Repetitive strain injury (RSI) is a general term used to describe the pain felt in muscles, nerves and tendons caused by repetitive movement and overuse.  It's also known as work-related upper limb disorder, or non-specific upper limb pain. 

It is caused by the overuse of muscles and tendons in the upper body through repetitive activities, or doing a high-intensity activity for a long time without rest, poor posture, or activities that require you to work in an awkward position. The condition mostly affects the forearms and elbows, wrists and hands, and neck and shoulders.  The specific conditions are so common they have common names: Tennis/ Golfer’s elbow (lateral/ medial epicondylitis), Mothers’ Wrist (DeQuervain’s tendonitis), Writers Cramp (Dystonia), and Rotator Cuff Tendonitis.  Despite being common, there tends to be a lot of misunderstanding about what RSI actually is.

The underlying factor in all RSIs is that our muscles of the upper limb are adapted to mobility and dexterity, and so often cross several joints in performing their action…  A good example, to illustrate this, is the muscles in the forearm that control the movements of the hand and fingers.  They are long and thin muscles that attach at the lower arm just above the elbow, and then run all the way across the elbow, across the wrist and in to the fingers: some of these forearm muscles cross four joints.  Their long thin structure dictates that they are not adapted for carrying loads or stabilising the wrist, but are very good at fine movements of the hand.  However, in our modern life, these muscles carry great loads of shopping, or work stably at a computer keyboard, or produce a powerful golf shot.  This results in repetitive overuse which is at first felt when performing the aggravating activity, but then often progresses to become constant. 

So, with this understanding, if you have a repetitive strain injury the first step in treatment is prevention of further injury by identifying and modifying the task or activity that is causing the symptoms.  If necessary, you may need to stop doing the activity altogether.   

Interestingly, the “repetitive strain injury” is not actually a primary strain at all. This is a key point because it is often misunderstood that the cause is chronic tendonitis (inflammation of the tendon) caused by microtears, but it is not.  Repeated loading causes the collagen in the tendon to start to degenerate (tendinosis), which weakens it, and predisposes it to microtearing.  On a cellular level the Type-1 collagen fibres are replaced by disorganised Type-3 collagen fibres.  This disorganisation is seen as a loss of fibre alignment and linking between fibres, and results in the tendon fibres being less able to bear loads.  On a tissue level, the tendon shifts from a white, glistening and firm appearance to a swollen dull-appearing, slightly brown and soft surface appearance. 

So, if we understand this, taking a course of anti-inflammatory painkillers such as Ibuprofen might help with the pain, but (since we now know is it is a chronic degenerative condition rather than an acute inflammatory one), using anti-inflammatories will not resolve it but will ease the pain.  What is going to help is stimulating normal collagen and tendon healing by reducing muscle spasm, and applying lengthening load to the tendon.  This is best done with massage, acupuncture, and stretching exercises.