How maximal whole-body and segmental angular momenta relate to fastball speeds in high school baseball pitchers

Generation of whole-body and segmental rotations are important objectives of baseball pitching and may be quantified using angular momentum about the body's center of mass (L_COM). However, the characteristics of L_COM during baseball pitching are not well understood, and it is not known whether generating more whole-body or segmental L_COM would be beneficial for the performance outcome of fastball speeds. We characterized whole-body and segmental L_COM and hypothesized that ball speed would positively associate with maximum whole-body, pelvis, trunk, pitching upper arm, forearm, and hand L_COM. Optical motion capture recorded fastballs thrown by 20 high-school pitchers. L_COM was computed and expressed relative to the global axes with the upward axis as global vertical, the forward horizontal axis from the mound towards home plate, and the leftward axis as the cross product of the upward and forward axes. Associations between ball speed and L_COM were examined using linear mixed models. Ball speed had significant positive associations with maximum whole-body and trunk L_COM about the leftward axis with small effect sizes. Characteristic profiles of L_COM in baseball pitching were identified. Maximum whole-body, trunk, and pitching arm L_COM were largest about the leftward axis and second largest about the upward axis, consistent with the goal to generate rotation in these directions. Segmental L_COM about the leftward and upward axes peaked sequentially, supporting that it was transferred from the lower body to the trunk and the pitching arm, towards maximizing momentum for the pitching arm segments.