Lying prone on the long box facing the back, extend arms and lift the heart away from the ground. Slowly lower back through the spine, folding over the box.
1B.
Down or up.
Long Box.
Inhale to lower, exhale to rise.
Mobilise shoulders and spine. Strengthen back extensors, multifidus, triceps, and shoulder extensors.
Progression: Add more springs.
Regression: Less springs.
Modification: Kneeling or knotted tricep kicks.