Search results for "Movement"
showing 10 items of 2021 documents
Determining the location of the body׳s center of mass for different groups of physically active people
2013
The purpose of the present study was to compare the location of the body center of mass (CoM) determined by using a high accuracy reaction board (RB) and two different segment parameter models for motion analysis (Dempster, 1955, DEM and de Leva, 1996 adjusted from Zatsiorsky and Seluyanov, ZAT). The body CoM (expressed as percentage of the total body height) was determined from several subjects including athletes as well as physically active students and sedentary people. Some significant differences were found in the location of the body CoM between the used segment models and the reaction board method for all male subjects (n=58, 57.03±0.79%, 56.20±0.76% and 57.60±0.76% for RB, ZAT and D…
Visual inference of arm movement is constrained by motor representations
2015
International audience; Several studies support the idea that motion inference is strongly motor dependent. In the present study, we address the role of biomechanical constraints in motion prediction and how this implicit knowledge can interfere in a spatial prediction task. Right-handed (RHS) and left-handed subjects (LHS) had to estimate the final position of a horizontal arm movement in which the final part of the trajectory was hidden. Our study highlighted a direction effect: end point prediction accuracy was better to infer the final position of horizontal motion directed toward the median line of human body. This finding suggests that the spatial prediction of end point is mapped ont…
Impaired control of an action after supplementary motor area lesion: A case study
2000
The kinematics of the action formed by reaching-grasping an object and placing it on a second target was studied in a patient who suffered from an acute vascular left brain lesion, which affected the Supplementary Motor Area proper (SMA-proper) (Matelli M, Luppino G. Thalamic input to mesial and superior area 6 in the macaque monkey. Journal of Comparative Neurology 1996;372:59-87, Matelli M, Luppino G, Fogassi L, Rizzolatti G. Thalamic input to inferior area 6 and area 4 in the macaque monkey. Journal of Comparative Neurology 1989;280:468-488), and in five healthy control subjects. The reach kinematics of the controls was affected by the positions of both the reaching-grasping and the plac…
Daily modulation of the speed–accuracy trade-off
2017
International audience; Goal-oriented arm movements are characterized by a balance between speed and accuracy. The relation between speed and accuracy has been formalized by Fitts’ law and predicts a linear increase in movement duration with task constraints. Up to now this relation has been investigated on a short-time scale only, that is during a single experimental session, although chronobiological studies report that the motor system is shaped by circadian rhythms. Here, we examine whether the speed–accuracy trade-off could vary during the day. Healthy adults carried out arm-pointing movements as accurately and fast as possible toward targets of different sizes at various hours of the …
Context-dependent neuroelectric responses during motor control
2015
Abstract Research on brain responses during motor control is usually performed under typical laboratory settings. However, everyday life and the laboratory differ in many aspects, such as purposeful and motivated behavior; and there's no awareness of “being measured” in everyday life. In the laboratory, movements are usually explicitly instructed, overtly measured and follow no intrinsic motivated purpose. Therefore, here we present a new method to measure and reliably analyze neuroelectric brain responses by EEG, as well as kinematics during the performance of grasping movements in two different behavioral contexts. One context (L) simulates a typical laboratory task and another context (E…
Anticipatory strategies of team-handball goalkeepers
2011
This study seeks to discover whether handball goalkeepers employ a general anticipatory strategy when facing long distance throws and the effect of uncertainty on these strategies. Seven goalkeepers and four throwers took part. We used a force platform to analyse the goalkeeper's movements on the basis of reaction forces and two video cameras synchronised at 500 Hz to film the throw using 3D video techniques. The goalkeepers initiated their movement towards the side of the throw 193 ± 67 ms before the release of the ball and when the uncertainty was reduced the time increased to 349 ± 71 ms. The kinematics analysis of their centre of mass indicated that there was an anticipatory strategy of…
Dynamic angular three-dimensional measurement of multisegmental thoracolumbar motion in vivo.
2008
Study design Method validation and in vivo motion segment study. Objective To determine in healthy subjects in vivo intervertebral segmental kinematics and coupled motion behavior in all 3 planes simultaneously for 3 segments and to evaluate whether these results differ from those in the normal population according to the literature. Summary of background data Few studies have provided a direct invasive approach to investigate segmental kinematics in vivo. Dynamic recordings of 3-dimensional segmental motion patterns of adjacent segments have rarely been reported. To date, no studies have examined the 3-dimensional segmental movements of the thoracolumbar junction in vivo in detail. Methods…
Effects of neuromuscular function and split step on reaction speed in simulated tennis response
2013
The purpose of this study was to examine whether split step (small hop before step) would be more beneficial than no-split condition in simulated tennis response situation. In addition, it was studied if movement time of the response is related to separately measured force production capabilities and reflex sensitivity of the players. Nine skilled male tennis players participated in this study. Subjects stood on a force plate and reacted to a light signal and moved to appointed direction as fast as possible. With split step the participants were 13.1% faster (P <0.05) than without split step from the start to the distal end of the so called close range movement continuum (2.70 m). This was …
Analyzing gastrocnemius EMG-activity and sway data from quiet and perturbed standing.
2007
In an experiment, we combined force plate measurements and surface EMG in studying quiet and perturbed standing, involving MS (Multiple sclerosis) and controls. The aim of this paper is to report the results thus obtained on the relation between filtered gastrocnemius (GA) EMG and the anterior-posterior center-of-pressure (A/P COP) coordinate. The main finding is the good correspondence between A/P COP and the filtered GA EMG in the low frequency range. The EMG envelope was calculated using a zero-lag filter. Combining this with time shifts around 250-350 ms produced a high correlation (85.5+/-8.4%) between the GA-EMG envelope and the A/P COP. This EMG-COP relation was closest when using a …
A comparison of the triceps surae and residual muscle moments at the ankle during cycling.
1991
The rigid linked system model and principles of inverse dynamics have been widely used to calculate residual muscle moments during various activities. EMG driven models and optimization algorithms have also been presented in the literature in efforts to estimate skeletal muscle forces and evaluate their possible contribution to the residual muscle moment. Additionally, skeletal muscle-tendon forces have been measured, directly, in both animals and humans. The purpose of this investigation was to calculate the moment produced by the triceps surae muscles and compare it to the residual muscle moment at the ankle during cycling at three power outputs (90, 180 and 270 W). Inferences were made r…