Repetitive strain injury (RSI) is an umbrella term for any injury resulting from chronic, frequent, and repetitive use of a muscle, its tendons, and the surrounding soft tissue, particularly in the neck, shoulders, arms, wrists, and hands. Generally causing some form of inflammatory pain, tingling, and numbness, RSIs are commonly sustained in the workplace and among athletes, both professional and recreational, who perform the same movements over and over. They may also be sustained by maintaining the same body position for prolonged periods on a regular basis, as in sitting in front of a TV or computer screen with poor posture. Examples of common repetitive strain injuries include carpal tunnel syndrome, muscle strain, tennis elbow, and Achilles tendinitis.
In the workplace, repetitive strain injuries tend to afflict the upper body and typically stem from poor posture, poor technique, and long periods spent in sedentary positions. Probably the best known of these is carpal tunnel syndrome. Often a consequence of typing on a keyboard and using a mouse, carpal tunnel occurs when the tendons of the wrist extensor muscles in the forearm become inflamed from overuse and impinge on adjacent nerves where they pass between the bones of the wrist through a space known as the carpal tunnel. Symptoms include pain, numbness, and tingling in the hands and the fingers that often will radiate up the arm.
Poor workplace habits also can lead to repetitive strain injuries, muscle strains. Whether a desk worker leans forward regularly to see the computer screen, or a factory worker reaches for an object over and over again, a muscle strain occurs when a muscle or muscle group must contract repeatedly and is not given adequate rest time. These muscle contractions may occur in a series of movements or in a prolonged contraction, as in holding the same position for an extended period. They can result in muscle strain, which will cause noticeable pain upon performing the movement that caused it, or inflammation of the tendons attaching that muscle to the bone, known as tendinitis.
Leisure activities, including everything from watching television to playing tennis, can also be the cause of repetitive strain injuries. Like workplace RSIs, any activity performed in a sedentary position can lead to injury, even something as innocuous as always watching TV with one’s head turned to the left or sleeping on planes with one’s head falling forward. Over time, the strain on the muscles and soft tissues can lead to pain, inflammation, and difficulty moving. Additionally, swelling around inflamed soft tissues can pinch the nerves nearby, leading to numbness, tingling, and radiating pain.
Many exercise-related injuries can be classified as repetitive strain injuries, even if they tend to be categorized separately. If the activity is performed so regularly that inadequate recovery time is permitted, and if it involves the same motion performed repeatedly, and if the damage is brought on over time rather than from an abrupt trauma, then the resulting injury could be considered an RSI. Tennis elbow, also known as lateral epicondylitis, fits into this category, as it is pain that develops where the common extensor tendon meets the humerus bone that results from repeated straightening of the elbow when swinging a tennis racket. Achilles tendinitis and rotator cuff syndrome, common to runners and baseball pitchers, respectively, are other examples of common repetitive stress injuries.