The kinematic analyses of softball target throwing performance

[[abstract]]Abstract The purpose of the study was to examine the differences in the softball target throwing performances. The movement kinematics was analyzed for the throwing movement from 8 elite women softball players and 8 novice female college students. The participants were required to use the over arm throwing pattern to throw a softball at a target 16 meters away for 15 trials. A high speed (200Hz) camera and the Gypsy18 motion capture system (120 Hz) were used to capture the throwing movement and the ball trajectory; The Microsoft Excel and Wolfram Mathematica were used for processing the data. The results showed that the softball players had significantly more accurate throwing performance than the novices, t(14)= 6.851, p <.05, and a higher ball velocity at release, t(14)=5.684, p <.05. For the throwing movement, the softball players had a significantly smaller knee angle for the lead leg at ball release, t(13)＝-2.932, p<.05; the trunk and head angles with respect to the horizontal plane at the ball release were larger, although did not quite reach the significant level, for the softball players, t(13)= 1.971, p =.089, t(13)= 2.180, p =.070. For the kinematics of the throwing arm at ball release, only the elbow angular velocity was found significantly larger for the softball players than the novices, t(13)= 2.339, p<.05. Qualitative analyses on the angular displacement of the elbow joint showed a consistent decrease-increase profile before ball release, characterizing the skill of “lead elbow” which was not found in any novices’ performance. In addition, observation on the angle-angle diagram of the shoulder-elbow joints showed that the differences of the throwing pattern between the 2 groups mainly came from the “back swing” and “elbow lift” segments. Based on the findings of the study, we suggest the following points to be emphasized in teaching target throwing task: for the throwing arm, focusing on the back swing, elbow lift movement and practicing the “lead elbow” technique; for the non-throwing arm movement, the thrower should take a larger forward step and keep the center of gravity low; preventing the head and trunk leaning backward during the throwing movement in order to maintain the forward speed.