The purpose of the present study was to clarify the influence of swing parameters by changing the hitting point in space in baseball batting. Twenty-eight skilled baseball players (12 professional and 16 universitylevel) participated. The participants were instructed to hit a ball that was tossed from 5 m away in the direction of the pitching mound. The balls were tossed to various locations with reference to the home plate. The participants were required to hit the balls in a specific direction according to the tossed course, i.e., a ball tossed to the inside of a home plate was stroked toward the same-field direction and one tossed outside of the home plate was stroked toward the opposite-field direction. The motions of the ball and bat during these attempts were recorded using a motion capture system operating at 500 Hz. The 3D coordinates of the ball center (hitting point) and the swing parameters included the speed of the head of the bat (bat-head speed) and the angle of the swing from a horizontal line (swing angle) measured immediately before ball impact and the time from the start of the swing to ball impact (swing time). These parameters were calculated in each trial. Analysis of a total of 644 trials revealed that the bathead speed tended to increase as the hitting point moved inside, forward, and low. Furthermore, the swing angle and swing time tended to increase as the hitting point moved inside, forward, and high. Stepwise multiple regression analysis demonstrated that the bat-head speed and swing angle were independently associated with (in the following order) the distance in the pitcher’s direction, the hitting height, and the inside-outside direction course (R2=.360 and R2=.589, respectively). These results suggest that the timing of swing initiation and bat acceleration during a swing motion are the main factors changing the swing parameters, and that in order to sharp hit a ball, it is important to impact the ball with the hitting point as close to the pitcher as possible.

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In recent years, as measurement devices have advanced due to sensor and information technology, we have been able to measure bat swing data just after baseball impact. Therefore, the purpose of this study was to examine the characteristics of a batter’s swing using batting skill assessments from baseball coaches with significant experience. Finally, the practicality and effectiveness of baseball coaching methods, particularly for batting, were verified through this study. The subjects were 25 male university baseball players (age: 19.8 ± 1.0 yrs, body height: 174.5 ± 5.4 cm; body weight: 72.8 ± 5.1 kg). The participants were instructed to hit the ball placed on a tee stand. Nine types of tee-batting positions (course / height) were set for each participant depending on the upper and lower limits of the strike zone according to the baseball rules. Our main findings were as follows: 1) The swing characteristics (Depth: swing time and vertical bat angle, Height: head speed, rolling angular velocity, bat radius of rotation, horizontal bat angle, and vertical bat angle, Course: rolling angular velocity) varied with respect to ball positions, 2) Through batting skill assessment by two baseball coaches with significant experience, a good batter’s swing can be characterized as high bat speed, short swing time, and high efficiency of rotational movement around the vertical axis. Additionally, the coaches suggested that for a good batter’s swing, the vertical bat angle should be stable and smaller than 9°. These results provide useful information on assessment of bat swing training methods and exercises to hit the ball to different positions. Furthermore, this study can aid baseball coaches and/or players to objectively analyze a bat swing of a player.

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