The effect of baseball bat properties and participant ability on youth hit ball speed

Abstract

The following describes the results of a batting cage study involving youth batters hitting with three types of baseball bats in two weight classes. Participants were allowed to select a bat length from within each type and weight according to their preference. The bats were then swung in random order. Reflective markers were placed on the bats and balls, allowing infrared cameras to track their motion from which speed was obtained. Given the differing ability of the participants, the study outcomes were normalized to the swing speed of each batter. Bat performance was quantified from the bat-ball coefficient of restitution. Laboratory measures of bat performance were shown to strongly correspond with the peak batting cage results. The ball exit speed of hollow bats exceeded that of traditional solid wood bats by as much as 5%. The ball exit speed was also found to be affected more by players’ ability than the bat type. Batter swing speed correlated strongly with bat inertia and was relatively insensitive to the bat-ball impact location, showing that participant effort was not biased by impact quality. Batter swing speed tended to depend more strongly on bat inertia than has been found in adult studies, which may be due to the smaller size of youth participants.