Abstract

The relationship between bat mass properties (mass and moment of inertia) and bat velocity (linear and angular) was investigated for baseball and softball. Seventeen male collegiate baseball players and 17 female collegiate softball players were tested swinging aluminium alloy bats engineered with various mass and moments of inertia. Motions of reflective markers attached to the pitched ball, bat handle and bat barrel were tracked with a high-speed three-dimensional motion analysis system. Linear velocity of the bat’s “sweet spot” (defined here as 15cm from the end of the bat barrel towards the handle) and angular velocity of the bat were calculated from the motion data. Analysis of variance revealed significant differences (P < 0.05) in bat linear velocity among the baseball bats tested (24.7-26.8 m ∙ s-1) and among softball bats tested (19.4-22.2 m ∙ s-1). Variations in bat angular velocity were non-significant for both the baseball bats (2080-2280 ° s-1) and softball bats (1740-1890 ° s-1). Regression analysis showed a linear correlation between bat linear velocity and bat moment of inertia, both for baseball and softball. Results from this study suggest that if limitations in bat velocity are desired, bat moment of inertia – not bat mass – should be regulated. Verf.-Referat