棒球過肩投擲上肢肢段動作控制對球速與轉速的影響

The impact of upper limb segment motion control on ball speed and spin rate in baseball over the shoulder throwing

本研究目的在於釐清棒球過肩投擲在人體動作控制與球體飛行表現的影響，以提升選手過肩投擲的表現。採用文獻回顧方式整合近年影響棒球過肩投擲動作與球體表現相關實證性研究，依序從運動學、上肢肌肉活化與手指壓力對球體球速與轉速的影響進行討論。結果發現，整體上肢肢段需著重肩關節外旋與肘關節向後屈曲的角度，並將位能轉化為動能增加投擲離手球速，並屈曲腕關節將球投出。在加速期除闊背肌外，肱三頭肌活化帶動手臂加速產生手臂速度來增加投擲效益，過程中以手部屈曲與手指施壓作為變換球路或增加尾勁的動力來源；手指指尖屈曲角速度則是影響球體轉速的主因，才造就球路的變化。因此，教練或選手在學習與訓練投擲動作時，除了著重上肢肌力訓練外，也需搭配適當手部屈曲角度、角速度與手指壓力，才能提升球速與轉速的變化。

The purpose of this study is to clarify the impact of over-the-shoulder throwing in baseball on human motion control and ball flight performance, in order to enhance the performance of players’over-the-shoulder throws. This study integrates empirical research related to the impact of baseball over-the-shoulder throwing motion and ball performance in recent years through literature review, and discusses the impact of kinematics, upper limb muscle activation, and finger pressure on ball speed and spin rate in sequence. The results found that the overall upper limb segment needs to focus on the angle of shoulder joint external rotation and elbow joint backward flexion, and convert potential energy into kinetic energy to increase the ball speed when throwing away, and flex the wrist joint to throw the ball out. During the acceleration period, in addition to the latissimus dorsi, the activation of the triceps brachii drives the arm to accelerate to generate arm speed to increase the throwing benefit. The process uses hand flexion and finger pressure as the power source to change the ball path or increase the tail force; the finger tip flexion angular speed is the main factor affecting the ball spin rate, which creates the change in the ball path. Therefore, when coaches or players learn and train throwing movements, in addition to focusing on upper limb strength training, they also need to match appropriate hand flexion angle, angular speed, and finger pressure to enhance the change in ball speed and spin rate.