Andrew Murray serve

With Andy Murray winning for the fourth time at Queens, albeit with a slightly shaky start, and Wimbledon just over a week away, the tennis season is well underway. As a physiotherapist I work closely with tennis players of various levels throughout the year and probably the most common injury we see is to the shoulder.

The majority of shoulder pain is diagnosed as a shoulder impingement by a GP, but what exactly does this mean? In my opinion ‘impingement’ is somewhat of an incomplete diagnosis. It is such an umbrella term covering a multitude if different problems that it is almost comparable to taking your car to the garage with an oil leak for a mechanic to tell you that you have an oil leak! That’s fine, but what you really want to know is why and what is causing it so that it can be fixed. This is the same with a shoulder impingement. To be told that you have shoulder impingement is basically someone confirming you have shoulder pain. I’m pretty sure you knew that before you attended the appointment. What you want to know is what is causing it and therefore what can you do to fix it.

The shoulder is an inherently unstable joint. If you were to give a specification to an engineer to design a strong, mobile, biomechanically efficient and functional joint the outcome would probably be almost the complete opposite to the shoulder that we all possess.

So what are the downfalls?

Firstly, both the ball and socket of your shoulder move; a definite disaster for any hope of stability. Obviously as you lift your arm the ball moves in the socket but also, during this same movement, the socket, which is part of your shoulder blade is also moving to keep the ball centred inside it. This is something like a seal moving to keep a ball balanced on its nose whilst the ball is also moving. To add to this there are 6 main muscles, which act on the shoulder blade, which incidentally just floats on your rib cage with no attachments to improve its hope of stability. These muscles are therefore the only thing keeping the shoulder blade in position and must work in complete harmony for the shoulder to move at all. Any imbalance in these muscles (tightness, weakness etc) will therefore wreak havoc with a shoulder.

Secondly, when you hear ‘ball and socket joint’, you envisage a nice deep cup with a ball jammed in it…. Unfortunately this is the next big problem. The shoulder joint is far from this! Picture a golf tea with an egg balanced on it and now turn this 90 degrees and you are closer to the truth! There is a rim of cartilage in an attempt to deepen the socket and the joint is under negative pressure in order to suck the ball into the socket but this still means that yet again the shoulder sacrifices stability in preference of mobility. This makes it even more incredible when you watch serves fly across the court at over 140 mph! Due to its shape the shoulder relies quite heavily on 4 smaller muscles called your rotator cuff (teres minor, supraspinatus, infraspinatus and subscapularis) to keep the ball inside the socket regardless of the position of your arm.

Shoulder impingement has long been thought to be trapping of the rotator cuff muscles in the bony archway under the shoulder blade. What we know is that this is nearly always caused by a biomechanical failing. The following are the most common reasons for this mechanism:

  • Weakness of the rotator cuff muscles and therefore a reduced ability to centre the ball inside the socket
  • Imbalance of the muscles acting on the shoulder blade meaning that it is unable to move correctly to maintain the centre of the ball inside the socket
  • Stiffness in your thoracic spine (upper back) that affects the position of the ball and socket and therefore ability of the muscles around the shoulder to function correctly

Hopefully, understanding the biomechanics and inbuilt inefficiencies of the shoulder will make it easier to understand why the above problems are all detrimental to the health of your shoulder. Most shoulder impingements occur after a period of over use for example playing in a hard tournament or working on a serve repeatedly.

In effect what happens is that you have one of the above root causes, which doesn’t give you any problems at all until you increase the demand on your shoulder and suddenly you upset the apple cart and develop pain. Hopefully you can see then, that should impingement is an outcome of a problem rather than the cause of it, and therefore as I said earlier a very poor diagnosis, if a diagnosis at all.

Treatment for shoulder impingement should always be conservative in the first instance. As shown above, successful outcome requires you identify the biomechanical inefficiency and correct it. Luckily, this is something that physiotherapists are very good at! Steroid injections can reduce pain and inflammation but won’t solve the problem as a stand-alone intervention. The same is true for surgical options. More room can be created for your rotator cuff to prevent ‘impingement’ by shaving away some bone, but unless the biomechanical problems are also addressed then current evidence suggest that there is perhaps as much benefit in immobilizing your arm in a sling for 6 weeks and resting as there is to undergoing surgery. If you have been diagnosed with a shoulder impingement by any professional then I would definitely challenge which factors are contributing to this to allow for successful treatment.

In summary

  • We are set up to fail with a poorly designed (for efficiency) shoulder that sacrifices stability for mobility
  • Understanding the biomechanics of the shoulder is key to understanding shoulder impingement
  • We demand high levels of function from our shoulder, which is probably not best designed to cope with repeated overhead actions like a tennis serve.
  • Learn to love your rotator cuff muscles, you have a lot to thank them for and keeping them strong and healthy and not shocking them with sporadic activities will mean they keep your shoulder functioning beautifully.
  • Seek physiotherapy assessment if you are having shoulder pain that doesn’t improve after a week as early treatment if far quicker and easier than undoing long standing muscle imbalances.

Hannah Dacre
Chartered Physiotherapist

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