Crunching Too High The ab crunch is a subtle movement that lifts the shoulder blades a few inches off the floor. Jerking the shoulders up adds momentum and reduces the effectiveness of the exercise. Bring your shoulders 1 or 2 inches off the floor imagining you are bringing your ribs https://getsocialnetwork.com/story3467508/uma-an%C3%A1lise-de-abdominal-crush