“While bicycle crunches may seem like a basic exercise, an American Council on Exercise research study found this exercise to be one of the most effective,” says Jessica Matthews, an exercise physiologist for the American Council on Exercise. It gets the job done by activating the abdominal wall and obliques.
How to do it: Lie on your back on the floor and place your fingertips behind your ears. Bring the knees in towards the chest and lift the shoulder blades off the ground by contracting the abdominals (avoid pulling on the neck). Straighten the right leg out to about a 45-degree angle while drawing the right shoulder towards the left knee. Then switch sides, bringing the left shoulder towards the right knee while extending the left leg at a 45-degree angle. Continue to alternate sides in a pedaling type motion.