title: Lateral trunk lean in pitchers affects both ball velocity and upper extremity joint moments.
abstract: BACKGROUND
  The incidence of upper extremity injuries in baseball pitchers is increasing. Over the past decade there has been a great deal of research attempting to elucidate the cause of these injuries, focusing mainly on the mechanics of the pitching arm with no examination of other key segments, such as the trunk. This is surprising, as coaches will often comment on trunk position in an effort to improve pitching outcomes.
  
  
  OBJECTIVE
  To determine the association between contralateral trunk lean and ball velocity and the moments about the elbow and glenohumeral joint.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  A total of 99 pitchers were recruited for this study and underwent a pitching analysis using 3-dimensional motion analysis techniques. A random intercept mixed-effects regression model was used to determine if statistically significant associations existed between contralateral trunk lean (away from the pitching arm side) and ball velocity, as well as the elbow varus moment and glenohumeral internal rotation moment.
  
  
  RESULTS
  The results demonstrated that the greatest contralateral trunk lean occurs around the time of the peak elbow varus moment. Statistically significant associations were found between contralateral trunk lean and increased ball velocity (P=.003) indicating that for every 10° increase in contralateral lean, ball velocity increased 0.5 m/s. Results also indicated that for every 10° increase in contralateral lean, elbow varus moments increased by 3.7 N·m and glenohumeral internal rotation moments increased by 2.5 N·m (P<.001 for both).
  
  
  CONCLUSIONS
  Study findings indicate that the positioning of the trunk plays a substantial role in pitching performance and pitcher injury potential. This work helps to demonstrate the importance of proper trunk mechanics in pitching and highlights the need for future research to understand the contribution of the trunk to pitching mechanics.
  
  
  CONCLUSIONS
  Pitching coaches and trainers can use the results of this study to stress the importance of proper trunk mechanics in pitching. Specifically, improving core strength and trunk control in an effort to maintain a more upright posture through the pitching cycle can reduce upper extremity joint stresses.
authors.affiliation: Orthopaedic and Sports Medicine Research, Connecticut Children's Medical Center, Farmington, Connecticut, USA msolomito@connecticutchildrens.org.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Solomito
authors.affiliation: Orthopaedic and Sports Medicine Research, Connecticut Children's Medical Center, Farmington, Connecticut, USA.
authors.forename: Erin J
authors.initials: EJ
authors.lastname: Garibay
authors.affiliation: Center for Motion Analysis, Connecticut Children's Medical Center, Farmington, Connecticut, USA.
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Woods
authors.affiliation: Center for Motion Analysis, Connecticut Children's Medical Center, Farmington, Connecticut, USA.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Õunpuu
authors.affiliation: Elite Sports Medicine, Connecticut Children's Medical Center, Farmington, Connecticut, USA.
authors.forename: Carl W
authors.initials: CW
authors.lastname: Nissen
mesh_terms: D000293:Adolescent; D001134:Arm Injuries / Q000209:etiology; D001484:Baseball / Q000293:injuries / Q000502:physiology*; D001696:Biomechanical Phenomena; D004551:Elbow Joint / Q000502:physiology*; D006801:Humans; D011187:Posture; D012399:Rotation; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000502:physiology*; D060726:Torso; D055815:Young Adult; D000092464:Elbow Injuries
keywords: biomechanics; elbow; moments; pitching; trunk