title: Intersegmental dynamics of 3D upper arm and forearm longitudinal axis rotations during baseball pitching.
abstract: The shoulder internal rotation (IR) and forearm pronation (PR) are important elements for baseball pitching, however, how rapid rotations of IR and PR are produced by muscular torques and inter-segmental forces is not clear. The aim of this study is to clarify how IR and PR angular velocities are maximized, depending on muscular torque and interactive torque effects, and gain a detailed knowledge about inter-segmental interaction within a multi-joint linked chain. The throwing movements of eight collegiate baseball pitchers were recorded by a motion capture system, and induced-acceleration analysis was used to assess the respective contributions of the muscular (MUS) and interactive torques associated with gyroscopic moment (GYR), and Coriolis (COR) and centrifugal forces (CEN) to maximum angular velocities of IR (MIRV) and PR (MPRV). The results showed that the contribution of MUS account for 98.0% of MIRV, while that contribution to MPRV was indicated as negative (-48.1%). It was shown that MPRV depends primarily on the interactive torques associated with GYR and CEN, but the effects of GYR, COR and CEN on MIRV are negligible. In conclusion, rapid PR motion during pitching is created by passive-effect, and is likely a natural movement which arises from 3D throwing movement. Applying the current analysis to IR and PR motions is helpful in providing the implications for improving performance and considering conditioning methods for pitchers.
authors.affiliation: Department of Sports Sciences, Japan Institute of Sports Sciences, Tokyo, Japan. Electronic address: n.assk-918@w9.dion.ne.jp.
authors.forename: Kozo
authors.initials: K
authors.lastname: Naito
authors.affiliation: Graduate School of Decision Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Takagi
authors.affiliation: School of Health and Sports Science, Chukyo University, Toyota, Japan.
authors.forename: Norimasa
authors.initials: N
authors.lastname: Yamada
authors.affiliation: Faculty of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: Graduate School of Decision Science and Technology, Tokyo Institute of Technology, Tokyo, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Maruyama
mesh_terms: D000054:Acceleration; D000328:Adult; D001132:Arm / Q000502:physiology*; D001484:Baseball / Q000502:physiology*; D001696:Biomechanical Phenomena; D004551:Elbow Joint / Q000502:physiology; D005542:Forearm / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D009068:Movement; D018482:Muscle, Skeletal / Q000502:physiology; D012399:Rotation; D012782:Shoulder / Q000502:physiology; D013696:Temperature; D019415:Torque; D055815:Young Adult; D000092464:Elbow Injuries
keywords: Baseball; Forearm pronation; Kinetic chain; Pitching; Shoulder internal rotation