Medial epicondylitis
Medial epicondylitis is less common and characteristically occurs with wrist flexor activity and pronation. Medial epicondylitis can result from (1) late forehand biomechanics where the player quickly snaps the wrist to bring the racquet head forward, (2) the back-scratch or cocking phase when serving, which places tremendous stress on the medial tissues of the elbow, (3) in the right elbow of a right-handed golf swing by throwing the club head down at the ball with the right arm rather than pulling the club through with the left arm and trunk (also referred to as "golfers elbow"), or (4) improper pulling technique with certain swim strokes, especially the backstroke (also referred to as "swimmers elbow").
It should be kept in mind that elbow epicondylitis is not limited to those persons playing tennis, golf, baseball or swimming and can result from any activity that puts the lateral or medial compartments of the elbow under similar repetitive stress and strain (e.g., hammering, turning a key, screw driver use, computer work, excessive hand shaking).