffman reflex (H-reflex), fascicle length (FL), pennation angle (PA) and fascicle velocity (FV) of soleus (SOL) muscle were compared between isometric and two eccentric conditions. Ten volunteers performed maximal plantarflexion trials in isometric, slow eccentric (25º/s) and fast eccentric (100º/s) conditions, each on a different randomized testing session...
November 8, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29096208/changes-in-the-soleus-h-reflex-test-and-correlations-between-its-results-and-dynamic-magnetic-resonance-imaging-abnormalities-in-patients-with-hirayama-disease
#7
Chaojun Zheng, Yu Zhu, Feizhou Lu, Dongqing Zhu, Shuo Yang, Xiaosheng Ma, Xinlei Xia, Robert Weber, Jianyuan Jiang
OBJECTIVE: To investigate changes in soleus H-reflex tests in patients with Hirayama disease (HD) and to analyse correlations between these changes and forward-shifting of the cervical cord during neck flexion. METHODS: The amplitude of the soleus H-reflex with and without vibration on the Achilles tendon was recorded bilaterally in 81 HD patients and 34 controls to measure both the vibratory inhibition index (VII) and the Hmax/Mmax ratio. The maximum forward-shifting degree of cervical cord during neck flexion was measured using dynamic magnetic resonance imaging in all HD patients...
October 3, 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/29091318/early-electrophysiological-findings-in-acute-inflammatory-demyelinating-polyradiculoneuropathy-variant-of-guillain-barre-syndrome-in-the-pakistani-population-a-comparison-with-global-data
#8
Ahmed Wali, Sara Khan
Acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and acute motor axonal neuropathy (AMAN) are the most common variants of Guillian Barre syndrome documented in the Asian population. However the variability of early neurophysiologic findings in the Asian population compared to western data has not been documented. Eighty seven cases of AIDP were retrospectively reviewed for their demographic, clinical, electrophysiological and laboratory data. Mean age of subjects was 31 ± 8 years with males more commonly affected...
November 1, 2017: Journal of the Peripheral Nervous System: JPNS
https://www.readbyqxmd.com/read/29055385/is-quadriceps-h-reflex-excitability-a-risk-factor-for-patellofemoral-pain
#9
Marcella Ferraz Pazzinatto, Danilo de Oliveira Silva, Evangelos Pappas, Fernando Henrique Magalhães, Fábio Mícolis de Azevedo
Patellofemoral pain (PFP) is one of the most common conditions in orthopedic practice while recent evidence has suggested that it may be a predisposing factor to patellofemoral osteoarthritis. In addition to biomechanical alterations associated with the pathomechanisms underlying PFP, the investigation of neurophysiological alterations has provided novel information in the understanding of the pathophysiology of PFP. For instance, women with PFP present lower amplitude of the vastus medialis (VM) H-reflexes compared to pain-free controls, which suggests that the excitability of spinal reflexes might be a promising tool for discriminating woman with PFP in clinical practice...
October 2017: Medical Hypotheses
https://www.readbyqxmd.com/read/28951323/preparatory-cortical-and-spinal-settings-to-counteract-anticipated-and-non-anticipated-perturbations
#10
Michael Wälchli, Craig D Tokuno, Jan Ruffieux, Martin Keller, Wolfgang Taube
Little is known about how the central nervous system prepares postural responses differently in anticipated compared to non-anticipated perturbations. To investigate this, participants were exposed to translational and rotational perturbations presented in a blocked (anticipated) and a random (non-anticipated) design. The preparatory setting ('central set') was measured by H-reflexes, motor-evoked potentials (MEPs), and short-interval intracortical inhibition (SICI) shortly before perturbation onset in the soleus of 15 healthy adults...
December 4, 2017: Neuroscience
https://www.readbyqxmd.com/read/28932008/h-reflex-changes-in-adolescents-with-idiopathic-scoliosis-a-randomized-clinical-trial
#11
Mohamed Salaheldien Mohamed Alayat, Ehab Mohamed Abdel-Kafy, Ashraf Mohamed Abdelaal
[Purpose] To detect H-reflex asymmetry and investigate the effect of direction sensitive exercise therapy protocol among patients with thoracolumbar and/or lumbar scoliosis. [Subjects and Methods] Fifty patients (10-17 years), Cobb's angle 10-20 degrees with thoracolumbar and lumbar scoliosis participated in the study. Soleus H-reflex was tested on both sides during prone lying position and standing position. Patients were randomly assigned into two groups. Group I received direction sensitive exercise therapy while the participants in group II received traditional exercise...
September 2017: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28931983/postactivation-depression-of-soleus-h-reflex-increase-with-recovery-of-lower-extremities-motor-functions-in-patients-with-subacute-stroke
#12
Yu Kawaishi, Naoki Matsumoto, Toshiya Nishiwaki, Tatsuro Hirano
[Purpose] The soleus H-reflex is depressed at stimulation rates greater than 0.1 Hz. This reflex depression is referred to as postactivation depression. Postactivation depression reflects the reduced efficacy of the Ia-motoneurons synapses when they are evaluated after a previous activation. The aim of this study was to determine whether the recovery of motor functions in the lower extremities affects the PAD of the soleus H-reflex in patients with subacute stroke undergoing rehabilitation. [Subjects and Methods] Eight patients with subacute stroke patients were recruited...
September 2017: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28922314/temporal-indices-of-ankle-clonus-and-relationship-to-electrophysiologic-and-clinical-measures-in-persons-with-spinal-cord-injury
#13
Kathleen J Manella, Kathryn E Roach, Edelle C Field-Fote
BACKGROUND AND PURPOSE: Clonus arising from plantar flexor hyperreflexia is a phenomenon that is commonly observed in persons with spastic hypertonia. We assessed the temporal components of a biomechanical measure to quantify ankle clonus, and validated these in persons with spasticity due to spinal cord injury. METHODS: In 40 individuals with chronic (>1 year) spinal cord injury, we elicited ankle clonus using a standardized mechanical perturbation (drop test)...
October 2017: Journal of Neurologic Physical Therapy: JNPT
https://www.readbyqxmd.com/read/28892581/direct-current-stimulation-modulates-the-excitability-of-the-sensory-and-motor-fibres-in-the-human-posterior-tibial-nerve-with-a-long-lasting-effect-on-the-h-reflex
#14
Francesco Bolzoni, Roberto Esposti, Carlo Bruttini, Giuseppe Zenoni, Elzbieta Jankowska, Paolo Cavallari
Several studies demonstrated that transcutaneous direct current stimulation (DCS) may modulate central nervous system excitability. However, much less is known about how DC affects peripheral nerve fibres. We investigated the action of DCS on motor and sensory fibres of the human posterior tibial nerve, with supplementary analysis in acute experiments on rats. In forty human subjects, electric pulses at the popliteal fossa were used to elicit either M-waves or H-reflexes in the Soleus, before (15 min), during (10 min) and after (30 min) DCS...
September 11, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28863075/hyperthermia-induced-neural-alterations-impair-proprioception-and-balance
#15
Khouloud Mtibaa, Athol Thomson, David Nichols, Christophe Hautier, Sébastien Racinais
PURPOSE: Hyperthermia has been shown to affect both central and peripheral nervous systems. However, the consequences of these alterations on the proprioceptive mechanisms underlying human movement control remain unclear. The aim of this study was to investigate the effect of passive hyperthermia on various measures of proprioception and balance, two key components of injury prevention and movement efficiency. METHODS: Following a familiarization session, 14 volunteers (8 males, 6 females) completed 2 experimental sessions in temperate (CON, 24°C) and hot (HOT, 44-50°C) conditions, in a counterbalanced order...
August 31, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28843638/local-vibration-inhibits-h-reflex-but-does-not-compromise-manual-dexterity-and-does-not-increase-tremor
#16
Francesco Budini, Luca Laudani, Sergio Bernardini, Andrea Macaluso
The present work aimed at investigating the effects of local vibration on upper limb postural and kinetic tremor, on manual dexterity and on spinal reflex excitability. Previous studies have demonstrated a decrease in spinal reflex excitability and in force fluctuations in the lower limb but an increase in force fluctuation in the upper limbs. As hand steadiness is of vital importance in many daily-based tasks, and local vibration may also be applied in movement disorders, we decided to further explore this phenomenon...
August 24, 2017: Human Movement Science
https://www.readbyqxmd.com/read/28841667/the-effects-of-d-aspartic-acid-supplementation-in-resistance-trained-men-over-a-three-month-training-period-a-randomised-controlled-trial
#17
RANDOMIZED CONTROLLED TRIAL
Geoffrey W Melville, Jason C Siegler, Paul W M Marshall
CONTEXT: Research on d-aspartic acid (DAA) has demonstrated increases in total testosterone levels in untrained men, however research in resistance-trained men demonstrated no changes, and reductions in testosterone levels. The long-term consequences of DAA in a resistance trained population are currently unknown. OBJECTIVE: To evaluate the effectiveness of DAA to alter basal testosterone levels over 3 months of resistance training in resistance-trained men. DESIGN: Randomised, double-blind, placebo controlled trial in healthy resistance-trained men, aged 18-36, had been performing regular resistance training exercise for at least 3 d...
2017: PloS One
https://www.readbyqxmd.com/read/28813867/therapeutic-effects-of-anti-gravity-treadmill-alterg-training-on-reflex-hyper-excitability-corticospinal-tract-activities-and-muscle-stiffness-in-children-with-cerebral-palsy
#18
Sh Parvin, A Taghiloo, A Irani, M Mehdi Mirbagheri
We aimed to study therapeutic effects of antigravity treadmill (AlterG) training on reflex hyper-excitability, muscle stiffness, and corticospinal tract (CST) function in children with spastic hemiplegic cerebral palsy (CP). Three children received AlterG training 3 days per week for 8 weeks as experimental group. Each session lasted 45 minutes. One child as control group received typical occupational therapy for the same amount of time. We evaluated hyper-excitability of lower limb muscles by H-reflex response...
July 2017: IEEE ... International Conference on Rehabilitation Robotics: [proceedings]
https://www.readbyqxmd.com/read/28750960/the-effects-of-opposite-directional-static-contraction-of-the-muscles-of-the-right-upper-extremity-on-the-ipsilateral-right-soleus-h-reflex
#19
Tomoko Shiratani, Mitsuo Arai, Hironobu Kuruma, Kazue Masumoto
The objective of this study was to explore the neurophysiological remote after-effects of resistive static contraction (SC) of the muscles of the upper extremity, considering the resistant direction on the ipsilateral (right) soleus H-reflex. The participants included 12 normal subjects with a mean (SD) age of 23.8 (2.8) years. The subjects were asked to maintain their upper extremity against the traction force, at a level of resistance that was 50% of the maximal SC strength. A 20-s SC of the muscles of the upper extremity utilizing contraction of the upper extremity muscles using a diagonal flexion (shoulder flexion-adduction-external rotation) or extension (shoulder extension-abduction-internal rotation), a proprioceptive neuromuscular facilitation (PNF) pattern was induced...
July 2017: Journal of Bodywork and Movement Therapies
https://www.readbyqxmd.com/read/28743726/why-new-spinal-cord-plasticity-does-not-disrupt-old-motor-behaviors
#20
Yi Chen, Lu Chen, Yu Wang, Xiang Yang Chen, Jonathan R Wolpaw
When new motor learning changes the spinal cord, old behaviors are not impaired; their key features are preserved by additional compensatory plasticity. To explore the mechanisms responsible for this compensatory plasticity, we transected the spinal dorsal ascending tract before or after female rats acquired a new behavior-operantly conditioned increase or decrease in the right soleus H-reflex-and examined an old behavior-locomotion. Neither spinal dorsal ascending tract transection nor H-reflex conditioning alone impaired locomotion...
August 23, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
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