It seems like suddenly big round colorful balls are everywhere—the gym, the chiropractor's, even doubling as office chairs. But I never really know what to do with them––it's fun to stretch your back and bounce for a minute, but then what?

Yamuna Body Rolling has responded to this apparently common concern with paragraphs and studios full of answers: They have entire exercise classes on inflatable balls that range from head-sized to jumbo beachball-sized. Started by Yamuna, a fitness trainer who's also a bodyworker, herbalist, and aromatherapist, the yoga- and pilates-influenced approach addresses specific muscle groups to build strength and expand range of motion. It's also an exercise and a massage (the balls smush muscles, releasing toxins, increasing blood flow, etc.) all in one childhood-reminding session. Their main studio is in Manhattan's Greenwich Village, but practitioners teach in 23 other states, plus the U.K., Spain, Italy, Sweden, and Canada. To get your roll on: yamunabodyrolling.com