Factors Influencing Ball-Player Impact Probability in Youth Baseball

BACKGROUND: Altering the weight of baseballs for youth play has been studied out of concern for player safety. Research has shown that decreasing the weight of baseballs may limit the severity of both chronic arm and collision injuries. Unfortunately, reducing the weight of the ball also increases its exit velocity, leaving pitchers and nonpitchers with less time to defend themselves. The purpose of this study was to examine impact probability for pitchers and nonpitchers. HYPOTHESIS: Reducing the available time to respond by 10% (expected from reducing ball weight from 142 g to 113 g) would increase impact probability for pitchers and nonpitchers, and players’ mean simple response time would be a primary predictor of impact probability for all participants. STUDY DESIGN: Nineteen subjects between the ages of 9 and 13 years performed 3 experiments in a controlled laboratory setting: a simple response time test, an avoidance response time test, and a pitching response time test. METHODS: Each subject performed these tests in order. The simple reaction time test tested the subjects’ mean simple response time, the avoidance reaction time test tested the subjects’ ability to avoid a simulated batted ball as a fielder, and the pitching reaction time test tested the subjects’ ability to avoid a simulated batted ball as a pitcher. RESULTS: Reducing the weight of a standard baseball from 142 g to 113 g led to a less than 5% increase in impact probability for nonpitchers. However, the results indicate that the impact probability for pitchers could increase by more than 25%. CONCLUSION: Pitching may greatly increase the amount of time needed to react and defend oneself from a batted ball. CLINICAL RELEVANCE: Impact injuries to youth baseball players may increase if a 113-g ball is used.