HOW: Get set-up on the ground with a band around the top of your feet. Lift both legs into the air with your knees bent and your knees positioned over your hips. While keeping one leg still and your low back flat against the ground, kick one leg in front of you straight, slowly bring it back and repeat on the other side.
FEEL: You will feel your hip flexor muscles on the side that did not move as well as your core muscles the entire time working with this exercise.
COMPENSATION: Do not lose hip position when keeping one side still or low back position, do not let your low back excessively arch.