本研究では，卓球中級者1 名のトップスピン・フォアハンドドライブを対象に，スピード意識と回転意識で打球した場合におけるボールの威力指数（並進成分と回転成分の運動エネルギーの和）を事例的に検討し，中級者が競技力を向上するための示唆を得ることを目的とした．被験者には，スピード意識と回転意識でトップスピン・フォアハンドドライブを15 試技ずつ全力で実施させ，ターゲットエリアに入った各5 試技を分析した．ボールスピード，回転量，威力指数，ラケット角度および打点高を比較した結果，スピードを意識した打球では，回転を意識した打球よりも威力指数が大きくなった一方で，トップスピンの回転量が減少し，ラケット角度が小さく，打点高が高くなる動作的特徴が認められた．これらの結果から，中級者においては，威力の向上のみならず，打球の安定性や対戦相手に与える影響を考慮し，回転を含めた打球戦略を構築する必要性が示唆された．

The purpose of this case study was to examine the ball power index—defined as the sum of translational and rotational kinetic energy—during topspin forehand drives performed by a single intermediate table tennis player under speed-focused and spin-focused conditions, and to provide practical implications for performance enhancement in intermediate players. The participant performed 15 maximaleffort topspin forehand drives under each condition, and five successful trials within a predefined target area were analyzed. Ball speed, spin rate, power index, racket angle, and impact height were calculated and compared between conditions. The results showed that speed-focused strokes produced a greater power index than spin-focused strokes; however, they were also characterized by a reduced topspin rate, a smaller racket angle, and a higher impact height. These findings suggest that, for an intermediate player, improving stroke performance requires not only increasing ball power but also considering stroke stability and the effects of spin on the opponent, thereby highlighting the importance of developing hitting strategies that appropriately integrate both speed and spin.