Power yoga is a general term used in the West to describe a vigorous, fitness-based approach to vinyasa-style yoga. Most power yoga is closely modeled on the Ashtanga style of practice. The term "power yoga" came into common usage in the mid 1990s, when several yoga teachers were looking for a way to make Ashtanga yoga more accessible to western students. Unlike Ashtanga, power yoga does not follow a set series of poses. Therefore, any power yoga class can vary widely from the next. What they have in common is an emphasis on strength and flexibility. The advent of power yoga heralded yoga's current popularity, as people began to see yoga as a way to work out. Power yoga brought yoga into the gyms of America.