目的：本研究的目的在於探討不同重量球投球訓練對球速、準度、爆發力、投球動作的影響。研究方法：24 名青少棒球員，依前測之球速能力分成實驗組及控制組；實驗組使用輕球（125g），控制組則是利用正常比賽用球（145g）做連續10 週，每週3 天相同投球組數及球數之投球訓練；訓練前、後隨機將受試者分成2 組分別實施測驗，第一組做做比賽用棒球（145g）、50g 球擲遠測試，第2 組請受試者全力朝靶心連續投擲10 球，以雷達測速槍測定球速；以攝影機拍攝球落點用以統計準度；以高速攝影機（600Hz）拍攝投球動作，利用Silicon Coach 動作分析系統進行肩關節最大外旋角度、投球出手瞬間揮臂速度及上軀幹前傾角度分析。研究結果：實驗組10 週訓練後球速、擲遠能力及投球出手瞬間揮臂速度均顯著提升（p<.05），但此現象在控制組並未發現。結論：本研究證實連續10 週投擲輕球訓練，能對於體型、體能、技術正在發展中的青少棒球員，明顯地提升投擲速度與遠度。

Objectives：This study examined the effects of use of light and standard ball throwing on pitching velocity, accuracy, power , and pitching movement among youth baseball playerh.Methods：Twenty four jouning high school players received pitching velocity test,and were divided into two groups based upon their pitching velocity. The first group undertook training with light ball (125g).throwing. The second group was trained under regular method with a standard baseball（145g）.All groups trained 3 days a week for 10 weeks. Before and after training, subjects were randomly assigned into 2 groups and tested respectively. Group 1 do the throwing distance test with standard baseball and a 50g-ball. Group 2 do the pitching velocity and accuracy test in Bullpen:subjects threw 10 consecutive pitches at the bull’s-eye, measured pitching velocity with radar gun, gathered accuracy of placement by camera shooting, and recorded pitching movement with high-speed camera（600Hz）.Silicon Coach Motion Analysis System was used to analyze the maximum shoulder external rotation angle, wind-up speed and forward trunk tilt at ball releasing moment. Results： After training, the experimental group improved significantly (p<.05) in pitching velocity, and wind-up speed at ball releasing moment, but no improvement was observed for the control group. Discussion：The results suggested that use of light-weighted ball throwing can improve their pitching velocity and throwing distance.