A Randomized Controlled Trial of the Immediate Effects of Muscle Energy Techniques on Posterior Shoulder Tightness.

Moore SD, Laudner KG, McLoda TA, Shaffer MA. J Orthop Sports Phys Ther. 2011 Apr 6. [Epub ahead of print]

We recently had a post on the effect of posterior mobilization techniques to improve posterior capsule mobility. This was based on the theory that the posterior capsule adaptively changes due to repetitive overhead throwing. Another theory is that the posterior muscles, including the rotator cuff and deltoid, may adaptively shorten causing decreases in both internal rotation and horizontal adduction. To address the muscular tightness that may be occurring, a muscle energy technique (MET) can be used. This technique has been effective in the spine and the lower extremity but has never been studied in the upper extremity. This study examined 61 division I baseball players that were randomly assigned to 1 of 3 groups: 1) MET for the horizontal abductors, 2) MET for the external rotators, and 3) a control group. In this study the MET interventions consisted of contract-relax stretches (isometric contraction: 5 sec, active assisted stretch: 30 sec, repeated 3 times). Glenohumeral internal rotation and horizontal adduction were measured prior to and immediately following the stretching technique. They found that the MET for the horizontal abductors group had a significantly greater increase in horizontal adduction motion compared to the control group and greater internal rotation compared to the MET for the external rotators group and the control group.

The results of this study suggest that a MET technique for the horizontal abductors significantly improved both horizontal adduction and internal rotation motion more than those stretched with the MET for the external rotators. MET is designed to improve the flexibility of muscles by reflexively inhibiting the agonist muscle during stretching. Based on these results the posterior shoulder muscles may have increased muscular tone at rest that increases muscular stiffness and therefore limits range of motion. Previous studies have shown that up to 4 days after eccentric exercise muscles have an increase in passive stiffness. The increases in range of motion may suggest that this passive muscular stiffness can be improved acutely. However, this study did not document the date of the last throwing session. It was only stated that the study was performed before any throwing had occurred on the day of testing. Therefore, it is impossible to know if there was decreased range of motion and increased passive muscular stiffness due to being within the 4 day window following throwing. With that being said, addressing both muscular and capsule tightness could be beneficial to maintain optimal glenohumeral range of motion and minimize the risk of shoulder and elbow injuries. However, we would need more research to confirm this hypothesis. Is this a commonly used technique in the clinic for overhead athletes? Have you had success?

Written by: Stephen Thomas
Reviewed by: Jeffrey Driban