The most common injury to golfers involves the rotator cuff. Impingement of the rotator cuff occurs when the tendons of the rotator cuff muscles are being pinched. This can be very painful, and if not addressed could lead to a tear in the rotator cuff. The pain is generally very sharp and it is difficult to move the shoulder throughout a complete range of motion. Common golf injuries to the elbow, forearm, wrist, and hand may involve tendonitis.
Tendons are the structures that connect the muscles to the bones so that movement can occur.
Tendonitis is the inflammation of the tendon. This can occur by overusing the muscle and it's tendon. Obviously, the golf swing uses these muscles repetitively, which can lead to the overuse type of injury. If you were to observe a professional golfer's swing, it is a very smooth motion, with what outwardly appears to be very little exertion. For the most part, they grip the club just right, and swing with the right tempo.