Position
Lie on a declined, flat, or inclined bench or platform with your back flat, shoulder blades and sacrum pressed firmly against the pad. With your legs together, flex your hips and knees to form approximately a 90-degree angle or set them according to the desired resistance. Hold firmly to the back or side of the bench, platform, or stationary object to anchor your upper body down.

Technique
Contract your abdominals. Begin pulling your pelvis up and toward your rib cage, attempting to move only one vertebra at a time. Continue to pull your pelvis toward the rib cage until your abdominals are fully contracted and your hips are tolled up slightly on the pad. Hold, continue to contract your abdominals, and breathe out any remaining air. Slowly lower your trunk and hips one vertebra at a time back to their original starting position, never releasing the tension from your abdominals. Repeat.