Change Of Coordinates Research Articles

Comparison of alterations in local field potentials and neuronal firing in mouse M1 and CA1 associated with central fatigue induced by high-intensity interval training and moderate-intensity continuous training.

The mechanisms underlying central fatigue (CF) induced by high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) are still not fully understood. In order to explore the effects of these exercises on the functioning of cortical and subcortical neural networks, this study investigated the effects of HIIT and MICT on local field potential (LFP) and neuronal firing in the mouse primary motor cortex (M1) and hippocampal CA1 areas. HIIT and MICT were performed on C57BL/6 mice, and simultaneous multichannel recordings were conducted in the M1 motor cortex and CA1 hippocampal region. A range of responses were elicited, including a decrease in coherence values of LFP rhythms in both areas, and an increase in slow and a decrease in fast power spectral density (PSD, n = 7-9) respectively. HIIT/MICT also decreased the gravity frequency (GF, n = 7-9) in M1 and CA1. Both exercises decreased overall firing rates, increased time lag of firing, declined burst firing rates and the number of spikes in burst, and reduced burst duration (BD) in M1 and CA1 (n = 7-9). While several neuronal firing properties showed a recovery tendency, the alterations of LFP parameters were more sustained during the 10-min post-HIIT/MICT period. MICT appeared to be more effective than HIIT in affecting LFP parameters, neuronal firing rate, and burst firing properties, particularly in CA1. Both exercises significantly affected neural network activities and local neuronal firing in M1 and CA1, with MICT associated with a more substantial and consistent suppression of functional integration between M1 and CA1. Our study provides valuable insights into the neural mechanisms involved in exercise-induced central fatigue by examining the changes in functional connectivity and coordination between the M1 and CA1 regions. These findings may assist individuals engaged in exercise in optimizing their exercise intensity and timing to enhance performance and prevent excessive fatigue. Additionally, the findings may have clinical implications for the development of interventions aimed at managing conditions related to exercise-induced fatigue.

Современная детская книжная иллюстрация: композиция, пространство, движение, время

The composition in a modern children’s book is associated with solving the problems of space and movement. Dynamics is part of the structure of the book, the book design system is determined by the movement of the plot, the principles of reception, the rhythm of the font and the alternation of images are dynamic. The principles of space construction in a modern children’s book are associated with the leading means of artistic expression of the art of graphics. The space of the book turns into a narrative, a space of history; narrative space acts as the theme of the image, and the void is also narrative as a kind of figure of silence. Space as an artistic technique uses the principles of panorama, division into plans, and the location of the horizon line. The transformation of time in the structure of a modern children’s book is focused on the concept of dialogue between the plot and the image. Time uses a reception complex, focusing on perception, viewing, interactive practices, book design can use the principle of repetition and return. The epoch style and font can mark the epoch. Space and time act in book design as a system of plot development, a spacetime continuum. The time of the narration, the time of the artist and the time of the viewer can exist in a synchronous and diachronic format. Time as a character change involves the interpretation of a theme, a change in spatial coordinates, search, study, movement. The use of a certain point of view and foreshortening in the composition of a modern children’s book illustration can be achieved by the technique of duplication of viewing, an image «from the back» or from above, a panoramic view and fragmentation. Classical «pictorial» composition and spatial construction are often used. The theme of movement in the composition of the book is associated with the popularity of the type of travelogue book (tales of wandering-the formation of a hero, educational literature, travel literature, guidebooks). Methods of constructing space in the book composition system – top view, angular composition, combination of spatial plans, close-up. The dynamics of the font correlates with the dynamics of the text, the letters «come to life». Several effects associated with new media: animation, cinematic effect of space, theatricalization, imitation of a recognizable screensaver. The serial nature of the images can apply a sequential arrangement of the stages of movement, «storyboard», step-bystep approach or removal of the object, dialogic composition, close-up.

Multi-User Tracking in Reconfigurable Intelligent Surface Aided Near-Field Wireless Communications System

An uplink multi-user tracking problem aided by multiple passive reconfigurable intelligent surfaces (RISs) is addressed in this work. Under a near-field circumstance, a multi-antenna base station (BS) localizes multiple moving single-antenna users by processing the received signals transmitted by users and reflected by RISs. Considering the users’ mobility and the potential obstruction of line-of-sight paths, a multi-user tracking system based on the extended Kalman filter (EKF) which fully exploits the temporal correlations between each user’s coordinate changes is designed. Then, the Bayesian Cramér–Rao bound (BCRB) of tracking errors is derived in a pattern consistent with the EKF process. Subsequently, an optimization scheme for passive phase shift design at the RISs is devised by minimizing the derived BCRB and is solved using the Gradient Descent method. Numerical results indicate that the accuracy of our tracking algorithm can approach the BCRB. With abundant RISs deployed and optimized, high-precision multi-user tracking via a single BS can be realized even in harsh localization environments.

Few sex-specific effects of fatigue on muscle synergies in a repetitive pointing task

Previous studies have identified some sex differences in how individual muscles change their activation during repetitive multi-joint arm motion-induced fatigue. However, little is known about how indicators of multi-muscle coordination change with fatigue in males and females. Fifty-six (29 females) asymptomatic young adults performed a repetitive, forward-backward pointing task until scoring 8/10 on a Borg CR10 scale while surface electromyographic activity of upper trapezius, anterior deltoid, biceps brachii, and triceps brachii was recorded. Activation coefficient, synergy structure, and relative weight of each muscle within synergies were calculated using the non-negative matrix factorization method. Two muscle synergies were extracted from the fatiguing task. The synergy structures were mostly preserved after fatigue, while the activation coefficients were altered. A significant Sex × Fatigue interaction effect showed more use of the anterior deltoid in males especially before fatigue in synergy 1 during shoulder stabilization (p = 0.04). As for synergy 2, it was characterized by variations in the relative weight of biceps, which was higher by 16 % in females compared to males (p = 0.04), and increased with fatigue (p = 0.03) during the elbow flexion acceleration phase and the deceleration phase of the backward pointing movement. Findings suggest that both sexes adapted to fatigue similarly, using fixed synergy structures, with alterations in synergy activation patterns and relative weights of individual muscles. Results support previous findings of an important role for the biceps and anterior deltoid in explaining sex differences in patterns of repetitive motion-induced upper limb fatigue.

Changes in Care Associated With Integrating Medicare and Medicaid for Dual-Eligible Individuals

There is growing interest in expanding integrated models, in which 1 insurer manages Medicare and Medicaid spending for dually eligible individuals. Fully integrated dual-eligible special needs plans (FIDE-SNPs) are one of the largest integrated models, but evidence about their performance is limited. To evaluate changes in care associated with integrating Medicare and Medicaid coverage in a FIDE-SNP in Pennsylvania. This cohort study using a difference-in-differences analysis compared changes in care between 2 cohorts of dual-eligible individuals: (1) an integration cohort composed of Medicare Dual Eligible Special Needs Plan enrollees who joined a companion Medicaid plan following a 2018 state reform mandating Medicaid managed care (leading to integration), and (2) a comparison cohort with nonintegrated coverage before and after the start of Medicaid managed care. Analyses were conducted between February 2022 and June 2023. Analyses examined outcomes in 4 domains: use of home- and community-based services (HCBS), care management and coordination, hospital stays and postacute care, and long-term nursing home stays. The study included 7967 individuals in the integration cohort and 3832 individuals in the comparison cohort. In the integration cohort, the mean (SD) age at baseline was 63.3 (14.7) years, and 5268 individuals (66.1%) were female and 2699 (33.9%) were male. In the comparison cohort, the mean (SD) age at baseline was 64.8 (18.6) years, and 2341 individuals (61.1%) were female and 1491 (38.9%) were male. At baseline, integration cohort members received a mean (SD) of 2.83 (8.70) days of HCBS per month and 3.34 (3.56) medications for chronic conditions per month, and the proportion with a follow-up outpatient visit after a hospital stay was 0.47. From baseline through 3 years after integration, HCBS use increased differentially in the integration vs comparison cohorts by 0.61 days/person-month (95% CI, 0.28-0.94; P < .001). However, integration was not associated with changes in care management and coordination, including medication use for chronic conditions (-0.02 fills/person-month; 95% CI, -0.10 to 0.06; P = .65) or follow-up outpatient care after a hospital stay (-0.01 visits/hospital stay; 95% CI, -0.04 to 0.03; P = .61). Hospital stays did not change differentially between the cohorts. Unmeasured factors contributing to differential mortality limited the ability to identify changes in long-term nursing home stays associated with integration. In this cohort study with a difference-in-differences analysis of 2 cohorts of individuals dually eligible for Medicare and Medicaid, integration was associated with greater HCBS use but not with other changes in care patterns. The findings highlight opportunities to strengthen how integrated programs manage care and a need to further evaluate their performance.

Boron coordination and three‐membered ring formation in sodium borate glasses: a machine‐learning molecular dynamics study

AbstractClassical molecular dynamics (CMD) simulations that employ analytical force fields have been commonly utilized to investigate mechanical, chemical, and thermal properties of oxide glasses owing to their superior computational efficiency. Conversely, simple functional forms limit the accuracy in modeling complicated glass structures, specifically, in alkaline borate glasses, which exhibit boron coordination numbers that vary nonlinearly with changes in glass composition and temperature. Machine‐learning potentials (MLPs), which are trained using datasets on energy and force evaluated via the density functional theory (DFT), are garnering significant attention as a novel simulation technology for enhancing the accuracy in modeling materials. Therefore, this study applied a universal MLP, PreFerred Potential (PFP) (trade‐name: Matlantis), to model sodium borate glasses, and its accuracy was verified in reproducing boron coordination and ring structures by comparing its results to available experimental data. We found that PFP can quantitatively reproduce the boron coordination change with glass composition without any empirical correction, while the boron coordination in the melts at high temperatures is overestimated, even though the qualitative variation was better estimated than CMD simulations. Furthermore, the MLP could generate many 3‐rings, unlike the analytical force‐field. Accordingly, we demonstrated superior accuracy of the MLP in modeling alkaline borate glasses, while discussing the challenges faced in reproducing the elaborated microstructures in borate glasses.

Choline alfoscerate in the correction of cognitive impairment

In preclinical and clinical studies, choline alfoscerate (CA) has proven to be highly effective in the correction of cognitive impairment (CI). The clinical effect of CA is seen in the improvement of mental activity, concentration, ability to remember and recall information, cognitive and behavioural responses, elimination of emotional instability and apathy. Experimental studies have shown the effectiveness of CA in preventing atrophic changes in the cerebral cortex. Based on several studies conducted on the use of CA in the treatment of CI, it can be concluded that oral administration of CA at a dose of 600 mg/day can be recommended both as monotherapy and as part of complex therapy in patients with cerebrovascular diseases such as chronic cerebral ischemia. As part of complex therapy for CI in Alzheimer's disease, a combination of CA at a dose of 1200 mg/day with donepezil at a dose of 10 mg/day may be recommended. Several studies have demonstrated the efficacy of CA in the treatment of post-COVID and post-traumatic CI. The efficacy of CA administration in the treatment of CI (including vascular dementia) following ischemic stroke and transient ischemic attacks has been demonstrated. When CA is taken, there is also a reduction in anxiety and depressive disorders, asthenia, the severity of pain symptoms and changes in coordination. The duration of therapy should be 60 to 90 days, depending on the severity of CI, followed by an observation phase of up to 2 years. For successful treatment with CA, it is necessary to carry out repeated courses of CI treatment. Today, a new drug Cerpechol (600 mg/7 ml) has appeared on the Russian market, which has all the effects of CA. The convenience of the new form (oral solution) makes it possible to use it in patients with swallowing disorders.

Coupling during collective cell migration is controlled by a vinculin mechanochemical switch.

The ability of cells to move in a mechanically coupled, coordinated manner, referred to as collective cell migration, is central to many developmental, physiological, and pathophysiological processes. Limited understanding of how mechanical forces and biochemical regulation interact to affect coupling has been a major obstacle to unravelling the underlying mechanisms. Focusing on the linker protein vinculin, we use a suite of Förster resonance energy transfer-based biosensors to probe its mechanical functions and biochemical regulation, revealing a switch that toggles vinculin between loadable and unloadable states. Perturbation of the switch causes covarying changes in cell speed and coordination, suggesting alteration of the friction within the system. Molecular scale modelling reveals that increasing levels of loadable vinculin increases friction, due to engagement of self-stabilizing catch bonds. Together, this work reveals a regulatory switch for controlling cell coupling and describes a paradigm for relating biochemical regulation, altered mechanical properties, and changes in cell behaviors.

Assessment of Muscle Coordination Changes Caused by the Use of an Occupational Passive Lumbar Exoskeleton in Laboratory Conditions.

The introduction of exoskeletons in industry has focused on improving worker safety. Exoskeletons have the objective of decreasing the risk of injury or fatigue when performing physically demanding tasks. Exoskeletons' effect on the muscles is one of the most common focuses of their assessment. The present study aimed to analyze the muscle interactions generated during load-handling tasks in laboratory conditions with and without a passive lumbar exoskeleton. The electromyographic data of the muscles involved in the task were recorded from twelve participants performing load-handling tasks. The correlation coefficient, coherence coefficient, mutual information, and multivariate sample entropy were calculated to determine if there were significant differences in muscle interactions between the two test conditions. The results showed that muscle coordination was affected by the use of the exoskeleton. In some cases, the exoskeleton prevented changes in muscle coordination throughout the execution of the task, suggesting a more stable strategy. Additionally, according to the directed Granger causality, a trend of increasing bottom-up activation was found throughout the task when the participant was not using the exoskeleton. Among the different variables analyzed for coordination, the most sensitive to changes was the multivariate sample entropy.

Higher-order chain rules for tensor fields, generalized Bell polynomials, and estimates in Orlicz-Sobolev-Slobodeckij and total variation spaces

We describe higher-order chain rules for multivariate functions and tensor fields. We estimate Sobolev-Slobodeckij norms, Musielak-Orlicz norms, and the total variation seminorms of the higher derivatives of tensor fields after a change of variables and determine sufficient regularity conditions for the coordinate change. We also introduce a novel higher-order chain rule for composition chains of multivariate functions that is described via nested set partitions and generalized Bell polynomials; it is a natural extension of the Faà di Bruno formula. Our discussion uses the coordinate-free language of tensor calculus and includes Fréchet-differentiable mappings between Banach spaces.

Back to the present: A general treatment for the tidal field from the wake of dynamical friction

Context.Dynamical friction can be a valuable tool for inferring dark matter properties that are difficult to constrain by other methods. Most applications of dynamical friction calculations are concerned with the long-term angular momentum loss and orbital decay of the perturber within its host. This, however, assumes knowledge of the unknown initial conditions of the system.Aims.We advance an alternative methodology to infer the host properties from the perturber’s shape distortions induced by the tides of the wake of dynamical friction, which we refer to as the tidal dynamical friction.Methods.As the shape distortions rely on the tidal field that has a predominantly local origin, we present a strategy to find the local wake by integrating the stellar orbits back in time along with the perturber, then removing the perturber’s potential and re-integrating them back to the present. This provides perturbed and unperturbed coordinates and hence a change in coordinates, density, and acceleration fields, which yields the back-reaction experienced by the perturber.Results.The method successfully recovers the tidal field of the wake based on a comparison withN-body simulations. We show that similar to the tidal field itself, the noise and randomness of the dynamical friction force due to the finite number of stars is also dominated by regions close to the perturber. Stars near the perturber influence it more but are smaller in number, causing a high variance in the acceleration field. These fluctuations are intrinsic to dynamical friction. We show that a stellar density of 0.0014 M⊙ kpc−3yields an inherent variance of 10% to the dynamical friction.Conclusions.The current method extends the family of dynamical friction methods that allow for the inference of host properties from tidal forces of the wake. It can be applied to specific galaxies, such as Magellanic Clouds, withGaiadata.

Spectrum Modelling as a Method for Temperature Correction of Organic Light Emitting Diodes Based on Three-Component Structures

OLED technology is widely used in various displays, which operate in a wide range of temperatures. For such devices, it is necessary to maintain the luminance and chromaticity coordinates at the given level when the external temperature changes. In this work, a program was developed that, based on the electro-physical characteristics and electroluminescence spectra of a white OLED sample at different temperatures and currents, as well as the spectral characteristics of the coloured filters, allows for selection of currents in the range of (1–25) mA, applied to each subpixel in such a way as to converge the chromaticity coordinates to the specified values. Various chromaticity coordinates were tested in the process of program execution, including CIE sources of type A, type B, type C, and type D65. In each of these cases, the program significantly reduced the difference in chromaticity coordinate changes with temperature. The obtained results will be used for gamma correction of micro-displays produced at the Cyclone Research Institute during their operation at a wide range of temperatures.

Hands-on visualization of the effect of fictitious forces with a laser pointer

Inertial motion looks like accelerated motion when observed from the point of view of a non-inertial reference frame. A non-inertial observer can then describe the trajectories by introducing fictitious forces, like the centrifugal and Coriolis forces, that arise from the coordinate change between reference frames. This well-known fact is part of the typical Physics syllabus for undergraduate scientists and engineers, and a number of interesting classroom demonstrations have been discussed in the literature. We present a complementary possibility for the visualization of the effect of fictitious forces by shining a blue laser beam on a rotating platform covered with a phosphorescent vinyl sheet. The laser can be moved in order to simulate inertial motion in the laboratory frame for the trajectory of the laser spot. This gets immediately imprinted in the rotating phosphorescent material resulting in non-inertial trajectories that can be readily observed and compared to the dynamics governed by fictitious forces. Since friction is not considered, this hands-on activity can be considered as a direct demonstration of the effect of pure fictitious forces in and out of the classroom. The approach is simple, inexpensive, fast and non-destructive, and can therefore be very convenient for active lecture demonstrations or individual activities of students. We also describe some educational possibilities of how to use the procedure in the classroom or in the laboratory.

Structural and Chemical Evolution of Highly Fluorinated Li‐Rich Disordered Rocksalt Oxyfluorides as a Function of Temperature

AbstractLi‐rich disordered rocksalt (DRS) oxyfluorides have emerged as promising high‐energy cathode materials for lithium‐ion batteries. While a high level of fluorination in DRS materials offers performance advantages, it can only be achieved via mechanochemical synthesis, which poses challenges of reproducibility and scalability. The definition of relationships between fluorination and structural stability is required to devise alternative methods that overcome these challenges. In this study, the thermal evolution of three highly fluorinated phases, Li2TMO2F (TM = Mn, Co, and Ni), is investigated in an inert atmosphere. Diffraction and spectroscopic techniques are utilized to examine their electronic and chemical states up until conditions of decomposition. The analysis reveals that the materials phase‐separate above 400 °C, at most. It is also observed that heat‐treated DRS materials exhibit intricate changes in the local coordination of the metals, including their spin, and ordering compared to the pristine states. The changes upon annealing are accompanied by a modulation of the voltage profile, including reduced hysteresis, when used as electrodes. These results provide an in‐depth understanding of the fundamental crystal chemistry of DRS oxyfluorides in view of their promising role as the next generation of Li‐ion cathodes.

Онтологические и аксиологические аспекты в оценке современного образования

The modern socio-cultural situation is characterized by the change of value coordinates, the breakdown of the familiar world and significant transformations in various spheres and areas. Most significantly, these changes affect the field of education, which is an essential element of spiritual culture. The content of educational pro-grams reflects the demands of modern society to the individual, to the complex of those competencies that he should possess. In the life of an individual and society as a whole, education should become an instrument of humanization, which is aimed at cognition and improvement of the world and oneself. In modern socio-cultural life, education is a significant sphere in which the development and realization of creative and spiritual poten-tial takes place. Education cannot be characterized as a certain amount of knowledge broadcast from the teacher to the student, its primary task is to create conditions for the process of cognition of the individual him-self and the surrounding world. Formation of worldview culture, which includes learned and accepted universal values, aspirations to improve their personal and professional qualities, is the aim and value of modern educa-tion.

Enhanced motor learning and motor savings after acute intermittent hypoxia are associated with a reduction in metabolic cost.

Breathing mild bouts of low oxygen air (i.e. acute intermittent hypoxia, AIH) has been shown to improve locomotor function in humans after a spinal cord injury. How AIH-induced gains in motor performance are achieved remains unclear. We examined the hypothesis that AIH augments motor learning and motor retention during a locomotor adaptation task. We further hypothesized that gains in motor learning and retention will be associated with reductions in net metabolic power, consistent with the acquisition of energetically favourable mechanics. Thirty healthy individuals were randomly allocated into either a control group or an AIH group. We utilized a split-belt treadmill to characterize adaptations to an unexpected belt speed perturbation of equal magnitude during an initial exposure and a second exposure. Adaptation was characterized by changes in spatiotemporal step asymmetry, anterior-posterior force asymmetry, and net metabolic power. While both groups adapted by reducing spatial asymmetry, only the AIH group achieved significant reductions in double support time asymmetry and propulsive force asymmetry during both the initial and the second exposures to the belt speed perturbation. Net metabolic power was also significantly lower in the AIH group, with significant reductions from the initial perturbation exposure to the second. These results provide the first evidence that AIH mediates improvements in both motor learning and retention. Further, our results suggest that reductions in net metabolic power continue to be optimized upon subsequent learning and are driven by more energetically favourable temporal coordination strategies. Our observation that AIH facilitates motor learning and retention can be leveraged to design rehabilitation interventions that promote functional recovery. KEY POINTS: Brief exposures to low oxygen air, known as acute intermittent hypoxia (AIH), improves locomotor function in humans after a spinal cord injury, but it remains unclear how gains in motor performance are achieved. In this study, we tested the hypothesis that AIH induces enhancements in motor learning and retention by quantifying changes in interlimb coordination, anterior-posterior force symmetry and metabolic cost during a locomotor adaptation task. We show the first evidence that AIH improves both motor learning and savings of newly learned temporal interlimb coordination strategies and force asymmetry compared to untreated individuals. We further demonstrate that AIH elicits greater reductions in metabolic cost during motor learning that continues to be optimized upon subsequent learning. Our findings suggest that AIH-induced gains in locomotor performance are facilitated by enhancements in motor learning and retention of more energetically favourable coordination strategies.

Local well-posedness of the plasma-vacuum interface problem for the ideal incompressible MHD

In this article, we consider the plasma-vacuum interface problem for the incompressible ideal MHD. The plasma magnetic field is tangential to the interface while the vacuum magnetic field vanishes. We shall prove the stability of the interface under the Taylor sign condition. By deriving the evolution equation of the interface in the Eulerian coordinates, we are able to identify different stability mechanisms which correspond to the hyperboliticity of this evolution equation. Once the optimal regularity of the interface is obtained, all the other quantities can be estimated in the Eulerian coordinates. Therefore, we do not need the change of coordinates or the use of the Alinhac's good unknowns.

Melanopsin enhances image persistence

Contributions of the inner retinal photopigment melanopsin to human visual perception are incompletely understood. Here, we use a four-primary display to produce stimuli differing in melanopsin versus cone contrast in psychophysical paradigms in eight subjects with normal color vision. We address two predictions from electrophysiological recordings of the melanopsin system in non-human mammals: melanopsin influences color and/or supports image persistence under visual fixation. We first construct chromatic contrast sensitivity contours for stimuli differing in melanopsin excitation presented as a central annulus (10°) or peripheral (22.5°) spot. We find that although including melanopsin contrast produces modest changes in the average chromatic coordinates in both eccentricities, this occurs equally at low (0.5Hz) and higher (3.75Hz) temporal frequencies, arguing that it reflects divergence in cone spectral sensitivity in our participants from that captured in standardized cone fundamentals rather than a melanopsin contribution to color. We continue to ask whether the established ability of melanopsin to sustain firing of visual neurons under extended light exposure has a visual correlate, using the optical illusion of Troxler fading in which blurred spots in periphery disappear during visual fixation. We find that introducing additional melanopsin contrast (+28% Michelson contrast) to either bright or dark spots increases fading latency by 35%± 8.8% and 41%± 13.6%, respectively. Our data argue that the primary contribution of melanopsin to perception under these conditions isnot to provide a color percept but rather to enhance persistence of low spatial frequency patterns during visual fixation.

Neural correlates of weight-shift training in older adults: a randomized controlled study

Mediolateral weight-shifting is an important aspect of postural control. As it is currently unknown whether a short training session of mediolateral weight-shifting in a virtual reality (VR) environment can improve weight-shifting, we investigated this question and also probed the impact of practice on brain activity. Forty healthy older adults were randomly allocated to a training (EXP, n = 20, age = 70.80 (65–77), 9 females) or a control group (CTR, n = 20, age = 71.65 (65–82), 10 females). The EXP performed a 25-min weight-shift training in a VR-game, whereas the CTR rested for the same period. Weight-shifting speed in both single- (ST) and dual-task (DT) conditions was determined before, directly after, and 24 h after intervention. Functional Near-Infrared Spectroscopy (fNIRS) assessed the oxygenated hemoglobin (HbO2) levels in five cortical regions of interest. Weight-shifting in both ST and DT conditions improved in EXP but not in CTR, and these gains were retained after 24 h. Effects transferred to wider limits of stability post-training in EXP versus CTR. HbO2 levels in the left supplementary motor area were significantly increased directly after training in EXP during ST (change < SEM), and in the left somatosensory cortex during DT (change > SEM). We interpret these changes in the motor coordination and sensorimotor integration areas of the cortex as possibly learning-related.

Relationships Between Task Constraints, Visual Constraints, Joint Coordination and Football-Specific Performance in Talented Youth Athletes: An Ecological Dynamics Approach.

Individual performance in team sports is a multifactorial reflection of how well a player can cope and accomplish tasks in varied playing situations. Thus, performance analysis should not only focus on outcomes, but also on underlying mechanisms of those outcomes. We adopted principles of the ecological dynamics approach (EDA) to investigate the effect of introducing constraints on players' joint coordination responses for a football-specific performance drill outcome. Seventeen talented youth football (soccer) players performed a football-specific drill under different conditions: basic constraints, additional defender dummies, stroboscopic glasses, and a combination of the latter two constraints. We recorded these players' execution time, passing accuracy, and lower extremity joint kinematics. We calculated joint coordination for hip-knee, knee-ankle, and trunk-hip couplings. The added constraints negatively affected execution time and passing accuracy, and caused changes in joint coordination. Furthermore, we identified a relationship between execution time and joint coordination. This study serves as an example how the EDA can be adopted to investigate mechanisms that underlie individual performance in team sports.