A major contributing factor to RSI is a poor, static posture. Sitting in the same position for long periods of time, with arms flexed, typing without proper breaks compounded with a poor posture increases the static loading on a large number of muscles throughout your body. Over time these muscles tend to become shorter and denser, impeding blood circulation in the arms, neck and shoulders.
The first signs of RSI begin to manifest four to five years before any debilitating hand pain. The signs usually indicating a problem are back pains, shoulder pains and/or neck aches. This mechanical tension leads to a tethering of the nerves within in the regions of tensed muscles (around the shoulders and upper back). After several years of performing this activity, this tensed state becomes the default state and RSI ensues. By correcting the ergonomics, taking appropriate breaks and performing correct stretches, one can prevent and recover from RSI.
Poor posture is a constant source of chronic stress. Such postures disrupt the usual muscular balance of your body. After some time, your body begins to compensate for this imbalance by contracting nearby muscles for additional support, tightening the connective tissues to further support the imbalance.
If these patterns are continued over a period of months and years, the fascial support of the body becomes more rigid, sticky and begins to interfere with the normal contractions/relaxations of muscles which inhibit the movement of surrounding nerves and blood vessels. Correcting poor posture is imperative in recovering from RSI.
Make sure the lighting isn’t too bright. If you see glare on your screen then move the screen, lower the light level and use a good quality anti-glare screen. Make sure that your screen doesn’t face a bright window or is backed to a bright window. Use a share or drapes to control the amount of lighting coming through a window.
Your computer room should have adequate fresh-air and ventilation. It should also have adequate heating or cooling, providing a comfortable environment whilst you work.
Excessive noise can cause stress that tenses muscles which increases RSI risk. Your computer room should be a quiet place, perhaps play low volume music. Try to avoid repetitive ambient noises if they cause an issue (like a fan, or dripping tap).