Set-up: Begin seated on the floor with your legs straight.
Movement: Engaging your abdominals and entire core, raise your knees towards your chest. Pause briefly at the top, then return to the start position under control. Maintain an active contraction in your abs and ensure core stability for the entire duration of the exercise.
Emphasis: Stability and control are key on this exercise, or the lower back is subjected to unnecessary stress. Do not use momentum.