The bicep curl has been overvalued by many gym bros across the nation for aesthetics and has gotten a bad rap for not contributing to performance or strength. However, the biceps brachii, in particularly the long head, is an important muscle of the glenohumeral joint in terms of stabilizing the head of the humerus in a neutral position. Due to its origin at the superior labrum and capsule it prevents humeral head elevation during overhead movement and thus preventing shoulder impingement.1
Impingement of the shoulder is a condition/symptom when a patient experiences discomfort with overhead motion with flexion or abduction due to compression of the rotator cuff between the bony structures of the humeral head and the acromion. The deltoid is a powerful muscle of the shoulder and if left unopposed by the smaller stabilizing muscles – it can lead to excessive upward movement of the humeral head and can compress the soft tissues under the acromion and thus causing impingement.
The combined effects of the infraspinatus, teres minor, subscapularis, and the long head of the bicep brachii prevent shoulder impingement by stabilizing the humeral head within the glenoid labrum and by providing downward translation of the humeral head during overhead movement to prevent shoulder impingement.
The suprapsinatus does help the smaller rotator cuff muscles in terms of stabilizing the humeral head. However, it does have a simular effect of creating up warding translation of the humeral head during abduction but it is very minimal.2
Before you start curling in the squat rack to decrease your symptoms, it is important to recognize the shoulder impingement can be caused by various dysfunctions:
- Inflammation of the soft tissues that pass through the subacromion space
- Poor biomechanics of the scapulothoracic joint
- AC joint dysfunction
- Anatomical structural variation of the acromion
- Instability of the shoulder
- Faulty posture
Therefore, it is important that you see your musculoskeletal provider to help you differentiate the cause so that your plan of attack is appropriate and effective.
References
- Kumar, VP, Satku, K, and Balasubramaniam, P: The role of the long head of the bicep brachii in the stabilization in the head of the humerus. Clin Orthop 244: 172 – 175. 1989
- Kisner, Carolyn, and Lynn A. Colby. Therapeutic Exercise: Foundations and Techniques. Philadelphia: F.A. Davis, 2012.
Dr. Brandon Parnham, DC 