When we begin to talk about the shoulder and tennis, we must first look at the anatomy. The shoulder is one of the most unstable joints of the body. Its shape is very much like a mechanical ball and socket joint. Unlike the deep ball and socket joint of the hip, the end of the humerus(upper arm bone ) inserts into a very shallow and unstable socket.
The shoulder also has a very poor ligament support system that is responsible for attaching one bone to another. This results in the shoulder primarily being supported by muscle. It is no wonder that it is a very common sports injury!
The primary stabilizers in the shoulder are the rotator cuff muscles. They are stressed in tennis during serving and if weak, will often get injured.

All strengthening exercises should be done after a light locomotor warm-up and stretches(see previous OTA magazine for sample stretches).

Beginners should start with approximately 60% of the maximum weight they can lift in the exercise. Begin with 10-12 repetitions for 3 sets. Strengthening should be 3-4 times per week off season and a minimum of 2 times per week in season.