Effects of Attentional Focus on Postural Sway and Brain Activity during a Single-Leg Stance Postural Control Task

Attentional focus influences performance during motor task execution. This study manipulated focus targets in a single-leg stance postural control task to examine which aspects of attentional focus affect postural control performance. Electroencephalography (EEG) was recorded during task execution to investigate the relationship between attentional focus and performance. Twenty-four students participated in the experiment. They performed a single-leg stance postural control task while instructed to focus their attention on specific targets. Four attentional focus conditions were used: head-top, lower dantian, sole, and fixation point. During the task, postural sway indices, EEG, and muscle activity were recorded. The results showed that total postural sway was significantly greater in the lower dantian and sole conditions than in the fixation point condition. Muscle activity did not differ significantly between conditions. Spectral analysis of EEG showed that in the sole condition, alpha 2 (10-12 Hz) power in the frontal and parietal regions was significantly higher than in the fixation point condition. Significantly greater alpha 2 power in the occipital region was also observed in the sole condition than in the head-top condition. These results indicate that an external focus (attention to the fixation point) stabilizes posture. In contrast, within an internal focus, attention to the sole and lower dantian increases postural sway, whereas attention to the head-top does not. Thus, the findings cannot be organized solely by the distinction between external and internal focus, and indicate that internal focus effects on postural control and brain activity differ depending on the body part attended to.