title: Shoulder proprioception is associated with humeral torsion in adolescent baseball players.
abstract: OBJECTIVE
  To determine the relationship between the amount of humeral torsion and a measure of active proprioception in adolescent male throwing athletes.
  
  
  METHODS
  Cross-sectional laboratory study with uninjured subjects.
  
  
  METHODS
  University of Sydney and NSW Institute of Sport.
  
  
  METHODS
  Participants were 16 adolescent male baseball players (15.0-18.1 years old, SD=16.3) holding baseball scholarships at the NSW Institute of Sport.
  
  
  METHODS
  The main outcome measures, active proprioception (shoulder rotation, in 90 degrees of arm abduction moving towards external rotation, using the Active Movement Extent Discriminating Apparatus) and humeral torsion (using an ultrasound-assisted method), were measured bilaterally.
  
  
  RESULTS
  A strong (r=0.88) and significant (p=0.001) correlation was found between increasing humeral retrotorsion and better active proprioceptive acuity in the non-dominant arm, while the relation was weaker (r=0.41) and did not reach statistical significance (p=0.120) for the dominant arm.
  
  
  CONCLUSIONS
  A cognitive processing capacity model, which suggests that greater humeral retrotorsion reduces neural processing requirements, has been proposed to explain the direct relationship between proprioceptive acuity and humeral retrotorsion.
authors.affiliation: University of Sydney, NSW, Australia. whiteley.rod@gmail.com
authors.forename: R J
authors.initials: RJ
authors.lastname: Whiteley
authors.forename: R D
authors.initials: RD
authors.lastname: Adams
authors.forename: L L
authors.initials: LL
authors.lastname: Nicholson
authors.forename: K A
authors.initials: KA
authors.lastname: Ginn
mesh_terms: D000293:Adolescent; D001484:Baseball; D003430:Cross-Sectional Studies; D006801:Humans; D006811:Humerus / Q000502:physiology*; D008297:Male; D009517:New South Wales; D011434:Proprioception; D012785:Shoulder Joint / Q000502:physiology*; D054159:Torsion, Mechanical