Difference in Transverse Plane Scapular Position of Professional Baseball Players Relative to Baseball Field Position

Abstract

The objective of this study was to identify the variation of the scaption angle of professional baseball players among field position played. Subjects consisted of 109 minor league professional baseball players reporting for the 2002 spring training season, who were under contract with the Anaheim Angels professional baseball organization. Subjects reported to a sports medicine/physical therapy clinic for their 2002 spring training pre-participation physical examination. The scaption measurements were taken as a component of the examination. Goniometric measurements were taken with the players in a relaxed standing position. Players were instructed to remain looking forward, roll their shoulders forward three times and then backward three times, and then hold that position for the measurement. A one-time goniometric measure of the player’s scaption angle for their dominant and non-dominant arms was recorded. Specific bony landmarks were used to establish the goniometric vector assignment. The spinous process of the T-4 vertebrae and the sternal notch were used to establish the sagittal vector. The triangle at the base of the spine of the scapula, and the posterio-lateral tip of the acromion were used to establish the transverse vector. The mean scaption angles for the dominant and non-dominant arms were 39.1° and 36.3°, respectively. Significant differences in the mean scaption angle of the player’s dominant arm existed between the shortstop position and the positions of center field, second base, and first base; and in the player’s non-dominant arm between the shortstop position and the positions of pitcher, second base, and center field. The 40.3° angle for the first baseman position was the greatest scaption angle, the mean angle for the shortstop position was the lowest at 34.3. Statistical differences in the scaption angle of dominant arms of baseball players exists between the shortstop field position and the positions of center field, second base, and first base. For the non-dominant arm, statistical differences exist between the shortstop position and the positions of pitcher, second base, and center field. Key Words: Scaption, Shoulder, Shoulder-girdle, Scapul