The shoulder is a complex joint with a very large range of motion in all directions and planes of motion. On the scale of mobility/stability based joints, the shoulder sits firmly at the mobile end of the spectrum. As a result, keeping the shoulder joint stable, robust and, most importantly, healthy can prove challenging at times. Shoulder complaints are some of the most common I see in both athletes and deskbound workers alike.
One of the main causes for this? Muscle imbalances.
Recent research has shown that the stabilising muscles around the scapula play a vital role in improving not only shoulder pain, but also neck and elbow pain. A well-functioning scapula provides a strong stable base for the shoulder joint to function upon. As the saying goes…
You can’t shoot a cannon from a canoe.
Unfortunately, traditionally not enough attention has been paid to the scapula stabilisers, resulting in a dominance of the muscles which roll the scapula forward (anterior tilt & protract) and also internally rotate shoulder. Ever heard of the rounded shoulder posture?
A lack of attention to the scapula stabilisers is the number one reason why this happens. Not because of what you are doing, but because of what you aren’t doing! This position is a biomechanical disadvantage for a large number of reasons which can lead to a number of shoulder injuries such as impingement, tendinopathy or chronic instability.
So what is the answer? Focusing on muscles which focus on:
- Scapula Retraction & Posterior Tilt
Scapula retraction and posterior tilt describes moving the shoulders ‘down & back’. Think about having a proud chest without your ribs flaring and your head poking forward. De Mey and colleagues  studied a range of shoulder rehabilitation exercises and reported the specific muscle activity they elicited across a range of scapula & shoulder stabilising muscles. The exercise which evoked the most muscle activity in the middle traps (alongside posterior deltoid & supraspinatus!) was the Prone Ts.
Another vital muscle in scapula retraction & posterior tilt is the lower trap. A recent study  identified the prone V raise as the most effective activation exercise for the lower trap. The exercise also showed high levels of activation of the middle trap, rhomboid major and upper trap. The involvement of the upper trap in this exercise may concern a number of people as traditionally it is thought of as a contributor to rounded shoulder posture – and you would be right if you were training elevation of the shoulder girdle (shrugs). In this case the upper traps function is the upwardly rotate the scapula, on of its key functions and vitally important in a healthy shoulder joint.
- Shoulder External Rotation
In traditional gym or strength & conditioning programs, very little time is spent isolating and strengthening the rotator cuff… and when it is, it is done very poorly! Look around your local gym and you will see the majority of people strengthen their rotator cuff in standing using a cable or band, sound familiar? Well this limits the amount of rotator cuff activity you can achieve. The main reason for this is that being in a standing position forces the rotator cuff to function to centrate the humeral head (ball) in the glenoid cavity (socket) and limited their ability to isolate specific movements such as external or internal rotation. Also, performing rotator cuff exercises when standing means that you perform them with a flexed elbow – meaning the bicep is contracting throughout the movement and compensating for the rotator cuff’s inability to function fully. No wonder that many people experience biceps tendinopathy.
Muscle imbalance is another key reason why isolating the muscles which perform shoulder external rotation is important. The most heavily trained muscles in upper body weight programs are the pecs and lats. Both of which have secondary functions of internally rotating the shoulder joint. This, coupled with a lack of isolated external rotation strengthening leads to an imbalance of the muscles which internally rotate the shoulder.
The previously mentioned study by De Mey and colleagues  also found that Side Lying External Rotations (SLER) reported the highest muscle activity in the Infraspinatus & Teres Minor muscles – the main muscles in external rotation. Another great exercise to train external rotation strength is Wall Walk Slides which force you to resist internal rotation through shoulder flexion.
A third key element of shoulder stability is proprioception, aka. knowing the position of your shoulder as it moves through space. Equally as important as strengthening the scapula and shoulder muscles is training the receptors and messengers of the shoulder the allow your nervous to control the joint effectively. There are a number of different ways to develop shoulder proprioception including strength training . One method that I use regularly with my athletes and private clients is by using perturbations which force the challenge the shoulder joint to reactively stabiliser through a wide range of motion developing both stability and proprioception.
Two examples of these exercises are :
Aqua Bag Presses – Although the aqua bag isn’t particularly heavy, the movement or “sloshing’ of the water inside the bag challenges the shoulder to control the movement throughout it’s range of motion.
Tall Kneeling Swiss Ball Rotations – This exercises not only challenges your shoulder joint to work through varied positions but it also stimulates the serratus anterior (another key muscle for shoulder stability that I will discuss in a later post) as actively you push into the wall.
ABOUT THE AUTHOR
Alex Morrell (MSc, BSc (Hons), MCSP) is a Sports Physiotherapist working in international and professional rugby alongside private practice. He has a keen interest in all things training & performance from his sports science/S&C background. (@theonlinephysiocoach)