選択反応条件下におけるソフトテニス・フォアハンド・ストロークのキネマティクス的分析

抄録

In this paper the authors introduce the results of the experiment analyzing the kinematic character of soft-tennis forehand drives, on the basis of a typical situation model in one-up-one-back formation with a three-dimensional DLT method. Forehand drives were executed under a two-choice reaction condition, which contrasted with a non-choice reaction condition (NCR, n=6), while for the analyzing, the choice reaction condition was divided into the repeated condition (REP, n=5) and the non-repeated condition (NRP, n=6). In case of REP, the same stimulus was repeated more than four times, but in case of NRP, the stimulus different from the immediately preceding one was presented.

The major results obtained in this investigation were as follows:

(1) In comparison of the choice reaction condition and the non-choice reaction condition, the accelerated sequences of the body differed distinctively; in the choice reaction condition the upper limb was accelerated before the trunk was.

(2) The angle of shoulder horizontal extension tended to be larger until about 0.05 sec before impact, and the height of contact-point tended to be lower in case of the choice reaction condition in comparison to the non-choice reaction condition.

(3) The contributions made by the internal rotation and the abduction of the shoulder joint to the racket-head velocity were slightly higher in case of the choice reaction condition (REP 52.9%, 10.1%; NRP 53.2%, 11.0%) than the non-choice reaction condition (NCR 49.3%, 5.4%).

(4) The contribution made by the wrist joint at just before impact tended to be higher in REP than in other conditions.

These results suggest that in order to make the ball-racket contact successful, subjects used different mechanics of the motions for accelerating the racket and employed certain strategies under choice reaction condition.