Sadly, many gyms still occupy their square footage with Ab Rollers. Trying to satisfy their lazy members, I suppose. Really, I would like to torch them. But I'm not violent or destructive, so there must be other uses for this thing?? (See title.)
My point is, they do nothing for your abs. When you see somebody sputtering about, flailing their torso back and forth within the confines of this product that some manipulative airhead has created to make a quick buck, please kindly show them a proper crunch. I will outline this below. The reason why the Ab Roller does NOT work is that it is indirect. Your hands are to push a bar, so that your torso closes, so that your abs contract by default. Really, it encourages the exemption of your abdominals altogether. (The machines in the gym in which you are seated, and pressing forward against resistance, are not any better.) They are a waste of space, a waste of time, a waste of effort. If, of course, you are the type of North American who adores the superfluous, continue bobbing your head around like an idiot. But my nails will be dug into my hands in your presence. Watch carefully as your fellow gym members "crunch" in this device. Your arms should be out of the equation, completely. Your abs' contraction should be the very first thing that happens, before any movement. From this contraction, the back is tightly clamped into the floor (and pelvis gripped and held still). The ribcage moves toward the hipbone, as you exhale. The chest remains expanded, shoulders back, and head completely neutral (the weight of your head is used as resistance for your abdominals). Pushing through the arms, to then move the head and shoulders, to then lightly shut the abs is just backwards. Try both, and report back.
*Sidenote - your arms can go behind the head, if you PROMISE not to support the weight of the head in the slightest. I prefer arms folded across the chest, simply adding weight to the load for the abs to press against, while they close and push through in an isolated force.
Perhaps I shouldn't be so harsh. It is important that people make an effort toward a stronger core and abdominal group. And I do pity those who pat themselves on the back for BEING (note the passivity) pulled through an exercise with good intentions. But hey - I'm here to burst bubbles and everyone will get over it... and be beaming, when they're finally strong. When their abs are assertive (not passive), wound tightly to protect an otherwise cranky back and to reveal a lean, delicious waistline.
Bottom line: If you have an ab roller, throw it out and use your brain. Peace and love and kisses!