目的：比較棒壘球壘前式與壘後式兩種不同壘上起跑方式之運動學和動力學上的差異。 方法：以中華女壘國家代表隊15名野手為研究對象，利用兩台Sony數位攝影機(60Hz)與單軸加速規(1000Hz)與一台AMTI測力板(1000Hz)。同步擷取兩種不同壘上起跑動作影像，以APAS分析軟體獲取跑壘時間和離壘瞬間速度等運動學參數。動力學以Acqknowledge3.5.2版軟體分析離壘瞬間的推進力最大力量、推進力衝量、垂直最大力量及垂直衝量等參數並除以個人體重(BW)作為標準化。所得數據以相依樣本t考驗進行統計分析，α定為.05。 結果：壘後式在總跑壘時間(3.19±0.11 sec vs.3.28±0.14 sec)、離壘瞬間速度(2.17±0.15m/s vs. 2.04±0.25m/s)、水平推進力衝量(0.03±0.014m/s vs. 0.02±0.012 m/s)、垂直最大力量(1.01±0.33Nt/BW vs. 0.53±0.34Nt/BW)及垂直衝量(0.19±0.068m/s vs. 0.08±0.048m/s)等參數上均顯著優於壘前式(p<.05)。 結論：整體而言，壘後式較壘前式可明顯縮短跑壘時間，但因離壘時機上的差異，造成有5名受試者(C.D.F.J.L)在總跑壘時間上壘前式快於壘後式，因此建議此5名受試者(C.D.F.J.L)宜採壘前式起跑方式，其餘受試者在能有效掌握離壘時機下建議壘球選手在所有壘包跑壘時以及棒球選手在三壘高飛犧牲打時，壘上起跑動作可採用壘後式，以取得較佳的時間優勢，提高跑者安全上壘的機率。

This study examined the kinematics and kinetics differences between the two kinds of baserunning starts, base-back and base-front starts, in baseball and softball. The subjects are fifteen players of the National Chinese Taipei Women's Softball Team (age=22.47±3.02yrs, weight=62.13±10.31kg, height=163.47±5.79cm, softball experience =10.00±2.56yrs). Two Sony 60Hz digital cameras and a synchronization of one-axial acceleometer (1000Hz) with a AMTI force platform were used for filming the two baserunning starts. All films were analyzed, filtered and linear-converted by ariel performance analysis system to obtain the baserunning time as well as the velocity of take-off. The force signals received by the Acknowledge 3.5.2 software were then analyzed and calibrated to get parameters of the maximum propulsive force, the propulsive impulse, the maximum vertical force and the vertical impulse. The resultant parameters were divided by individual bodyweight (BW) as the normalizer. The data were statistically analyzed with descriptive statistics and a paired sample t-test (α=0.5). The result indicated that base-back start is significantly better in baserunning time (3.19±0.11s vs. 3.28±0.14s), velocity of take-off (2.17±0.15m/s vs. 2.04± 0.25m/s), the propulsive impulse (0.03±0.014m/s vs. 0.02±0.012 m/s), the maximum vertical force (1.01±0.33Nt/BW vs. 0.53±0.34Nt/BW) and vertical impulse (0.19±0.068m/s vs. 0.08±0.048m/s) than the base-front start (p<.05). Because the base-back start saves more baserunning time than the Base-Front start, we suggested that softball players in all kinds of baserunning situations as well as the baseball players encountering the third-base outfield sacrifice fly adopt the base-back start for a better time advantage and a greater chance to reach the base safely.