This study used dynamic intramuscular EMG to compare shoulder muscle activation during live pitching in 15 throwers with confirmed anterior glenohumeral instability versus 12 healthy throwing controls. It defines which muscles fire abnormally and during which phases, providing a neuromuscular map for rehabilitation design.
A throwing athlete with anterior instability does not have a purely ligamentous problem. The dynamic stabilizers have failed too, and this paper maps exactly which ones and when. The subscapularis, pectoralis major, latissimus dorsi, and serratus anterior are all markedly underactive at the precise moment they are needed most: the transition from late cocking into acceleration.
This is the neuromuscular basis for why internal rotator strengthening and serratus anterior retraining are non-negotiable in any rehabilitation program for these athletes, whether conservative or postoperative. Before returning a thrower to sport after instability repair, verify that eccentric internal rotator control and scapular protraction have been specifically trained and tested.
This paper also explains why impingement and instability coexist in throwers. Deficient serratus anterior function narrows the subacromial space, so the rotator cuff tendinitis you see in these athletes is partly a downstream consequence of scapular dyskinesis, not simply a separate diagnosis.
This study used dynamic intramuscular EMG to compare shoulder muscle activation during live pitching in 15 throwers with confirmed anterior glenohumeral instability versus 12 healthy throwing controls. It defines which muscles fire abnormally and during which phases, providing a neuromuscular map for rehabilitation design.
A throwing athlete with anterior instability does not have a purely ligamentous problem. The dynamic stabilizers have failed too, and this paper maps exactly which ones and when. The subscapularis, pectoralis major, latissimus dorsi, and serratus anterior are all markedly underactive at the precise moment they are needed most: the transition from late cocking into acceleration.
This is the neuromuscular basis for why internal rotator strengthening and serratus anterior retraining are non-negotiable in any rehabilitation program for these athletes, whether conservative or postoperative. Before returning a thrower to sport after instability repair, verify that eccentric internal rotator control and scapular protraction have been specifically trained and tested.
This paper also explains why impingement and instability coexist in throwers. Deficient serratus anterior function narrows the subacromial space, so the rotator cuff tendinitis you see in these athletes is partly a downstream consequence of scapular dyskinesis, not simply a separate diagnosis.