BOSU Dead Bug

Target muscles

The dead bug is an anti-extension drill: the transverse abdominis and rectus abdominis keep the lower back pinned flat while the opposite arm and leg lengthen and try to pull it into an arch. The obliques add anti-rotation as the limbs move on diagonals, and the hip flexors control the lowering leg. Performed on the dome, the small instability sharpens the brace and gives instant feedback when the core slackens.

How to perform

Setup

Lie with the dome under your mid-back (or press your hands into it overhead, depending on the variation), knees stacked over hips at ninety degrees and arms reaching at the ceiling. Exhale hard, flatten the lower back, and lock that brace before anything moves.

Execution

Slowly lower one arm overhead and the opposite leg toward the floor, exhaling as they extend and keeping the lumbar spine glued down the whole time. Stop the moment you feel the back want to arch, then return to the start and switch sides. The limbs move on a slow count; the win is keeping the ribcage down and the pelvis still while they travel. If the back lifts off, you have gone too far — shorten the range.

Common mistakes

• Letting the lower back arch off the surface as the limbs extend.
• Holding the breath instead of exhaling to deepen the brace.
• Rushing the reps so momentum, not control, moves the limbs.
• Lowering the leg past the point where the core can stay locked.

Progressions and regressions

Regress by moving only the legs (or only the arms) until the coordination clicks, or by keeping the lowering leg higher. Progress by adding a light weight in the hands, slowing each rep to a four-second extension, or extending both opposite limbs nearer the floor.

Programming notes

Use it in a warm-up to prime the brace or as core accessory work, 2-3 sets of 8-10 slow reps per side. It teaches the bracing pattern that protects the spine under heavy squats and deadlifts, so it pairs well as a primer before lower-body strength work.