I spend a lot of time criticizing those crummy ab machines.
But what If I told you there was an very effective, simple, dirt cheap piece of equipment you could buy? Well, there is–the ab wheel.
Got ten bucks (or less)? Then order one and try it out. You can click the image to buy one at Amazon, but any store/brand will do.
By the way, here’s one of the best videos I found so far demonstrating the proper use.