Journal of Medical and Biological Engineering, 30(3): 177-180 177 Different Limb Kinematic Patterns during Pitching Movement Between Amateur and Professional Baseball Players Lan-Yuen Guo 1,* Wei-Yin Lin 1 Yu-Jung Tsai 1 Yi-You Hou 1,2 Chih-Chang Chen 3 Chich-Haung Yang 4 Chu-Chung Huang 3 Yi-Hsien Liu 5 1 Department of Sports Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan, ROC 2 Department of Medical Information Management, Kaohsiung Medical University, Kaohsiung 807, Taiwan, ROC 3 Human Computer Interaction Technology Center, Industrial Technology Research Institute South, Tainan 734, Taiwan, ROC 4 Department of Physical Therapy, Tzu-Chi College of Technology, Hualien 970, Taiwan, ROC 5 Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC Received 5 Feb 2009; Accepted 27 Nov 2009 Abstract Recent studies focused on the biomechanics of the pitching have exclusively studied professionals, whereas there is little information on amateur pitchers. Notably, amateur pitchers with improper techniques may result in suboptimal performance and can potentially lead to injury. The present study was aimed to compare the kinematics of the upper extremity during the action of baseball pitching between amateur and professional players. Eighteen subjects (including 8 amateur with 0.9 years mean pitching period, and 10 professional pitchers with 6.7 years mean pitching period) were recruited. Ten kinematic parameters for different instances and phases of pitching cycle were calculated to examine differences between professionals and amateurs. Our results showed four of the ten kinematic parameters with significant difference between these two groups. The parameters included elbow flexion and stride length at foot contact phase, maximum shoulder external rotation at arm cocking phase and knee flexion at ball release phase. The findings suggest that correct pitching movement may assist in increasing ball velocity and potentially prevent injury. Keywords: Baseball, Pitching, Kinematics, Amateur, Professional 1. Introduction Baseball is a common sport in Taiwan, which is generally played starting in childhood. However, amateur pitchers with improper techniques can often sustain injuries, especially children who have just started pitching. Thus, it is logical to speculate that in order to avoid injuries, the best strategy is to ensure proper pitching mechanics [1]. Despite the complicated nature of pitching, accurate pitching motion is associated with greater pitching velocity and reduced sport injury risk [2]. Previous studies indicated differences between professional pitchers by analyzing some of the best pitchers’ throws [3]. However, there is little information comparing the motion pattern of body segments between professional and amateur pitchers, although researchers have verified that the biomechanical variables have a high repeatability among professional pitchers. Professional players show consistent motion pattern of * Corresponding author: Lan-Yuen Guo Tel: +886-7-3121101 ext. 2737 ext. 11; Fax: +886-7-3138359 E-mail: [email protected]upper extremity and trunk during pitching movement. Escamilla et al. studied several biomechanical variables, including shoulder external and internal rotation, shoulder abduction, shoulder horizontal adduction, elbow flexion and external rotation, among baseball pitchers during the 1996 Olympic games [4]. That study found all good performers had high similarity in pitching motion and most pitchers adopted overhead pitching to reach greater velocity. Overhead pitching motion of professional pitchers can be divided into six phases: wind-up, stride, arm cocking, arm acceleration, arm deceleration and follow-through [5]. Skillful pitching in a joint motion is characterized by activation from proximal to distal joints for greater energy output. In the acceleration phase, the pitchers extend the elbow in a second; the motion produced is not only by the elbow joint, but also the other joint components, such as shoulder girdle rotation, combined together. Although biomechanical characteristics of professional pitching have been well documented [6-8], there is little information that compares the characteristics of pitching mechanics between professional and amateur pitchers. The purpose of this study was to compare the kinematic patterns of upper extremity during baseball pitching movement between amateur and professional players. We hypothesized that there
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Journal of Medical and Biological Engineering, 30(3): 177-180 177
Different Limb Kinematic Patterns during Pitching Movement
1Department of Sports Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan, ROC 2Department of Medical Information Management, Kaohsiung Medical University, Kaohsiung 807, Taiwan, ROC
3Human Computer Interaction Technology Center, Industrial Technology Research Institute South, Tainan 734, Taiwan, ROC 4Department of Physical Therapy, Tzu-Chi College of Technology, Hualien 970, Taiwan, ROC
5Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC
Received 5 Feb 2009; Accepted 27 Nov 2009
Abstract
Recent studies focused on the biomechanics of the pitching have exclusively studied professionals, whereas there
is little information on amateur pitchers. Notably, amateur pitchers with improper techniques may result in suboptimal
performance and can potentially lead to injury. The present study was aimed to compare the kinematics of the upper
extremity during the action of baseball pitching between amateur and professional players. Eighteen subjects (including
8 amateur with 0.9 years mean pitching period, and 10 professional pitchers with 6.7 years mean pitching period) were
recruited. Ten kinematic parameters for different instances and phases of pitching cycle were calculated to examine
differences between professionals and amateurs. Our results showed four of the ten kinematic parameters with
significant difference between these two groups. The parameters included elbow flexion and stride length at foot contact
phase, maximum shoulder external rotation at arm cocking phase and knee flexion at ball release phase. The findings
suggest that correct pitching movement may assist in increasing ball velocity and potentially prevent injury.
Keywords: Baseball, Pitching, Kinematics, Amateur, Professional
1. Introduction
Baseball is a common sport in Taiwan, which is generally
played starting in childhood. However, amateur pitchers with
improper techniques can often sustain injuries, especially
children who have just started pitching. Thus, it is logical to
speculate that in order to avoid injuries, the best strategy is to
ensure proper pitching mechanics [1]. Despite the complicated
nature of pitching, accurate pitching motion is associated with
greater pitching velocity and reduced sport injury risk [2].
Previous studies indicated differences between professional
pitchers by analyzing some of the best pitchers’ throws [3].
However, there is little information comparing the motion
pattern of body segments between professional and amateur
pitchers, although researchers have verified that the
biomechanical variables have a high repeatability among
professional pitchers.
Professional players show consistent motion pattern of