نشریه رشد و یادگیری حرکتی - ورزشی
پیاپی 37 (پاییز 1398)

The aim of the current study was to determine the effect of two types of aerobic exercises on static and dynamic balance of the elderly women. 36 elderly women (60 to 75 years old) were randomly assigned to three groups: 1) walking or jogging (n=12) 2) exercise in water (n=12) 3) control (n=12). Groups 1 and 2 participated in walking (jogging) and exercise in water program for 8 weeks, 3 session per week. The control group had their own daily activities and did not participate in any special kind of sports during this program. Sharpened Romberg and stick balance tests were used to measure the dynamic and static balance. Analysis covariance test (SPSS21) was used to check research hypotheses and to determine the difference among the groups. The results showed significant differences in posttest scores between experimental and control groups (P˂0.05). The results also showed that the group 1 (walking and jogging) gained more scores in dynamic and static balance than the group 2 (exercise in water). It seems that both types of the aerobic exercises especially walking and jogging are appropriate for decreasing the difficulties of this group and can be used as an exercise program in training centers.

Theoretically, skill presentation will change behavior through processes such as imitation and motor repetition. If we want learning to happen, we need a process called training. Training can be delivered by the instructor through verbal and non–verbal instructions to the learner. One type of non–verbal instruction is pattern representation in which learner can learn through observation. The purpose of this model is to use the pattern representation as a means of transmitting information. Thus, the aim of this study was to evaluate the effect of three training immediate, interspersed and combined imitation on Juno kata form performance. Therefore, 45 girls (9-12 years old) in Tehran city voluntarily participated in this study and were divided into three groups (each group 15 subjects) based on the type of intervention. Groups of immediate, interspersed and combined imitation had special imitation training programs with specific repetitions. In order to quantify data, 10-point Kata scale was used. As the data distribution and variance homogeneity were obtained, the result of analysis of variance with repeated measures showed that all three observational methods helped to improve the performance and this progress remained stable in the retention and transfer tests (P≤0.05). Also, the results of multivariate analysis of variance showed the priority of immediate imitation group on interspersed (P=0.0005) and combined (P=0.0005) imitation groups. The combined imitation group gained better scores than interspersed group (P=0.0005) and this differences was stable in retention and transfer tests.

The aim of this study was to compare quiet eye in children with high and low motor proficiency. In this causal-comparative study, 40 children (7 to 14 years old) in Isfahan city were selected by multiple cluster sampling method. Participants performed throwing and catching task in 10 trials. The data of quiet eyes were recorded by an eye tracking device (Ergoneers) and analyzed by Dikablis 3.1 software when performing the desired task.  After the evaluation of data normality, the data were analyzed by independent t test and Pearson correlation coefficient at the significance level of 0.05. Independent t test results showed that children with high motor proficiency were better in the onset of QE (P=0.0001), offset of QE (P=0.023), QE duration (P=0.0001) and catching performance (P=0.0001) than children with lower motor proficiency. Also, the results showed a significant negative relationship between the catching performance and the onset of QE and a significant positive relationship between the catching performance and the offset of QE and QE duration in both groups of children with high and low motor proficiency. The results of the study generally revealed that the QE is considered as an effective variables associated with motor performance and appropriate to expertise level.

The aim of this study was to determine the effects of errorless practice on learning an aiming skill in mentally retarded adolescents. 40 mentally retarded adolescents were assigned to four practice groups based on intelligence quotient and working memory capacity. The task was to throw basketball mini balls into a target with concentric circles. The practice of groups was different from each other. The subjects performed 200 practice attempts in 5 practice blocks in the acquisition stage. Single task and dual task tests were implemented immediately, with 24-hour latency and one-week latency. The secondary task involved counting even numbers forward. The results showed that the groups with the least error and the least involvement in work memory during the practice outperformed other groups in acquisition stage, the single task test and dual task test. The findings of this study were consistent with the Adam's closed loop theory, the reinvestment theory, and the estimates of the challenge point framework regarding errors in the acquisition stage, but they were contradictory with the estimates of the schema theory. These findings also provided evidence to support the claim of the challenge point framework and the reinvestment theory about special individuals (mentally retarded).

Psychological states affect focus of attention and play a mediating role in its effect on motor performance and learning. The present study investigated the effect of practice under psychological pressure and attention focusing with instruction on learning billiard shot. Participants were 48 female volunteer students (19-23 years old) who were randomly selected and assigned to 4 experimental groups (internal focus under high and low pressure, external focus under high and low pressure). The groups practiced for 8 sessions after the pretest. Acquisition test was performed in the last session of practice, and the retention test was conducted with 2 and 10 days of delay after the last practice session. The accuracy of the shots was scored according to the distance of the ball from the pit. The results of U Mann-Whitney test showed priority of internal attention in the acquisition and 10-day delay retention tests and priority of practice under low pressure in 10-day delay retention test (P<0.05). The results of Kruskal–Wallis test and pairwise comparisons indicated priority of the acquisition of internal attention under high pressure on external attention under high pressure and the priority of delayed retention of internal attention under low pressure on external attention under high pressure (P<0.05). It seems that given the nature of skill in terms of unchanged environmental conditions and high accuracy and attention requirements especially in the early stages of learning, practice under low psychological pressure conditions and internal focusing will result in more delayed retention for novice people

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 theories

The aim of this study was to investigate the effect of handedness and task difficulty on effective target width and temporal accuracy of the Fitts’ speed-accuracy tradeoff task. The present study was semi-experimental and the tools used included Edinburgh handedness questionnaire, light pen, speed-accuracy measurement device, laptop, chronometer, and metronome. The statistical population consisted of students aged between 14 and 15. The sample included 20 students who participated in this study by convenience sampling method. They were divided into two groups: left-hand and right-hand (each group 10 subjects). Each participant performed 4 trials (each trial 30 seconds) of dual target tapping task in rhythm with the metronome sound. The trials consisted of two easy and difficult tasks and each subject performed each task with dominant and not-dominant hands in rhythm with the metronome sound set up at 300 milliseconds. For statistical analysis of data, variance analysis with repeated measures was used at the significance level of 0.05. The results showed that in dominant hand, the handedness and difficulty of the task had no significant effect on the effective width of the target (P=0.973, P=0.611). Also, the handedness did not affect the average time lag (P=0.135, P=0.785), but in non-dominant hand, the average time lag was more for the difficult task than the simple task (P=0.001). In difficult tasks, participants seem to be trying to keep the spatial error rate constant by reducing the speed of the movement and to sacrifice speed for the spatial accuracy. Also, the time error (mean lag) is more influenced by the difficulty of the task than the handedness.

One of the topics of interest to motor behavior researchers is to examine the different effects of attention strategies on motor behavior and brain activity.The aim of this study was to investigate the role of attention instructions on alpha and theta wave variations and the accuracy of dart throwing. 20 male students novice in dart (age range 19-22 years old) were voluntarily selected. This study was application. Firstly, the participants performed 10 attempts of dart throwing in the baseline (no attention instructions). Then, as a counterbalance, 20 practice attempts were performed in both the external and internal attention strategies. In all attempts, the alpha and theta brain waves of the subjects were recorded using biofeedback device and the radial error formula was used to measure accuracy. The data were analyzed by in-group variance analysis with repeated measures and Bonferroni post hoc test at a significance level of 0.05. The results showed that the external attention strategy increased the accuracy of the dart throwing (P=0.0001), increased alpha wavelength (P=0.01) and reduced theta wave (P=0.01) in comparison with the internal attention strategy. These findings showed the need to use attention instructions particularly external attention in targeting skill task at a beginner level; therefore, it is suggested that coaches should use external attention strategy to improve the accuracy and intelligence of the brain in beginners.