Motor Control最新文献

Fatigue experienced by individuals with multiple sclerosis (MS) during activities of daily living affects their balance and increases the risk of falls. The aim was to assess the effect of fatigue induced by a functional task on balance control in individuals with MS. The study involved 10 individuals with MS and 10 gender-matched healthy volunteers who performed a functional sit-to-stand task using a standardized chair and metronome until they reported an inability to continue. Motor Control and Sensory Organization tests were implemented using Dynamic Posturography three times: before, immediately after fatigue, and after a 30-min rest period. The Motor Control Test revealed that individuals with MS, compared to healthy controls, showed significantly longer latencies during small, medium, and large amplitudes of backward perturbation. Longer latencies were observed in the MS group after fatigue, specifically during small and large amplitudes of forward perturbations. The Sensory Organization Test discovered that following fatigue, the MS group demonstrated significantly lower equilibrium scores compared with healthy controls in the following conditions: eyes closed (p < .001), sway-referenced visual surround (p = .02), and sway-referenced support surface (p = .03). Functional fatigue induced by sit-to-stand tasks significantly impacted outcomes of both the Motor Control and Sensory Organization tests of balance control in individuals with MS. These findings lay the groundwork for future investigations into the role of fatigue in balance control in individuals with MS.

Despite the main clinical criteria for Autism Spectrum Disorder (ASD) diagnosis being the dysfunction of socio-communicative interaction abilities and the presence of restricted interests and repetitive behaviors, sensory-motor dysfunctions are also frequently observed in this population. Moreover, among sensory-motor issues, both postural control and visual processing may be impaired. The main aim of this scoping review is to synthesize the evidence on the relationship between visual behavior and postural control dysfunctions in children and adolescents with ASD. This scoping review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol, Extension for Scoping Reviews guidelines, and was registered a priori on the Open Science Framework. PubMed, CINAHL, Embase, PsycINFO, Scopus, and Web of Science databases were consulted. Primary studies with any study design were included. No time, geographical, or study setting limitations or language restrictions were applied. A total of 646 articles were found in the initial search, but only 14 studies met the full inclusion criteria. Findings highlighted that studies on the relationship between vision and posture in ASD children and adolescents are scarce, and their results are contrasting because of the significant heterogeneity in the methods. This scoping review carried out a relevant survey of the literature considering the relationship between vision and posture in ASD. Nonetheless, the characteristics of the included sample and the methodology used in the analyzed studies were highly variable. Thus, rigorous study methods with population-specific objective outcome measures are needed to draw generalizable conclusions.

Anterior cruciate ligament reconstruction (ACLR) can result in persistent deficits in postural stability particularly under dual-task conditions involving cognitive demands. This study investigated the effects of cognitive tasks from different domains on postural control among individuals with ACLR compared with healthy controls. Twenty-five individuals with ACLR and 25 asymptomatic matched controls performed three cognitive tasks of backward counting (working memory), Stroop Color-Word Test (executive function), and Benton's Judgment of Line Orientation (visuospatial perception) under single- (seated) and dual-task (single-leg stance on rigid and foam surfaces) conditions. Postural stability was quantified by measuring center-of-pressure sway area and sway velocity in anterior-posterior and medial-lateral directions. Cognitive performance was evaluated by counting task errors. Results indicated significantly greater postural sway in the ACLR group compared with controls across all tasks (p < .01), with the Stroop Color-Word Test significantly increasing mean sway velocity compared with the no-task condition (p < .01) in only the ACLR group. ACLR participants also demonstrated consistently greater cognitive errors under all conditions. However, cognitive errors were not significantly affected by increased postural difficulty. Findings suggest that executive function tasks uniquely exacerbate postural control deficits following ACLR, highlighting the clinical importance of incorporating targeted cognitive-postural training focusing on executive control into rehabilitation protocols.

Different attentional focus strategies are commonly employed in sports training, with the external focus of attention (EF) strategy shown to enhance performance in the standing long jump. However, the underlying muscular dynamics responsible for this improvement remain unclear. In this study, we utilized a Latin square design to recruit 12 healthy male participants, each undergoing standing long jump testing under EF, internal focus (IF), and control conditions. During the take-off phase, we synchronously recorded kinematic and dynamic data. Inverse dynamics calculations were performed on the dynamic and kinematic data. Compared with IF and control, the EF condition exhibited longer jump distances, lower projection angles, and higher peak horizontal take-off velocities and impulses alongside increased center of mass displacement during the eccentric phase and decreased center of mass displacement during the concentric phase (p < .05). The peak muscle force and rate of muscle force development of the vastus lateralis, vastus medialis, vastus intermedius, and gluteus maximus during the take-off phase were also higher in the EF group (p < .05). These results indicate that the EF strategy optimizes standing long jump mechanics by enhancing the efficiency of eccentric muscle contractions, thereby increasing stored elastic potential energy in the muscles. Consequently, this leads to greater muscle force and rate of muscle force development during the concentric phase, ultimately resulting in increased jump distances.

Introduction: Chronic ankle instability (CAI) is a common sequela of lateral ankle sprains that impairs postural stability during functional tasks. External biofeedback may be an appropriate rehabilitation tool to improve functional movement; however, more research is needed to determine its effectiveness in dynamic tasks in individuals with CAI. This study aimed to assess the effect of real-time external biofeedback via laser on dynamic postural stability indices during a single-limb forward hop-to-stabilization task in participants with CAI.

Methods: Eighteen participants with CAI completed five successful forward hop-to-stabilization jumps with and without external biofeedback using a single-dot laser attached to the distal tibia. A single inertial measurement unit fastened to the lower back captured dynamic postural stability indices in the vertical, anterior-posterior, medial-lateral, and the resultant of each plane during the 5 s after landing. The mean difference between biofeedback and no biofeedback was assessed using independent t tests.

Results: Our results indicate no significant differences were observed between forward hop-to-stabilization tasks with and without real-time external biofeedback in individuals with CAI.

Discussion: More research is needed to determine the appropriate biofeedback tool location and modality type of external biofeedback in addition to the minimum amount of training exposure to improve dynamic postural stability during a single-limb landing task.

The review is based on theoretical advances in the field of motor control that view the neural control of movements as a subfield of natural science. We accept the theory of hierarchical control of movements with basic commands, reciprocal, and coactivation, at different levels of the hierarchy, from the control of whole-body actions to the control of individual joints and digits. The principle of abundance views the numerous elements participating in all actions as an important feature that allows movements to combine dynamical stability with adaptability. This principle is readily compatible with the uncontrolled manifold hypothesis. These concepts have been applied to analysis of consequences of fatigue, natural aging, and a range of neurological disorders, from large-fiber peripheral neuropathy to brain disorders. Mechanisms of rehabilitation of movement disorders and improvement of motor performance are discussed. Important pieces of information are missing in the described theoretical frameworks in particular those related to mapping between the theoretical levels of control and coordination and neurophysiological circuitry. New directions of studies are sketched that may lead to progress in understanding applied aspects of motor control.

Background: Individuals with Parkinson's disease (PD) with freezing of gait (FoG) exhibit difficulty with changes in sensory input, indicating a potential sensorimotor integration deficit. Understanding how levodopa impacts balance particularly in FoG, is critical. As traditional postural sway measures may not fully capture the complexity of balance control, rambling and trembling decomposition of the center of pressure allows a more detailed assessment of postural control by distinguishing between supraspinal and spinal contributions, offering insights into sensorimotor integration deficits. This study aims to analyze the effects of medication and FoG on rambling and trembling in quiet standing in individuals with PD.

Methods: We analyzed 13 individuals with PD with FoG (PD freezers) and 19 individuals with PD without FoG (PD nonfreezers) while quiet standing on a rigid and malleable surface under (ON) and without (OFF) dopaminergic medication. Area, root mean square, and mean velocity were calculated for rambling and trembling trajectory.

Results: For the rambling, all variables were significantly higher on the malleable compared with the rigid surface. For trembling, (a) all variables were higher on the malleable compared with the rigid surface (p < .001), and (b) area and medial-lateral root mean square were significantly higher ON compared with OFF medication for both groups of participants similarly.

Conclusion: Our results strengthen the evidence that PD freezers have the same postural sway in quiet posture as PD nonfreezers, using similar mechanisms to control the posture. In addition, levodopa influences spinal mechanisms more than supraspinal ones in individuals with PD in quiet standing.

Task difficulty is a major factor that affects postural control and stability. However, there is little information about the effects of task difficulty on postural control during gait termination in combination with a manual task. The present study investigated postural control during combined gait termination and a manual task with different levels of manual task difficulty. Right-handed, healthy young adults (n = 15) performed five trials of combined gait termination with a manual fitting task for each of four different manual task conditions, varying target size (large and small) and distance (short and long). Average time-to-contact of the center of pressure and upper body (sternum) was assessed in three separate phases of the combined task: preparation, reaching, and stabilization phases. Longer reaching distance reduced time-to-contact not only in the reaching phase but also in both the preparation and stabilization phases. However, there were no effects of target size on time-to-contact. These results indicate that increasing manual task demands requires integration throughout gait termination and can impact postural stabilization after task completion even in young healthy adults.

Background: Increased sway within a stationary base of support (BoS) is often interpreted as worse postural control. However, larger persons may have larger feet, facilitating broader sway patterns within their wider/longer base. Time to boundary (TtB) incorporates foot placement dimensions into the calculation and, thus, may not be confounded by dissimilar anthropometric features.

Methods: Ninety-seven healthy adults stood quietly on a force platform for 150 s with their feet together while barefoot. BoS characteristics, center of pressure motion, and TtB were calculated and correlated with body height for eyes open and closed conditions.

Results: BoS width, length, and total area positively correlated with body height. Path length and sway area were positively correlated with height for both vision conditions, with stronger correlations observed with eyes closed. At the same time, TtB was not correlated with height in either visual condition. Consequently, the tallest 20 individuals in the sample displayed greater path length and sway areas but equal TtB as the shortest 20 persons.

Conclusion: Observed differences in position-based center of pressure measures could be an artifact of body size inequality not postural (in)stability. Meanwhile, TtB is normalized to BoS and is, therefore, not confounded by anthropometric differences.