Injury & Rehab: Rotator cuff impingement – a weight training dilemma

Common weight training exercises can lead to shoulder impingement, and if not addressed early the condition can result in a cycle of pain and restricted movement. Physiotherapist Tim Keeley looks at how to identify, treat and prevent reoccurrence of this shoulder injury.

KEY POINTS

• Impingement can occur when the rotator cuff tendons or bursae get caught or trapped in the ‘sub-acromial space’ during certain arm movements, causing inflammation of the tendon and pain
• If the tendonitis is not addressed, the tendon becomes weaker and the function of the rotator cuff is compromised, leading to the cycle of impingement
• In severe chronic and long term cases, the tendon becomes so weak it tears
• The most common cause of impingement is having an ‘unbalanced’ shoulder and performing repetitive heavy pressing exercises that do not adequately recruit the postural (stabiliser) muscles
• Previous injuries, weak supporting muscles and ligaments, and other factors can contribute to shoulder imbalance that is commonly at the root of impingement.
• The problem usually recurs through a ‘cycle of impingement’, making it essential to break this cycle for successful recovery.

During the past few months at our clinic we have had a greater than usual number of patients presenting with shoulder impingement-type pain and injuries. The ‘impingement’ scenario can be a major dilemma for people who are trying to recover and return to weights and exercise without causing further problems.

Breaking the cycle of pain and injury is the key. Successful recovery involves good advice and treatment, exact instruction on the right rehab exercises and order of progression, coupled with a long term plan of prevention that is simple enough to be adhered to.

Sub-acromial shoulder impingement

The shoulder joint moves with two muscle systems, a postural system and a power system. The postural muscles control the shoulder blade movement and stability (i.e. serratus anterior, trapezius) and the shoulder joint rotation movement and stability (the rotator cuff). The power muscles (deltoid, lats, pecs), meanwhile, move the arm bone around.

Impingement can occur when the rotator cuff tendons or bursae get trapped in the ‘sub-acromial space’ which is the gap between the roof of the shoulder (acromion) and the ball of the humerus (glenoid head) during the arm movement, mostly abduction above 90 degrees. As the tendons get caught, a number of things can occur; most commonly, the rotator cuff insertion where the supraspinatus attaches is squashed and rubbed on other structures, causing inflammation of the tendon (tendonitis) and pain.

If the tendonitis is not addressed, the tendon becomes weaker over time and the person develops a ‘tendinopathy’ where the tendon structure slowly degenerates and the function of the rotator cuff is compromised, leading to the cycle of impingement and the training dilemma.

The sub-acromial bursae, which sits on top of the tendon, protecting it from the bony roof of the shoulder, can also become inflamed with more severe impingement. This, in turn, reduces the space for the tendon to slide and adds to the compression problem. In the most severe chronic and long term cases, the tendon becomes so weak it tears, usually near the insertion into the top of the humerus.

Does your client have impingement?

Localised intense pain usually means the client already has an inflamed tendon or bursae. The pain is most commonly felt on the edge of the shoulder, sometimes radiating down the outside of it. There is a symptom of a ‘painful arc’ where, when the arm is raised outwards and upwards (abduction), the inflamed part of the tendon or bursae gets caught in the sub-acromial space, producing pain; then, further through abduction, the sore part of the tendon moves away from the structures and the pain usually lessens at the top of the movement. With severe impingement, the pain does not lessen at the top and with a tear in the tendon there is significant power loss into abduction and lateral rotation, and the client is unable to fully raise the arm.

Why is it happening?

There are many factors that lead to the impingement process, and if not addressed early can become a cycle that worsens as time goes on. The most common cause is having an ‘unbalanced’ shoulder and performing repetitive heavy pressing exercises such as bench press and overhead shoulder press.

Most people have an imbalance between their left and right arms (being left or right handed) as well as an imbalance within the shoulder muscles (power vs. postural). So, firstly, when training in the gym doing exercises like shoulder press or bench press, where the hands are fixed to a bar, one arm leads the other and the bar acts as a stabiliser between the two.

The problem with fixed bar exercises in a pressing position, whether it be above the head or outwards, is that there is less requirement for the postural (stabiliser) muscles – the rotator cuff – to act in controlling the shoulder.

As one arm is stabilised through the bar by the other, it’s easier to push heavy weights, hence the results of these exercises in muscle growth and strength gains in the aesthetic pecs and deltoids (and why these exercises are so popular!).

Secondly, the force generated by the power muscles (pecs, deltoids) during the heavy press or abduction movement of the arm, outweighs the functional ability of the rotator cuff muscles. This creates an increased movement of the humeral head into the sub-acromial space, as due to the force of the power muscles impingement is created. Basically, the pull of the big muscles is too great and the little muscles simply can’t keep up.

This imbalance is increased with weak scapular stabilisers and tight rotator cuff muscles, mostly because muscles like serratus and lower trapezius are underdeveloped due to a lack of functional and stability exercises and an overuse of power and pressing exercises. If you have had a previous injury to the shoulder (like falling on the shoulder from a bike or when skiing, or a dislocation in sport) then the ligament stability may be compromised, in addition to the weakened rotator cuff. If the position of the ball in the socket is an anterior (forward) position, the movement of the shoulder is not ideal.

Tightness in the back of the shoulder further increases this irregular movement, along with poor technique during exercise. When the weight is too heavy, the lifter generally cannot keep good form and compensates, because they don’t have the strength in the postural muscles to hold the body and shoulder in the correct position, nor keep the correct muscle firing pattern during the concentric and eccentric phase.

During a bench press, the scapular movement is restricted, and so the alignment of the shoulder joint socket is compromised. This creates an increased shearing force at the shoulder joint structures and rotator cuff. The tendons are overused and become fatigued and inflamed, fail to stabilise and rotate the shoulder, and create impingement again.

Breaking the cycle

In almost every case we see, the problem recurs through a ‘cycle of impingement’. Breaking this cycle is essential for successful recovery. Because the rotator cuff tendons are sore, inflamed and weakened, they don’t perform their stabilisation and movement assisting jobs. Once they start becoming weak, the continuation of conventional exercises, like lateral raises, and shoulder and bench presses, will result in the tendons getting increasingly caught. The tendon and rotator cuff complex becomes weaker and more inflamed, it loses its function and the problem gets worse.

Rest alone, which is what most people do, does not fix the issue. They rest until the pain subsides and initially don’t seek physio assistance and rehab exercises. What they don’t realise, however, is that inside their shoulder the rotator cuff function has significantly reduced. The tendons have become weak, and they stay weak unless rehabilitated. Waiting for too long before rehabilitation will create too much weakness, and strengthening the shoulder too early will result in reaggravation.

At the same time, returning to normal exercises too early without enough rehabilitation, or progressing the exercises too quickly (through boredom or poor guidance), will return the impingement. If a client has not properly rehabilitated the shoulder to its full function again, they will be a candidate for impingement over time. Even if your serratus anterior, trapezius and rotator cuff muscles are developed, if the pecs and rhomboids are more developed, then you have a relative functional weakness in the stabilisers, and an unbalanced shoulder – which is a very common problem.

The solution

At the client’s first episode of injury pain, advise them to consult a physio to test if they have impingement and to diagnose whether they have a significant injury. The physio will provide personalised and structured treatment, education, taping and pain relieving exercises, which will help reduce the pain and inflammation. They will then undergo a rehabilitation program of a progressive course of exercises to increase the mobility, control and strength of the scapular and rotator cuff muscles and improve overall function.

Rehab and stability exercises need to begin at a low level, and in the right sequence, with very slow progression and advancement of difficulty and resistance. For this process, the selection of correct closed kinetic chain exercises will work more quickly and more effectively than open chain exercises. These rehabilitation exercises should be continued as part of the ongoing shoulder training regime.

Ongoing prevention

Once the shoulder is strong enough to return to standard weight training exercise, the client’s shoulder training program will need to have a greater focus on stability (as opposed to purely muscle building), be varied often and incorporate multidirectional movements with less load.

When initially resuming training, the client should avoid heavy or repetitive movements above shoulder height, bench press, lateral raises, front raises, and any exercise that places excessive demand on the rotator cuff. Any advanced, new or sport specific exercise programs should always be checked over by the physio before commencement.

Tim Keeley, B.Phty, Cred.MDT, APA

With over 22 years’ experience in physiotherapy and the fitness industry, Tim is Principal Physiotherapist and Director of Physio Fitness, a clinic based in Sydney’s Bondi Junction. He is also the Director of physiorehab.com, an online education and rehab program platform.

physiofitness.com.au / physiorehab.com / facebook.com/physiofitness

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