2015 Volume 19 Issue 3 Pages 126-136
In baseball, a special type of offensive technique, called bunt, is used to ground the ball with the intention of advancing a baserunner and/or scoring a runner from third base. Unlike in the normal batting, the primary goal of a bunt is to minimize the speed of the batted ball. The purpose of this study was to describe the impact characteristics of bunt for minimizing the batted ball speed in baseball bunt. Thirty-one healthy men having experience of baseball for five years or longer participated in the study. Each subject performed eight to thirty-two trials of bunt, aiming at grounding the ball toward the pitcher. Behavior of ball impact was recorded with two high-speed cameras (2500 fps) for three-dimensional analysis. Stepwise multiple regression analysis was conducted to predict the batted ball speed (Y) from impact location of the bat relative to the sweet spot (short axis: X1 & X12 long axis: X3 & X32), bat speed immediately before impact (X2) and distance between the position of the top-hand and bottom-hand (X4). The batted ball speed was associated with the four variables (Y=17.5+0.0069X12 +1.12X2-241.5X32-11.72X3, R2=0.95), in particular, the squared value of the impact location of short axis of the bat (X12) was found to make the largest contribution to the prediction of the batted ball speed. These results indicate that making the ball impact in the middle of the bat width is the more important skill, than either moving the bat in the direction of a catcher before impact or making the ball impact at the distal end of the bat, for minimizing the batted ball speed in bunt.
