1. Expert-novice Differences in SMR Activity during Dart Throw
Ming-Yang Cheng, Li-Chuan Lo, Chung-Ju Huang, Tsung Min Hung
Introduction
■ No interactions (F = 2.841, p = 0.087, eta squre = 0.11) was found. However, the GROUP main effect was significantly different (F = , p < .05, eta square = 0.82). The mean SMR power for experts 3s before the dart throw was significantly higher than novice and was maintained stably higher. There was no difference in the main effect of time (Figure 1).
Method
■ Purpose: To test whether the Hz EEG power only occurred in the sensory motor cortex but not in the other regions.
■ Hypothesis: The mean power with Hz for last 3s prior to execution in frontal lobe, parietal lobe and occipital lobe had no difference.
■ Statistics: 2 (GROUP) x 3 (TIME) two-way ANOVAs mixed design were applied to test the difference in power with Hz in all regions.
■ Result: No interaction result for group and time factors. However, group main effects was significant in all regions.
SMR power maintain a higher trend for expert than novice during preparation before dart throwing.
Control analysis
■ Rationale:
The application of EEG to examine motor behavior provides a high-resolution metric to capture the temporal dynamics of regional cerebral cortical activity related to performance (Hung, 2008). Recent studies addressed some EEG attention indicators related to optimal precision sports performance prior to execution, however, there were few studies on the relationship between SMR activity and precision sports performance. .
■ SMR (Sensory motor rhythm)
12-15 Hz rhythm in sensory motor cortex, which activity is negatively related to the activity of sensory motor cortex (Sterman, 1996).
Higher SMR activity is associated with reducing the somatosensory interference to maintain the perception and attention during information processing under preparation state (Vernon et al., 2003), and action inhibition, relaxed attention focusing, large working memory (Gruzelier, Egner, & Vernon, 2006).
■ Hypothesis:
Dart throw experts closer to throwing have higher SMR power than novice.
The mental state prior to execution has a major influence on the performance, especially in self-paced sports (Salazar et al., 1990; Zinsser, Bunker & Williams, 2006).
14 Elite players
15 Novices
60 dart throw tests in 6 sessions. Each section included 10 dart throws
2 (GROUP) x 3 (TIME) two-way ANOVA mixed design, α = .05.
EEG data acquiring
SMR: The mean power value of C3 and C4 with a frequency of Hz.
Action detection: bipolar was set in the interior of the right-hand forearm.
Sample data: 3000ms prior to execution.
Performance
Attention
Mental state
Attention is the key element of mental state related to peak performance (Krane & Williams, 2006; Vietta, Peper, Schmid, 2006)
Figure 1 Mean SMR power (μV) for expert and novice during preparation of dart throw.
■ SMR power before execution: Experts > Novices
Experts’ skill level had achieved automaticity, thus their performance didn’t rely on the feedback of external kinesthesis information.
The enhancement of SMR power was related to the improvement of attention (Egner, 2004). Experts before execution might maintain their attention under higher level.
■ Control analysis: the higher mean power of Hz is not restricted to sensory motor area.
The result of cerebral activity changing among multi-regions has been confirmed by previous study (Egner, 2004). Thus, attention enhancement is not only due to promoting power of Hz in sensory motor area, but a result of multi-regions’ interaction.
EEG power with Hz belonged to β1 and higher β1 represented the vigilance attention of general awake (Steriade, 1993). Thus, experts they were probably under general awake state and maintained optimal attention focusing before action execution.
Discussion
Result
Group T3 T2 T1
Mean
Expert
0.53 (0.29)
0.58 (0.30)
0.60 (0.44)
0.57*
Novice
-0.57 (0.23)
-0.64 (0.21)
-0.65 (0.21)
-0.43
-0.02
0.26
-0.03
Table 1 Mean SMR power (μV) for expert and novice during preparation of dart throw.
Sport and Exercise Psychophysiology Lab., National Taiwan Normal University, Taiwan