Lay on your back with your knees bent. Bring one knee up and place your same side palm on your thigh above your knee. Keep your elbow straight. Push your hand into your leg and pull your leg into your hand; do not move. Tighten your abdominals to produce the force you are putting into the push from your hand and leg. The more intensely you press the harder it will be. Start with about 50% of max effort and adjust accordingly form there. Do this for 10-30 seconds.
Muscles Targeted: (1) abdominals and obliques (2) hip flexors