title: Do isometric pull-down exercises increase the acromio-humeral distance?
abstract: OBJECTIVE
  To evaluate the effect of isometric shoulder extension in 90° shoulder flexion on the acromio-humeral distance, to establish the force required to achieve a clinically important increase in the acromio-humeral distance, and to investigate the practicality and reliability of real-time ultrasound measurement of the acromio-humeral distance in 90° shoulder forward flexion.
  
  
  METHODS
  Prospective single-group intervention.
  
  
  METHODS
  King's College London, Guy's Campus.
  
  
  METHODS
  Twenty healthy volunteers [five males and 15 females (40 shoulders)] with a mean age of 32 (standard deviation 10, range 19 to 55) years were recruited from the faculty and staff at King's College London.
  
  
  METHODS
  The acromio-humeral distance in asymptomatic participants was measured using real-time ultrasound in the neutral position at rest, at 90° shoulder flexion at rest, and while performing an isometric pull-down exercise at 100%, 50%, 30% and 10% maximal voluntary isometric contraction.
  
  
  METHODS
  Real-time ultrasound measures of the acromio-humeral distance.
  
  
  RESULTS
  Of the 20 participants, 38 shoulders were imaged. In 90° shoulder flexion, pull-down exercises at all levels of force increased the acromio-humeral distance compared with no pull-down (P<0.05), but this was only clinically significant in males. Measures had excellent short-term intra-operator reliability.
  
  
  CONCLUSIONS
  Isometric pull-down exercises lead to an increase in the acromio-humeral distance in asymptomatic males that may be clinically important, and therefore may be an appropriate exercise for patients with shoulder pathology. Ultrasound measurement of the acromio-humeral distance in 90° shoulder flexion is practical and reliable.
authors.affiliation: King's College London, School of Medicine, Guy's Campus, London, UK. Electronic address: paul_sealey@hotmail.com.
authors.forename: P
authors.initials: P
authors.lastname: Sealey
authors.affiliation: King's College London, School of Medicine, Guy's Campus, London, UK.
authors.forename: D
authors.initials: D
authors.lastname: Critchley
mesh_terms: D000174:Acromion / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D000328:Adult; D000367:Age Factors; D001696:Biomechanical Phenomena; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D006811:Humerus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D012737:Sex Factors; D012785:Shoulder Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014463:Ultrasonography; D055815:Young Adult
keywords: Impingement; Pull-down; Rotator cuff; Shoulder; Subacromial space; Ultrasound