Scapular dyskinesis

When you raise your arm out to the side or reach forward, your shoulder joint is not the only thing moving. Your shoulder blade also rotates and glides over your ribs. This coordinated movement of the upper arm bone (humerus) and shoulder blade, at a ratio of roughly 2 to 1, is called scapulohumeral rhythm. This coordination allows you to raise your arm high.

Scapular dyskinesis is the term used when this coordination does not look smooth. It refers to a noticeable difference in the shoulder blade's position, movement path, or timing. It is also called altered scapular movement or abnormal scapular motion. In everyday language, people may say, "My shoulder blade sticks out" or "My shoulder blade lifts away from my ribs."

A professional will usually look at your shoulder blades from behind while you are standing, checking the following:

1. At rest — They look at the height of the shoulder blades on both sides, their distance from the spine, and whether the inner borders lift away from the ribs. 2. While raising and lowering the arms — You slowly raise your arms out to the sides or forward and lower them several times. Holding light dumbbells can sometimes make differences easier to see. 3. Checking the rhythm — They check whether the shoulder blades move upward smoothly as the arms rise, and whether they suddenly drop or stick out as the arms lower.

The visible patterns are sometimes described in categories, such as the lower tip of the shoulder blade sticking out, the inner border lifting away from the ribs, or the upper border rising excessively. When the shoulder blade protrudes more distinctly like a wing, it is called scapular winging and is covered separately.

The shoulder blade is not attached to the ribs by a bony connection; several muscles hold it in place and move it. Changes in the strength and timing of these muscles can therefore change how its movement looks.

• Serratus anterior — This muscle holds the shoulder blade against the ribs and rotates it forward.
• The lower part of the trapezius and the rhomboid muscles — These pull the shoulder blade downward and toward the spine to stabilize it.
• Stiffness around the shoulder — Shortened chest muscles or stiffness at the back of the shoulder can restrict shoulder blade movement.
• Fatigue — After prolonged exercise or using your arms in the same position for a long time, muscle fatigue can change the movement.
• Pain — When the shoulder hurts, the body may change its movement pattern to avoid painful stimulation.

So, rather than simply meaning that "the shoulder blade is out of alignment and causing pain," the altered movement can sometimes be a result of pain or fatigue. It varies from person to person, so it is helpful to consider both possibilities rather than viewing it in only one way.

Shoulder blade movement varies slightly between people, between postures, and even with how someone is feeling that day. This means there is no clear dividing line between normal and abnormal.

According to data from Burn and colleagues in 2016, this movement pattern was observed in approximately 61% of athletes in sports involving frequent overhead arm use, such as baseball and volleyball, and approximately 33% of athletes in other sports. This means it is also commonly seen in people with no pain or discomfort at all. In addition, when Hogan and colleagues reviewed studies of athletes in 2021, they found no clear difference in the occurrence of shoulder injuries between athletes with and without these movement findings. Even if the visible appearance of the shoulder blades differs slightly, it can be viewed as individual variation if there is no pain or functional difficulty.

• You feel an ache or a lack of strength at the back of the shoulder when raising your arm.
• One shoulder blade looks more prominent in a mirror or photo.
• It is difficult to keep your arms raised for a long time, and your shoulders tire easily.
• The shoulder and the area around the shoulder blade on the side carrying a backpack become achy easily.
• You feel your shoulder blades shifting up and down during jumping jacks or push-ups.

The foundation is practicing slow, precise use of the muscles that stabilize the shoulder blade.

• Wall push-up plus — Place your hands on a wall and gently push your body away from it. At the end, push a little farther so your shoulder blades move forward over your ribs. This is useful for learning what it feels like to use the serratus anterior.
• Wall slide — Bend your elbows and place them against a wall, then slowly slide your arms upward. Keep your shoulders from rising toward your ears.
• Band row — Pull on a resistance band, drawing your shoulder blades toward your spine, then slowly release.
• Chest stretch — Place your arm against a doorframe and open your chest forward to stretch the muscles at the front of your chest.
• The right pace — Moving slowly and accurately is more important than doing many repetitions quickly. Try watching your shoulder blade movement in a mirror as you practice.
• In daily life — When sitting for a long time, roll your shoulders backward every 20–30 minutes to loosen them up, and alternate the side on which you carry your bag.

• Your shoulder blade suddenly protrudes and it becomes difficult to raise your arm.
• You lose strength around one shoulder and shoulder blade, and the weakness gradually worsens.
• Your movement changes after a shoulder injury, and the pain persists.
• Shoulder pain disrupts your sleep at night, or does not improve after several weeks of self-care.