Remove the DIMOVE blocks in the rails. Place the heels on the treads. Slide your glutes as close to the unit as possible.
Tighten glutes, bring hips up, pull rail toward glutes, and hold for a moment. Slowly extend legs and return to starting position. Keep hips raised at all times!
Short stretching is recommended, as cramps can quickly develop in this position.
Place arms to the side of the body for more stability.
For a bigger challenge: remove locking pins to get even more out of the movement.