A topspin rate exceeding 110 rps reduces the ball time of arrival to the opponent: a table tennis rally study.

This study experimentally investigated the factors affecting the time a table tennis ball with topspin takes to reach the opponent. Six skilled young players and one coach performed topspin forehand strokes under the observation of three high-speed cameras. As the distribution of the participants' measurements was uneven, additional data were collected using a launching machine that could control the ball speed and spin. To verify the effect of the spin rate on speed decay by drag, the translational speed was measured at 0.15 s after passing the baseline (23 m/s); the balls with topspin ≥110 rps, close to participants' average (117 ± 29 rps) were 1.4 m/s faster than those with topspin ≤80 rps. The horizontal ball speed changed in the range of -3.1 to 2.6 m/s owing to table bounce. At topspins ≥110 rps the ball reached a point 1 m past the end line (estimated receiving position) 27 ± 5 ms faster than at topspins ≤80 rps, for the same initial speed. The relationship between spin rate and travel time was non-linear with boundaries at 80 and 110 rps. Therefore, maintaining a spin rate of ≥ 110 rps along with a high initial speed is an effective strategy for reducing the opponent's preparation time.

Relationship between impact characteristics and launch direction in softball hitting: A study involving elite players.

In the game of softball, the batter should possess the necessary skills to hit the ball toward various directions with high initial speed. However, because various factors influence each other, there are limitations to the range that can be controlled by the batter's skill. This study was aimed at extracting the impact characteristics associated with the launch speed/direction and batted ball spin and clarifying the important skills required to improve the batter's hitting performance. In our experiments, 20 female softball players, who are members of the Japan women's national softball team, hit balls launched from a pitching machine. The movements of the ball and bat before, during, or after the impact were recorded using a motion capture system. Stepwise multiple regression analysis was performed to extract factors relating the side spin rate. The undercut angle (elevation angle between the bat's trajectory and the common normal between the ball and bat: ΔR2 = 0.560) and the horizontal bat angle (azimuth of bat's long axis at ball impact: ΔR2 = 0.299) were strongly associated with the side spin rate (total R2 = 0.893, p < 0.001). The undercut angle in opposite-field hitting was significantly larger than that in pull-side hitting (p < 0.001). The side spin rate was associated with the undercut angle because the bat's distal (barrel) side inclined downward (-29.6 ± 8.7°) at impact. The ball exit velocity was higher when it was hit at a smaller undercut angle (R2 = 0.523, p < 0.001). Therefore, it is deemed desirable to focus on maximizing the ball exit velocity rather than ball spin because the ball-bat impact characteristics vary inevitably depending on the launch direction. Meanwhile, the use of the ball delivery machine and the slower pitched ball are the limiting factors in the generalization of the findings.

Does the combination of different pitches and the absence of pitch type information influence timing control during batting in baseball?

Baseball pitchers use various pitch types to reduce hitting accuracy, but little is understood of the practical strategy of using visuomotor skills and timing control to respond to different pitches. This study examined 1) effectiveness of pitch type combinations, and 2) relationship between the presence and absence of advance information about the next pitch and the timing error. Twenty-six high school baseball players hit a ball launched from a pitching machine in a combination of fastballs (34.3±1.3 m·s-1), curveballs (25.4±1.0 m·s-1), and slowballs (25.5±0.9 m·s-1). Each participant performed three conditions. (1) Continuity condition (15 trials), in which the same pitch type was thrown five times consecutively. (2) Random condition (30 trials), in which pitch type was not preliminarily conveyed to the participants. (3) Open condition (20 trials), in which the next pitch type was preliminarily conveyed to participants. Participants' hitting movement was recorded by an optical motion capture system and force platform. We calculated timing error based on the difference between the measured impact location (ball position relative to the batter's body at ball-bat impact) and optimal impact location. The timing error between n-th pitch type, (n-1)-th pitch, and the presence or absence of advance information about pitch type (open vs random condition) were analyzed using three-way repeated ANOVA. The results showed that the (n-1)-th pitch type did not affect the timing of impact (p = 0.338). In contrast, the timing errors in open conditions were fewer compared to random conditions (p < 0.001). These results indicate that the pitch type sequence has insignificant effects, and advance information about pitches affects the timing errors. Therefore, having two or more pitch types, reducing the fluctuation of the pitching motion, and the early trajectory of the ball between different pitches potentially lead to increase timing errors.

Acceptable timing error at ball-bat impact for different pitches and its implications for baseball skills.

In baseball hitting, batters need high precision timing control to hit the ball with bat's sweet spot. Knowing the acceptable range of timing error for hitting the ball in the aimed direction for various pitch types is helpful to understand whether the cause of the batter's mis-hit is a spatial or temporal error and highlight the motor skills required by the batter. The purpose of this study was to determine the acceptable timing error in different baseball pitches and the impact characteristics of mis-hits. Twenty-six high school baseball players hit a ball launched from a pitching machine with three types of pitches: fastballs, curveballs, and slowballs. We recorded the three-dimensional behavior of the ball, bat, and human body (pelvis) using an optical motion capture system. We then defined the optimal impact location based on timing accuracy, and determined the acceptable range of timing error by the interactive relationship between the horizontal orientation of the bat's long axis at the time of ball impact and the horizontal direction of the batted ball. The ±30° width in the horizontal direction of the batted ball was set as the precondition for the tolerance of timing. The acceptable timing error was ±7.9 ms for fastballs, ±10.7 ms for curveballs, and ±10.7 ms for slowballs, and the optimal timing for outside pitches was approximately 10 ms later than that for inside pitches. The timing error was also explained 38.1% by variation in the impact location along the long axis of the bat (R2 = 0.381, P < 0.001) and was minimized at a position close to the bat's sweet spot. These results suggest that the optimal impact location and acceptable range of timing error depend on the pitching course and speed and that timing accuracy is essential to achieve the spatial accuracy required to hit the ball at the bat's sweet spot.