Place your forearms on the box and move the carriage forward and backward using only your shoulders.
1B.
Down or up.
Short Box.
Exhale to rock forward, inhale to come back to plank.
Develop muscular strength of the transverse abdominis, pelvic floor, multifidus, and obliques. Scapular and pelvic stabilisers.
Progression: 1Y.
Regression: 1B or knees on platform, hands on carriage. Find a 3/4 plank, push the carriage away, then bring wrists back under shoulders (foam protector needed).