Miyazaki Shigeaki, Yamako Go, Totoribe Koji, Sekimoto Tomohisa, Kadowaki Yuko, Tsuruta Kurumi, Chosa Etsuo
Rehabilitation Unit, University of Miyazaki Hospital, 5200 Kihara Kiyotake, Miyazaki, Miyazaki, 889-1692, Japan.
Department of Mechanical Design Systems Engineering, Faculty of Engineering, University of Miyazaki, 1-1 Gakuen Kibanadai-nishi, Miyazaki, Miyazaki, 889-2192, Japan.
BMC Sports Sci Med Rehabil. 2021 Mar 17;13(1):26. doi: 10.1186/s13102-021-00255-7.
Although shadow pitching, commonly called "towel drill," is recommended to improve the throwing motion for the rehabilitation of pitching disorders before the initiation of a throwing program aimed at returning to throwing using a ball, the motion differs from that of normal throwing. Learning improper motion during ball release (BR) may increase shoulder joint forces. Abnormal throwing biomechanics leads to injures. However, there has been no study of shadow pitching focusing on the BR position. The purpose of the present study was to evaluate the BR position and kinematic differences between shadow pitching and normal throwing. In addition, the effect of setting a target guide for BR position on throwing motion was examined in shadow pitching.
The participants included in this study were 20 healthy male students who were overhand right-handed pitchers with no pain induced by a throwing motion. Participants performed normal throwing (task 1), shadow pitching using a hand towel (task 2), and shadow pitching by setting a target of the BR position (task 3). A motion capture system was used to evaluate kinematic differences in throwing motions, respectively. Examination items comprised joint angles and the differences in BR position.
BR position of task 2 shifted significantly toward the anterior, leftward, and downward directions compared with task 1. The distance of BR position between tasks 1 and 2 was 24 ± 10%. However, task 3 had decreased BR deviation compared with task 2 (the distance between 3 and 1 was 14 ± 7%). Kinematic differences were observed among groups at BR. For shoulder joint, task 2 showed the highest value in abduction and horizontal adduction among groups. In spine flexion, left rotation and thorax flexion, task 2 was significantly higher than task 1. Task 3 showed small differences compared with task 1.
The BR position of shadow pitching deviated significantly in the anterior, leftward, and downward directions compared with normal throwing. Furthermore, we demonstrated that the setting of BR target reduces this deviation. Thus, the target of BR position should be set accurately during shadow pitching exercises in the process of rehabilitation.
尽管影子投球（通常称为“毛巾练习”）被推荐用于在开始使用球进行投球以恢复投球能力的康复训练之前改善投球动作，但该动作与正常投球不同。在球出手（BR）时学习不正确的动作可能会增加肩关节受力。异常的投球生物力学导致受伤。然而，尚未有针对影子投球中BR位置的研究。本研究的目的是评估影子投球和正常投球之间的BR位置和运动学差异。此外，还研究了在影子投球中为BR位置设置目标引导对投球动作的影响。
本研究的参与者为20名健康的男性学生，他们是右利手的过肩投手，投球动作不会引起疼痛。参与者进行正常投球（任务1）、使用毛巾进行影子投球（任务2）以及通过设置BR位置目标进行影子投球（任务3）。使用运动捕捉系统分别评估投球动作中的运动学差异。检查项目包括关节角度和BR位置的差异。
与任务1相比，任务2的BR位置明显向前、向左和向下偏移。任务1和任务2之间BR位置的距离为24±10%。然而，与任务2相比，任务3的BR偏差减小（任务3和任务1之间的距离为14±7%）。在BR时各组之间观察到运动学差异。对于肩关节，任务2在各组的外展和水平内收方面显示出最高值。在脊柱前屈、左旋和胸廓前屈方面，任务2明显高于任务1。任务3与任务1相比差异较小。
与正常投球相比，影子投球的BR位置在前、左和下方向上有明显偏差。此外，我们证明设置BR目标可减少这种偏差。因此，在康复过程中的影子投球练习中应准确设置BR位置目标。
