Journal of Motor Behavior最新文献

This study examined the effects of point-light action observation therapy (PL-AOT) on muscle activation, upper extremity function, and activities of daily living (ADL) in stroke patients. Thirty-two participants were randomly assigned to either a PL-AOT group or a traditional AOT group. Both groups received 30-minute sessions, five times a week for four weeks. Assessments included the Fugl-Meyer Assessment for Upper Extremity (FMA-UE), Action Research Arm Test (ARAT), Box and Block Test (BBT), Korean Modified Barthel Index (K-MBI), Motor Activity Log (MAL), and surface electromyography (sEMG). Both groups showed significant improvements in all outcomes after the intervention (p < .05). However, the PL-AOT group demonstrated significantly greater gains in upper extremity function, ADLs, and muscle activation compared to the traditional AOT group (p < .05). Additionally, co-contraction ratios indicated positive changes in shoulder and elbow joint coordination only in the PL-AOT group. These findings suggest that PL-AOT may be more effective than traditional AOT in promoting motor recovery and functional improvements in individuals with stroke.

Complexity and local dynamic stability (LDS) of electromyographic (EMG) signals are valuable indicators for understanding motor control mechanisms and distinguishing skill levels in dynamic sports such as wrestling. This study investigates the relationship between complexity and LDS of EMG signals to understand the neuromuscular mechanisms underlying skill differentiation in wrestling. The complexity [using the Higuchi fractal dimension (FD)] and LDS [using the largest Lyapunov exponent (LLE)] activity of the upper limb muscles were calculated in elite and sub-elite wrestlers (N = 72) during the arm-drag and double-leg attack techniques. The correlation between complexity and LDS was evaluated using Pearson's correlation coefficient, and random forest analysis was used to determine their importance in differentiating skill levels. Elite wrestlers showed higher complexity, LDS, and correlation between complexity and LDS in EMG signals than sub-elite wrestlers. Random forest analysis showed that complexity is more important than LDS in differentiating skill levels. The findings show that training programs should be designed according to athletes' skill levels. Training programs should adopt a phased approach, initially targeting LDS and motor control and integrating complex exercises to promote adaptability and variability in motor responses. This approach can help athletes improve their motor control and achieve higher skill levels.

This study examined the effects of self-controlled versus instructor-controlled demonstration on learning basketball free throws in children with different motor imagery abilities. Forty boys aged 9-12 were randomly assigned to four groups based on imagery ability (high/low) and demonstration type (self/instructor-controlled). In self-controlled conditions, participants could choose when to receive the skill demonstration from the instructor. Performance was evaluated using the basketball free throw test, and motor imagery ability was measured using the Motor Imagery Questionnaire for Children (MIQ-C). Following a pretest, participants trained for ten sessions every other day, with each session consisting of twenty throwing trials. Assessments included a post-test (after the last session) and retention and transfer tests (one week later). The results indicated that self-controlled groups performed better than instructor-controlled groups across all phases (p = .001). Additionally, skill learning was not significantly impacted by motor imagery ability (p > .05). These findings suggest that regardless of children's motor imagery skills, the self-controlled demonstration method enhances basketball free throw learning. The superiority of the self-controlled condition, regardless of imagery ability, emphasizes how crucial it is to give learners control over their training when it comes to learning basketball skills.

There is a lack of research on the effects of fatigue and dual-task motor performance in people with Multiple sclerosis (MS), especially in women. Using a group of 20 women with MS and 20 healthy controls, we examined the effects of fatigue and attentional demands on center of pressure (COP) displacements during upright stance. Anterior-posterior (AP), Media-lateral (ML), and total COP displacements, and also ankle plantar flexors' strength were measured. Results indicated that fatigue and dual-task resulted in higher ML COP displacements in both groups, but unlike controls, MS patients had higher ML displacements during the dual-task compared to single-task trials. Additionally, while fatigue resulted in an increased single-task AP and total COP displacements in both groups, it yielded higher dual-task AP and total COP displacements only in MS patients. Moreover, MS patients had weaker ankle plantar flexors compared to healthy controls, but the plantar flexors-mainly soleus-maximum voluntary contraction (MVC) was only associated with fatigued single-task balance performance in MS patients. Our study confirmed the adverse effects of fatigue and dual-task on balance performance, especially in MS patients. Further research is required on whether the modulation of balance performance of ankle plantar flexors' MVC depends on fatigue and attentional task demands.

This study investigated the effects of neck angle on center of mass (CM) stability and joint angle variability in the handstand. Seven experienced female gymnasts performed handstands in extended, neutral, and flexed neck angles. Kinematic data were collected using a 3D motion capture system, and variability was assessed for wrist, elbow, shoulder, hip, and neck angles and, CM position. The findings showed that the extended neck angle posture exhibited the lowest CM variability, aligning with its prevalent use in practice and competition. Regression analyses revealed that joint angle variability was significantly corelated to CM motion, with the typical extended neck angle related to shoulder, wrist, and neck angle variability contributions (33%, 23%, and 21%, respectively). In contrast, the neutral neck angle was moderately corelated to hip variability (32%), while the flexed neck angle showed a dominant reliance on neck angle variability (63%). The results show the strong role of neck angle in the postural variability of the handstand that is mediated by joint angle variability, visual information and tonic reflex support.

This study investigates cognitive-motor interference by combining Raven's Progressive Matrices Test (RPMT) with treadmill walking. Two groups of healthy adults-20 young adults (born after 1995) familiar with treadmill walking and 18 older adults (born before 1980) without treadmill experience-completed both single-task and dual-task conditions. Cognitive performance (RPMT score) and gait metrics (stride interval variability and sample entropy) were recorded. Results revealed diverse interference patterns, with a predominance of gait-prioritization strategies under dual-task conditions. Significant differences between groups were found: younger adults showed greater cognitive performance decline, while older adults increased stride interval under dual-task conditions. A negative correlation between gait variability and complexity suggested adaptive motor strategies in some participants. This dual-task paradigm offers a standardized framework to explore both individual and group variability in multitasking performance. These insights may inform the design of safer environments and interventions targeting populations with different cognitive-motor profiles.

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.

This study investigated the effects of muscular fatigue on the accuracy of force control in the respective generation and relaxation phases while performing an isometric handgrip force-tracking task. Participants were instructed to track a target line moving upward and downward, corresponding to 0 to 30% of maximum voluntary contraction (MVC) at a constant for 7 s. Eight sets of 25 continuous trials each were conducted. The force-tracking accuracy and electromyography (EMG) of extensor carpi radialis (ECR) and flexor carpi ulnaris (FCU) were evaluated. The force-tracking accuracy was compared between the phase (upward: generation and downward: relaxation), set (first and eighth), and within-set periods (early: 1-5, middle: 10-15, and late: 20-25 trials). The force-tracking accuracy at the middle and late periods significantly declined compared to the early period in the relaxation phase. Integrated EMG of ECR and FCU was significantly larger in the generation than in the relaxation phase. The integrated EMG of FCU in the generation phase was significantly different between the periods. Furthermore, the median frequency of FCU was significantly different between the phases and periods. These findings suggest that the effects of muscular fatigue on force control varied between generation and relaxation due to the amount and frequency band of muscle activity.

The principles of specificity and similarity play a crucial role in supporting the transfer and retention of motor performance in general sports training. Nevertheless, the extent to which force control ability translates into dynamic performance remains unclear. We aimed to investigate the effect of force control training on the transfer and retention of balance control in 18 young individuals. The force control training utilized a visual-guided force tracking task with either a uniform or non-uniform sinusoidal wave in ankle plantar flexors (PF). Postural stability was assessed by measuring the center of pressure (COP) in a single-leg standing posture. Despite consistent repetitions, no significant differences in COP parameters were observed between the pre- and post-training assessments. However, significant differences were noted between the pre-training assessments and the post-training assessments conducted one week later, utilizing a randomized order. Shifting from a regimen of constant repetition to a randomized order has a positive impact on the transfer and retention of acquired motor skills. This approach, based on the motor learning theory, holds promise for enhancing the motor performance of athletes and patients undergoing rehabilitation.

During reaching, arm choice depends on handedness, success, and effort; however, whether these factors influence leg choice for goal-directed stepping is still unknown. We aimed to quantify the kinematics and behavioral patterns of leg choice and to explore whether success and/or effort influence leg choice during goal-directed stepping under two Choice conditions in 20 right-leg dominant neurotypical adults. We adapted the classic center-out target array; participants stepped to pre-cued targets with an emphasis on accuracy without time constraints. The first set of trials was always Free for which either leg could be chosen. The second set of trials was verbally Constrained for which there was no choice as only the left non-dominant leg was to be used. We separately compared success, effort, and subjective difficulty between Free and Constrained trials for left and right target regions. In Free, participants uniformly selected the limb ipsilateral to the target. While success and subjective difficulty were not influenced by Choice, effort varied depending on Choice. Our preliminary findings suggest that during goal-directed stepping, leg choice depends on effort and may be independent of leg dominance and subjective difficulty, while the difficulty of the Constrained Choice condition can improve success independent of leg used.