Calisteniapp

Lie face up on the floor with your whole body extended

Squeeze your abs, hamstrings, and glutes together to rotate your hips backwards, eliminating the lumbar curve and getting your lower back to touch the ground.

When you return to the starting position, exaggerate the opposite movement, maximizing your lumbar curvature so that you can feel the difference between one position and another.

Try not to leave your hands off the ground so that you also work on the mobility of your shoulders