An Examination of an Isometric Core Rotation Test and its Relationship to Baseball Exit Velocity in Division II Collegiate Players

Abstract

The purpose of this study was to examine an isometric core rotation test and its relationship to baseball exit velocity in Division II collegiate players. This was a replication study based on Spaniol et al. (2010). Data collection involved assessing isometric core rotation force with a digital crane scale, followed by measuring baseball exit velocity with a radar gun. Both assessments were conducted for three trials on the dominant and non-dominant sides, respectively. The reliability of the three test trials for the isometric core rotation and baseball exit velocity tests for the non-dominant and dominant sides were assessed with Cronbach's alpha values. The reliability values were as follows: isometric core rotation test non-dominant side (0.873), isometric core rotation test dominant side (0.955), baseball exit velocity non-dominant side (0.942), and baseball exit velocity dominant side (0.922). Independent t-tests were conducted to assess differences between the dominant and non-dominant sides in isometric mean core rotation force and baseball mean exit velocity, respectively. Pearson correlations were conducted to assess the relationship between the isometric mean core rotation force and the baseball mean exit velocity. The key finding was a significant (p = 0.026) and moderate positive relationship (r = 0.570) between the dominant-side isometric mean core rotation force and the dominant-side baseball mean exit velocity. Additionally, a significant (p = 0.002) and moderate positive relationship (r = 0.733) was found between the non-dominant side isometric mean core rotation force and the dominant side baseball mean exit velocity. The isometric mean core rotation force was not significantly different between the dominant and non-dominant sides (p = 0.86); whereas the baseball mean exit velocity was significantly different between sides (p = 0.0004). Therefore, on the dominant side, players had learned to effectively transfer isometric core rotational force into a dynamic bat swing, as reflected in baseball exit velocity. These findings highlight the importance of isometric core rotation strength in baseball players, due to its moderate relationship with baseball exit velocity. The use of the crane scale, as in this study, represents a reliable, inexpensive, time-efficient, and practical method for monitoring sports-specific core fitness in baseball players.