How do shrug-exercises affect the medial scapular muscles?
Scapular dyskinesis is often present in patients with shoulder and neck pain conditions. These patients frequently show a dysbalance between their upward rotators: upper trapezius (UT) and serratus anterior (SA) and downward rotators: levator scapulae (LS), rhomboid major (RM) of the scapula. The "shrug"-exercise has been prescribed in rehabilitation programmes to improve the upward rotation of the scapula. This study revealed that activity levels of the medial scapular muscles depend upon the specific shoulder position while performing the shrug and retraction exercises and showed the lowest activation during the "shrug overhead" exercise.
Shrug exercises have been described and executed differently and to date no evidence exists which gives insights into the effect on medial scapular muscle activation during shrug exercises. Thus, this study aimed to investigate the activation of medial scapular muscles during shrug exercises in different shoulder positions.
Twenty-six healthy subjects participated in this study. They performed shrug exercises in three different positions: 1) "shrug exercise": shoulder elevation 2) "shrug overhead": shoulder elevation with arms in overhead position 3) "retraction overhead": shoulder retraction with arms in overhead position. During these exercises electromyography (EMG) was collected from the upper, lower (LT) and middle trapezius (MT), LS and RM.
The UT and LS showed the highest activity during the "shrug" exercise. MT, LT, and LS had the highest activity during the "retraction overhead" shrug exercise. Only the activity of the UT was not significant different and showed moderate activation levels during all three exercises.
This study provided evidence, that the "shrug" exercise should be applied if the purpose of the exercise is to promote UT activity with minimal activity of the RM and LS. The "retraction overhead" exercise can be recommended when general activation of the posterior scapular musculature is required.
> From: Castelein et al., Man Ther 21 (2016) 250-255(Epub ahead of print). All rights reserved to Elsevier Ltd. Click here for the Pubmed summary.