Fig 1.
Definition of the global coordinate system and the bat coordinate system.
The drawing represents the instant of ball-bat contact from the top view (left) and front view (right). Impact X deviation is the distance between the sweet spot of the bat (white circle; rss) and the center of the ball (rImp) in the direction of bat vector. Impact Z deviation is the distance between the sweet spot of the bat (white circle; rss) and the center of the ball (rImp) in the direction of bz.
Table 1.
Mean speeds (SD) of bat head and sweet spot (m/s) immediately before the ball-bat impact in tee batting and experimental conditions.
Table 2.
Mean and mean SD for each participant’s average ball arrival location in the global coordinate system (mm).
Fig 2.
Scatter plot of the location of the ball center at the moment of ball-bat contact in all trials.
The dashed line represents the barrel of the bat. The diamond symbol indicates the mean location of the distribution. The vertical and horizontal bars represent the mean SDs for the impact X and Z deviations for each participant. Each circle color corresponds to the data from one participant. (a) R+150 condition in the slow ball setting. (b) A-150 condition in the slow ball setting. (c) NO condition in the slow ball setting. (d) R+150 condition in the fast ball setting. (e) A-150 condition in the fast ball setting. (f) NO condition in the fast ball setting.
Fig 3.
Ball locations in the slow ball setting and the fast ball setting for each visual occlusion condition (top view).
The dashed line represents the outer half of a home plate for a right-handed batter. Each circle color indicates the ball locations at the moment of ball-bat contact for one participant. The diamond symbol represents the mean location of the distribution. The vertical and horizontal lines indicate the mean value of the SDs (i.e., the precision) of the ball locations at the moment of ball-bat contact for each participant.
Fig 4.
Standardized variability (mean + standard deviation) of the ball-bat contact location for each subject for the impact X deviation (Bat X), impact Z deviation (Bat Z), and timing (Ball Y) under the slow ball setting (SLOW) and fast ball setting (FAST).
Variability for Bat X and Bat Z were calculated using standardized SDs for the impact X deviation and impact Z deviation with SDs for the arrived ball location in the Xglobal and Zglobal directions. Variability for Ball Y was calculated using a standardized SD for the ball location at ball-bat contact in the Yglobal direction with a SD for the expected ball location in the Yglobal direction at the time of the average ball flight time of all the trials, with the measured ball speed of each trial. Each color of the bar represents an occlusion condition: black, R+150, gray, A-150, and white, NO. (*Standardized variability of the impact Z deviation under both ball speed settings was significantly larger in the R+150 condition than in the A-150 and NO conditions [p < 0.05]).