Journal of Motor Behavior最新文献

A holistic focus (HF) has been found to significantly improve performance over an internal focus (IF), in a similar way to an external focus (EF). There is a need to understand the effectiveness of a HF by investigating kinematic and kinetic outcome measures. 19 college-aged adults performed 12 vertical jumps under four conditions in a counterbalanced design. The conditions were, IF, EF, HF, and control, or no focus condition. All participants performed the vertical jumps on a force plate with 16 reflective markers placed on the lower extremities. Separate repeated measures ANOVAs with Sidak post-hoc were used to analyze jump height, flight height, peak force, takeoff velocity, and knee and hip flexion. A significant main effect for jump height was observed (p < 0.001). HF and EF jumped significantly higher than IF (p < 0.001; p < 0.001). EF also jumped significantly higher than control (p<.05). No significant main effects were observed for any kinematic or kinetic dependent variables. The results of this experiment support previous research by observing performance benefits of HF and EF over an IF. However, the benefits of HF and EF cannot be attributed to the kinetic or kinematic changes.

Adopting a postural configuration may be regarded as preparation for the performance of an upcoming movement. However, it is unclear how different postural configurations affect motor performance. The aim of the current study was to examine how body posture - sitting versus standing - influences fast and accurate planar point-to-point hand movements. Twenty-three healthy adults performed a "Go/No-go" paradigm while doing repetitive point-to-point movements. Arousal levels, which may change due to the change in posture, were independently manipulated by using a sham threat of electrical stimulation. Upper limb kinematics, center of pressure displacement, and galvanic skin responses were recorded in four test conditions: sitting and standing with and without arousal manipulation. Descriptive performance measures were computed and analyzed using multiple analyses of variance. A difference in arousal level was observed in the two conditions with the arousal manipulation, but no difference in arousal level was found between sitting and standing. Center of pressure displacement onset was found to be earlier in the two standing conditions compared to those in sitting. No difference was found in upper limb performance between the two postures, nor due to the arousal manipulation. We concluded that under the tested conditions, body posture does not appear to affect upper limb performance.

This review verified the extent, variety, quality and main findings of studies that have tested the neurophysiological and clinical effects of muscle tendon vibration (VIB) in individuals with sensorimotor impairments. The search was conducted on PubMed, CINAHL, and SportDiscuss up to April 2024. Studies were selected if they included humans with neurological impairments, applied VIB and used at least one measure of corticospinal excitability using transcranial magnetic stimulation (TMS). Two investigators assessed the studies' quality using critical appraisal checklists and extracted relevant data. The 10 articles included were diverse in populations and methods, generally rated as 'average' to 'good' quality. All studies reported an increased corticospinal excitability in the vibrated muscle, but the effects of VIB on non-vibrated muscles remain unclear. Positive clinical changes in response to VIB were reported in a few studies, such as a decreased spasticity and improved sensorimotor function. These changes were sometimes correlated with corticospinal effects, suggesting a link between VIB-induced plasticity and clinical improvements. Despite the limited and heterogeneous literature, this review supports the facilitatory influence of VIB on motor outputs controlling vibrated muscles, even with altered sensorimotor functions. It highlights knowledge gaps and suggests future research directions on VIB mechanisms and clinical implications.

Gait stability and walking direction control are conventionally attributed to coordination among somatosensory, visual, and vestibular systems. Recent evidence of functional interdependence between masticatory and neuromuscular systems indicates that the stomatognathic system is neurologically integrated with various body systems relevant to movement planning and execution. This study investigated the effects of unilateral molar biting and incisor biting on walking with and without visual feedback. A cohort of 31 healthy young adults aged 21 to 30 years (average age of 23.93 ± 1.89) participated in this study. Three types of errors in walking direction (angle error, position error, and curve error) were computed. Our findings indicate that, in right-handed individuals, irrespective of visual feedback, unilateral biting caused systematic deviations toward the biting side from initiation to termination of walking. The consistent deviation in walking, particularly during unilateral right biting conditions in right-handed individuals, may indicate a complex interplay between masticatory function and gait control mechanism, potentially influenced by handedness and motor lateralization within the cortex. This study establishes a foundation for future research exploring the interrelation between bite location, visual feedback, and motor control in diverse populations. This research may provide insight for more efficient interventions for gait-related disorders.

This study aimed to compare the effects of electroacupuncture on traditional acupoints and muscle belly of different target muscles against upper limb dysfunction in stroke patients with hemiplegia. A total of thirty-nine stroke patients with subacute hemiplegia were randomly divided into the control group (n = 19) and observation group (n = 20). The control group was treated with physical therapy and normal electroacupuncture, while the observation group was treated with physical therapy and ultrasound-guided electroacupuncture on the muscle belly. After three weeks' intervention, the scores of Barthel Index, Fugl-Meyer assessment and Action Research Arm Test were compared between the two groups. Before the intervention, there were no significant differences in the scores of Barthel Index, Fugl-Meyer assessment and Action Research Arm Test between these two groups. After three weeks' intervention, there was significant increase in the scores of Barthel Index, Fugl-Meyer assessment, and Action Research Arm Test between the observation and control groups. Electroacupuncture on muscle belly under ultrasound guidance could significantly improve the performance of activities of daily living, motor function and the upper limb function in patients with subacute hemiplegia after stroke, and its effect was superior to electroacupuncture on the acupoints.

According to Fitts' law, an individual's speed-accuracy tradeoff is only related to the object's properties. According to previous research, the movement time to hit the current target can be affected by the target of different size on the previous trial where the Fitts' law task is affected by trial history. However, in a dyadic context, the question is whether there is still a trial-to-trial transfer across individuals. In this study, Experiment 1 was conducted to investigate whether the current trial would be affected by the previous trial performed by the partner in a dyadic task. The results showed trial-to-trial transfer between individuals was affected by the difficulty of the action. The current movement was only affected by the previous difficult trial but not simple task. In order to investigate whether observing only novel targets would affect the current movement, we conducted Experiment 2, which showed that observing the target was not sufficient to generate effect transfer between trials. These findings suggest that the goal-directed movement can be affected by the observation of others. In addition, the effect of trial-to-trial transfer between individuals was influenced by task difficulty, which proved this effect was not a simple imitation.

Knee osteoarthritis (KOA) is a prevalent and severe condition with versatile effects on human locomotion, including alterations in neuromuscular control. Muscle synergies are understood as functional low-dimensional building blocks within the neuromuscular organization. To examine alterations in muscle synergy patterns during locomotion tasks in the presence of KOA, 40 participants, including 20 with medial KOA (KL-Score ≥ 2), performed level walking, as well as ramp and stair ascent and descent trials at self-selected speeds. Sixteen-Channel bilateral surface electromyography (sEMG) and marker-based motion capture data were collected. Non-negative matrix factorization (NNMF) was applied to the sEMG data for muscle synergy extraction. During level walking and descending conditions, structural changes in muscle synergy composition were observed in the KOA affected limb when compared to the unaffected side and control group. Alterations included fewer, merged synergies with prolonged activation coefficients and a higher percentage of unclassifiable synergies. No major alterations were observed during ascending conditions. No significant differences in gait speed and stride length were observed. These results indicate that muscle synergy composition can be altered in the presence of KOA regardless of age and gait speed, but not during all forms of locomotion.

Motor competence is associated with the perceived difficulty of a task. This study hypothesized that children with higher motor competence perceive certain tasks as less challenging than their peers with lower motor competence. As a result, children with higher motor competence were expected to set more ambitious goals for themselves while learning a new task compared to children with lower motor competence. To investigate the relationship between motor competence and the difficulty of self-set goals during motor learning, we included 48 children aged between eight and ten years, stratified into terciles; our analysis focused on 32 children from the highest and lowest terciles. The experimental task required participants to throw a 100 g bean bag toward a target located 3 meters away. Children were instructed to set goals before each block of 10 trials during the learning phase. Pretest, retention, and transfer tests were administered without imposed goals. Motor competence was assessed using the Motor Competence Assessment, which integrates scores from the task used to evaluate motor learning and the percentage increase in each block to assess the difficulty of the self-set goals. The findings revealed no significant correlation between motor competence and the difficulty of self-set goals. Nevertheless, higher motor competence was linked to enhanced performance during the acquisition phase, retention and transfer tests. These results suggest that although motor competence is associated with improved motor learning, it does not influence the level of challenge of the goals that children set for themselves.

The aim of this study was to determine the effect of cognitive interference by using the Dual-Task (DT) paradigm on gait parameters according to sex, and age. Additionally, we aim to explore the relationship between Dual-Task-Cost (DTC), physical fitness, cognitive functioning, and weight status in schoolchildren. One hundred schoolchildren participated in this study (age = 8.83 ± 1.82 years). They were randomly assigned to Comfortable Linear Gait (CLG: gait in a straight path) or Complex Gait (CG: gait over obstacles) with and without interference. For CLG, boys and girls showed a reduction in gait speed (p < 0.001), cadence (p < 0.01), and step length (p < 0.001). In addition, double support time (p < 0.05) and cadence coefficient of variance (boys= p < 0.01; girls= p < 0.05) increased in the DT condition. In the CG, both sexes (p < 0.001) exhibited a worse execution time. There were significant effects on speed DTC between 8-9 vs. 10-11 years in CLG and 6-7 vs. 10-11 years in CGT (p < 0.05). In conclusion, gait parameters during CLG and CG are modified in the DT condition, resulting in a slower gait with shorter steps, regardless of age and sex. DTC is associated with physical fitness and cognitive function.

The aim of this study was to compare the kinematics of reaching tasks at different speeds between children with neonatal brachial plexus palsy (NBPP) and unaffected controls. This cross-sectional study included thirteen children with NBPP (10 ± 2 years old, of which six had upper Erb's palsy and seven had extended Erb's palsy) matched for age and sex with thirteen unaffected controls. Kinematic data were acquired using a Motion Monitor unit with a 3D motion tracking electromagnetic system (Liberty, Polhemus). Scapular, upper limb, and head were recorded during forward reaching tasks (hand on overhead ball and hand to head) and a backward reaching task (hand on the back pocket). The study revealed reduced shoulder flexion and extension in children with NBPP during hand on ball and on the back pocket tasks compared to unaffected controls. Limited elbow flexion was also observed in children with NBPP during the hand on ball and hand on the head tasks. During the hand to head task, children with NBPP presented increased head flexion compared to unaffected controls. Scapular kinematics analysis showed increased posterior tilt in children with NBPP during forward reaching (the hand on ball and hand to head tasks). In the backward reaching task (hand on the back pocket), the NBPP group exhibited reduced scapular external rotation compared to unaffected controls. These findings indicate distinct kinematics in the scapula, shoulder, elbow, and head during reaching tasks for children with NBPP compared to controls. Furthermore, different execution speeds did not alter the kinematic differences between the groups.