The effect of internal, external, and holistic focus of attention on standing long jump performance in novice and skilled karatekas.

An important application for training instructions is found in directing one's attentional focus. This direction can occur in different internal, external, or holistic forms. However, comparison between these three forms of instructions is a relatively recent development rarely reported at different skill levels or various sports including karate. Therefore, the present study attempts to investigate the effects of three forms of instructions on standing long jump performance in skilled and novice karatekas. The participants were 60 skilled and novice karatekas (all females; mean age: 21.32 ± 1.65) who completed 12 standing long jump trials under different focus conditions (3 trials for each condition: internal, external, holistic and control condition) in a counterbalanced order. Our findings suggested significant main effects, indicating that skilled karatekas outperformed the novices. The findings also showed that regardless of skill levels, the participants exhibited similar performance under external and holistic focus conditions while performance in both of these conditions was superior compared to performance under internal focus and control conditions. No difference was observed between the control and internal focus conditions. It seems that skilled and novice karatekas may benefit from holistic and external focus of attention instructions which enhance their motor performance. Thus, it is recommended that coaches should incorporate these two types of attentional focus instructions into their training sessions.

The effect of a visual illusion and self-controlled practice on motor learning in children at risk for developmental coordination disorder.

Numerous efforts have been made to test the OPTIMAL theory of motor learning in healthy children and adult populations. However, only a small number of studies have tested this theory in children with cognitive-motor disorders, such as developmental coordination disorder (DCD). The present study aims to examine the individual and additive effects of a visual illusion and self-controlled practice on a golf putting task in children at risk for DCD based on the OPTIMAL theory. Forty children at risk for DCD (mean age = 8.57 ± 1.05 years) were randomly assigned to four experimental groups (1-small visual illusion + self-controlled practice; 2-big visual illusion + self-controlled practice; 3-small visual illusion + yoked; 4-big visual illusion + yoked). Following 12 pretest trials of a golf putting task, the participants completed 5 blocks of 12 trials of practice on the first day. A retention test (12 trials) and a transfer dual-task test (12 trials) were conducted on the second day. The results indicated that in retention test the big visual illusion + self-controlled practice group was significantly better than the small visual illusion + yoked group (p = 0.01), while there was not any other significant difference between groups at retention test as well as between all groups at practice phase and transfer test (p > 0.05 for all comparisons). In other words, an additive effect has been observed just in the retention test but not the practice phase as well as transfer test. In general, the results of this study support the OPTIMAL theory of motor learning in children at risk for DCD and suggests to all educators who work with these children to use the combination of the visual illusion with self-controlled practice to improve the motor learning of children at risk for DCD.

The Effect of Brain Anodal and Cathodal Transcranial Direct Current Stimulation on Psychological Refractory Period at Different Stimulus-Onset Asynchrony in Non-Fatigue and Mental Fatigue Conditions.

The psychological refractory period (PRP) effect occurs when two stimuli that require separate responses are presented sequentially, particularly with a short and variable time interval between them. Fatigue is a suboptimal psycho-physiological state that leads to changes in strategies. In recent years, numerous studies have investigated the effects of transcranial direct current stimulation (tDCS) on motor control. The present study aimed to investigate the effects of two tDCS methods, anodal and cathodal, on PRP in ten different conditions of stimulus-onset asynchronies (SOAs) under non-fatigue and mental fatigue conditions. The participants involved 39 male university students aged 19 to 25 years. In the pre-test, they were assessed using the PRP measurement tool under both non-fatigue and mental fatigue conditions. The mental fatigue was induced by a 30-min Stroop task. The test consisted of two stimuli with different SOAs (50, 75, 100, 150, 300, 400, 600, 900, 1200, and 1500 ms). The first was a visual stimulus with three choices (letters A, B, and C). After a random SOA, the second stimulus, a visual stimulus with three choices (colors red, yellow, and blue), was presented. Subsequently, participants were randomly assigned to the anodal, cathodal, and sham stimulation groups and underwent four consecutive sessions of tDCS stimulation. In the anodal and cathodal stimulation groups, 20 min of tDCS stimulation were applied to the PLPFC area in each session, while in the sham group, the stimulation was artificially applied. All participants were assessed using the same measurement tools as in the pre-test phase, in a post-test phase one day after the last stimulation session, and in a follow-up phase four days after that. Inferential statistics include mixed ANOVA, one-way ANOVA, independent, and dependent t-tests. The findings indicated that the response time to the second stimulus was longer at lower SOAs. However, there was no significant difference between the groups in this regard. Additionally, there was no significant difference in response time to the second stimulus between the fatigue and non-fatigue conditions, or between the groups. Therefore, tDCS had no significant effect. There was a significant difference between mental fatigue and non-fatigue conditions in the psychological refractory period. Moreover, at lower SOAs, the PRP was longer than at higher SOAs. In conditions of fatigue, the active stimulation groups (anodal and cathodal) performed better than the sham stimulation group at higher SOAs. Considering the difference in response to both stimuli at different SOAs, some central aspects of the response can be simultaneously parallel. Fatigue also affects parallel processing. This study supports the response integration phenomenon in PRP, which predicts that there will be an increase in response time to the first stimulus as the interval between the presentation of the two stimuli increases. This finding contradicts the bottleneck model. In this study, the effectiveness of cathodal and anodal tDCS on response time to the second stimulus and PRP was found to be very small.

Neurofeedback training and motor learning: the enhanced sensorimotor rhythm protocol is better or the suppressed alpha or the suppressed mu?

A large number of previous studies have examined how different neurofeedback-based techniques may influence motor learning. However, only a few studies attempted to compare the effects of these different techniques on motor learning. Therefore, the present study attempts to examine the effects of neurofeedback training on motor learning in novice golfers, using three protocols, namely enhanced sensorimotor rhythm (SMR) at Cz, suppressed alpha waves at Fz, and suppressed mu waves at Cz. The participants were 64 adults (32 females; mean age = 22.31 ± 2.25 years). The study consisted of a pretest stage (day 1), intervention (6 sessions, over two weeks, 3 sessions per week), short-term retention (one day after intervention), and long-term retention (two weeks after intervention); in the pretest and short-term and long-term retention, motor performance for golf putting (12 trials) as well as amplitudes of SMR wave at Cz, alpha at Fz, and Mu at Cz were recorded. During each intervention session, the participants in three neurofeedback groups and a sham group first performed neurofeedback training (enhanced SMR at Cz, suppressed alpha at Fz, and suppressed Mu at Cz) for 20 min. Then, the participants in all groups performed three blocks of 12 trials consisting of golf putting training. The results indicated no difference between the sham and the experimental groups in the acquisition stage, as individuals in all groups experienced similar improvement in putting accuracy. However, in the short-term retention, all the three neurofeedback groups outperformed the sham group, although in the long-term retention, only the SMR group and the Alpha group showed a better performance than the sham group while the Mu group did not exhibit a notably better performance than the sham group. Our results also showed significant variations in the amplitudes of the SMR, alpha, and mu waves depending on the neurofeedback intervention provided, while no significant variation was observed in the sham group. Based on these results, it is recommended that coaches should make further use of enhanced SMR at Cz or suppressed alpha at Fz as their neurofeedback interventions to facilitate longer-term motor learning in golfers.