A good pair of leggings has a way of making it to the top of your gym clothes pile week after week after week. There's no substitute for ones that don't fall down mid-workout, keep their shape, and wick sweat when needed. Hot new styles and printed pairs are totally fun to rock—these chic tights have received our fashion department's stamp of approval—but when you're suiting up for a no-holds-barred kind of serious workout, function is tantamount. We test drove a lot of leggings out there and here are our pics of running leggings designed to withstand the test of grime (and sweat!).