In-game Cervical Exercises to Reduce Subsequent Post-game Decrease of Shoulder Internal Rotation Range of Motion and External Rotation Strength in Baseball Pitchers

Glenohumeral internal rotation deficit (GIRD) and rotator cuff weakness have been identified as predisposing factors in sustaining a shoulder or elbow injury in pitchers. The appearance of GIRD in symptomatic throwers has been attributed to osseous adaptations as well as soft tissue restrictions of the posterior capsule, deltoid and posterior cuff. Trakis identified that those adolescent pitchers with pain complaints had presented with weakness of the posterior shoulder musculature. Tyler noted preseason supraspinatus weakness was significantly associated with an increase in shoulder and elbow injury risk in high school pitchers. Despite studies indicating a correlation with rotator cuff weakness and injury, there is a lack of consensus on the underlying cause of the rotator cuff weakness.

The presentation of GIRD and rotator cuff weakness typically occurs in tandem and a question arises if these are linked, and if they might actually occur in response to the act of throwing. A subsequent loss of internal rotation range of motion and weakness of external rotation has been noted immediately following pitching. In a study of 67 asymptomatic professional pitchers, Reinold found a significant loss of passive shoulder internal rotation (IR) immediately following pitching that was also evident 24 hours after throwing. Reinold purported that the altered range of motion may be related to acute musculotendinous adaptations in response to the eccentric muscle activity of the external rotators during the throwing motion. Gandhi found a decrease in external rotation strength and a statistically and clinically significant decrease in voluntary muscle activation of the infraspinatus immediately following pitching in a simulated game. His contention was that the weakness was due to incomplete neuromuscular recruitment.

The posterior rotator cuff demonstrates large electromyographic (EMG) activity during the act of throwing. Overused muscle shortens over time, changing the muscle length-tension properties and becoming more readily active and weaker after time. The cause of the weakness may be neuro-reflexive or structural in nature. The combination of loss of IR and weakness of the external rotators might be explained by the concept of "tightness weakness" as described by Janda. The author's propose that the loss of shoulder internal rotation range of motion and external rotation strength may be linked and centrally mediated from the cervical spine. The act of throwing will produce a compressive force in the mid-cervical spine related to the compensatory movement of cervical extension, lateral flexion and rotation towards the throwing side. Pheasant demonstrated a decrease in shoulder external rotator strength following a maintained postural position of forward head and rounded shoulders for only 5 minutes. He noted that the resultant lower cervical flexion that accompanies the forward head posture can create foraminal stenosis at C4-C5, thereby causing a compression of the C5 nerve root.

In a case series, Pheasant demonstrated an increase in external rotation strength and resolution of pain complaints in 2 overhead athletes presenting with shoulder impingement by performing cervical retraction and cervical retraction with extension. He surmised that intermittent compression of the C5 nerve root could impair nerve function and ultimately cause rotator cuff weakness by affecting the suprascapular and axillary nerve that innervate the supraspinatus, teres minor and infraspinatus, and that the cervical retraction exercises reduced the compression. Internal rotation range of motion pre-intervention was only visually estimated and there was no indication of that motion being compared to the non-involved shoulder or if there was an improvement in motion following implementation of the exercises.