What’s old always becomes new again — even with workout routines. The hot workout class of the moment isn’t brand-new. It’s Pilates, a core-focused routine first popularized almost a century ago. Pilates, yoga, barre and other “lower-impact” exercise classes are gaining popularity, as Americans turn away from previously-popular “higher-impact” classes, such as CrossFit. But lower-impact doesn’t necessarily mean “easy.” Three guests joined MPR News host Angela Davis to talk about the benefits of these low-impact classes, sometimes called “functional fitness,” and how they can fit into your routine. Guests:   Ayanna Rakhu, Ph.D., is a graduate of the University of Minnesota School of Kinesiology with a background in sport and exercise psychology. Rakhu is a physical activity expert who focuses on swimming. Libby Grundhoefer is a Pilates instructor and personal trainer with the Minnesota Jewish Community Center. Gretchen Bierbaum is the owner of Straightline Dance Fitness, a fitness studio in northeast Minneapolis.