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Sensorimotor Impairments and Strategies in Adults with Intellectual Disabilities

Eli Carmeli, Tamar Bar-Yossef, Claudette Ariav, Rosy Paz, Hanna Sabbag, and Ran Levy

Adults with intellectual disabilities (ID) show a greater tendency toward deconditioning and having a sedentary lifestyle than their peers without disabilities. The aim of this study was to characterize sensorimotor deficits through coordination tests and during static and dynamic balance. Eight tasks that involved the integration of hand movements with visual information were used here, as well as the Posture Scale Analyzer system to examine postural stability. During static and dynamic standing tests with the eyes closed, the postural stability of people with ID was accompanied by a small sway rate. In the ID group, the frontal plane movements were significantly larger (p > .05) than the sagittal plane movements. The participants with ID showed a significantly lower score than the control group in all the sensorimotor tests. Our observations on balance and coordination capabilities might have significance for understanding the mechanisms underlying movement dysfunction in adults with ID and offer some new approaches for their possible prevention.

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Unsupported Eyes Closed Sitting and Quiet Standing Share Postural Control Strategies in Healthy Individuals

Murielle Grangeon, Cindy Gauthier, Cyril Duclos, Jean-Francois Lemay, and Dany Gagnon

The study aimed to (1) compare postural stability between sitting and standing in healthy individuals and (2) define center-of-pressure (COP) measures during sitting that could also explain standing stability. Fourteen healthy individuals randomly maintained (1) two short-sitting positions with eyes open or closed, with or without hand support, and (2) one standing position with eyes open with both upper limbs resting alongside the body. Thirty-six COP measures based on time and frequency series were computed. Greater COP displacement and velocity along with lower frequency measures were found for almost all directional components during standing compared with both sitting positions. The velocity, 95% confidence ellipse area, and centroidal frequency were found to be correlated between unsupported sitting and standing. Despite evidenced differences between sitting and standing, similarities in postural control were highlighted when sitting stability was the most challenging. These findings support further investigation between dynamic sitting and standing balance.

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Motor Control Strategies in a Continuous Task Space

Christoph Schütz, Matthias Weigelt, Dennis Odekerken, Timo Klein-Soetebier, and Thomas Schack

Previous studies on sequential effects of human grasping behavior were restricted to binary grasp type selection. We asked whether two established motor control strategies, the end-state comfort effect and the hysteresis effect, would hold for sequential motor tasks with continuous solutions. To this end, participants were tested in a sequential (predictable) and a randomized (nonpredictable) perceptual-motor task, which offered a continuous range of posture solutions for each movement trial. Both the end-state comfort effect and the hysteresis effect were reproduced under predictable, continuous conditions, but only the end-state comfort effect was present under nonpredictable conditions. Experimental results further revealed a work range restriction effect, which was reproduced for the dominant and the nondominant hand.

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Effects of Wearing Slippers While Obstacle Crossing in Healthy Young Adults: Strategy for Toe Clearance Enhancement and Prevention of Slipper Loss

Kento Tanaka, Yusuke Sekiguchi, Keita Honda, and Shin-ichi Izumi

obstacle crossing while wearing slippers compared with level walking or obstacle crossing without wearing slippers. Understanding the strategy for obstacle crossing while wearing slippers may provide a scientific basis for planning rehabilitation programs to prevent falls. Methods Participants Sixteen

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Adaptations in Bilateral Mechanical Power Patterns during Obstacle Avoidance Reveal Distinct Control Strategies for Limb Elevation versus Limb Progression

Assane E.S. Niang and Bradford J. McFadyen

The present study investigated the adaptations of specific power bursts during the combined contexts of the proximity (lead vs. trail limb) and height of an obstruction in relation to limb elevation versus progression. Ten young, adult, male subjects walked at their natural speed during unobstructed walking and the bilateral avoidance of moderate and high obstacles. Hip flexor generation power was unaffected by obstacle height for the leading limb and always delayed for the trailing limb. The knee extensor absorption power burst at toe-off was also eliminated for the trailing limb and was found to reappear in mid-swing. Few differences were seen for ankle push-off power. The results suggest that the hip joint is dedicated to limb advancement only, while the knee joint is directly involved in limb elevation and the control of multiarticular effects.

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The Effect of Load Uncertainty and Foreperiod Regularity on Anticipatory and Compensatory Neuromotor Control in Catching

William P. Berg and Michael R. Hughes

Muscle activation was measured using EMG in 28 males (n = 28) while participants caught visually identical balls of known and unknown weights (50, 1.32, 2.18, and 2.99 kg) under variable (1–10s) and constant (3s) foreperiods. EMG integrals were computed for three time intervals before the catch (anticipatory), and one after (compensatory). Load uncertainty caused the CNS to use an anticipatory strategy characterized by preparation to catch balls of an unknown weight by utilizing about 92% of the muscle activation used to catch the heaviest possible ball under the known weight condition. The CNS appeared to scale anticipatory muscle activation to afford an opportunity to catch a ball of an unknown weight between .50 and 2.99 kg. The constant 3s foreperiod, which permitted temporal anticipation, did not influence the anticipatory neuromotor strategy adopted by the CNS to cope with load uncertainty. Load uncertainty also altered compensatory neuromotor control in catching.

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Experience and Net Worth Affects Optimality in a Motor Decision Task

Heather F. Neyedli and Timothy N. Welsh

Previous research has shown in a motor decision task involving a target (yielding a reward) and overlapping penalty area (yielding a loss), people initially aim closer to the penalty area than optimal. This risky strategy may be adopted to increase target hits, thereby increasing net worth. The purpose of the current study was to determine whether the starting net worth level (either 5,000 or 0 points) affected the influence of task experience on endpoint selection. It was hypothesized the 5,000-point group should adopt a less risky strategy and aim further from the penalty area than those with 0 points. Net worth affected participants’ initial endpoint where the 5,000-point group aimed further from the penalty circle, and closer to the optimal endpoint, than the 0-point group. The 0-point group adapted their endpoint over the course session to aim closer to the optimal endpoint whereas no such change was seen in the 5,000-point group. The results show that changing the participants’ reference point through initial net worth can affect the optimality of participants’ endpoint and how endpoints change with experience.

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A Study of the Effects of Motor Experience on Neuromuscular Control Strategies During Sprint Starts

Zhengye Pan, Lushuai Liu, Yuan Sun, and Yunchao Ma

the task, implying that the neuromuscular control strategy may be a critical factor influencing the performance of the sprint start ( Park & Caldwell, 2022 ). Therefore, the investigation of neuromuscular control strategies for the starting maneuver may provide theoretical references for the training

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The Effect of Nonspecific Task Constraints on Quadrupedal Locomotion: I. Interlimb Coordination

Jill Whitall, Larry Forrester, and Nancy Getchell

The present study examined the effect of nonspecific task constraints on the multilimb coordination task of preferred-speed crawling. Adult subjects undertook three trials each of the following randomly ordered conditions: forward prone (FP), backward supine (BS), backward prone (BP) and forward supine (FS). Subjects adopted specific coordinative solutions consistent with task-related function rather than anatomical specification. The patterns were relatively stable, with BP being least stable. Across conditions, subjects changed their velocity in a predictable order that corresponded to the various constraints. These velocity changes were largely attributable to stride length adjustments and not limb frequency. Within a condition, neither velocity nor anthropometrics appeared to influence the coordinative solution. Overall, rather large differences were found in coordinative solutions, possibly owing to the nature of the tasks and/or individual searching strategies. The results were interpretable within a dynamic approach to coordination and support the idea that coordination is functionally rather than anatomically determined.

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Prehension Combined With Gait in Individuals With Chronic Low Back Pain

Priscila Abbári Rossi Manciopi, Natalia Madalena Rinaldi, and Renato Moraes

Low back pain (LBP) can affect performance in the combined task (CT) of gait and prehension, since it increases muscle activity amplitude during voluntary movements, impairs the anticipatory postural adjustments and reduces gait speed. We analyzed and compared the effect of adding the prehension movement toward a dowel located at three different heights (80, 100 and 120% of the lower limb length) on gait of individuals with and without LBP. The CT caused anticipatory adjustments, showing that gait changes started during the approach phase and continued on the step corresponding to grasping, especially for the lowest dowel height. Furthermore, individuals with LBP reduced walking speed, increased the width of the base of support, increased electromyography activity of low back trunk muscles, and increased the margin of dynamic stability compared with control group. These results suggest that individuals with LBP used a strategy to reduce threat to body stability due to addition of the manual task.