Quiz: Which Move Will (Really) Flatten Your Abs?
Who wouldn't love to tighten and tone their tummy? But it's not always obvious which moves will really do the trick. So we asked a pro--Jessica Matthews, MS, an exercise physiologist with the American Council on Exercise--for her expert opinion.
ANSWER Both—but the first is a more efficient option. “Plank activates more muscles,” says Matthews, “and it’s gentler on the spine.”