title: Anterior shoulder forces in professional and Little League pitchers.
abstract: BACKGROUND
  The developing musculoskeletal system of a youth pitcher is substantially different from that of the adult professional pitcher, predisposing the younger players to a different set of injuries.
  
  
  METHODS
  High-speed videography of 39 professional and 13 youth pitchers were obtained. High-speed motion analysis was performed to calculate average anterior forces and arm positions at maximal force generation.
  
  
  RESULTS
  Professional players generated an average of 33.8+/-14.4 N/kg maximal anterior force, corresponding to 151.9+/-17.0 degrees of external rotation. Youth pitchers generated 16.2+/-3.8 N/kg of anterior forces, corresponding to 118.0+/-23.4 degrees of external rotation. The degree of coronal abduction and horizontal abduction between the 2 groups were not significantly different-92.4+/-9.0 degrees in professionals versus 91.7+/-7.9 degrees in the youth and 11.1+/-11.1 degrees of horizontal abduction in professionals versus 7.8+/-14.1 degrees in the younger throwers. Professional pitchers exerted higher internal rotation torque at 19.4+/-4.1 Nm/kg versus 5.6+/-1.0 Nm/kg in youth, and compressive forces were found to be 121.7+/-21.7 N/kg in professional pitchers compared with 47.5+/-7.6 N/kg in the youth pitchers.
  
  
  CONCLUSIONS
  Youth pitchers experience significant anterior shoulder forces and internal rotation torques, although these are lower than professional pitchers.
  
  
  CONCLUSIONS
  Overhead throwing as a youth can lead to shoulder injuries and can predispose the shoulder to more significant injuries as an adult pitcher.
authors.affiliation: Department of Orthopaedics, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Arun J
authors.initials: AJ
authors.lastname: Ramappa
authors.forename: Po-Hao
authors.initials: PH
authors.lastname: Chen
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hawkins
authors.forename: Tom
authors.initials: T
authors.lastname: Noonan
authors.forename: Tom
authors.initials: T
authors.lastname: Hackett
authors.forename: Michelle B
authors.initials: MB
authors.lastname: Sabick
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Decker
authors.forename: David
authors.initials: D
authors.lastname: Keeley
authors.forename: Michael R
authors.initials: MR
authors.lastname: Torry
mesh_terms: D000328:Adult; D000367:Age Factors; D001265:Athletic Injuries / Q000209:etiology*; D001484:Baseball / Q000502:physiology*; D001696:Biomechanical Phenomena; D002648:Child; D006801:Humans; D041641:Musculoskeletal Development / Q000502:physiology; D012399:Rotation; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000502:physiology*; D019415:Torque; D014741:Video Recording