The triceps stretch is designed to improve the flexibility of the triceps muscle.
The triceps brachii muscle extends the forearm, straightens it out from a bent position and assists in pulling the entire arm inward (adduction). It has three heads called long, lateral, and medial. The long head arises from the infra-glenoid tuberosity, a slight projection just below the glenoid cavity. The lateral head arises on the upper rear surface of the humerus. The medial head is covered by the bellies of the other two but arises on the rear shaft of the humerus about were the two outer bellies merge. The fibers of this muscle insert into a large tendon which inserts on the olecranon process (at the top rear of the ulna).
Tightness in the elbow extensor muscles is the main cause of tennis elbow, or pain in the lateral elbow during arm movements. This tightness is usually caused by overworking or straining these muscles or by working against resistance with the arm fully extended. Therefore, any activity that uses these muscles can lead to tightness. Consequently, this stretch is beneficial not only for tennis players but also for swimmers. Alternatively, strain can result if the muscle is constantly overstretched by tight elbow flexors or if the arm is muscle bound (inability to completely straighten the arm).
Doing this stretch while seated in a chair with a back allows better control of balance. A greater stretching force can be applied to the muscles when the body is balanced. Also, do not perform this stretch for an extended period because this stretch greatly reduces blood flow to the shoulder.