How to: Lay flat on the floor, fully elongated with arms straight above head and legs fully extended on the floor. Draw your navel inwards and slowly raise both legs & arms to a vertical position meeting at the center, allowing the head, shoulders & mid-back to come off the floor. Be sure to keep your legs & arms straight. Slowly return to starting position in a controlled fashion being sure to keep the abdominals drawn-in, repeat just before you touch the ground.
Compensations: Watch for arching of the lower back, using momentum, bending your knees and tucking your chin to your chest.