Shoulder muscle activity in open and closed-chain abduction
This study found that open-chain (OKC) abduction promotes the recruitment of rotator cuff muscles, highlighting their role in responding to medial deltoid activity.
On the contrary, closed-chain (CKC) abduction poses less demands on the rotator cuff, given that the movement is performed with external stabilization.
Thus, it can be started earlier in the rehabilitation process. Of all the muscles studied, only the activity of the middle deltoid was similar across exercise type and different loads.
CKC shoulder exercises have been gaining in popularity as an alternative to traditional open-chain exercises used in shoulder rehabilitation. The former are thought to provide greater joint compression, reducing the need for muscle control of joint translation.
However, there are no studies comparing muscle activity using CKC (shoulder press) and OKC (free weights) shoulder abduction exercises.
29 healthy volunteers underwent EMG testing during CKC and OKC shoulder abduction exercises at 25%, 50%, and 75% of their 1RM. Surface and deep sensors were placed on the supraspinatus, infraspinatus, subscapularis, serratus anterior, lower trapezius and medial deltoid muscles.
With the exception of middle deltoid, all muscles showed differences in activity between load and type of exercise.
The results support the use of CKC exercises earlier in rehabilitation, as they elicit lower levels of muscle activity for the same load and allow a higher range of motion to be used.
OKC exercises are needed when the goal is to adequately rehabilitate the shoulder in preparation for functional activities.
> From: Reed et al., J Sci Med Sport 21 (2017) 462-466 (Epub ahead of print). All rights reserved to Elsevier Ltd. Click here for the online summary.