Although you may not call it by name, you use your infraspinatus muscle every time you brush your hair, throw a ball or otherwise move your shoulders. One of your four rotator cuff muscles in your shoulder, the infraspinatus muscle is your main external rotator, according to Sports Injury Clinic. When this muscle becomes too tight, injury can occur. Prevent muscle tightness by stretching before and after exercise.

Posterior Shoulder Stretch

Your infraspinatus is located on the back of your body. It connects your shoulder blade to the bone in your upper arm. You can stretch your infraspinatus by placing your right arm across the front of your body and then using your left arm to press your right elbow toward your left shoulder. The Sports Injury Clinic recommends maintaining this stretch for 10 to 30 seconds.

Internal Rotation

Stretch your shoulders before and after vigorous exercise that uses shoulder rotation. The internal rotator stretch improves flexibility of your infraspinatus and your teres minor rotator muscles. To perform this exercise, lie on your left side. Hold your left arm in a 90 degree angle, with the upper part of your arm on the floor. Reach up with your right hand and place your right palm on top of your left hand. Press your left hand and arm down toward the floor, like pushing on a lever. Hold the stretch for 30 seconds. Repeat the exercise on the other side.

Broom-Stick-Assisted Stretch

You can use props -- such as a broom stick, thick dowel rod or baton -- to aid the flexibility of your infraspinatus. Grasp a stick with your right hand and raise it up over your head, like a flag. Bend the elbow of your right arm and allow the stick to point down toward the ground behind you to the left. With your left hand, reach behind you to grab the other end of the stick. Position your left elbow so it is at shoulder height. With your right hand, press the stick against your left shoulder, internally rotating your shoulder. Hold the stretch for 30 seconds. Repeat on the other side.

Exercise Frequency and Warm-Ups

You can perform shoulder stretches on a daily basis. Before you stretch your infraspinatus, warm up your shoulder by swinging your arms while walking briskly for five minutes. Warming up increases blood flow to your muscles and lubrication to your joints, which reduces your chance of injury. Hold each stretch for a minimum of 10 seconds. Repeat each stretch two or three times.