Biomechanical Manifestations of Choking Under Pressure in Baseball Pitching

Abstract

Baseball pitching is a complex whole-body movement that requires repeatability to achieve successful outcomes. Previous research has identified that release parameters, or the position and orientation of the baseball coming out of the hand, being important to the location of the ball as it crosses home plate. Additionally, decreases in the variability of these release parameters have been shown to positively influence season-long performance in baseball pitchers. However, there has not been an investigation into the effect that situational pressure, such as a practice versus game setting or different in-game situations, have on the variability of pitching mechanics. Increases in situational pressure often cause the athlete to underperform, which is constituted as choking under pressure. While choking under pressure is multimodal in nature, there are physical presentations, such as freezing degrees of freedom, that occur. The current study seeks to investigate the physical presentations of choking under pressure by identifying changes in variability of arm slot from practice to a game setting, along with during different in-game situations, using Leverage Index as a proxy for in-game situational pressure. Biomechanics data were collected on college baseball pitchers during practices and game settings using a markerless motion capture system. To achieve a representative design and natural experiment, athletes went about their normal practice or game protocols, with no influence from the researchers. Twenty-one college baseball pitchers (14 RHP, 7 LHP, 1.86 ± 0.06m, 93.7 ± 6.8kg) were included in the investigation into changes between practice and game settings, while ninety-one pitchers (62 RHP, 29 LHP, 1.88 ± 0.06m, 93.5 ± 9.8kg) were included in the in-game analysis. The primary findings of the current study include a significant increase in arm slot variability when moving from a practice setting to a game setting, with pitcher who have a higher mean arm slot variability being less affected by the change in setting. Additionally, as Leverage Index, or situational pressure, increased during the game there was significant reduction in arm slot variability, with individualized findings. These findings point to an individualized and multifaceted approach to prevent choking under pressure, which should include professionals from multiple disciplines.