Quantifying Acromiohumeral Distance in Overhead Athletes With Glenohumeral Internal Rotation Loss and the Influence of a Stretching Program
Maenhout A, Van Eessel V, Van Dyck L, Vanraes A, Cools A. Am J Sports Med. 2012 Aug 6. [Epub ahead of print]
It is well known that overhead athletes develop a loss of internal rotation (IR; also called glenohumeral internal rotation deficit or GIRD) and a gain of external rotation (ER). Recently, it has been demonstrated that baseball players with GIRD are more likely to develop shoulder injuries. It has been suggested that GIRD is caused by a tight posterior capsule and during ER the tight capsule may alter the arthrokinematics of the shoulder by moving the head of the humerus in a posterior-superior direction thereby decreasing the acromiohumeral distance (AHD). However, it currently unknown if this occurs and if stretching of the posterior shoulder improves motion and the AHD. Therefore, the purpose of the study was to compare bilateral AHD in overhead athletes with GIRD (> 15° loss of IR) and to examine the effect of the sleeper stretch on AHD and IR. The authors assessed bilateral range of motion (IR, ER, and horizontal adduction) in the supine position with the scapula stabilized among sixty-two overhead athletes with GIRD. AHD was measured using diagnostic ultrasound at rest, 45°, and 60° of abduction. Athletes were then randomly divided into a stretching (n = 30) or a control (n = 32) group. The stretching group performed the sleeper stretch daily (3 reps of 30 sec holds) for 6 weeks on the dominant arm. All stretching was performed by the athletes with no sessions from physical therapists or athletic trainers. The control group did not perform the sleeper stretch but were asked to maintain normal activities. Range of motion and AHD were reassessed after the 6-week intervention period. At baseline, the authors found that dominant arms’ IR and horizontal adduction were significantly less and ER was greater compared to the non-dominant for both groups. Also, AHD was smaller on the dominant arm compared to the non-dominant. When examining the effect of stretching there was a significant increase on the dominant arm for IR, horizontal adduction, and AHD at all positions. There were no changes on the dominant arm of the control group.
This study is the first to demonstrate that the dominant shoulders of overhead athletes with GIRD have reduced AHD compared to the contralateral shoulder and that sleeper stretching improves the AHD in just 6 weeks. Clinically, this is a very important finding which gives support for both the hypothesis that GIRD will cause a decrease in AHD and that stretching not only improves ROM but also increases the AHD. A loss of AHD has been suggested to cause impingement of the rotator cuff and lead to tendon degeneration or even tears. Maximizing the AHD may minimize the risk of impingement and maintain the health of the rotator cuff. Previous research has found that GIRD can increase the chance of shoulder injury. By performing the sleeper stretch the athlete can eliminate GIRD and increase AHD thereby reducing the likelihood of injury; however, more research may be needed to verify the reduce risk of injury. One limitation of the study was that AHD was not assessed at 90° of abduction which is the functional position of overhead athletes. However, based on their data there was a significant improvement at all of the tested shoulder positions up to 60°. This may suggest that a similar finding would have occurred at the 90° position. It would also be interesting to examine other methods to increase IR in overhead athletes (posterior joint mobilizations, active release, etc). A nice follow-up to this study would be to follow these athletes over the season to evaluate injury rates. What are your thoughts on this study? Do you currently use the sleeper stretch or do you have other ways to reduce GIRD? Do you think a decrease in the AHD contributes to shoulder injuries in overhead athletes with GIRD?
Written by: Stephen Thomas
Reviewed by: Jeffrey Driban
Related Posts:Maenhout A, Van Eessel V, Van Dyck L, Vanraes A, & Cools A (2012). Quantifying acromiohumeral distance in overhead athletes with glenohumeral internal rotation loss and the influence of a stretching program. The American Journal of Sports Medicine, 40 (9), 2105-12 PMID: 22869627