Effect of Imagining the Strategy of Play and Imagining the Motor Skill on Youths' Sport Performance in Karate

Introduction: The present study aimed to determine the effect of imagining the play strategies in comparison with imagining the motor skills on performance during a sports competition course.Methods: Participants were 30 (19 men, 11 women) karatekas who were evaluated as upper than moderate in terms of performance level. In the beginning, participants' ability and past experiments in motor imagery were assessed. Then, they took part in a quasi-experimental design of one of three strategic imagery, movement imagery, or control groups. Each person immediately after combatting with an opponent performed the required action depending on the group and finally competed against the same previous opponent, again.Results: The results showed that karatekas had excellent imagery ability, especially in preserving the temporal characteristics of the movement, and at the past competitions, specifically before their matches, they had used both cognitive-general and cognitive-specific imagery. Also, the nonparametric analysis demonstrated that in the quasi-experimental design, the strategic imagery group gained a higher point difference during the post-test, however, the movement imagery or control group did not differ significantly.Conclusion: The research findings revealed that strategic imagery has more advantages compared to skill imagery, suggesting that strategies of play can be used between the matches as an effective factor in sports success

Offline Learning in Children: The Effect of Night Sleep and Wakefulness on Memory Consolidation of a Complex Motor Task

Background and Aims Sleep after a new sequence memory training can enhance the explicit memory in children. However, children’s sleep-dependent motor memory consolidation particularly in implicit complex sequence tasks is unclear. Therefore, this study aims to investigate the role of night-time sleep and wakefulness on children’s motor memory consolidation following an implicit complex task.Methods In the current study, 26 boys aged 9-12 years were randomly assigned in two groups of sleep and awake. Acquisition phase included 10 blocks of 96 trials. The sleep group performed initial training at 8 (±1) PM while the awake group performed it at 8 (±1) AM by using the dynamic arm movement task. The participants were not aware of the sequence order. After training, the children’s performance was tested after 12 hours.Results The results of 2×2 Mixed ANOVA in the consolidation phase showed the significant main effect of block on response time (P=0.000) and prediction error (P=0.023). However, the interaction effect of block and group were not significant on response time (P=0.566) and prediction error (P=0.887). Conclusion The sequence memory consolidation in children under an implicit complex task can be improved offline regardless of having sleep between training and test sessions. Hence, sleep is not necessary for offline enhancement of motor sequence skills. Passage of time is effective for improvement in dynamic arm movement task. Therefore, the role of sleep in offline learning of motor skills depends on the nature of the task used in training

Muscles Activity in the elderly with Balance Impairments in walking under Dual tasks

Objectives: Each step during gait requires different attention demands that will affect muscles activity. The study of changes in the timing and intensity of the muscles activity in walking with dual task has received less attention from researchers. The purpose of this study was to evaluate changes in electromyography patterns of gait with cognitive dual tasks in balance impaired elderly. Methods: Thirty older adults were recruited for this study. People were selected through berg balance test. Subjects walked 12-meters in two conditions, normal walking and walking with a cognitive dual task. Spatial-temporal kinematic parameters were recorded through the motion analysis and muscles activities were recorded through electromyography system. The data obtained was analyzed using repeated measures ANOVA at a significant level of p< 0.05. &nbsp;Results: The results showed that walking under dual tasks would decrease gait speed and increase stride time and stance time. Also muscle activity in Tibialis anterior and Vastus lateralis in stance-phase would decrease significantly in dual tasks as compared with single task (p< 0.05), but timing of muscle activity would not change in dual task conditions.&nbsp; Conclusions: Based on the results, it can be argued that walking under a dual task can change spatial-temporal parameters and muscle activity in gait pattern in the elderly with balance impairment. One explanation could be that the decreased control of the central nervous system on muscle activity in stance phase due to the performing of a dual task

The Effect of Equipment Modification on Acquisition and Retention of Motor Skill in 9-10-Year-Old Children with an Emphasis on Working Memory Capacity

The aim of this study was to investigate the effect of equipment modification on acquisition and retention of basketball free throw skill in children aged between 9 and 10 with an emphasis on working memory capacity. 40malestudents were randomly selected and divided into 4 groups of modified and standard equipment with high and low working memory capacity based on the Memory for Digit Span assessment by Wechsler. Mini-basketball rules were used as a reference. The acquisition phase included 10 sessions, 4blocks each session and 15 attempts each block. Free throw basketball test (AAHPERD) was conducted as the pretest and acquisition and retention tests were conducted after a week. In the acquisition phase, 2x2x2 multivariate analysis of variance (eqipement×working memory×test) with repeated measures showed that interactive effect between working memory (high and low) and test (pretest and posttest) on performance was significant. Also, interactive effect between equipment (standard and modified) and test (pretest and posttest) on performance was significant while the interactive effect of working memory, equipment and test on performance was not significant. In retention phase, 2x2 multivariate analysis of variance (eqipement×working memory) showed that the main and interactive effect of working memory and equipment on performance was significant. The results showed that the effect of equipment employment in working memory levels on performance was similar in both pretest and posttest and also it seems that the effect of the modified equipment on performance in retention test was better in children with low working memory than children with high working memory

The Effect of Visual Illusion on the Learning of a Targeting Motor Skill in Children

The aim of this study was to investigate the effect of visual illusion on the learning of a targeting motor skill in children. The research method was semi-experimental with repeated measurement design and retention test. The statistical sample consisted of 36 children (10 years old) who were selected by convenience sampling method. They were divided into 3 groups: larger circle perception, smaller circle perception and control after the goal size had been estimated. The Ebbinghaus illusion displayed on the ground and the tennis ball to throw from top of the shoulder towards goal were used in this study. Firstly, the participants performed 10 trials at the pretest stage. Then, they performed six 10-trial blocks in the acquisition phase. 48 hours after the last acquisition session, a retention test was performed in 10 trials. To analyze the data, mixed analysis of variance with repeated measures, one-way analysis of variance and Tukey post hoc test were used. The results showed a significant difference among the groups both in the acquisition and retention phases and this difference was in favor of the smaller circle perception group. In general, the results of this study indicated the beneficial effect of visual illusion on learning a sport skill. Therefore, coaches and sport authorities are suggested to use this variable to improve performances and training session

The effect of a selected training program under dual-task and single-task conditions on the cognitive flexibility of children with developmental coordination disability

The purpose of this study was to investigate the effect of a selected training program under dual and single-task conditions on the cognitive flexibility of children with developmental coordination disorder. The research method was semi-experimental and with a pre-test-post-test- follow-up design with control group. The statistical population of this study included male students with developmental disorder in Ahvaz city. From the mentioned population, a sample of 39 subjects who were eligible for inclusion in the study was selected by available sampling method. After the Trail Making Test as a pre-test, they were randomly assigned to three groups: Exercise Dual task (n=13), single task training (n=13) and control (n=13). Then, the two experimental groups performed a selected training program with different conditions for 8 weeks and 3 sessions each 45 minutes each week. At the end, all subjects were followed by a Trail Making Test and two months later, a follow-up test. Data analysis using one-way covariance analysis as well as t-test showed that in post-test, cognitive flexibility in dual task group was superior to both single and control group (P < 0.05). In the follow-up test, this superiority remained only rather than the control group. Also, the single task group was superior to the control group in the post-test (P <0.05). Compared to single-task approaches, dual-task-based exercises can improve the cognitive flexibility of children with developmental coordination disorder, so using this method in the planning of classes is suggested for this group of children

Effects of Dual-Tasks on Spatial-Temporal Parameters of Gait in Older Adults With Impaired Balance

Objectives:&nbsp;The study of spatial-temporal parameters and their changes in walking with dual tasks, symmetry in right and left legs functions as well as changes in these parameters have received scant attention from researchers. Therefore, the purpose of this study was to evaluate the changes in spatial-temporal parameters of walking due to their simultaneous execution with cognitive dual-task in older people with impaired balance. Methods & Materials:&nbsp;Thirty older adults with weak balance voluntarily participated in this study. The study subjects were selected through Berg and Mini-Mental State Examination (MMSE) tests. The subjects who got scores lower than 52 in the Berg test were allowed to participate in the study. On the other hand, those who got scores lower than 23 in the MMSE test were excluded from the study. After subjects&rsquo; familiarity with the measurements and taking their informed consents, they walked 12 meters under 2 conditions; normal walking and walking with a cognitive dual-task. Spatial-temporal kinematic parameters were recorded by Vicon cameras. Then, by using the Polygon software, the variables of cadence, walking speed, step length, stride length, duration of step and stride, duration of stance and swing, time of single leg support and double leg support, separation of other leg, touching of other leg to the ground, and time of separation of fingers were calculated in terms of percentages of walking cycle. The obtained data were analyzed using repeated measures ANOVA.&nbsp; Results:&nbsp;The results showed that among the examined parameters, the variables of cadence and walking speed during walking with dual-task were reduced significantly compared to normal walking. The duration of the step, stride, time of double support, time of single leg support, the time of standing and swing in walking along with dual-task compared to normal walking showed a significant reduction (P<0.05). Asymmetry index in walking with dual-task compared to normal walking showed a significant increase in parameters of cadence, duration of step and stride; however, the changes in other parameters were not significant. The findings showed that the changes in stepping parameters from one step to the next one in walking with dual-task compared to normal walking had no significant changes.&nbsp; Conclusion: The results showed that the duration of double reliance and stance increase when walking with dual task than when normal walking. Therefore, in the elderly with poor balance, doing dual-task with walking could increase the risk of fall. With regard to increase in asymmetry in walking with dual-task, it seems that mutual harmony and symmetry is very sensitive to concurrent cognitive task. This asymmetry in the function of legs is considered a risk factor in falling. Thus, based on the results, walking of the elderly with poor balance needs better cognitive performance. Doing concurrent cognitive tasks could intervene with attention sources and consequently change the walking pattern. Therefore, we recommend that the older people with weak balance and prone to falling should refrain from cognitive dual-task during walking and focus on walking itself. &nbsp;&nbsp

The Effect of Errorless, Errorful and Random Practices on Learning of the Relative Timing of a Selected Motor Task: An Emphasis on Implicit and Explicit Learning Approaches

The aim of this study was to investigate the role of the errorless, errorful and random practice schedules on the acquisition and learning of relative timing in a motor task. 51 male students (age: 22±4 years old) were selected and randomly assigned to four groups (control, errorful, errorless, and random). This study was carried out in five phases: pretest (PRT), acquisition (ACQ), 10-min retention and transfer and 24-hour retention and transfer. In the acquisition phase, a timing task with three different difficulty levels (simple, moderate, and difficult) was practiced in three sessions of 45 trials with feedback by experimental groups. In order to analyze the data, a mixed-design analysis of variance model with repeated measures on each variable was used in the acquisition and retention phases. The one-way analysis of variance (ANOVA) was used in the other phases. The findings of relative timing showed no significant differences among the groups in the pretest (P˃0.05). Additionally, in retention and transfer tests, errorless group had better performance than errorful, random and control groups (P≤0.05). Errorless group performed better than the random and errorful groups in 24-hour transfer test of the secondary task (P≤0.05). These results showed that practice in errorless conditions leads to a better learning of the task and its generalization to new conditions that are consistent with the implicit learning and reinvestment theorie

The role of speed-based strategy instruction on learning and transfer of motor sequences in a complex task

Study aim: The purpose of this study was to investigate the impact of speed-based strategy instruction on motor sequence learning and transfer

The Effect of Different Levels of Impulsivity on Learning of Sport Skills in Open and Closed Environments

The main aim of this study was to investigate the effect of different levels of impulsivity on learning of skills in open and closed environments. Participations were forty-eight male with 10 to 12 years old that signed in low impulsivity, med impulsivity, high impulsivity and control groups (combined group) in accordance to the distribution of impulsivity scores. Before and after basketball skills training program, Harrison’s basketball shooting test was used to evaluation of performance and learning of skills in open and closed environments during pre-test, post-test, retention and transfer test. The results showed a significantly differences between groups for attentional functions (p=0.0001). The results of post-test and retention showed advanced performance in open environment with the increased levels of impulsivity (p=0.003). While about closed environment, progressive performance was aligned with Low levels of impulsivity groups (F=0.001). But in the transfer tests, differences between the groups were not significant (F=0.09), that was performed under the competitive goal condition. It is possible that impulsivity has a facilitator and an attenuator role in learning of various sportive skills, perhaps in open and closed environments