The infraspinatus muscle is attached to the back of the shoulder blade on one end and to the back of the upper arm bone on the other. It assists with horizontal abduction and lateral rotation of the upper arm within the shoulder socket. Exercising the infraspinatus regularly can help the muscle function effectively and may prevent certain shoulder injuries. Consult your physician if you experience pain or other discomfort while exercising.
Stretching the infraspinatus requires lengthening the muscle by either adducting your shoulder horizontally -- pulling your arm across your upper chest -- or rotating it inward. The seated bent-over infraspinatus stretch, for example, involves leaning forward from a seated position, placing your hands on your waist with your thumbs pointed downward and elbows flexed, and pressing your elbows toward the floor until you feel light tension through your shoulders and upper back. You can perform the same exercise from a standing, bent-over position as well. Hold the end position for 10 to 30 seconds, deepening the stretch slightly with each exhalation as you breathe normally. Or repeatedly execute the stretch and return to the starting position over the same amount of time.
A physical therapist may prescribe a series of isometric, or static-contraction, exercises if you injure your infraspinatus muscle, especially for early in the rehabilitation process, when moving through normal ranges of motion may cause pain or aggravate your injury. The isometric horizontal abduction and lateral rotation exercises are two examples that you might include in such a program. Isometric horizontal abduction involves placing the back of your hand against a wall with your arm extended at shoulder height and pressing your hand into the wall for five to 10 seconds at a time. Perform the second exercise in the same fashion, but start with your elbow flexed to 90 degrees and anchored to the side of your abdomen.
Horizontal Abduction Exercises
The infraspinatus is one of the primary horizontal abductors of the shoulder joint. Abduction occurs when your spread your arms apart in front of your chest, so performing resistance exercises through this range of motion on a regular basis strengthens the muscle. The incline reverse lateral dumbbell raise is an example of such as exercise: Lie face-down on an inclined bench, and hold dumbbells below your chest with your arms fully extended, then repeatedly separate your arms to shoulder height, arcing the weights away from each other, and return to the starting position. Perform similar exercises from a standing, bent-over position or a seated position by using two cable-row machines positioned side by side.
External Rotation Exercises
Externally, or outwardly, rotating your shoulder against external resistance regularly also helps strengthen the infraspinatus muscle. This is particularly important for athletes who perform overhead arm motions frequently, including baseball and softball players, swimmers, tennis players and volleyball players. Use either a dumbbell or a resistance band to perform external-rotation exercises. Lie on your side on a bench with the dumbbell in your top hand and your forearm crossing your belly, then repeatedly lift your forearm until it's parallel to the floor or slightly farther, keeping your elbow anchored to your side, and return to the starting position. Perform the same motion from a standing position if you're using a resistance band, making sure the band stretches as you outwardly rotate your arm.