Plank Saw

The plank saw, also called the body saw, is a dynamic anti-extension core exercise. From a forearm plank on the toes, the whole body drives forward and back a few centimetres while the spine holds neutral. The shifting load is resisted by the trunk, so anti-extension is trained under movement rather than in a static hold. The exercise builds trunk stiffness against a changing line of pull. Used in the Kettlebell Complex protocol as a core finisher across the Power Endurance sessions.

Mechanics and load path

Set up on the forearms with elbows under the shoulders, toes tucked, body in a straight line. Shift the whole body forward so the shoulders travel slightly past the elbows, then glide back under control. The range is small, a few centimetres each way, and the hips stay level throughout. This is the forearm-plank rock, distinct from the two-handed body see-saw, which is a different exercise.

The failure mode is the lower back sagging as the body shifts back and the lever on the trunk lengthens. At that point the load transfers off the deep brace and onto the spinal extensors. The trunk resists extension through the whole travel, which raises the demand over a still plank.

In the Kettlebell Complex protocol

The plank saw runs as a core-finisher station across the Power Endurance sessions, rocking for a work interval with control favored over range. It pairs with the Dead Bug and the Windshield Wiper, building an anti-extension and anti-rotation block at the end of the session.

Used in: Program 01 — Kettlebell Complex