Generation Mechanism of Linear and Angular Ball Velocity in Baseball Pitching

Abstract

Abstract:The purpose of this study was to quantify the functional roles of the whole-body's joint torques including fingers' joints in the generation of ball speed and spin during baseball fast-ball pitching motion. The dynamic contributions of joint torque term, gravitational term, and motion-dependent term (MDT) consisting of centrifugal force and Coriolis force, to the generation of the ball variables were calculated using two types of models. Motion and ground reaction forces of a baseball pitcher, who was instructed to throw a fastball into the target, were measured with a motion capture system with two force platforms. The results showed (1) the MDT is the largest contributor to ball speed (e.g., about 31 m/s prior to ball release) when using 16-segment model, and (2) the horizontal adduction torque of pitching-side shoulder joint plays a crucial role in generating ball speed with conversion of the MDT into other terms using a recurrence formula.

Quantification of a Ball-Speed Generating Mechanism of Baseball Pitching Using IMUs

“…Since the contributions of individual terms to the ball speed with respect to the data constructed using the identified initial orientation parameters were similar to the contributions calculated from the mocap information (Figure 4), the ball-speed generating mechanism can be quantified by using IMUs. Similar to the results of a previous study [1], the MDT is the largest contributor to the ball speed prior to ball release. Although detailed results are omitted due to space restrictions, the contributions of individual joint torques to the generation of the ball speed when considering the generating factor of the MDT for the data constructed with the identified initial orientation parameters were similar to the contributions calculated from the data measured with a motion capture system.…”

“…where 𝑽 is the generalized velocity vector consisting of linear velocity vectors with respect to the center of gravity (CG) and angular velocity vectors for all segments; 𝑨 𝑻 and 𝑨 𝑮 indicate the coefficient matrices for the active joint torque vector 𝑻 and gravitational force vector 𝑮, respectively; A V V indicates the motion-dependent term (MDT) consisting of force and moment caused by centrifugal and Coriolis forces and the gyroscopic effective moment; and A Err is the modeling error term consisting of the acceleration constraint term of the shoulder joint and fluctuation terms caused by segment lengths and anatomical constraint joint axes [1].…”

“…Furthermore, the MDT was converted to other terms using the same method as in a previous study [1]. 3a).…”

“…The capability to throw a high-speed fast ball is a crucial factor of a good pitcher in baseball games. Previous studies have shown that the motion-dependent term (MDT), consisting of centrifugal forces and the Coriolis force of the multi-link system, significantly contributes to the generation of ball speed in baseball pitching [1][2][3]. The large contribution of the MDT, which is sometimes called the "whip-like" effect, has been quantified with respect to motion data measured with a motion capture (mocap) system and high-speed camera system.…”

Direct and indirect effects of joint torque inputs during an induced speed analysis of a swinging motion

“…Greater understanding of how each joint torque contributes to speed generation through these indirect effects is still 7 needed. A conversion algorithm that quantifies the generating factors of the MDT has been introduced briefly (Koike and Harada, 2014), but without detailed methods, and was applied to high-speed swinging motions including the tennis serve (Koike and Harada, 2014), baseball batting (Koike and Mimura, 2016b), rugby place kicking (Koike and Bezodis, 2017), and baseball pitching (Koike, Uzawa and Hirayama, 2018). Although the factors contributing to the generation of the distal-point speed were examined for these motions, the direct and indirect effects of the joint torque inputs were not separately quantified.…”