If you have any of these symptoms, you should see a qualified doctor for diagnosis and treatment. RSI is a cumulative trauma that develops over a period of time. RSI arises from a combination of physical tension, repetitive motion, and improper posture. Computer users are exposed to all of these, as well as to poor typing habits that target the more delicate muscles of the hand and wrist in particular. The human body and all its components depend on blood for oxygen and nutrients.
Blood is transported through the muscles by embedded capillaries.
The by-products of such anaerobic metabolism, such as lactic acid, cause pain. Tensing a muscle repeatedly during any activity will increase the pressure around blood vessels and restrict blood flow. If the muscle is not relaxed, blood can't run through. Surrounding muscle fibers will then tense up. As blood flow is blocked even more, the problem spreads.