優秀棒球投手跨步型態對軸心腳力學之影響

本研究目的針對使用不同跨步型態投法（高壓投法、推蹬投法）之優秀棒球投手的軸心腳運動學與動力學特徵進行分析探討，以期找出高壓投法、推蹬投法的差異。受試者為20位優秀大專甲組成棒投手（年齡20.41 ± 1.60歲，身高180.00 ± 5.56公分，體重 80.37 ± 10.88公斤，最快球速 38.44 ± 2.04 m/s），調查其基本資料，並使用Stalker Sport測速槍、Motion Analisis System與AMTI三軸測力板分別針對球離手瞬間的球速與受試者投球過程中的運動學與動力學參數進行測量。資料處理以EVa Real-Time Software將實驗所蒐集到的數據，輸出至Matlab、Excel軟體進行實驗資料處理，再進行分組。統計分析利用SPSS 12.0以獨立樣本t檢定，針對高壓投法、推蹬投法的受試者在運動學與動力學參數進行差異性分析，顯著水準p < .05。結果顯示，高壓投法組受試者身高顯著高於推蹬投法組，軸心腳膝關節伸展角度最小值到達時間、軸心腳投球方向地面反作用力峰值到達時間顯著晚於推蹬投法組，軸心腳推蹬投球方向、垂直地面方向地面反作用力衝量顯著小於推蹬投法組。本研究發現高壓投法與推蹬投法的關鍵差異在於投球動作跨步期軸心腳之膝關節屈曲角度與軸心腳之地面反作用力的大小與出現的時序。推蹬投法較依賴軸心腳推蹬的力量，高壓投法可能較依賴軀幹、上肢的力量，訓練時也應特別加強這些部位的肌力，以提升投球表現，避免受傷。

關鍵字

高壓投法；推蹬投法；膝關節

並列摘要

This study was focused to examine the differences of kinematic and kinetic characteristics for elite baseball pitchers' pivot legs between different stride types in pitching (tall-and-fall and dip-and-drive). Twenty elite college male baseball pitchers (age: 20.41±1.60 years, height: 180.00±5.56 cm, weight: 80.37±10.88 kg, maximum ball speed: 38.44±2.04 m/s) were volunteered to be the subjects in the research. Stalker Sport speed gun, Motion Analysis System and AMTI force plate were used to measure the ball velocity, kinematic and kinetic characteristics after an investigation of height, body weight, age, years of playing baseball, years of pitching, maximum ball velocity, medical history and healthy situation. EVa Real-Time Software was used to output the raw data of each marker and the raw data of force plate during pitching. Participants were assigned to the tall-and-fall group and the dip-and-drive group according to this data. All statistical and correlation analyses were performed with SPSS (12.0) software and the significance was set at p＜.05. An independent t-test was performed for ball velocity, kinematic and kinetics characteristic to test the differences between tall-and-fall group and dip-and-drive group. The results showed that tall-and-fall group was significantly greater in body height, lower in the ground reaction force impulse of pitching in pivot leg and later in the timing of minimum knee flexion angle, and maximum ground reaction force than dip-and drive group. This study found that the timing and amount of knee flexion angle and ground reaction force in pivot leg during stride phase were the key differences between tall-and-fall and dip-and-drive groups. Dip-and-drive pitching depended on the press force of pivot leg, and tall-and-fall pitching maybe depended on the muscle strength of trunk and upper limb in pitching. Strength training for those muscles should be emphasized respectively to improve the pitching performance and prevent injury.