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. Back Arch In the past, it was recommended to keep your back flat against the floor https://bookmark-media.com/story18141180/5-fatos-f%C3%A1ceis-sobre-renato-cariani-descrito