子どものリズミカルな運動の調整能の発達について

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Infants acquire an upright bipedal walk that lasts until they are about one year old, after which they begin to acquire various patterns of movement. In preschool children, both the nervous system and perceptual motor ability have already begun to improve. Therefore, improvement of motor performance would appear in tasks of skill rather than in the tasks of muscular strength. Timing is essential in the execution of skillful movement. There are two temporal elements involved. One is adjustment to am moving target, in which timing involves a single response to a coincident-anticipation task; the other is rhythm, which involves timing movements to correspond to a certain tempo. This paper focused on the repetitive movement sequence and investigated the developmental characteristics of motor control in those movements in children from 3 to 12 years old. In experiment 1, the subjects performed tasks involving, synchronization and maintenance of an externally prescribed tempo, and they were then asked to control and regulate their own movements. A 500-msec interval was considered the preferred tempo for subjects aged 3 to 12 years. When the target pulse (interval) was withdrawn, younger children (3-4 years old) could not maintain the required tempo and changed the tapping frequency to a speed of their own. Children over 7 years old could regulate their movements to adjust to the external stimuli to which they had responded during the movement sequence. It is suggested that some developmental transitions in the central nervous system occur between 4-5 and 6-7 yeas of age, and these'improvements' temporally modify the control of movement. In experiment 2, the subjects executed the task of responding to a set of indicated auditory stimuli as quickly as possible by tapping. In the younger children (3-4 years old), stimuli seemed to promote responsive motion, accelerating the motion itself as the stimuli continued. Although younger children could perceive the time lag, they could not adjust their timing to the stimuli while continuing to tap. Regarding continuous repetitive movement, poor consistency was observed in younger children. On the other hand, in children in early stages of elementary school (7-8 years old), cognition of a time lag in their responses seemed to inhibit the continuity of response. Furthermore, when the subjects executed repetitive movement, attempting to maintain a certain tempo constantly, they could not often do that rhythmically using whole of the body, coordinating upper and lower extremities. It was suggested that movement control was affected also by the level of peripheral maturation. Although a maximal limit of effort is often the focus of developmental study in the field of physical education, regulated movement that required submaximal effort was investigated in this study. From the results, the possibility is suggested that the tempo of the rhythm and movement, particularly self-inhibitory movement, is introduced efficiently to assist in the execution of skilled movement.