It is a WORKOUT!! for the abs!Ouchy! I tried doing a plank and OMG, I thought someone needed to get the plate number on the truck that hit me the next day.
I was doing forearm planks (on your forearms instead of on your hands). They are harder on the abs, I think. I did a straight arm plank, and I could feel it in my upper arms the next day. I really want to work my upper arms, so I kept doing that style. I have old lady flabby upper arms. But I do have to say, they are looking better these days!