| Budget Amount *help |
¥13,400,000 (Direct Cost: ¥13,400,000)
Fiscal Year 2000: ¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 1999: ¥7,300,000 (Direct Cost: ¥7,300,000)
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| Research Abstract |
The aim of this study was to examine the human ability to predict and time voluntary movements by using "catch" and "dodge" movements as typical examples of movements that need timing control.
As for the catch, muscle activities of the badminton smash were analyzed. After three successive tones with a fixed time interval, at the time of fourth tone, a shuttlecock was released instead of tone and subjects smashed it aiming at the target on the wall. The skilled players showed a more constant time from peak EMG amplitude to impact. Immediately after impact, the EMG activity of the agonist muscles, triceps brachii and flexor carpi radialis, of the skilled players decreased ; in the unskilled participants, however, it continued until well after impact. The time from peak EMG amplitude to impact in the distal muscles, extensor carpi radialis and flexor carpi ulnaris, was more variable in the unskilled than in the skilled participant even after 6 days of practice, but the proximal muscles of
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the unskilled participant had a similar pattern of activity to that of the skilled player. Thus, controlling the distal muscles appears to be important for achieving accurate performance of the smash in badminton.
When the shuttlecock was released unexpectedly early, the silent period of the extensor carpi radialis, normally observed during smash motion, disappeared and motion became clumsy in feinted subjects.
As for the dodge, instead of fourth tone, a ball was dropped and subjects were asked to dodge it after waiting as long as possible. The results showed that the motor preparation based on prediction needs 1〜2 sec to be completed, and the prepared state can be maintained at least 3 seconds. When the ball release time (stimulus) was predictable, subjects seemed to adopt a strategy that the preparation is made in time with the most probable time of release. When subjects failed to dodge, EMG onset was delayed and the intensity of agonist muscle activity was low, indicating the motor command is not properly constructed. Less
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