When doing a sit-up with the AbMat™, we recommend that you begin
with the hands between the legs. This will allow your body to learn
the new movement correctly. It is also the easiest of the three
methods. If you need to add resistance, place your hands on your
chest or behind your head. If you decide to place your hands behind
your head, be careful not to begin the movement by starting momentum
with your elbows.