Shoulder stability exercises in-depth

Overhead sports & shoulder injuries

The shoulder plays an important role in overhead activities. Athletes in overhead sports like basketball, tennis and volleyball are more prone to shoulder injuries. The shoulder complex consists off two joints: the scapulathoracic joint (joint formed by ribcage and shoulder blade) and the glenohumeral joint (joint formed by shoulder blade and upper arm). Shoulder injuries in the overhead athlete are often related to a loss of function of the scapulathoracic joint.

Scapular muscle imbalances

Muscle imbalances between the muscles that attach to the scapula or strength deficits of these scapular muscles lead to alterations in the resting position or abnormal motion of the scapula. Research shows that a disturbed equilibrium between the three parts of the trapezius muscle changes the normal movement pattern of the scapula. The upper part of the Trapezius contracts to soon and too much, compared to the lower part of the Trapezius that is activated to slow and has a weak contraction. A disturbed balance between a strong upper Trapezius and a weaker Serratus anterior also results in abnormal scapular motion.

Relationship between overhead movements & scapular muscle imbalances

The upper part of the Trapezius is, due to its postural role, highly active in upper body exercises or movements executed while standing or seated. Especially overhead movements and exercises for the deltoid muscles (big shoulder muscle) in an upright position highly activate the upper part of the Trapezius with little contraction of the lower and middle part. That's why overhead athletes or athletes that overemphasize incline and overhead pressing are more prone to scapular muscle imbalances and to scapulothoracic dysfunction and instability.

Exercises to improve scapular muscle balance & stability

To improve or restore scapulothoracic stability, exercises and positions must be used that activate the lower Trapezius (LT), middle Trapezius (MT) and Serratus anterior (SA) and minimally activate the upper Trapezius (UT). The prone and side-lying position minimize the postural role of the upper Trapezius. Research shows that exercises for the scapula retractors, in the prone and side-lying position, promote lower Trapezius and middle Trapezius activation while minimally activating the upper Trapezius. In the push-up and its variations a high activity in the Serratus anterior with minimal activity in the upper Trapezius was observed.

The rotator cuff

The rotator cuff provides stability in the glenohumeral joint, by compressing the joint and preventing excessive translation. The rotator cuff muscles (Supraspinatus, Infraspinatus, Teres minor, Subscapularis) have their origin on the scapula. To effectively stabilise the glenohumeral joint they need to operate from a stable scapular base. Closed kinetic chain exercises (exercises where the hand is the base of support) promote cocontraction of the rotator cuff musculature. The enhanced cocontraction of the rotator cuff musculature during closed chain exercises, and the low UT/SA ratio advocate the use of push-ups in addition to the bench press and its variations.

Coaching key to prevent shoulder injuries

Combine overhead pressing for strength, with exercises for scapulothoracic and glenohumeral stability, to prevent injury and to enhance effectiveness of the muscles that lift the arm.