What Is Tennis Elbow?  Tennis elbow, or lateral epicondylitis,
is painful inflammation of the elbow joint caused by repetitive
stress (overuse). The pain is typically felt on the outside
(lateral) part of the upper arm just above the elbow when you
straighten or fully extend your arm.  What Causes Tennis Elbow?
Any activity that involves repetitive twisting of the wrist can
trigger tennis elbow. This includes tennis and other racquet
sports, swimming, golfing, turning a key, or using a
screwdriver, hammer, or computer.  The tendon is the part of a
muscle that attaches to the bone. Forearm muscles attach to the
outer bone of the elbow. Researchers are finding that tennis
elbow often occurs when a specific muscle in the forearm—the
extensor carpi radialis brevis (ECRB) muscle—is damaged. The
ECRB helps stabilize the wrist when the elbow is straight.
Repetitive stress weakens the ECRB muscle, causing microscopic
tears in the muscle’s tendon at the point where it attaches to
the outside of the elbow. These tear