Stand on the chair and grip handholds to stabilize your upper body.
Press your back against the pad and keep the shoulders relaxed.
Bend the knees and contract the abs to lift the knees to hip level.
Try not to arch the back or swing the legs up.
Slowly lower back down and repeat for 1-3 sets of 12-16 reps.
The captain's chair leg raise, usually available in most gyms, works the rectus abdominis as well as the obliques.