Like Vinyasa, Ashtanga classes have a faster and more vigorous flow. Most classes last 90 minutes and include constant movement between postures that require considerable strength and balance.
Within a certain level of practice, all Ashtanga classes consist of the same sequence of postures. Some classes are led by an instructor, while others are "open" and allow for students to practice at their own pace. Only when a student masters the first level of Ashtanga postures does he or she move on to more challenging levels.