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In this study we investigated the compressive quasi-static mechanical properties and dynamic impact behavior of baseballs. Our purpose was to determine if static testing could be used to describe dynamic ball impact properties, and to compare static and dynamic properties between traditional and modified baseballs. Average stiffness and energy loss from 19 ball models were calculated from quasi-static compression data. Dynamic impact variables were determined from force–time profiles of balls impacted into a flat stationary target at velocities from 13.4 to 40.2 m/s. Peak force increased linearly with increasing ball model stiffness. Impulse of impact increased linearly with ball mass. Coefficient of restitution (COR) decreased with increasing velocity in all balls tested, although the rate of decrease varied among the different ball models. Neither quasi-static energy loss nor hysteresis was useful in predicting dynamic energy loss (COR²). The results between traditional and modified balls varied widely in both static and dynamic tests, which is related to the large differences in mass and stiffness between the two groups. These results indicate that static parameters can be useful in predicting some dynamic impact variables, potentially reducing the complexity of testing. However, some variables, such as ball COR, could not be predicted with the static tests performed in this study.

The purpose of this study was to examine the batting cage performance of wood and nonwood baseball bats used at the youth level. Three wood and ten nonwood bats were swung by 22 male players (13 to 18 years old) in a batting cage equipped with a 3-dimensional motion capture (300 Hz) system. Batted ball speeds were compared using a one-way ANOVA and bat swing speeds were analyzed as a function of bat moment of inertia by linear regression. Batted ball speeds were significantly faster for three nonwood bat models (P < .001), significantly slower for one nonwood model, and not different for six nonwood bats when compared with wood bats. Bat impact speed significantly (P < .05) decreased with increasing bat moment of inertia for the 13-, 14-, and 15-year-old groups, but not for the other age groups. Ball-bat coefficients of restitution (BBCOR) for all nonwood were greater than for wood, but this factor alone did not correlate with bat performance. Our findings indicate that increases in BBCOR and swing speed were not associated with faster batted ball speeds for the bats studied whose moment of inertia was substantially less than that of a wood bat of similar length.

Pitched-baseball trajectories were measured in three dimensions during competitions at the 1996 Summer Olympic games using two high-speed video cameras and standard DLT techniques. A dynamic model of baseball flight including aerodynamic drag and Magnus lift forces was used to simulate trajectories. This simulation together with the measured trajectory position data constituted the components of an estimation scheme to determine 8 of the 9 release conditions (3 components each of velocity, position, and angular velocity) as well as the mean drag coefficient C_D and terminal conditions at home plate. The average pitch loses 5% of its initial velocity during flight. The dependence of estimated drag coefficient on Reynolds number hints at the possibility of the drag crisis occurring in pitched baseballs. Such data may be used to quantify a pitcher’s performance (including fastball speed and amount of curve-ball break) and its improvement or degradation over time. It may also be used to understand the effects of release parameters on baseball trajectories.

The role of physical and psychological skills as predictors of performance and survival in professional baseball was studied in a sample of 104 minor league baseball players. Psychological and physical skills were largely uncorrelated with one another and appear to be measuring separate and independent skill domains. Preseason scores on the Athletic Coping Skills Inventory (ACSI-28) and coaches’/managers’ ratings of the same skills on an ACSI Rating Form each accounted for as much performance variance in batting average (approximately 20%) as did physical skills when differences in the latter were statistically controlled, and the psychological measures accounted for substantially more variance in pitchers’ earned run averages than did the expert ratings of physical skills. The psychological skills measures also predicted athletes’ survival in professional baseball 2 and 3 years after they were obtained. Bayesian hit rate anlayses indicated substantially increased survival predictability over simple base rate predictions.

This study investigated differences in kinematic and temporal parameters between two velocity groups of baseball pitchers. Data were collected from 127 healthy college and professional baseball pitchers. Those who threw faster than 1 SD above the sample mean (>38.0 m/s) were assigned to the high velocity group (n = 29), and those who threw slower than 1 SD below the sample mean (<34.2 m/s) were assigned to the low velocity group (n = 23). Twelve kinematic parameters and 9 temporal parameters were measured and analyzed. The pattern of lead knee movement was also investigated. Maximum shoulder external rotation, forward trunk tilt at the instant of ball release, and lead knee extension angular velocity at the instant of ball release were significantly greater in the high velocity group. Maximum lead knee flexion angular velocity was significantly greater in the low velocity group. Seventy percent of the high velocity group showed knee extension during the approach to ball release, whereas the low velocity group showed a variety of knee movement patterns involving less knee extension and more knee flexion. The greater shoulder external rotation in the high velocity group produced an increased range of motion during the acceleration phase.