// Injury & Rehab: the gym junkie’s shoulder

As the most muscular of all body parts, the shoulder is highly susceptible to imbalance. Personal trainers need to understand and promote good practice in order to discourage ‘hypertrophy at the price of good biomechanics’ says Ulrik Larsen.

Even the average gym client can spot the rounded shoulders, collapsed chest and ‘no-neck’ characteristics of those who pump heavy iron night and day. Perhaps it is harsh to single out this obsessive minority for criticism; is it possible that these extreme athletic physiques are simply worse versions of the average muscular physique?
An eye trained in assessing pathomechanics (mechanical forces that adversely change the body’s structure and function) will soon come to the conclusion that, in fact, very few shoulders actually look ‘OK’. We all sit at computers, get stressed, and let muscle tension get the better of us. Muscle imbalance will always take its toll on the very fragile non-muscular structures of the shoulder, even if you don’t have huge muscles. And if you have well-developed muscles, are you OK to ignore the twinge in your shoulder when lifting a 100kg barbell?

The roof, the floor and the furniture of the shoulder

To appreciate the deep and underlying biomechanics of the shoulder, let’s start by introducing the image of the house:

The poor biomechanics of a bad house

The majority of ‘niggling’ impingement problems felt by your clients will be the result of either the 'roof caving in', or an 'unstable floor'. Here’s what’s probably going on:

Roof caving in due to muscular imbalance around the scapula

A repetitive and perpetual downward force of the acromion process onto the ball is the most common destructive pattern in active shoulders. The roof of the shoulder is literally crushing down onto the furniture. This movement is specifically called ‘downwards rotation’ or ‘anterior tilt’ of the scapula, and is primarily created by pectoralis minor, levator scapulae and the rhomboids. These muscles will dominate over the critical serratus anterior muscle, resulting in scapular winging and poor control of protraction and retraction during the movement. Therefore, any simple push-pull exercise has the potential to include too much downward force of the roof into the living space, and the most common ‘furniture’ that gets damaged is the supraspinatus tendon. Tearing, rubbing, and scuffing of this tendon accounts for most shoulder pain in your clients.

The scapular renovator muscles that normally need to be called in to prevent the roof caving in onto the living space are the serratus anterior, lower trapezius and the upper trapezius (this is quite controversial in the fitness industry, but not for many physiotherapists).
In combination, these shoulder renovators mainly produce upward rotation (and posterior tilt) of the scapula. By itself serratus anterior produces scapular protraction during the pushing movement, and lower trapezius produces posterior tilt and depression during the pulling movement. Together they are the perfect antidote to the dominance of pectoralis minor, rhomboids and levator scapulae. Without activation and strengthening of these muscles, no true and lasting improvement of shoulder pain is possible.

Unstable floor moving due to muscular imbalance within the glenohumeral joint

You could liken this pattern to the furniture riding up into the ceiling as the floor lifts and sways out of control. Here, the imbalance is between the internal and external rotators of the rotator cuff. Specifically, the external rotators of the cuff (infraspinatus and teres minor) gradually dominate over the lone internal rotator (subscapularis), creating destructive anterior shearing and superior movement forces. This explains why simply prescribing external rotator cuff strengthening exercises can make a shoulder worse.

The glenohumeral renovator muscle that normally needs to be called in for a renovation of the glenohumeral joint (such that the floor stops moving excessively and riding up into the living space) is subscapularis.

The more recent physiotherapeutic research into glenohumeral dysfunction and injury is prolific in the focus on subscapularis as the main muscle that needs activation and retraining for effective rehab of rotator cuff dysfunction.
Subscapularis is the perfect humeral depressor and posterior glider. It counter-balances the external rotation force of infraspinatus, teres minor and to some degree posterior deltoid, thereby preventing anterior shearing and elevation into the sub-acromial space. It may also enhance serratus anterior biomechanical efficiency.

Overcoming muscle imbalance

Although currently lacking formal research to validate its effectiveness, the pioneering technique of iso-integration (using thera-tubing during a movement to overcome muscle imbalance) is at the cutting-edge of muscle activation work. It can be applied to most joints, not just the shoulder.
Let’s apply the concept to overcome common shoulder muscle imbalances with two exercises: the one-arm dumbbell row and the chest press.

One-arm dumbbell row

Classic pathomechanics: Imbalanced rowing action from the scapular retractors, demonstrating excessive elevation and downward rotation during the main movement (dominant rhomboids and levator scapula over lower trapezius). The tubing will optimise scapular retraction and isolate lower traps.

Tubing requires the arm to sustain internal rotation force during the one-arm dumbbell row movement, thereby indirectly improving lower trapezius function. Note the pronated hand position.

Action: Hold tubing on tension from in front of client during movement (the more muscular the client, the more tension is required). Dumbbell and tubing are held together in the hand, as the movement is performed.

Effect: The direct effect of the tubing is to activate the glenohumeral internal rotator subscapularis, but by reverse-origin insertion it will pull the scapula away from an elevated and downwardly rotated position towards a more pure retraction movement, thereby indirectly activating lower trapezius. Most commonly, the client will feel an improved contraction of this muscle, and hence improved latissimus dorsi action. In terms of muscle biomechanics, the middle-lower trapezius will tend to grow at the same rate as the upper trapezius/rhomboids and levator scapula. Trigger points and pain in the neck (even headaches) will also be reduced.

Chest press

Classic pathomechanics: During the lowering phase of the chest press, the scapula prematurely ceases to retract; instead the scapula lurches into downward rotation/ anterior tilt, and the glenohumeral joint shears anteriorly, possibly into external rotation and excessive horizontal extension. Effectively the roof is caving in and the floor is shifting at the same time! This movement is the reason that bench press remains one of the most damaging movements in the gym for the fragile supraspinatus and other furniture under the shoulder roof.

Tubing will directly activate the subscapularis, thereby improving muscle balance and preventing injury to the supraspinatus tendon under the roof of the shoulder.

Action: During chest press, tubing is held in the hand or attached to the barbell, on the side of the shoulder pain, with the tension directed overhead by the trainer.

Effect: The direct effect of the tubing is to activate the glenohumeral internal rotator subscapularis, which will pull the glenohumeral joint posteriorly and inferiorly away from the acromion process. It will neutralise any external rotation and horizontal extension pathomechanics, and activate serratus anterior to function eccentrically during the lowering phase. Consequently, it prevents downward rotation and anterior tilt of the scapula. In terms of muscle biomechanics, the pectoralis minor is prevented from dominating over pectoralis major, so this becomes an extremely useful tool in the optimisation of muscle development around the chest

Importantly, if there is any pain at all during chest press, the tubing needs to be applied in an attempt to reduce the pain, hence its value as a rehab drill for the retraining of subscapularis and serratus anterior.

In summary, everything possible should be done to prevent the spiral into muscle imbalance and degenerative change in the fragile furniture of the shoulder. It is recommended that massage and iso-integration are used regularly during workouts with this objective in mind. Prevention is much better than cure, especially since this method will also help your client build their musculature in the way they desire. Flexibility of the dominant power muscles and activation of the deeper stability muscles will ensure the equilibrium is maintained.

Ulrik Larsen, B Phty
An Australian sports physiotherapist specialising in sports injury management, Ulrik has decades of experience working with personal trainers and their clients, including elite athletes and their coaches. His passion for giving fitness professionals competence to manage clients with injuries led him to develop the Rehab Trainer course, which is now delivered internationally through his network of similarly-minded physiotherapists. For more information visit www.rehabtrainer.com.au or call 0423 861 342.