Scaption

There are three broad ways to raise your arm.

• Flexion — Raise your arm straight forward in front of your body.
• Abduction — Raise your arm out to the side of your body.
• Scaption — Raise your arm somewhere between forward and sideways, in a direction about 30 degrees away from straight ahead.

Scaption is short for “scapular plane elevation.” The scapula does not lie flat against the back; it rests at an angle on the curved surface formed by the ribs. Its joint surface therefore faces diagonally forward rather than straight ahead. This orientation defines the scapular plane. Scaption is the movement of raising the arm along this plane.

The glenohumeral joint is structured so that the rounded head of the upper arm bone rests in a shallow socket in the scapula. When you raise your arm in the scapular plane, the head of the upper arm bone moves in line with the socket, causing less twisting of the capsule and ligaments surrounding the joint. This is why raising the shoulder can feel smooth.

As the arm rises, the scapula also moves along the chest. Coordination in which the scapula rotates about 1 degree for every approximately 2 degrees of arm elevation is called scapulohumeral rhythm. During this movement, the deltoid muscle raises the arm while the rotator cuff works with it to hold the head of the upper arm bone in the socket. It is not a movement performed by just one muscle; the whole shoulder works together.

When you reach for something on a shelf, hang clothes on a high hanger, or raise your arms to wash your hair, your arms usually move diagonally, somewhere between forward and sideways. Trying to raise your arms only straight forward or directly out to the side often feels awkward instead. This means that, in everyday life, our bodies use the most comfortable path for moving our arms.

Scaption is widely used as a basic movement in shoulder exercises.

1. Stand with your feet shoulder-width apart and your arms down by your sides. 2. Slowly raise both arms in a direction about 30 degrees away from straight ahead, forming a “V” shape. 3. Pause briefly at about shoulder height, then slowly lower your arms. 4. Start with light water bottles or no weights, and hold small dumbbells once you become comfortable with the movement.

The movement feels different depending on your hand position. With your thumbs pointing up, it is called “full can”; with your thumbs pointing down, it is called “empty can.” Keeping the thumbs up tends to cause less of a catching sensation at the front of the shoulder, so if you are new to the exercise, try starting with your thumbs up.

Keep a few things in mind.

• Do not shrug your shoulders. If the muscles near your neck engage first, your shoulders will roll upward. Keep your shoulders comfortably lowered and raise only your arms.
• You do not need to go above shoulder height. Use only as much range of motion as feels comfortable for your body.
• Do not use momentum. Lower your arms slowly, at the same speed you used to raise them.
• Do not hold your breath. Breathe out as you raise your arms and breathe in as you lower them.

Scaption is often used as a reference movement in studies that analyze shoulder movement with 3D imaging or measure muscle activity with electromyography. It allows researchers to make comparisons using the same plane of movement, helping them describe details such as how much the scapula rotates.