title: EMG activity of selected rotator cuff musculature during grade III distraction and posterior glide glenohumeral mobilization: results of a pilot trial comparing painful and non-painful shoulders.
abstract: OBJECTIVE
  The objectives of this pilot study were to investigate rotator cuff activity that may be present during grade III distraction and posterior glide mobilization of the glenohumeral (GH) joint, as well as to examine any differences in response between painful and non-painful shoulders utilizing these techniques.
  
  
  METHODS
  EMG data were collected using Delsys EMGworks(®) software and Trigno(®) mini-wireless electrodes for the supraspinatus, infraspinatus and upper trapezius musculature during grade III GH distraction and posterior glide mobilization. A total of 20 shoulders (10 painful, 10 non-painful) were recruited from a sample of convenience. Submaximal voluntary dynamic contraction against gravity was used as reference for each of the three selected muscles. Participants underwent two trials of each mobilization, and the mean results for each group were assessed using descriptive statistics (mean, standard deviation) and effect size.
  
  
  RESULTS
  Both the painful and non-painful groups exhibited considerable levels of rotator cuff activity during each test parameter, with the painful group consistently generating higher supraspinatus and infraspinatus RMS and peak force activity. Analysis of the peak combined rotator cuff activity during distraction (d = 0.58) and posterior glides (d = 0.64) suggests moderate-to-high practical significance of the results.
  
  
  CONCLUSIONS
  GH distraction and posterior glide mobilizations have traditionally been thought of as passive treatment procedures. The results of this pilot study indicate that the supraspinatus and infraspinatus are significantly active during these techniques. Findings suggest that during these techniques, the total infra/supraspinatus EMG activity approaches the level produced while raising the arm against gravity.
  
  
  METHODS
  2b.
authors.affiliation: School of Physical Therapy, Texas Woman's University, Houston, TX, USA; Department of Physical Therapy, University of New England, 716 Stevens Ave., Portland, ME, USA.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Swanson
authors.affiliation: School of Physical Therapy, Texas Woman's University, Houston, TX, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Holst
authors.affiliation: School of Physical Therapy, Texas Woman's University, Houston, TX, USA.
authors.forename: John
authors.initials: J
authors.lastname: Infante
authors.affiliation: School of Physical Therapy, Texas Woman's University, Houston, TX, USA.
authors.forename: James
authors.initials: J
authors.lastname: Poenitzsch
authors.affiliation: School of Physical Therapy, Texas Woman's University, Houston, TX, USA.
authors.forename: Alexis
authors.initials: A
authors.lastname: Ortiz
keywords: EMG; Mobilization; Rotator cuff; Shoulder