Before we delve into ways to assess infraspinatus function, pain, and exercises, lets do a quick anatomy review

Infraspinatus Anatomy

The infraspinatus is one of the four muscles of the rotator cuff of the shoulder. The rotator cuff’s responsibility is to stabilize the ball-and-socket joint of the shoulder, or the glenohumeral joint.

Glenoid=Socket

Humerus=arm bone

In the image below, the infraspinatus is highlighted. On the left side of the image, you can see it tucked beneath other muscles, such as the latissimus dorsi (lat), deltoid, and trapezius. On the right side, the trap, deltoid, and lat are all peeled away, uncovering the full presentation of the muscle.

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Infraspinatus Action

In addition to helping the other rotator cuff muscles stabilize the shoulder joint, the infraspinatus externally rotates the upper arm.

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Pain & Dysfunction in the Infraspinatus

One way to tell that you have some pain or weakness in your infraspinatus is to actively externally rotate your arm, and see what happens. Can you move it through a full range of motion? Does it hurt when you externally rotate? This could be a sign of a tear or weakness.

If you do have some pain or weakness, don’t be alarmed. According to a recent study, about 30% of adults over 60 years old, and 62% of adults over 80 have tears in their rotator cuffs. Many of these are asymptomatic, meaning they cause no pain or dysfunction at all. Many people have tears that don’t require surgery and can improve with exercise. As a student physical therapist working with patients that have shoulder pain, many of them are concerned about having to get surgery. In these cases, I always inform them that a tear in the rotator cuff is incredibly common, and surgery is oftentimes not needed! Unfortunately, some patients are quite debilitated by tears and require surgery, in which case rotator cuff exercises enter the picture after that. 

Things to watch out for include sharp or throbbing pain that doesn’t change with moving positions, a feeling of heaviness in the shoulder or chest, or worsening symptoms with activity that follows a predictable pattern. If these symptoms are present, you may have something more serious going on and seeing a physician is recommended.

Infraspinatus and Teres Minor Exercises

In order from easiest to hardest

1. Shoulder external rotation isometric: stand with a towel underneath your arm, and push the back of your wrist against the wall. Hold for ~5 seconds and relax. Doing 2-3 sets of 8-12 reps is a good place to start for all of the following exercises.

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2. Banded shoulder external rotation: Bringing the muscle actively through the range of motion is a good progression to strengthen the infraspinatus. I like this one because it engages both sides of the shoulders and back.

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3. Face Pulls: This exercise involves more muscles, so you get more bang for your buck. Interestingly, this exercise will target the infraspinatus muscle more effectively than the other ones. A recent study compared infraspinatus muscle activity using electromyography, where they put probes into the muscles and assess how much they activate during certain movements. They found that infraspinatus muscle activity was highest when the arm was in 90 degrees of abduction. This is demonstrated in the picture below, where the arm is parallel to the ground and the forearms are in an upright position.

In this article, we covered:

• Anatomy of the infraspinatus and the rotator cuff as a whole

• The action of the infraspinatus muscle

• How to assess pain or dysfunction in the infraspinatus muscle, and why we shouldn’t be alarmed by occasional aches and pains in the shoulder (they are common!)

• Exercises for the infraspinatus and how to progress them appropriately 

With that information, you are in a better position to take control of your shoulder health and improve your strength and function!

 

 

 

Sources:

[1] Davies, Clair, and Amber Davies. The Trigger Point Therapy Workbook: Your Self-Treatment Guide for Pain Relief. 3rd ed., New Harbinger Publications, Inc., 2013.

[2] https://www.mdpi.com/2227-9032/11/14/1977

[3] https://ahc.aurorahealthcare.org/fywb/x08252.pdf

[4] https://www.performancehealthacademy.com/thera-band-shoulder-retraction-external-rotation.html