Open Books (Side-Lying Thoracic Rotation)

MobilityBWMat

Side-lying rotational drill where the top arm 'opens' across the body toward the floor behind you, training thoracic rotation while the hips stay anchored by a bent bottom leg.

Demo: Physical therapy demo channel

Sets

2

Reps

8-10 per side

Rest

20s

Contraindications

None significant — low-risk, controlled range drill.

Setup

Lie on your side, hips and knees bent to 90 degrees, arms extended together in front at shoulder height.

Execution

  1. 1Keeping the knees stacked and glued together, rotate the top arm and chest open toward the ceiling and floor behind you
  2. 2Follow the moving hand with your eyes
  3. 3Go as far as control allows, then return to the start
  4. 4Move with the breath, exhaling as you open

Key cues

  • Knees stay stacked and still throughout
  • Let the eyes lead the rotation
  • Reach long through the fingertips, don't just twist the shoulder
  • Control the return, don't just drop the arm back

Common faults

  • Letting the top knee lift off the bottom knee
  • Only rotating the arm, not the thoracic spine
  • Rushing the movement instead of controlling it
  • Holding breath through the rotation

Tweaks

  • Hold at end range for 2-3 breaths for a static variant
  • Add a small pulse at the deepest point of rotation
  • Support the head with a pillow if neck strain occurs

Regressions

Progressions

Muscles

Primary: Thoracic Rotators, Obliques

Secondary: Pecs, Lats

Notes

A go-to corrective for people who rotate through the low back instead of the upper back.

Sources

Attribution: Standard physical therapy / golf fitness staple