連続および複合打球動作が打球成績に及ぼす影響 : ダイナミカルシステムアプローチからの検討

Abstract

Previous experimental studies (Yamamoto and Gohara, 1999; 2000) have shown that continuous hitting movements have a hierarchical fractal structure, as predicted by dynamical systems approaches with external temporal input. The switching input condition in the previous experiments showed higher performance than when periodic input was applied. To extend this finding to motor learning, we therefore examined the influence of a similar complex hitting action on performance using novices as subjects. Hitting performances of novices were recorded under two conditions: one where two different hitting actions (forehand and backhand tennis strokes) were switched repeatedly-as was the case for the switching condition used in the previous experiment- and one where only one of the two strokes was repeated, corresponding to the periodic input condition. In the complex hitting condition, the end phase and the next preparatory phase were shown to be "fused" in the intermediate phase, as a consequence of exploiting the inertia of the trunk rotation movement, and subjects showed better performance under the complex hitting condition than under the continuous hitting condition. These results suggest that when more than two different classes of novel movements need to be acquired, the movement combination that exploits the physical inertia would be more effective than repeating each movement individually.