title: Shoulder muscle activity during the modified dynamic relocation test and side-lying shoulder external rotation: a cross-sectional study on asymptomatic individuals.
abstract: OBJECTIVE
  (1) to compare activity levels between monitored muscles during the dynamic relocation test (DRT); (2) to assess changes in muscle activation variability over 10 trials; (3) to assess within-muscle difference activity levels between the DRT and the unloaded side-lying shoulder external rotation exercise.
  
  
  METHODS
  This is a cross-sectional, laboratory-based, repeated measures study. Thirty asymptomatic individuals performed the DRT and unloaded side-lying external rotation. The order of exercises was randomized. Superficial electromyography was used for recording the supraspinatus, infraspinatus, middle deltoid, posterior deltoid, pectoralis major, and latissimus dorsi muscles. The main outcome measures were mean muscle activity, expressed as % of maximal isometric voluntary contraction.
  
  
  RESULTS
  We found significant between-muscles differences in activity (Ft= 14.11,p< 0.001) during the DRT. Post hoc analysis suggested between-trial variability did not change over the 10 trials, (F= 18.2,p< 0.001). Within-muscle comparisons between the DRT and side-lying shoulder external rotation suggested significant differences between these exercises (F= 32.37,p< 0.001).
  
  
  CONCLUSIONS
  considering the monitored muscles, supraspinatus, infraspinatus, pectoralis major, and latissimus dorsi are the main muscles contracting during the DRT. Of all monitored muscles, supraspinatus muscle was the only one presenting higher activity levels during the DRT when compared to the unloaded side-lying shoulder external rotation.
authors.affiliation: Centre for Health, Activity and Rehabilitation Research - School of Physiotherapy, University of Otago, Dunedin, New Zealand.
authors.forename: Daniel Cury
authors.identifier: 0000-0001-9287-9187
authors.initials: DC
authors.lastname: Ribeiro
authors.affiliation: School of Physical Education, Sport & Exercise Sciences, University of Otago, Dunedin, New Zealand.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Shemmell
authors.affiliation: Centre for Health, Activity and Rehabilitation Research - School of Physiotherapy, University of Otago, Dunedin, New Zealand.
authors.forename: Carrie
authors.initials: C
authors.lastname: Falling
authors.affiliation: Centre for Health, Activity and Rehabilitation Research - School of Physiotherapy, University of Otago, Dunedin, New Zealand.
authors.forename: Gisela
authors.initials: G
authors.lastname: Sole
keywords: Manual therapy; Motor control; Rotator cuff muscles; Shoulder