HOW: Begin laying on your back with your knees bent. From here, bring your feet up off the floor and bend your elbows to help support your head as you bring it off the floor as well. From this position, bring your opposite elbow and knee together performing a bicycle-type motion with your legs as you rotate your elbows across your torso.
FEEL: You should feel your core muscles working as you perform the bicycle-type motion in a controlled manner.
COMPENSATION: Do not let your straightened leg hit the ground while performing this exercise. Maintain control and keep the leg elevated.