剣道の上達に伴う伸張反射活動の調節能力
2002 年 35 巻 2 号 p. 1-9
詳細
2002 年 35 巻 2 号 p. 1-9
The present study investigated the relation between the level of progress in kendo performance and the ability of modulation to stretch reflex activities including the long latency components. We used motor tasks that required positioning a handlebar, held in the hand, over two different target positions in response to a rapid muscle stretch in the wrist flexor. The target positions were a position 30°C to the extension side (extension task) and a position 30°C to the flexion side (flexion task)of the neutral wrist position. The records of motor tasks were the time taken to stop the handlebar on the target positions from stretch onset (time to stop). The short and long latency activities (M1 and M2 components) of stretch reflexes were measured by averaging the rectified electromyogram (EMG) s recorded with surface electrodes over the wrist flexor. The subjects were 21 healthy university students (mean 21.2 years), comprising 7 kendo players of a high skill level (high skill group),7 kendo players of a middle skill level (middle skill group) and 7 inexperienced persons (inexperienced group). The main results were as follows:
1) The activities of M1 and M2 components in the extension task decreased for all subjects.
2) The activities of M2 components in the flexion task increased for all subjects.
3) The degree of decreased or increased reflex activities in the high skill group, middle skill group and inexperienced group were larger in that order.
4) The time to stop in the high skill group, middle skill group and inexperienced group were reduced in that order too.
In this experiment, the tension produced by the stretch reflex activities of the wrist flexor should obstruct the voluntary movements when the target position is the extension side of the wrist joint. Contrary to this, when the target position is the flexion side, the increase of the reflex tension should help to perform the voluntary movements. Therefore, the modulation of stretch reflex activities including the long latency components is rational for motor tasks in the study. Moreover, the ability of modulation to stretch reflex activities increased according to the progress in kendo skill. Based on these findings, we claim that the ability of modulation to stretch reflex activities with the appropriate motor control of the forearm is closely connected with good performances in kendo.
