What is Repetitive Stress Injury (RSI)?

RSI is a term that includes several different conditions that result from overuse of muscles and tendons.  Most of the time, when somebody is talking about RSI, they are referring to tendinitis (alternately spelled tendonitis), carpal tunnel syndrome, tennis elbow (a special type of tendinitis), or tendinosis (a chronic form of tendinitis).


Tendinitis is an inflammatory condition that results from repeatedly stressing a tendon.  In response to the stress, the tendon develops very small V-shaped micro tears which cause pain, irritation, and inflammation.

Is accompanied by an intense burning sensation in the forearm  flexors (these are the muscles and tendons that cause your hand  to close and  terminate mostly about 3 inches down the arm from the elbow crease).  This burning sensation can also include a prickly sensation that gets worse when touching things or gripping.  The pain can last several months.

A good overview of tendinitis is located here


Eventually, my acute case of tendinitis went away, but I noticed that things had not returned exactly to the way they were. To begin with, I lost some endurance. I found that I could only type two or three paragraphs straight through before my muscles started to feel tight and I noticed small, sharp pains where my flexor muscles met the tendons near the elbow.  I was experiencing  tendinosis.

Tendinosis is what develops when you fail to let a case of tendinitis heal correctly. The V-shaped tears in the tendon, instead of being filled in with type I collagen, get filled in with scar tissue and type III collagen (For a very detailed discussion of collagen types visit tendinosis.org).  This type III collagen and scar tissue, instead of being white and firm, appears dull and brown and is much weaker than type I.  The result is very long-term (if not permanent) weakening of the tendon.

Carpal Tunnel Syndrome

Carpal Tunnel Syndrome is essentially compression of the median nerve in the wrist.  The nerve is especially vulnerable in the wrist because tendons required for finger movement as well as the median nerve must pass through a very small space in the wrist called the carpal tunnel. Irritation or inflammation in this area decreases the space available for the nerve to pass through, leading to tingling or a slight loss of feeling in the fingers.

This tingling sensation is felt in all of the fingers except the pinky finger and may include the palm.  The pinky finger is not affected because movement and sensation is controlled by the ulnar nerve.

In my case, the tingling sensation was present all the time, but was aggravated by touching or tapping objects.  I also experienced numbness in my hands that would wake me up at night.

There are two tests that are easy to do to help figure out whether you might be suffering from Carpal Tunnel Syndrome. The first one is the Tinel’s sign (video of tinel’s sign here), and is performed by tapping over the median nerve to try to induce a tingling sensation.  The second test is called Phalen’s test (video of Phalen’s test here), where the hands are pressed together with the palms outward. Again, if tingling is experienced after 30 seconds or so then there is an indication that Carpal Tunnel Syndrome might be the diagnosis.

Overview of Carpal Tunnel Syndrome

Tennis Elbow

Tennis elbow, also known as lateral epicondylitis, is inflammation and pain located where the forearm extensors  (the muscles and tendons responsible for opening your hand) attach to the elbow.  It is often called tennis elbow because many tennis players who have poor form in their backhand place extra stress on these tendons, resulting in inflammation. However, computer users can also get tennis elbow from improper typing technique (For example, using “the claw”).

More information on tennis elbow