Buttock augmentation is one of the fastest growing areas of plastic surgery. Such procedures surged 86 percent from 2013 to 2015.1 But whether you're looking for a rounder, firmer or curvier behind, you can achieve many of these coveted effects with exercise."They don't want it to look flat or saggy back there People are looking for that nice curvaceous shape to their glutes — and to have that you need muscle."