What stretches will keep my shoulder healthy for baseball/softball?

Flexibility exercises should focus on the chest, back muscles, and shoulder muscles. These muscles attatch to the shoulder region and play a pivotal role in shoulder mechanics. Start by foam rolling (a form of self-massage) the latissimus dorsi (large back muscle) and thoracic spine (muscles between your shoulder blades). Next static stretch your latissimus dorsi with a ball lat stretch, your pectorals with a doorway stretch, and the rear deltoid with a posterior shoulder stretch. Be sure to hold each stretch for 30 seconds. This will give your muscles enough time to relax and elongate. In addition, light strengthening exercises after stretching will further aid in keeping your shoulders healthy. Try performing a ball cobra, a standing cable shoulder external rotation, and a dumbbell scaption for 1-3 sets of 10-15 repetitions of each exercise.

There are many stretchs that you can do. I would recommend the sleeper stretch. Start be laying on you side with your bottom arm flat on the ground extend the arm front of you. As if you are pointing straight ahead in front of you. Bend at your elbow so that you fingers are now pointing straight up into the cecilling. With your other hand grab the wrist of the hand that is pointing to the cecilling. Now pull down so that the palm of the hand is now facing the floor. This stretch is great for the rotator cuff and all the deltoid muscles in the shoulder. The rotator cuff is the most important part of the shoulder that you want to be healthy for success in baseball or softball. 

Using stretch bands or tubing for dynamic stretching for the shoulder is great for maintaining your shoulder health.

With your elbow at a 90 degree horizontal at shoulder level, pulling the bands/tubing forward and backward will fire up and strengthen your shoulder muscle complex, while activating the synovial fluid, lubricating the shoulder joint.

This stretching is particularly helpful for your shoulder right before you begin throwing. Be sure the stretch bands/tubing you’re using is at the proper strength resistance.