Hanging Leg Raise
STEP 1. While holding onto a chinup bar using an overhand grip, hang with your knees bent slightly.
STEP 2. Pull your hips up as you curl inward toward your chest using the muscles of your lower abs. Life your knees as close to your chest as possible, rounding your lower back at the top. Then, pause, feel the contraction in your lower-abdominal muscles, and return to the position you began with.