Your Pilates Teacher mentions core a number of times in your Pilates session or class. One student told me she thought her core was from the bottom of her bra to her hips -- which is close -- but she also told me that "she didn't have those muscles". What we found, is that those muscles were definitely there, she just needed to learn how to engage them and use them. One thing we'd like to encourage is your questions. If you don't understand what your Pilates teacher is saying to you, or you're not sure how to execute an exercise, please ask. You don't have to ask in class, but catch the teacher or Marybeth after class and let them show you that move in isolation. Pretty soon you will be able to differentiate between the layers of your core in your body as you participate in a class!
It takes recruitment of all these layers to produce maximum stability, as when doing Long Stretch or Side Splits on Reformer. But when you are bending forward as with Roll Up, you are using the outer most layer primarily. When side bending as with Mermaid you are primarily recruiting your side layer. It’s important to engage in balanced workouts that include all the core muscles for best alignment and function.
With Pilates, we work from the inside out. We create stability first and movement second. Start with your abdominal wrap and strong exhale and move from there. Here's a video to help you understand!