Power Yoga is a fairly new form of yoga, exploding in the early 90s. It is a free flowing and dynamic mix of postures from various traditions. You can definitely expect to sweat in a power class so bring a towel. Power Yoga tends to be more fitness-based and while it opens and closes with the usual warm-up and cool-down, it will not go so deep into the spiritual and meditative side of most yoga. It is considered a less strict and more playful yoga class, and often has a background of hip hop or other funky upbeat tunes. At times these classes will be taught in heated rooms.