Shauna M Hey Shauna, this workout is part of a series of 7 classes. There's 2 on the Mat, Reformer and Tower plus a chair. So the Thass® theme builds on itself. The Thass® is the musles around your thigh (excluding your hipflexors/quads). These connections help you connect your legs to your center. Hope this helps! Thanks for taking class with me and hope you can check out the others. xx