Shoulder injuries are one of the most common injuries presented to our clinicians at Perfect Balance Clinics. They can range from tightness in the neck and shoulder region, to muscular aches in the shoulders, to more complicated bio-mechanical problems. In my experience shoulder injuries can be prevented by corrective advice on training regimes and postural correctness during general day-to-day activities. The people that are most at risk from developing shoulder injuries rather counter intuitively are those that use computers for long periods during the day. Yes that’s right, using a computer is seriously bad for your shoulder health!
The main reason for shoulder damage is simply due to correct length tension relationships of the muscles surrounding the shoulders. The shoulder is an inherently unstable joint, unlike the hip, and this means that the main support in the shoulder joint comes from the surrounding ligaments and shoulder musculature, primarily the rotator cuff muscles. The rotator cuff muscles are a group of muscles surrounding the front (1 muscle- subscapularis) and the back (3 smaller muscles- teres minor, supraspinatus and infraspinatus). These 4 muscles along with the support ligaments form the main basis for support in the shoulder complex. It is upon this support that we are able to perform the larger more compound movements in the shoulder, such as lifting the arm up in front of the body and to the side or performing a press up. If the ball and socket joint is not supported from these passive and active supporting mechanisms then we are in trouble and dysfunction will occur.
Sitting at a desk for hours on end and using a mouse basically causes muscle imbalance in the shoulder region. The subscapularis begins to work in a shortened position where the shoulder is held in front of the body and this begins to form the downwards spiral in shoulder dysfunction. The opposing stabilising rotator cuff muscles, being located at the back of the ball and socket begin to work in a lengthened position.
Now imagine this – if you were standing holding a bucket of water with your arms straight down by your side the water may appear heavy but more than likely you would be able to lift the bucket for a long time. This is because the mass of the bucket is close to the axis (point of rotation) about which torsional stress (turning force) may be applied thus resulting in very little torsional stress on the shoulder, therefore you are able to hold the bucket successfully as the tension in the joint and stress on the muscles is minimised. Now visualise yourself with the same amount of water but this time holding the bucket out to the side of you. As the mass of the object is now far away from the axis of rotation, there is a great deal more torsional stress, effectively making the bucket of water seem heavier! This leads to massive amounts of stress not only on the rotator cuff but also leads to recruitment (use) of other muscles as a result of the excess load on the shoulder complex.
Admittedly the mouse is supported on the desk and you are not lifting a massive load in a ‘stressful’ position, but the same problem is inherent. The problem being the abnormal length and tension relationship between the shoulder stabilisers and the mobilisers (large muscles such as pectorals, serratus anterior and lower trapezius). Muscles work better in a shortened position, up to a point, if they are in a lengthened position there is a mechanical disadvantage in how the cross bridges (smaller subunits of how a muscle contracts) form thus resulting in an apparent weakness of the muscle. An example of this can be seen in an arm wrestle, if one person has their arm more bent than the other person, therefore moving the arm closer to their body, effectively making the muscles shorter in their arm and longer in their opponents arm, they will have a significant mechanical advantage over their opponent, try it out!
So coming back to our development of faulty shoulder mechanics. The arm using the mouse is working for extended periods, sometimes up to 4-5 hours in a very mechanically disadvantaged position, this creates shortening of the pectoral muscles and subscapularis, front muscles, and lengthening of the posterior muscles, teres minor, infraspinatus and supraspinatus. Also, shortening of the pectoralis minor muscle results in protraction of the shoulder girdle and scapular, thus resulting in an apparent closure of the space in which the supraspinatus tendon runs.
Now take this faulty shoulder into the gym, onto the tennis court or golf course and wait for disaster to happen! The excessive load on the posterior elements of the rotator cuff cause these stabilising muscles to become effectively useless at stabilising the ball and socket joint, just like the weight of the bucket got heavier when you took the arm to the side, the muscles of the shoulder are now having to work in a distinctively mechanically disadvantaged position, thus more stress develops on them. Repeated stress leads to repeated weakness on the rotator cuff and stress on the tendon soon becomes more permanent. Shoulder tension and headaches result from the excessive stress on the other supporting musculature around the shoulder. Before you know it you are permanently in pain and waiting in the surgeons office for an orthopaedic consultation. This can all be prevented with correct posture and biomechanical integrity of the shoulder joint.
At Perfect Balance Clinic we aim to restore the balance and integrity of the shoulder complex by advice on exercise and stretching as well as a few other helpful hints and tips. To find out more contact us to book an appointment.