This is a great exercise for the lower abs. Leg raises can be done hanging from a bar, hanging from the rings, supporting yourself on a vertical bench, or, as in my video, supporting yourself on the rings.
The idea is to keep your legs as straight as you can and lift them up in front of you as far as possible, hold, and then lower them back toward the floor. When in the lowered position, your feet should be hovering above the ground but not touching the ground.
Keep your movement slow and controlled. The effort of hanging or supporting your body is not really part of the exercise, and moving too fast will cause your body to swing which we don’t want, since the focus here is on the lower abs.
Doing this exercise with bent knees will enable you do to more reps, with a longer range of motion. The bent knee version is good if you can’t to full leg raises, or if you’re exhausted from full leg raises but still want to keep going.