What you wear to cover your booty can make or break a run (chafing, anyone?). Luckily, your options are way more varied than old-school gym shorts. Loose, tight, short or long—you have choices when deciding what style and coverage you want below the belt. We had more than 50 testers in all shapes and sizes put different skirts through the ringer. Real runners took popular styles for a handful of test runs (and a wash or two) to find the most durable, comfortable and stylish bottoms out there.