consistsof when you make the movement to lift your hands off the ground and then holdagain. Push- two chairs in which you will support your arms to do the bendingand the other chair you will place behind to support the feet. Science based six pack is almost the same as the simple bending, butthe muscles of the body will have to strain more to balance the body and notfall. You must take two chairshttp://x4up.org/science-based-six-pack/