Most barre-based classes use a combination of postures inspired by ballet and other disciplines like yoga and Pilates. The barre is used as a prop to balance while doing exercises that focus on isometric strength training (holding your body still while you contract a specific set of muscles) combined with high reps of small range-of-motion movements. Also, don’t be surprised if your class incorporates light handheld weights to bring the burn during all those reps, as well as mats for targeted core work.