The effect of imagery exercises on activation of shoulder muscles

To identify the effect of imagery exercises on activity of the shoulder muscles.

A sample of 23 healthy participants (17 females and 6 males), with no history of shoulder injury, participated in the present study. Surface bipolar electrodes were applied over the supraspinatus, infraspinatus, posterior deltoid, middle deltoid, anterior deltoid, and pectoralis major. Participants performed six imagery exercises: flexion, extension, abduction, adduction, external rotation, and internal rotation. Root mean square of myoelectric activity of shoulder muscles was calculated for statistical analysis. The RMS during rest was used as an offset and also to normalize the activity of each muscle during imagery exercises.

Performing the imagery exercises resulted in significant activation of the shoulder muscles (P < 0.01). In the case of the supraspinatus muscle, significant difference (P< 0.05) was found among exercise types but no significant value was seen for infraspinatus muscle. In flexion, abduction, adduction, and internal rotation imagery exercises, the correlation observed between muscles activation was significant (P<0.01).

Supraspinatus highly activated in exercises including elevation of the arm. Activation of infraspinatus in all exercises suggest its important stability role in glenohumeral joint.