Exercise · Core

Bird dog

On hands and knees, you extend one arm and the opposite leg until both are level with your back, then swap. Where the dead bug asks the spine to resist bending, this asks it to resist twisting — the multifidus, the small muscle spanning segment to segment along the spine, does anti-rotation work in Momentum's muscle map, and it appears on the system's inhibited list for the core. It sits in the same activate-glutes-and-core step of the low back flow, and adds a first, low-load rep of hip extension without the low back paying for it.