本研究の目的は，劣悪な環境に長期間置かれて育ってきたにもかかわらず，それにめげずに立ち直った青年について，立ち直りを可能にした外的・内的要因を発達心理学の観点から検討することである。実母から苛酷な虐待を長期間受けながら立ち直ったDave Pelzer氏（「“it”と呼ばれた子」の著者）が書いた5冊の著書を用いて，なぜ彼が立ち直れたのか，何がそれを可能にしたのかについて分析を行った。その結果，まわりからのサポートを得られたこと，本人が心理的強さや肯定的な志向等のresilienceをもっていたこと，そしてサポートや状況要因と本人のもつ逆境に耐えうる資質がうまくかみ合って，マイナス要因を補強しプラス方向に導いたことが示された。また自分の経験を振り返り著書にまとめたり講演をする中で，senseof coherenceをもつようになっていった可能性も示された。更に彼がもつ強さの源はどこにあるのかについても検討を行い，生得的なものもあると同時に虐待を受ける前の幼少期の経験が関連していること，Eriksonの第1, 第2段階の発達課題をしっかり達成していたことが強さを培い，その後の劣悪な状況をくぐり抜けさせたことが示唆された。

The purpose of this study was to analyze and compare the kinematics of two tennis forehand ground strokes, cross-court stroke and straight shot stroke, for world-top female tennis players in official games. Forehand strokes of the players at Japan Open '96 and '97 and Fed Cup (Japan vs Germany) held in Tokyo were videotaped with two high speed VTR cameras operating at 200 Hz. Analyzed world-top female tennis players were S. Graf, A. Huber, K. Date, A. Frazier, N. Sawamatsu, A. Sugiyama, and N. Kijimuta. They all were right-handed. Three dimensional coordinates of body landmarks, the racket and ball were obtained with a DLT method. Angular kinematics of the upper limb, the trunk and the racket, and the impact parameters were calculated.

The results were summarized as follows:

1) In the cross-court stroke, the racket tip at the impact was positioned more forward (p < 0.001), and the impact position was nearer (p < 0.05) and more forward (p < 0.001) relative to right shoulder than those of the straight shot stroke.

2) Pre-impact racket maximum velocity and post-impact ball velocity were significantly greater in the cross-court stroke than in the straight shot stroke (p < 0.001, p < 0.05).

3) In the cross-court stroke, the extension of the elbow joint before the impact, the snap motion of the wrist joint just before the impact and the forward rotation of shoulders during the forward swing were greater than those of the straight shot stroke (p < 0.05). The horizontal adduction of the shoulder joint before the impact was greater in the straight shot stroke than in the cross-court stroke (p < 0.05).

4) There were two patterns of change in the shoulder rotation angle. In pattern 1 shown by S. Graf, A. Huber and K. Date, the shoulders were rotated more forward just before the impact in the cross-court stroke than in the straight shot stroke. In pattern 2 shown by A. Frazier, N. Sawamatsu, A. Sugiyama and N. Kijimuta, the shoulders in the straight shot stroke were kept in backward position than those of the cross-court stroke during the forward swing.

These results indicated that the racket angle at impact, the impact position and the racket velocity just before the impact were critical factors to determine the direction of the ball struck in ground stroke. The motions of the trunk and the arm which controlled these impact parameters were the snap of the wrist joint, the flexion/extension of the elbow joint and the horizontal adduction/abduction of the shoulder joint before the impact and the forward rotation of shoulders during the forward swing.