HANGING LEG RAISES
For this exercise, you need a horizontal bar from which to hang. A doorway chinning bar will work, although ideally the bar should be high enough to allow your legs to hang straight without touching the ground
Take a slightly-wider-than-shoulder width grip on the bar and hang.
With knees slightly bent, raise your legs until your knees almost touch your chest (Fig.5-a). Begin this movement by rocking your pelvis forward, and maintain a forward pelvic tilt throughout the exercise. The curling action of the pelvis is crucial without it the psoas are doing most of the work, not the abs (Fig. 5-b).
Hold for one second, then lower your legs.
Perform the reps slowly enough that your body doesn't swing. Also, keep your upper torso as relaxed as possible: resist the temptation to do a partial pull up with each rep as this wastes energy and shifts your focus off the abs.
If you find that your arm and shoulder strength limit your ability to hang, try one of the following alternate approaches to Hanging Leg Raises.