title: Scapula kinematics of pull-up techniques: Avoiding impingement risk with training changes.
abstract: OBJECTIVE
  Overhead athletic activities and scapula dyskinesia are linked with shoulder pathology; pull-ups are a common training method for some overhead sports. Different pull-up techniques exist: anecdotally some are easier to perform, and others linked to greater incidences of pathology. This study aims to quantify scapular kinematics and external forces for three pull-up techniques, thus discussing potential injury implications.
  
  
  METHODS
  An observational study was performed with eleven participants (age=26.8±2.4 years) who regularly perform pull-ups.
  
  
  METHODS
  The upward motions of three pull-up techniques were analysed: palms facing anterior, palms facing posterior and wide-grip. A skin-fixed scapula tracking technique with attached retro-reflective markers was used.
  
  
  RESULTS
  High intra-participant repeatability was observed: mean coefficients of multiple correlations of 0.87-1.00 in humerothoracic rotations and 0.77-0.90 for scapulothoracic rotations. Standard deviations of hand force was low: <5% body weight. Significantly different patterns of humerothoracic, scapulothoracic and glenohumeral kinematics were observed between the pull-up techniques. The reverse technique has extreme glenohumeral internal-external rotation and large deviation from the scapula plane. The wide technique has a reduced range of pro/retraction in the same HT plane of elevation and 90° of arm abduction with 45° external rotation was observed. All these factors suggest increased sub-acromial impingement risk.
  
  
  CONCLUSIONS
  The scapula tracking technique showed high repeatability. High arm elevation during pull-ups reduces sub-acromial space and increases pressure, increasing the risk of impingement injury. Wide and reverse pull-ups demonstrate kinematics patterns linked with increased impingement risk. Weight-assisted front pull-ups require further investigation and could be recommended for weaker participants.
authors.affiliation: Department of Bioengineering, Imperial College London, UK. Electronic address: joe.prinold04@alumni.imperial.ac.uk.
authors.forename: Joe A I
authors.initials: JA
authors.lastname: Prinold
authors.affiliation: Department of Bioengineering, Imperial College London, UK.
authors.forename: Anthony M J
authors.initials: AM
authors.lastname: Bull
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012306:Risk; D012540:Scapula / Q000502:physiology*; D019534:Shoulder Impingement Syndrome / Q000517:prevention & control*; D012785:Shoulder Joint / Q000502:physiology*
keywords: Biomechanics; Kipping; Repeatability; Shoulder; Skin-fixed scapula tracking; Supraspinatus