Side-lying Open Book

Side-lying Open Book is a mobility – thoracic rotation exercise involving Rhomboids, Trapezius. Use these steps to learn the movement and work with your coach to choose a suitable level.

Last updated: 2026-10-31 · DynPerformance

Primary muscles: Rhomboids, Trapezius
Secondary muscles: Pectoralis major, Obliques
Exercise type: Mobility – thoracic rotation

Exercise technique

Position
Lie on your side with your hips and knees bent to approximately right angles.
Knee support
Stack your knees and place a thin support beneath them if needed.
Arms
Reach both arms forward at chest height with your palms together.
Open
Move your upper arm backward in a wide arc, turning your chest toward the ceiling.
Pelvis control
Rotate your rib cage without separating the upper knee from the lower knee.
Gaze
Follow the opening hand with your eyes and keep your neck relaxed.
Return
Exhale, pause briefly, then return your arm to its starting position and switch sides.

Key technique points

Keep your knees touching.
Initiate rotation through your rib cage.
Do not require your hand to touch the floor.
Keep your shoulder away from your ear.
Exhale slowly as you open.
Reduce the range when your pelvis begins to rotate.

Common mistakes

Separating the knees

Do not lift the upper knee and substitute lower-back and hip rotation for the intended movement.

Forcing the hand to the floor

Do not press the arm into the floor beyond your shoulder’s range.

Moving only the arm

Do not keep your rib cage still and move only the shoulder backward.

Rotating the lower back excessively

Do not roll your pelvis backward and reduce the thoracic rotation.

Leaving the head behind

Do not fix your gaze forward and twist your neck.

Returning too quickly

Do not fling your arm forward and lose controlled rotation.

Frequently asked questions