In this day and age we commonly use computers at work or play. Prolonged use can lead to a change or adaptation in your posture whereby the muscle of your chest shorten and contract, causing the muscle of your upper back and shoulder to become stretched and weak.
There are some very simple steps we can take to ensure we are not putting ourselves at risk. It could be a case of speaking to your HR or occupational health department with regard to altering your work station setup. Or it may be a case to use a few simple exercises and stretches to maintain your flexibility and posture while at your desk.