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Motor Control

Marcio Jose Dos Santos, Renato Claudino, Giovana Zarpellon Mazzo
The goal of this study was to investigate the timing of compensatory postural adjustments (CPAs) in older adults during body perturbations in the mediolateral direction, circumstances that increase their risk of falls. The latencies of leg and trunk muscle activation to body perturbations at the shoulder level and variables of center of pressure (COP) excursion, which characterize postural stability, were analyzed in 40 older adults (non-fallers and fallers evenly split) and in 20 young participants. The older adults exhibited longer latencies of muscular activation in 8 out of 15 postural muscles as compared to young participants; for three muscles, the latencies were longer for the older fallers than non-fallers...
October 21, 2016: Motor Control
Aaron Manzanares, Ruperto Menayo, Francisco Segado
In a sport conditioned by natural elements such as sailing, visual perception is a key factor for the performance. The research has shown that the visual behaviour of athletes at different skill levels varies, which may cause differences in the performance achieved. The aim of this research was to examine the visual behaviour of sailors from different ranking positions at the start of a race in a simulated situation. Twenty junior sailors (N=10 top and N=10 bottom ranking) participated in the study. The visual behaviour was recorded at the start of a sailing simulation...
October 21, 2016: Motor Control
Bianca Miarka, Katarzyna Sterkowicz-Przybycien, David H Fukuda
The purpose of the present study was to create a probabilistic neural network (PNN) to clarify the understanding of movement patterns in international judo competitions by gender. Analysis of 773 male and 638 female bouts was utilized to identify movements during the approach, gripping, attack (including biomechanical designations), groundwork, defense, and pause phases. PNN and χ(2) tests modeled and compared frequencies (p≤0.05). Women (mean[interquartile range]: 9.9[4;14]) attacked more than men (7.0[3;10]) while attempting a greater number of arm/leg lever (women: 2...
October 13, 2016: Motor Control
Tyler W D Muddle, David H Fukuda, Ran Wang, Joshua J Riffe, David D Church, Kyle S Beyer, Jay R Hoffman, Jeffrey R Stout
This study examined the effect of a 10-week introductory judo course on postural control during a bilateral reactionary gripping task using varied stance conditions. Twenty volunteers were divided into experimental (JDO) or control (CON) groups. Countermovement jump (CMJ) was measured and center of pressure (COP) variables were evaluated while performing a bilateral reactionary gripping task under varied stance conditions during pre and post testing. No interactions were observed for the COP variables (p>0...
October 13, 2016: Motor Control
Preeti D Oza, Shauna Dudley-Javoroski, Richard K Shields
H-reflex depression (diminution of amplitude after a conditioning stimulus) is mediated presynaptically and therefore can help distinguish central versus peripheral mechanisms of fatigue. We examined the effects of a dynamic exercise protocol on H-reflex depression using two conditioning methods: homonymous conditioning (paired-pulse tibial nerve stimulation); and heteronymous conditioning (common peroneal nerve stimulation). Ten subjects performed dynamic contractions of the soleus muscle through 30° ankle range of motion...
October 13, 2016: Motor Control
Ângela Fernandes, Andreia S P Sousa, Nuno Rocha, João Manuel R S Tavares
The aim of this study was to compare postural control strategies during gait initiation in single- and dual-task conditions in individuals in early stages of Parkinson´s Disease (PD). The activation timing of tibialis anterior occurred significantly later in the individuals with PD than in the controls (p=0.05), and a significant interaction between the groups, conditions and limbs was found (p=0.027). Differences between the single- and dual-task conditions were observed for the activation timing of the tibialis anterior (p=0...
August 19, 2016: Motor Control
Tiago M Barbosa, Wan Xiu Goh, Jorge E Morais, Mário J Costa
The aim was to examine the variation of linear and nonlinear proprieties of the behaviour in participants with different levels of swimming expertise among the four swim strokes. Seventy-five swimmers were split into three groups (highly qualified experts, experts and non-experts) and performed a maximal 25m trial for each of the four competitive swim strokes. A speed-meter cable was attached to the swimmer's hip to measure hip speed; from which speed fluctuation (dv), approximate entropy (ApEn) and fractal dimension (D) variables were derived...
August 19, 2016: Motor Control
Mark L Latash
Living systems may be defined as systems able to organize new, biology-specific, laws of physics and modify their parameters for specific tasks. Examples include the force-length muscle dependence mediated by the stretch reflex, and the control of movements with modification of the spatial referent coordinates for salient performance variables. Low-dimensional sets of referent coordinates at a task level are transformed to higher-dimensional sets at lower hierarchical levels in a way that ensures stability of performance...
August 19, 2016: Motor Control
Marco Tramontano, Alessandra Medici, Marco Iosa, Alessia Chiariotti, Giulia Fusillo, Leonardo Manzari, Daniela Morelli
BACKGROUND: Cerebral palsy (CP) has been defined as a non-progressive disease of movement and posture development. Physical therapy techniques use different forms of sensory stimulation to improve neuromotor development. AIM: The aim of this study was to assess the efficacy of a vestibular stimulation training in improving motor functions in cerebral palsy. POPULATION: Fourteen children with CP were randomly separated into two different groups in a cross-over trial...
August 19, 2016: Motor Control
Rupal Mehta, Marco Cannella, Sharon M Henry, Susan Smith, Simon Giszter, Sheri P Silfies
Trunk muscle timing impairment has been associated with non-specific low back pain (NSLBP), but this finding has not been consistent. This study investigated trunk muscle timing in a subgroup of patients with NSLBP attributed to movement coordination impairment (MCI) and matched asymptomatic controls in response to a rapid arm-raising task. Twenty-one NSLBP subjects and 21 matched controls had arm motion and surface EMG data collected from 7 bilateral trunk muscles. Muscle onset and offset relative to deltoid muscle activation and arm motion, duration of muscle burst and abdominal-extensor co-contraction time were derived...
August 19, 2016: Motor Control
Hiroko Tanabe, Keisuke Fujii, Motoki Kouzaki
We aimed to investigate joint coordination of lower limbs in dancers during tiptoe standing and the relationship between joint coordination and muscle co-activation. Seven female ballet dancers performed tiptoe standing with six leg positions (five classical dance positions and one modern dance position) for 10 s. The kinematic data of the metatarsophalangeal (MP), ankle, knee, and hip joints was collected, and surface electromyography (EMG) of over 13 lower limb muscles was conducted. Principal component analysis was performed to determine joint coordination...
August 19, 2016: Motor Control
Haidzir Manaf, Maria Justine, Hui-Ting Goh
Attentional loadings deteriorate straight walking performance for individuals post-stroke, but its effects on turning while walking remain to be determined. Here we compared turning kinematics under three attentional loading conditions (single, dual-motor, and dual-cognitive task) between stroke survivors and healthy controls. Nine chronic stroke survivors and 10 healthy controls performed the Timed Up-and-Go test while their full-body kinematics were recorded. Onset times of yaw rotation of the head, thorax and pelvis segments and head anticipation distance were used to quantify turning coordination...
August 19, 2016: Motor Control
Daniel Feeney, Igor Jelaska, Mehmet Uygur, Slobodan Jaric
We examined the effects of unilateral muscle fatigue on the performance and coordination of grip (GF; normal component acting between the hand and object) and load force (LF; tangential component) in bimanual manipulation tasks, as well as the associated lateral differences. Eleven participants performed various symmetric bimanual tasks either without fatigue, or after fatiguing the GF producing muscles of either the non-dominant or dominant hand. The GF/LF ratio of the fatigued and non-fatigued hand decreased and increased, respectively, while the neither the effects of fatigue on the task performance and GF-LF coordination, nor the lateral differences were revealed...
August 19, 2016: Motor Control
Kelly Jones, Karen Croot
There are few investigations comparing practice schedules in speech motor learning, despite certain schedules being recommended for the clinical treatment of speech motor disorders. This study compared effects of random, blocked and mixed practice on tongue twister accuracy in unimpaired speakers. We hypothesized that blocked practice would benefit acquisition of learning, but that random practice and mixed blocked-then-random practice would yield superior retention of learning. We found that the random and blocked-random practice schedules yielded superior accuracy at the end of the acquisition phase of learning and at a 1-week retention test...
October 2016: Motor Control
Paul G Taylor, Michael Small, Kwee-Yum Lee, Raul Landeo, Damien M O'Meara, Emma L Millett
Entropy is an effective tool for investigation of human movement variability. However, before applying entropy, it can be beneficial to employ analyses to confirm that observed data are not solely the result of stochastic processes. This can be achieved by contrasting observed data with that produced using surrogate methods. Unlike continuous movement, no appropriate method has been applied to discrete human movement. This article proposes a novel surrogate method for discrete movement data, outlining the processes for determining its critical values...
October 2016: Motor Control
Tsung-Yu Hsieh, Matheus M Pacheco, Karl M Newell
The goal of present experiment was to test whether different speed-accuracy paradigms outcomes (time minimization and time matching) were due to different temporal and spatial task constraints. Fifteen participants twice performed 100 trials of time minimization and time matching tasks with the yoked temporal and spatial requirements (criterion time and target width). The results showed that performing an aiming movement under the same spatial and temporal constraints resulted in similar outcomes with distributional properties (skewness and kurtosis) being slightly affected by practice effects...
October 2016: Motor Control
Hideyuki Tanaka, Wataru Mizuno, Masato Iwami
This study used a pantomime paradigm to investigate whether simulated motor actions are generally effective in estimating the force necessary to accurately drive an object toward the required target. Eleven subjects were asked to vertically throw a rubber ball toward three different targets and then catch it, all while sitting in a chair (ACT). In addition, they performed the same task under a condition whereby mechanical interactions with the rubber ball were minimized. This condition encompassed two different modes: pantomime (PANTO) and imagination without swings (IMAGE)...
October 2016: Motor Control
Markus Janczyk, Wilfried Kunde
According to the Perception-Action-Model (PAM), the human visual cortex consists of the ventral vision-for-perception and the dorsal vision-for-action streams. Performance decrements with increasing variation of nominally task-irrelevant stimulus features (Garner-Interference) was suggested as an empirical tool for identifying contributions of these streams: vision-for-perception, but not visionfor-action, should suffer from Garner-Interference, but inconsistencies in this argument were revealed by several studies...
October 2016: Motor Control
Olav Raastad, Tore Kristian Aune, Roland van den Tillaar
The aim of this study was to investigate if making the skill acquisition phase more difficult or easier would enhance performance in soccer juggling, and if this practice has a positive intertask transfer effect to ball reception performance. Twenty-two adolescent soccer players were tested in juggling a soccer ball and in the control of an approaching ball at a pre, post and retention test. The participants were randomly divided in a small ball size and bigger ball size training group that both trained four times per week for 6 weeks...
October 2016: Motor Control
Katherine G Holste, Alia L Yasen, Matthew J Hill, Anita D Christie
The purpose of this study was to assess the effect of a cognitive task on motor cortex excitability and inhibition. Transcranial magnetic stimulation of the motor cortex was performed on 20 healthy individuals (18-24 years; 9 females) to measure motor evoked potentials (MEPs) and cortical silent periods at baseline, during, and following a secondary cognitive task. The MEP amplitude increased from 0.50 ± 0.09-0.87 ± 0.50 mV during a secondary cognitive task (p = .04), and returned to baseline (0.48 ± 0.31 mV; p = ...
October 2016: Motor Control
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