Right now I am finally wrapping up Assessment and Treatment of Muscle Imbalance: The Janda Approach, a book that I would consider to be a must read for those who care to understand poor movement in an effort to understand what good movement actually looks like as well as to enhance your evidence base for exercise selections. In reading the book, I have picked up a great deal of knowledge, interesting ideas, and things that I will be sharing with you today.
1. Overhead athletes physiological strength balance should be checked by comparing eccentric strength of the external rotators to concentric strength of the internal rotators of the humerus. It seems that those with poor ratios as mentioned are at a greater likelihood of injury; this idea has been confirmed in badmintoners, volleyballers, and baseball athletes. In these same groups of athletes, internal rotation torque generally overpowers the external rotators ability to control the motion and may lead to injury. Thus, for those in the performance realm and for the late-stage rehab crowd, it would be valuable to add in not only isolated concentric external rotation, rhythmic stabilization work, but also accentuated eccentric work targeting the external rotators.
2. In dealing with dysfunctional shoulders, particularly impingement syndromes, it is wise to address both shoulders as there is a tendency for both shoulders to show deviations from normal function--good force coupling, scapular mechanics--bilaterally despite one being more of a problem than another. As discussed previously, these are definitely worth addressing in the athletic development groups because unattenuated imbalances may increase likelihood of injury. Additionally, early identification of potential problems lead to the best outcomes in swimming athletes, who generally demonstrate impingement and GH instability.
3. Despite the mechanics shoulder being a primary player in shoulder pain syndromes, a whole body evaluation should still be executed. The authors of the book note that in screening single leg stance, many with shoulder pain syndromes may hike the involved shoulder, which to them may indicate that the primary movement fault exists somewhere else in the body. Without finding the primary source, the local approach will only take you so far.
4. In athletes who play overhead, total motion should be the primary indicator of mobility. While the dominant arm in most athletes will show less internal rotation than the non-dominant side, this may largely be a result of humeral retroversion. In these athletes, it is likely the case, however, that some mobility/flexibility work into internal rotation can be warranted, especially after long outings where the posterior cuff experiences a lot of eccentric contractions as we've discussed previously. Additionally, soft tissue work to the same structures may offer value in limiting potential trigger point weakness that may lead to a lack of eccentric control.
5. We need to begin considering the joint capsule's integrity as, in the glenohumeral joint, many are rich with up to four types of mechanoreceptors that help to modulate feedback and feed forward control of overhead activity. In the event of altered GH stability, there may be pattern changes that occur as a result of proprioceptive inhibition or facilitation to help the body avoid injury. For example, many overhead athletes with GH instability demonstrate increased biceps activity along with decreased activity of the internal rotators of the shoulder. Naturally, this is not going to help the athlete reach peak performance.
So there you have it, a few tidbits about the shoulder that may be of interest to you. Have a great weekend.