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Dead Bug

Also called: Supine opposite arm/leg reach

Primary muscles: Transversus abdominis

Secondary muscles: Rectus abdominis, External oblique, Internal oblique

Plane: sagittal

Equipment: bodyweight

What it is

Lying on your back with arms and knees up, slowly lowering opposite arm and leg toward the floor while keeping the low back flat.

Purpose

Trains bracing and trunk control while limbs move — a low-back-friendly way to build core stability.

Starting position

Lie on your back, arms reaching straight up over the shoulders, hips and knees bent to 90°.

Step by step

  1. Brace the core so the low back stays gently flat against the floor.
  2. Slowly lower one arm overhead and the opposite leg toward the floor, keeping the low back still.
  3. Return to the start and repeat on the other side.

Breathing

Exhale as the arm and leg lower; inhale as they return.

Coaching cues

"Keep your low back glued to the floor the whole time."

Common mistakes

Letting the low back arch off the floor as the limbs lower; moving too fast to keep control; holding the breath.

Easier regression

Move only the legs (keep arms still), or reduce how far the leg/arm travels.

Harder progression

Increase the range of motion, or add a light ankle weight once control is excellent.

Alternatives

Bird-dog (lower back region), plank.

Who may benefit

Beginners and anyone who finds standard crunches uncomfortable for the low back.

Who should modify or avoid it

Very safe for most; if the low back cannot stay flat even with a small range, reduce further or seek guidance.

Why this exercise works

Moving opposite limbs challenges the deep core (transversus abdominis, obliques) to keep the pelvis and low back still, which is precisely the anti-movement skill needed to protect the spine during real-life lifting and reaching.

⚠ Safety note

Only lower the arm/leg as far as the low back can stay flat — range of motion should shrink, not the control.

Sources

“The transversus abdominis increases intra-abdominal pressure and helps stabilize the lumbar spine during limb movement.”

Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.3 Axial Muscles of the Abdominal Wall, and Thorax

Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19

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