Take an overhand grip on a chin-up bar. Hang straight while relaxing. To maintain your grip comfortably, you may need to use wrist straps. Also, try using a two over one grip. This grip is done by wrapping your hand around the bar and then, placing the index and middle fingers over the thumb. It’s an extremely strong grip.
1. Inhale and raise your knees as high as possible; be sure to move your knees to your chest by shortening your torso.
2. Exhale as you complete the movement, i.e., as your knees near your chest.
Notes: This exercise works the following muscles: iliopsoas, Rectus femoris, and tensor Fasciae lataeas as you raise your legs. Also, the Rectus abdominis and, to a lesser extent, the obliques as you move your knees to your chest.