To investigate the interference effect in volleyball players and nonathletes ( ns=10) when they executed both saccadic and key-press reaction time (RT) tasks concurrently, the two groups responded to the onset of peripheral visual stimuli as quickly as possible in single and dual conditions. In the single condition, subjects responded with either saccadic eye or key-press movement. In the dual condition, they responded concurrently with both saccadic eye and key-press movements. In both groups, the key-press RT was longer in the dual condition than in the single condition. However, the amount of key-press RT delay was remarkably smaller for the volleyball players than for nonathletes. This suggests the motor command to initiate manual movement of volleyball players might be less interfered with by a concurrent oculomotor command to initiate saccadic eye movement when compared to that of nonathletes.

[Purpose] It is very important to consider effects that postural deviations has on muscle activity when treating low back pain. Therefore, activities of trunk and hip joint muscles in healthy adults while they attempted three postural conditions of neutral, sway-back, and lordosis was compared and evaluated in this study. [Subjects and Methods] The subjects comprised 17 healthy adult male volunteers. The muscle activity and spinal curve were measured while the subjects attempted different postural conditions (neutral, sway-back, and lordosis) as defined in the text. [Results] Activity of trunk and hip inner muscles was decreased in sway-back posture, and only activity of the trunk back muscles was increased in lordosis. [Conclusion] This results were suggested that postural deviations affected muscle control in the lumbo-pelvic area.

Previous researchers reported that EMG Reaction Time (RT) for a key press in peripheral and central visual fields decreases with practice. The practice effects on the RT for peripheral visual field transferred to the RT for the central visual field, and vice versa. The present study investigated whether practice effects on the RT for peripheral and central visual fields and the corresponding transfer effects lasted 3 wk. or not. 16 male subjects were divided into two groups, one practicing using peripheral vision, the other practicing using central vision. Each group practiced RT tasks for 3 wk. 3 wk. after practice terminated, the practice effects and the transfer effects were maintained as a significant decrease in RT was found over the 3-wk. retention interval, suggesting that once the neural correlates of responding quickly are improved, the improved performances are remarkably stable for at least 3 wk.