Korean J Sports Med.  2019 Dec;37(4):130-133. 10.5763/kjsm.2019.37.4.130.

Is Hyperabduction Arm Position in Early Cocking Phase Really Dangerous for Baseball Pitchers?

  • 1Center for Shoulder, Elbow and Sports, Neon Orthopaedic Clinic, Seoul, Korea.
  • 2Department of Orthopaedic Surgery, Konyang University Hospital, Daejeon, Korea. ossurgeon@kyuh.ac.kr
  • 3Professional Baseball Team, Doosan Bears, Seoul, Korea.


Certain pitching mechanics is thought to lead pitchers in danger of surgical risk and decrease performance. The objective of this study is to analyze the effect of shoulder hyperabduction position during early cocking phase in association with surgical risk and performance in professional baseball players.
From 2009 to 2013, total of 93 candidates reached minimum inning qualification. After exclusion criteria (overlapped players, foreign players, age over 31 years, proceed to other league and retirement), 19 players were analyzed with slow-motion pitching video for hyperabduction of the shoulder and hyperpronation of forearm in cocking-phase. Also players were analyzed with innings pitched, earned run average (ERA), walks and hits divided by innings pitched (WHIP) and surgical history with database offered by official Korean Baseball Organization website.
Out of total 19 players, nine players had hyperabduction arm movement and 10 players did not. Group with hyperabduction had average age of 24.3 years old, average inning/ERA/WHIP for 5 years were 55 innings/yr, 6.52 ERA/yr and 1.33 WHIP/yr, respectively, and seven players (77%) had surgeries eventually. Group without hyperabduction arm movement had average age of 25.4 years old; average inning, ERA/WHIP for 5 years were 127 1/3 innings/yr, 4.84 ERA/yr, and 1.32 WHIP/yr, respectively and five players (50%) went for surgeries. Player performance (ERA, p=0.66; WHIP, p=0.14) was not statistically influenced by the certain arm position at cocking phase but average inning pitched was statistically affected (p<0.01).
Hyperabduction of shoulder in early cocking phase of throwing motion does not lead to decrease in performance (ERA, WHIP) but will result in tremendous decline of average IP. Also, risk of surgery is not associated to hyperabduction motion of the shoulder.


Baseball; Hyperabduction; Inverted W; Pitching; Shoulder
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